GROUNDNUTS (Arachis hypogaea) [As groundnuts are also a grain legume crop, they are covered in detail in DLCP 401 Field Crop Production - Pulses]

Transcription

1 DLCP 432 Industrial Crop Production - Oil Crops - Groundnuts GROUNDNUTS (Arachis hypogaea) [As groundnuts are also a grain legume crop, they are covered in detail in DLCP 401 Field Crop Production - Pulses] Groundnuts, also called peanuts, monkey-nuts and earthnuts, are grown as an oilseed and grain legume crop. They are a major cash crop, and widely grown in practically all the tropical and sub-tropical regions of the world for direct use as food, for oil, and for the high protein meal produced after oil extraction. Groundnuts are a highly nutritious food; whole groundnuts and groundnut meal, produced by expressing the oil, are rich in protein, minerals and vitamins. Groundnut protein serves as an excellent supplement to cereals and other starch crops. Summary Groundnuts are usually grown at altitudes ranging from sea level to 1600 m.a.s.l. It is best to avoid areas above 1600 metres. A well drained light sandy loam is most suitable for this crop. Heavy soil with poor drainage can be damaging to the plant because it stops the penetration of the pegs in the soil. Very poor yields per hectare have been recorded in areas with heavy soils. It is necessary to avoid areas where the soil moisture content is too high; an annual average of about mm rainfall, well-distributed through the growing period, is enough for the crop. In the Melka Werer and Gode areas groundnuts are grown successfully under irrigation. The most suitable time for sowing is the first half of June - late sowing at the end of July or into August is very harmful to the plant. Optimum plant population is determined by soil type, expected rainfall, and other factors, but as a guide, a plant population of approximately ,000 plants/ha ( kg seed) for bunch types, and half this for spreading types is acceptable in areas of adequate rainfall ( mm). Population should be reduced as expected rainfall decreases. For instance, at 600 mm, a population of 50-60,000 plants/ha would be more appropriate. Plant spacing is related to method of harvesting. There are no specific spacings that must be rigorously adhered to. In Ethiopia, the often recommended chemical fertiliser rate is 100 kg of di-ammonium phosphate (DAP) per hectare at the time of sowing. Four leading varieties are recommended for use on a wide scale in Ethiopia: Shulamith, GA , NC2, and Virginia Bunch. All four varieties require a maximum of four to five months from the date of sowing to harvesting. Due to high yields of groundnuts, this crop is regarded as the most promising oil crop in the country. An average of forty to fifty quintals per hectare is commonly obtained on stations. On demonstration plots and farmers lands where the recommended cultivation techniques are correctly applied, an average of thirty-five quintals is currently achieved. This compares to the present national average of thirteen quintals per hectare, which includes peasant farming systems. Oil It is estimated that some two-thirds of total world production of groundnut production is crushed for oil, with the remainder being eaten as whole nuts or paste. Groundnut

2 DLCP 432 Industrial Crop Production - Oil Crops - Groundnuts oil, more commonly known to consumers as peanut oil, is pale to medium yellow in colour, depending on the refining process and local consumer preference, bland or with a slightly nutty flavour. In general, the darker the oil, the poorer the quality, and a brown tinge suggests overheating of nuts during processing. The oil is mainly used as a cooking and salad oil, with minor amounts incorporated into margarines and similar products. Stability of a cooking or salad oil is an important characteristic, and is generally related to the linoleic acid content: the greater the proportion of linoleic acid, the lower the stability, that is the shorter the shelf-life. Runner types of groundnuts usually contain less linoleic acid in their oil than bunch types, and untreated oil made from runner groundnuts is thus more stable. The oil content of groundnut varies with the type grown and the locality. Average fatty acid composition of different types of groundnut oil. Erect type Runner type Unsaturated Oleic Linoleic Saturated Palmitic Stearic Arachidic Lignoceric Unsaponifiables Ethiopian production (FAO, 1997): Area Harvested: 420,000 ha Average Yield: 1,286 kg/ha Production: 540,000 tonnes

3 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed NIGER SEED (Guizotia abyssinica) CLASSIFICATION Niger seed belongs to Tribe: Heliantheae Family: Compositae Genus: Guizotia Species: Guizotia abyssinica (syn. G. oleifera) A: flowering shoot; B: lower leaf; C: young capitulum; D: capitulum in longitudinal section; E: ray floret; F: disc floret; G disc floret in longitudinal section; H: achene; I: achene in longitudinal section. GENERAL Guizotia has its centre of gene variation, and centre of origin, in the Ethiopian highlands, and G. abyssinica has been collected in Ethiopia from cultivation, as a weed and growing wild. There are no recognised varieties of cultivated niger. Niger was once widely, if locally, grown in East and West Africa and Zaire, but as an oilseed crop it is now almost wholly confined to Ethiopia, where it is known as noug.

4 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed It has been grown as a green manure in Central and Southern Africa, but as an oilseed it was not considered to be profitable enough to be included in the rotation. It is most widely grown in India and Pakistan, where it is an important local oilseed. Niger should be considered primarily as a valuable oilseed crop for smallholder production, especially in those areas where other oilseeds are few. It has considerable potential as a source of edible oil, and could form the basis of smallscale extraction plants. Niger seed produces an oil suitable for edible and industrial purposes, the press cake being used as animal feed and manure, and the whole plant used for fodder or green manure. Noug is a stout, erect, moderately branched annual herb, usually less than one metre tall, with attractive yellow flowers, whose seeds produce an edible oil. Although there are no distinct varieties of noug, there is considerable variation resulting in locally distinct strains, and selection for specific characteristics should be relatively simple. Strains can vary, for example, in the colour of the stems and leaves, height and degree of branching, time to maturity, seed size, colour and constituents. The following description of noug is generally applicable, although details of specific local types differ. PLANT CHARACTERISTICS Root system The root system is usually well developed, with a central tap-root and branching laterals, but, since the plant is often grown on poor or stony soils, roots seldom develop to their maximum. Under experimental conditions, noug roots showed exceptional resistance to waterlogging. Stem The stem is usually round, approximately 2 cm in diameter when mature, up to, but usually less than, 1.5 m in height, bearing small, soft hairs. Colour is usually green to reddish-green, depending on cultural conditions, and becoming more-orless yellow with age. Local strains may have a distinctive stem colour, the green being replaced to some extent by red or reddish-yellow. Stems are usually moderately branched, and the degree of branching is mainly dependent on environment, as is the height at which branching commences. The extent of branching directly affects the yield, since the capitula (heads of flowers) are borne terminally on stem and branches. It has been determined in India that the number of branches and their capitula accounted for 52% of the variation in seed yield. Thus, the spatial arrangement of plants in the field has a major effect on potential yield. Leaves The leaves are opposite, sometimes alternate on the upper stem, sessile, lanceolate, cm in length and 3-5 cm in width, softly hairy on both surfaces. The leaf margin is dentate, and the blade tapers to a point. Dark green is the usual colour, but lower leaves frequently show a distinct yellow tinge. Similar to stem colour, the leaves of a local strain may be more-or-less yellow, occasionally with a yellow tinge. The capitula are surrounded by leafy bracts arranged in numerous rows, the outer bracts being leaf-like, lanceolate, and up to 2 cm in length. The inner

5 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed rows of bracts become progressively smaller, and finally merge into the flattened paleas of the receptacle, which is usually cm in diameter. Flowering A plant may produce thirty to forty flower heads under suitable conditions, exceptionally twice this number. The flowers develop from leaf axils in clusters of two to five. The heads flower over an extended period, fifteen to thirty days, and since this results in uneven ripening, losses from shattering can be high. The period from emergence to flowering is approximately ninety days, but, as noug is grown in a wide range of environments and this period is directly affected by climate, it is more often shorter than longer. It can also be shortened by a reduction in daylength. Flowers on the capitula are of two kinds - disc and ray florets. The latter can number eight to fifteen, are bright yellow, becoming more golden with age, and are sterile. Disc florets, usually less than forty-five in number, but occasionally more, are arranged in three whorls, those at the edge opening first, followed progressively by the next in line to the centre of the head, as with sunflower. The process is usually completed in five to eight days. A floret opens and liberates pollen early in the morning, the style emerges about midday, and the stigma lobes separate and curl backwards in the evening. The stigma lobes rarely curl sufficiently to touch the style, and the plant is thus essentially self-sterile. Insects are more important than wind as pollinators, and although noug is essentially cross-pollinated, some self-pollination is known to occur. The extent to which bees influence seed set was demonstrated when plants were allowed to flower on cages from which bees were either introduced or excluded. Plants visited by bees had forty seeds per head, while those without bees set only fifteen seeds per head. Similar results have been obtained elsewhere, so, although the proportions may vary, the presence of an adequate insect population is essential for high seed yield. Noug is extremely attractive to insects, and for this reason is often interplanted with sunflower, when the increased insect population also increases seed set in the sunflower component of the mixture. A doubling of seed yield has been recorded in India from such an association. Temperature at flowering affects the duration of this period, and also the fertility of the pollen. For Indian strains of noug, a temperature of 30 C or above adversely affects both. At C, the flowering period for individual heads is five to sixteen days, and the total flowering period for a single plant can range from fifteen to thirty days. Ethiopian strains of noug are less tolerant of high temperatures at flowering than Indian - flowering of Ethiopian types occurs only in the temperature range of C. An increase in temperature of 5-10 C for other than a very short period reduces the number of blooms per plant and the fertility of pollen. Locally high temperature can also shorten the period from flowering to seed maturity, which is usually some forty to forty-five days. Fruits The fruit is an achene, typical of the Compositae, small, some 3-5 mm in length and 1.5 mm in width, almost lanceolate in shape, without pappus. The testa is hard, glossy, and usually black, but mottled seed occasionally occurs. Normally, 1000-seed weight is in the range 3-5 g. There are usually between fifteen and thirty

6 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed mature seeds per head, occasionally more, and a varying number of immature seeds or pops at the centre, as occurs with sunflower. Unlike safflower, mature noug seeds are easily dislodged, and shattering in the field prior to harvest is a major problem. The oil content of noug seeds varies widely, between 25 and 45 percent for unimproved types, and percent in selected strains. Protein content can vary from 12 to 25 percent. Oil The expressed oil is very pale yellow, or may have a bluish tint, depending on the method of extraction and refining. Locally expressed oil has a short storage life, quickly becoming rancid, and is therefore seldom available in any quantity except in Ethiopia or India. It is an edible oil, often virtually odourless with a slight nutty taste. It is the most easily available domestically-produced oil in Ethiopia, and in India is a substitute for the more expensive and more highly regarded sesame oil, of which it is a common adulterant. In Ethiopia, noug seeds are occasionally crushed to prepare a non-alcoholic drink. A more common use is for the seed to be boiled with dough prepared from enset to make a more tasty porridge. Poor-quality oil is used as a general lubricant, in soap manufacture, and in lamps. It is also widely used in India, and to a lesser extent in Ethiopia, as a body oil to promote a smooth skin and supple joints. Noug oil contains approximately 50% linoleic and 30% oleic acid, although experimental strains have been recorded with up to 85% linoleic acid. There is a wide variation in published analyses of noug oil, since seed constituents, oil content and oil constituents all vary. The strain of noug, and locality where grown, also have a major influence on all characteristics. Average composition and fatty acid content of noug seed (Source: Weiss, 1983) Fatty acids % of total Kenyan seed % Oleic Oil Linoleic CP Palmitic CF Stearic Carbohydrate Arachidic Ash 4.03 Myristic Calcium 0.37 Linolenic Phosphate 0.36 ADAPTATION Climatic requirements Noug is essentially a short-day, temperate region plant that has also adapted to a semi-tropical environment. It has been grown between 200 and 2500 m.a.s.l., but can be found at much higher altitudes. However, the highest recorded seed yields are produced between 500 and 1000 m.a.s.l. under semi-tropical conditions with adequate moisture. In Ethiopia, the main growing areas are between 1600 and 2500 m.a.s.l., bisected by the 10 N latitude, although it can be found growing in small patches throughout the country. In India, it grows well on the plains, and up to 2000 m in more hilly districts. Thus, there is a basic difference in environment between Ethiopian and Indian strains, which are sufficiently differentiated to vary in their reaction to specific climatic conditions, day length, temperature, rate of growth, and so on.

7 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed Noug requires moderate temperatures during growth, C; above 30 C, the rate of growth and flowering are adversely affected, and maturity is hastened. Ethiopian strains are apparently more severely affected by high temperatures than are those from India. In the Ethiopian highlands, night-time temperatures of down to 9 C has no apparent effect on growth, but frost will kill young seedlings. Its effect on older plants is not well documented, but growers in Ethiopia sow to avoid frost. The recommended sowing dates in Ethiopia are from mid-may to mid-july. Noug will grow under poor cultural and soil conditions, but requires adequate rainfall over the main growing period to produce a commercially acceptable yield. It is not a dryland crop, although it is often found growing in poor, sandy or stony soils. A rainfall of mm is considered the optimum; 800 mm will produce a reasonable yield if spread over the growing period; above 2000 mm, growth may be depressed. However, the plants can withstand periods of very high soil moisture during the vegetative stage. High wind, or hail, when the seed is mature will cause severe shattering, but, at other periods of growth, it is of little importance. It is possible that strains of noug could be selected for a much wider range of climate. Soils Noug can be found growing on a wide range of soil types, but appears to perform best on clayey loams or sandy clays. It is widely believed that noug does well on poor soils, but, in practice, the plants seldom have any choice! Invariably, when observation plots of noug have been planted on more fertile soils in the same locality, or given adequate nutrients and water, the difference in growth and yield has been quite remarkable, especially in Ethiopia. In Ethiopia, noug is grown in the highlands on the dark-brown clays of the south Begemdir regions, the red-brown clay loams of Gojam, and more loamy clays around Addis Ababa. The common heavy clays and black cotton soils are not the most suitable for noug, although it is often sown on them. Samples taken from fields growing noug in Ethiopia gave a ph range of The most suitable ph range has not been determined, but since acid soils are widespread in the highland tropics, and crops that grow well on them are relatively few, it would probably be profitable to select for this characteristic within local noug types. Some noug selections are also moderately salt tolerant, a valuable attribute in an oilseed. Fertilisers The fertiliser requirements of noug are ignored in most peasant sowings, the crop being expected to benefit from fertiliser applied to suit the major component of the mixed crop. Pure stands are the exception, and noug is often expected to grow on the residual fertility from previous crops, with the minimum of added nutrients. Small growers do not consider noug important enough to warrant the use of precious cash resources needed more urgently elsewhere, with the result that yields are often extremely low. The inoculation of leguminous plants with species-specific Rhizobium bacteria to promote nitrogen production and uptake through root nodulation is wellknown, but it appears that noug can benefit from a similar root association. In greenhouse trials, it was shown that inoculation of soil used in the trials with soil in which noug had previously been grown, considerably increased yields. It was suggested that mychorriza which grew on the roots of plants growing in the

8 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed inoculated soil contributed by increasing uptake of phosphate. This beneficial association may also explain why noug grows well on relatively infertile soils. The most common fertiliser used on noug in India is animal manure of some kind, usually of indifferent quality, but the profitability of so doing is questionable. In India, 4000 kg/ha of FYM produced no significant increase in yield over nil FYM, and doubling the amount from 5000 to kg/ha FYM also produced a non-significant increase. It appeared that FYM at any level was unprofitable, although relatively small amounts of nitrogen in the same area produced substantial increases in yield. FYM (kg/ha) Nitrogen (kg/ha) Treatment Yield Nitrogen is the nutrient that most often increases noug yields, with the response to potassium and phosphate extremely erratic and generally very small. In some cases, fertilisers gave negative responses due to increased early shattering. For a better performance, it is advisable to grow the crop in more fertile soils, to attempt to sow at the optimum time, and to perform more effective weed control. CULTIVATION Land preparation for small grains such as sorghum, wheat and millet is suitable for noug, but since it is generally grown as an intercrop, lands are cultivated to suit the most important component, with the result that noug often suffers from unsuitable land preparation. Noug seed is small, therefore a level seed-bed is essential to ensure an even depth of planting and subsequent emergence. The most usual method of sowing is broadcasting; in India, seed is sometimes mixed with sand to assist even distribution. The land is then harrowed to cover the seed. If mechanical planters are used, the seed should be sown 1-3 cm deep, depending on soil type and soil moisture. The seed should not be mixed with fertiliser, nor placed in contact with it in the seed-bed. Seed must be sown into moist soil, but the level of available soil moisture adequate to sustain germination and emergence varies with soil type. A higher level is necessary in sandy soil than clay. A seed-bed temperature of C is the optimum; below 10 C impairs germination; above 35 C can cause uneven emergence. There should be no danger of frost during germination or in the seedling stages. Noug germinates very quickly under optimum conditions: it can be above ground in 3-5 days in India; in Ethiopia, 5-10 days is more common. A soil moisture deficit in the seedling stage affects the growth of noug more severely than at other times. Noug grows rapidly once the seedlings are established, and its dense growth allows it to compete with annual weeds. Provided pre-planting operations have removed the majority of weeds, two further weedings are generally sufficient. HARVESTING Noug normally matures days after emergence, but strains with a shorter maturation period of days have been selected in India. In Ethiopia, noug requires an average of three months in areas situated below 2000 m.a.s.l., but,

9 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed at higher elevations, the time between the date of sowing and harvesting is around five months. The maturation period stated for a strain is often arbitrary, frequently being the mean of that period over which the heads become mature. This may well be 20 days, and since the seeds are not held firmly in the head, those that ripen first begin to shed their seeds before the later heads are mature. Up to 25% of the seeds can be lost in this way. Manual harvesting is normally with some kind of sickle, the plants then being dried in the field for two to three days, bundled and laid in rows to dry, and either threshed in the field or on the traditional threshing area. The timing of cutting the crop is often arbitrary, with other factors, such as labour requirements elsewhere, or the necessity of harvesting the dominant crop in the mixture, being considered of greater importance than selecting the optimum period for noug. The time of harvesting is more accurate when noug is grown in pure stands, but even then field losses are high. Threshing in Ethiopia is generally carried out by oxen treading out the seeds, or pulling a small threshing sledge. Both these methods result in soil contamination of the seed, with the inevitable result that the crop s commercial value is drastically reduced. Hand threshing is not difficult, does little damage to the small, hard seeds, and in areas where labour is plentiful, or has to be found employment, is probably the best method. A yield of over 600 kg/ha has been quoted by the Ethiopian government for crops grown in pure stands on moderately fertile soils, and 642 kg/ha was obtained at the Debre Zeit Experimental Station. STORAGE Clean, whole noug seeds store easily, and, because of their small size, take up relatively little space. Noug seed is attractive to insect and other storage pests, and so must be adequately protected. For smallholder seed storage, 200 litre drums fitted with lids, and the seed dusted with insecticide, have proved most effective. PESTS The following have been recorded as pests on noug in Ethiopia: Heliothis species Bollworm Spodoptera species Leafworms Macrosiphum compositae Aphid Frankliniella schultzei Thrips Unknown Leafhoppers Sphaerocoris annulus Stink bug Dioxyna sorocula Fruit fly (maggots) Birds can also become a pest at harvest, often attracted by the seed fallen from mature flower heads. Damage is exacerbated by birds attempting to perch on plants, so causing additional shattering. DISEASES There are very few records of diseases in noug, and it may well be that the plant is resistant to some of the more widespread pathogenic fungi. Leaf spots are

10 DLCP 432 Industrial Crop Production - Oil Crops - Niger seed commonly seen on noug plants, but are seldom accurately identified. The most frequently recorded in Africa are caused by Cercospora species and Alternaria species. Bacterial blight caused by Pseudomonas species occurs in Africa. IN ETHIOPIA Recommended Varieties - No improved varieties have been so far been released. It is recommended to use local variety using selected seeds from healthy plants. Altitude - Noug is a highland crop. It is best suited to elevations between 1800 and 2000 metres above sea level. Types of Soils - Noug is a very well-adapted crop found in various highland areas in Ethiopia. It performs better in loamy clay fertile soils, but it can stand conditions such as heavy clay and waterlogged soils, where many other crops will fail. It is recommended to avoid coarse-textured soils with a high percentage of sand and gravel. Rainfall - The crop gives better yields where the average annual rainfall reaches 1000 mm in the high altitudes. In areas at altitudes below 2000 m, an average annual rainfall of mm is sufficient provided, it is well distributed through the main growing period. Time Of Sowing - The best time for sowing is the end of June or in early July. In waterlogged soils, sowing can be delayed until the end of August, and the crop will grow on residual moisture. Seeding And Spacing - Seed rate 15 to 20 kg/ha, when the seeds are sown in rows cm apart.

11 DLCP 432 Industrial Crop Production - Oil Crops- Linseed LINSEED (Linum usitatissimum) [Since linseed, or flax, is a dual-purpose plant (oil and fibre), reference will be made here to production systems for both uses. Linseed oil, obtained from seed of the flax plant, is primarily used in industry; but some is used for edible purposes in Eastern Europe. The plant will be referred to as linseed in this document.] BOTANICAL DESCRIPTION Linseed is an erect glabrous annual herb. The stems are cm tall, corymbose-branched above, terete, and greyish-green. It has a distinct main stem with numerous branches at the top, which produce flowers. Branches from the base of the plant may also occur depending on variety, stand, and environment. The plant has a branched taproot system that may extend to a depth of cm in coarse textured soil. The leaves are grey-green, alternate, linear-lanceolate, numerous, flat, cm long, 2 4 cm broad, acute to acuminate, gradually and slightly narrowed at base, and glaucous. The flowers are borne in loose, terminal, leafy racemes or open cymes, on long erect pedicels, 2 4 cm long. There are five sepals, which are longacuminate, ovate-oblong, 5 7 mm long, entire, eglandular, 3-nerved, margins serrulate, and about half as long as the petals. The petals are obovate, 1 cm or more long, and coloured blue, white or different shades of purple, blue or pink. Most commercial varieties have blue petals. The fruit is a 5-celled capsule, or boll, on long erect pedicels, globose-ovoid, 7 10 mm high, about 7 mm across, surrounded by the persistent calyx, and is indehiscent. The number of seeds reaches ten per capsule, under most conditions an average of six to eight seeds per boll is normal. Some varieties produce bolls that tend to split open from the apex in varying degrees, whereas other varieties have bolls that remain tightly closed. Varieties with tight bolls suffer less weather damage to ripe seeds and resist shattering better than varieties with split bolls. Most current commercial seed linseed varieties have semi-tight bolls. The seeds may be various shades of yellow, brown, greenish-yellow, greenish-brown, or nearly black. Seed colour of most commercial varieties is light brown. They are shiny, varying in size, weighing from 3 12 g per 1,000 seeds, flat, oval, with one end rounded, the other pointed. Linseed is normally self-pollinated, but insects cause some natural crossing. Frequency of cross-pollination seems to be associated with varietal differences and environmental conditions. Individual flowers open in the first few hours after sunrise on clear, warm days, and the petals usually fall before noon. DISTRIBUTION Linseed is native to Central Asia and Mediterranean region. Remains of linseed plants have been found in refuse of stone-age dwellings in that region. Cultivated in Mesopotamia, Assyria and Egypt for over 5,000 years, linseed is now cultivated in many countries around the world. The plant is from the Central Asian,

12 DLCP 432 Industrial Crop Production - Oil Crops- Linseed Near Eastern and Mediterranean centres of diversity. Linseed cultivars are reported to tolerate disease, drought, fungi, grazing, high ph, rust, virus, and weeds. Over 300 linseed cultivars are known in the world. In any area, they should be selected for the best over-all performance in the growers locality and purpose, (fibre, seed, or both). For fibre production, long-stemmed varieties that are sparsely branched are best. For seed production, shorter, branching varieties should be selected. For fibreseed production, a combination of these factors is necessary. ECOLOGY Linseed requires a cool temperate or subtropical region, where the temperature is favourable for production of spring-sown small grains. Seed linseed is raised under a fairly wide range of conditions, but fibre linseed requires abundant moisture and cool weather during the growing season, and warm dry weather during harvesting of seed and fibre, especially where water-retting is practised. In some areas dew-retting is practised. Relative humidity at noon should be about 60 70%. The crop requires mm of rainfall, if spread evenly over growing season, with 25 mm falling just before or after planting. More important than total rainfall is the amount of precipitation that falls during the growing period. Adequate moisture and relatively cool temperatures, particularly during the period from flowering to maturity, seem to favour both high oil content and high oil quality. It needs a relatively long ripening period between flowering and harvesting. The typical life cycle of linseed consists of a 45 to 60 day vegetative period, followed by a 15 to 25 day flowering period, and 30 to 40 day maturation period. Warm, dry weather is desirable at the heading stage, to cause the plants to branch and produce seed. After vegetative growth has finished, dry weather is required for curing the seed. Linseed needs abundant moisture; dry conditions make plants short and woody. Waterlogging is detrimental. Regions with heavy storms, or high wind incidence, are unsuitable. Linseed is more sensitive to salt than most field crops. Linseed is a cool-season crop that may be grown in the dry season in tropical environments. The crop is adapted to medium- or heavy-textured soils. Well-drained, loamy soils overlying a clay subsoil are best, with ph 5 7. Very light, highly fertile soils are not desirable, as they produce tall, rank growth tending to lodge. Linseed is reportedly grown in Boreal Moist, to Wet, through Tropical Very Dry Forest ecological zones. In these areas, the ph ranges from , the annual precipitation from cm, and the annual mean temperature from 6-27 C. It grows best at temperatures below 21 C, and is frequently grown at high altitudes ( m) in the tropics. Lolium and Phleum plants have allelopathic effects on Linum, reducing its carbohydrate synthesis. USES Linseed is cultivated for its fibre (flax) and oil. The seeds contain 20 30% protein, and are the source of linseed oil, one of the oldest to have been used commercially. Linseed seeds contain 40-60% of a drying oil. Linseed oil has been used as a drying agent for paints, varnishes, lacquer, and printing ink. Unfortunately these markets have eroded somewhat over the years with the production of synthetic resins and latex. Paint and varnish industries consume about four-fifths of the

13 DLCP 432 Industrial Crop Production - Oil Crops- Linseed linseed oil produced. It is also used in enamels, linoleum, oilcloth, and patent leather, and as waterproofing for raincoats, slickers, and tarpaulins. In some countries it is used as edible oil, and in soap manufacture. Linseed oil is also used in printers ink, for making sand forms for metal casting, and as spray on concrete roads to prevent ice and snow from sticking; linseed oil also preserves the concrete and prevents surface cracking and wear. Linseed cake or linseed meal is the linseed seed with most of the oil pressed out; 3 6% of oil remains in the cake. It is used as feed for livestock and is prized for its high protein content, about 35% crude protein. Linseed straw from seed linseed varieties is used in the manufacture of upholstery tow, insulating material, rugs, twine, and paper. Some of the better quality straw, produced in the more humid sections or under irrigation, is used in manufacture of cigarette and other high-grade papers. Linseed straw is rarely fed to livestock. If mature and of good quality, it is about equal to oat or barley straw in feed value. It can be used safely as the only roughage for cattle, because of its high cellulose and lignin content. The fibres are digested like other fibrous materials and do not accumulate in the stomach to form indigestible balls. Green linseed straw should not be grazed or fed as it is high in prussic acid. Occasionally the straw is harvested and used to produce some paper products. Folk Medicine Seeds are considered emollient, demulcent, pectoral, diuretic, and astringent. Crushed seeds make a good poultice, either alone or with mustard; lobelia seed is added in the poultice for boils. Sometimes seeds are roasted and used in a poultice; sometimes they are employed as an addition to cough medicines. Linseed tea is used for colds, coughs, and irritation of the urinary tract, when honey and lemon juice may be added. Internally, oil is given as a laxative. Linseed oil mixed with an equal quantity of lime water, known as carron oil, is applied to burns and scalds. Oil mixed with honey is used as a cosmetic for removing spots from the face. In veterinary medicine, oil is used as a purgative for sheep and horses, and a jelly formed by boiling seeds is often given to calves. Recently there has been some interest in seed linseed as a health food, because of the high amount of polyunsaturated fatty acids in the oil. Oil and Mineral composition of linseed seed. Fatty acid % of total fatty acids Mineral element % Mineral element ppm Linolenic 49.3 K 0.89 Zn 56.9 Linoleic 14.7 P 0.60 Fe 46.2 Oleic 24.1 Mg 0.33 Mn 32.0 Stearic 4.3 Ca 0.21 B 11.5 Palmitic 6.1 Na 0.04 Cu 9.5 CULTIVATION Propagation is usually by seed. Linseed may also be propagated vegetatively from stem cuttings. Seed is recovered from the fibre crop. Plump and disease-free

14 DLCP 432 Industrial Crop Production - Oil Crops- Linseed (resistant to linseed wilt) seed should be selected. The best seedbed for linseed is similar to the ideal seedbed for small seeded grasses and legumes. It should be well worked. The soil should be firm to avoid large air pockets. The seedbed may be worked fairly shallowly, except where deeper ploughing is required when linseed follows maize. Autumn ploughing of linseed fields is preferable, if the erosion potential of the land is not high, as it allows the soil to settle. Cultivation following early autumn ploughing will aid in weed control. In the spring, shallow discing and harrowing are the usual practices of seedbed preparation. The soil should be packed by rolling, discing, or harrowing, and the surface levelled before planting. A well-prepared firm seedbed will ensure sowing at the proper depth, and this will result in prompt and uniform germination. The seed rate varies from 30 kg/ha for seed production to160 kg/ha for fibre production. A seeding rate of kg/ha of good seed is recommended. Lower seeding rates often result in more severe weed problems. A cm planting depth is suggested in clay soils. Linseed seed is comparatively small and may fail to emerge from greater depths, especially if crusting occurs. Inexperienced growers often plant too deep, especially if the soil is loose. Early seeding gives the highest yields in most years. Planting is sometimes delayed to allow cultivation for weed control in fields where weeds may be a very serious problem. Late planting of linseed may not cause as great a yield reduction as it does with small grains. Seed is sown in rows 11.5 to 75 cm apart in various countries, depending on whether plant is grown for fibre (closer) or seed (each plant given more room). Linseed should be sown at depth of cm with a grain drill, rather than with a broadcast-seeder. However, in some countries, seed is broadcast and harrowed in. Linseed germinates at a lower temperature than many of the grassy weeds that may become troublesome later. The seed coat of linseed is easily damaged during harvest and handling. Sometimes this damage is so slight it is not visible, but even such slightly damaged seed is susceptible to seed decay. Sound, uninjured linseed seed should always be selected for planting if available. Linseed responds especially well light irrigation, as it is a shallow-rooted crop. When crop begins to ripen, irrigation should be withheld to hasten maturity. If soil is kept wet, blooming may continue indefinitely. The total amount of water applied is usually 9,000-12,000 cu m/ha; between one and ten water applications may be necessary per season. The crop responds to the application of nitrogen, but not phosphate, fertiliser. Between 50 and 90 kgn/ha is required for optimum yields. Compared with other crops, linseed requires relatively small amounts of nutrients. Linseed requires about the same soil fertilisation programme as small grains. Lime should be applied to maintain the soil ph in the range If large amounts of fertiliser are required, it is commonly applied to the previous crop in the rotation. Stands of linseed will likely be reduced if the combined total rates of N, P 2 O 5 and K 2 O applied with the seed exceed 22 kg/ha.

15 DLCP 432 Industrial Crop Production - Oil Crops- Linseed Direct organic manuring should be avoided when fibre linseed is grown on well-cultivated soils that are amply supplied with nutrients, as heavy manuring can produce heavy yields, but there is an accompanying fall in the quality of the fibre. The aim in fertilising is to improve the yield without causing corresponding fall in quality. Organic manures, such as farmyard manure, are best applied to the preceding crop. Microelements may be needed on a particular soil, and should be added after a soil test. Various rotation plans are followed in different countries in which 6 11 years intervene between linseed plantings on a given piece of land. An important factor in determining the yield of linseed in the tropics is the time of sowing. Experiments conducted at several locations in the Sudan savannah zone of Nigeria show that planting soon after the onset of the dry season gives maximum yields. Mean yields of irrigated linseed sown on different dates in the Sudan savannah zone of Nigeria Seed Sowing date yield (kg) October November November December January January Linseed is an excellent companion crop to help establish small seeded grasses and legumes. Plant characteristics that favour its use as a companion crop are: limited leaf area and short stature which allow much light to reach the forage seedlings early maturity a less extensive root system than many crops which reduces competition for soil moisture. WEED CONTROL Weeds are generally more of a problem in linseed than in small grain. Growers should sow linseed on relatively weed free land. Post-harvest tillage should be used to suppress perennial weeds, and to stimulate germination of annual weed seeds. Good weed control with a minimum of weed seed production in the preceding year's crop will facilitate a cleaner linseed field. Delayed sowing of linseed to permit additional spring tillage for weed control may be successful in some fields but the planting delay may be detrimental to the linseed. HARVESTING Linseed is more difficult to harvest than small grains; however, linseed does not shatter or lodge as easily. Because of green weeds and uneven ripening, linseed is usually windrowed and allowed to dry before threshing. The crop is ripe enough to

16 DLCP 432 Industrial Crop Production - Oil Crops- Linseed harvest when 90% of bolls have turned brown, although it can be pulled at beginning of seed ripening, since immature seed bolls mature after harvest and produce viable seed. Linseed is usually ripe when the stems turn yellow, the bolls turn brown, and the seed can be easily threshed. In wet years, the stems may remain green and the plants continue to flower long after the early bolls are ripe. Under such conditions linseed should be harvested when all but the very late bolls are ripe. It is important to harvest soon after it is mature because weeds usually become a greater problem. If left standing for a long period of time, the seed quality for oil purposes may be seriously reduced. Proper harvest time is important in linseed production. Early harvest reduces yield, while late harvest can change the chemical make-up of the oil, and thus its quality and value. Most linseed cultivars mature in days, but some require more than 200. Linseed seed may be harvested in the same manner as wheat. Care in threshing necessary to prevent cracking of seed for propagation. Maturity of linseed is judged by the colour of the bolls (seed capsules) rather than by the colour of the straw. For storage, seed must have a low moisture content of 8 10%. Linseed plants are cut as close to the ground as possible. The cut plants are allowed to dry, after which they are threshed, either by hand or by using appropriate manual threshers. Clean seed is obtained by winnowing and sieving. Linseed seed over 11% moisture usually cannot be stored safely for extended periods. Linseed should be left in the windrow or stook to dry until the seed reaches this moisture level. Seed containing large amounts of green weed seed and inert matter should be cleaned before storing. Linseed should only be stored in dry tight bins or containers. Linseed seed will flow through very small openings. When crop is grown for the fibre, it is pulled by hand; machines are still not entirely satisfactory. The pulled linseed is stooked in the field until dry, when the seed is threshed in such a way as to prevent the breaking of the straw. Stems are harvested when the lower two-thirds of stem have turned yellow and the leaves have fallen from it, about 1 month after the appearance of first flowers. Straw is then retted, by bacterial fermentation, to remove gums and resins from the fibre. Retting may be simple exposure of the straw to the weather for 2 3 weeks. Depending, on weather; it may take up to 8 weeks, or until the dew and rains have removed the resins and the fibre is loosened, or more complicated methods of soaking in water for about a week under specific regulation of time and temperature. When straw has been properly retted, it is dried, broken and scutched to separate the fibre from the bark and stems, after which it is baled and is then ready to be manufactured. Fibres are about 50 cm long on average, but may vary from up to 1 m. Linseed fibres are in the cambium layers of the plant, and are bast or phloem fibres. They occur in bundles in the pericycle; each bundle containing about individual fibres. Each stem contains about 30 fibre bundles forming a ring around the stem. Retted linseed contains about 64% cellulose, 17% hemicellulose and 2% lignin. Before straw is retted, seed capsules are removed, (called "rippling"), usually by machine. One ton of fibre linseed yields 100 kg of seed. It is possible to extract fibre from linseed straw without retting, (called "green linseed"). After straw is deseeded, it is taken directly to the breaker and the scutcher. This fibre has a

17 DLCP 432 Industrial Crop Production - Oil Crops- Linseed considerable amount of extraneous matter attached, making it necessary to de-gum before spinning the fibre. This method usually results in a higher production of short tow fibre than there is with retted linseed fibre. OIL PRESSING In Eastern Europe, the seed is generally first cold pressed, the cold-press oil being used in foods. A later hot press yields additional industrial oil. In the U.S., oil extraction is generally hot press, followed by solvent extraction, and the oil is not used as food. The press cake from hot pressing is used as livestock feed. The linseed seed contains a cyanogenic glucoside that forms hydrocyanic acid by enzyme action unless the enzyme is inactivated by heat. BIOTIC FACTORS When grown for seed, linseed is self-pollinating. Cross-pollination does not seem to increase seed yield consistently. Diseases Many fungi have been found on linseed, but the most serious diseases are linseed wilt, several rusts, and seedling blights. Some of the causative agents are Alternaria lini, Ascochyta linicola, Botrytis cinerea, Colletotrichum lini, Fusarium oxysporum, Melampsora lini, Mycosphaerella linorum, Oidium lini, Phoma lini, Pythium spp., Rhizoctonia solani, Sclerotinia fuckeliana, Sclerotium rolfsii, Septoria linicola, and Sphaerella linorum. Rust (Melampsora lini), wilt (Fusarium oxysporum), leaf spot (Alternaria lini), grey mould (Botrytis cinerea) and Sphaerella linorum cause appreciable losses. The main form of control is to use resistant varieties. Rust is a fungus disease that first appears as yellow orange pustules on the leaves and stems. The spore masses are darker colour in later stages. Good fall ploughing that buries straw and stubble aids in controlling the disease, but the most efficient control for rust is the use of resistant varieties. Wilt is a soil-borne fungus disease. It is most serious where linseed is not rotated with other crops. Some varieties are highly resistant to this disease. Seedling Blight diseases attack the germinating seed. The fungi may enter the seed through cracks in the seed coat. Seed treatment will help to prevent losses. Important viruses causing disease in linseed are: Aster yellows (Chlorogenus callistephi), beet curly top and Yellows. Linseed may be parasitised by Cuscuta epilinum, C. epithymum, C. indecora, C. pentagona and Striga spp. The bacteria Agrobacterium tumefaciens and Pseudomonas atrofaciens also cause diseases. Aster Yellows and Crinkle are both diseases that are transmitted by certain insect vectors. These diseases may be present to a limited extent each season: however, losses are usually light.

18 DLCP 432 Industrial Crop Production - Oil Crops- Linseed Pests Insects are not generally a serious problem in linseed production. However, various insect pests may infest linseed from time of emergence to maturity. To keep damage low, fields should be examined regularly for pests and control measures promptly taken. Cutworms damage the seedlings by cutting off the plants at or near the soil surface. Severe damage may be done in 1 or 2 days when the plants are young. Aphids sometimes become so abundant on linseed that all the plants in a field may be covered with them. These infestations normally cause little damage. The aster leafhopper, like aphids, feeds by sucking juices from the linseed plants. The leafhopper can carry the mycoplasm that causes aster yellows and infect the plants with this disease while feeding. Grasshoppers may be a hazard to linseed, especially before harvest. If flying adults invade a field, they can quickly cause large numbers of bolls to drop to the ground by chewing through the succulent portions of the small stems below the bolls. In the spring young hoppers may also damage seedling linseed. Nematodes isolated from linseed include the following: Ditylenchus spp., Helicotylenchus spp., Heterodera spp., Meloidogyne spp., Paratylenchus spp., Tylenochorhynchus spp., and Xiphinema spp. IN ETHIOPIA Recommended Varieties - Two varieties, Victory and Concurrent, are recommended for wide-scale production, and are available to farmers. Altitude - The crop is grown in Ethiopia at altitudes above 1800m. Optimum altitude ranges are 2300 to 2800 m. Types Of Soils - Well-drained fertile, clay loam to sandy soils are most suitable for the crop. It performs best in areas with deep moist soils, with ph between 6.6 and 7.6. Rainfall - Linseed is planted in areas where the average annual rainfall is around mm, well-distributed over the growing period. The plant is very sensitive to drought, and places with below-average rainfall must be avoided. Time of Sowing - As linseed is a highland crop, the time of sowing must be carefully planned. Late seeding can result in frost damage. Sowing must not be carried out after the end of June. Seeding and Spacing - Linseed is grown both for fibre and for oilseed. When planted for fibre, spacing between rows should be around 20 cm; when planted for oilseed, a wider spacing between rows is recommended, about 40 cm. Seed rate is approximately kg per hectare.

19 DLCP 432 Industrial Crop Production - Oil Crops- Linseed Rate and Types of Fertilisers - Linseed is a crop of relatively low fertility requirements. It reacts better to N fertilisers than to P or K. It is not advisable to use any fertilisers on fertile alluvial soils. But, in areas with poor degraded soils, some fertilisers can be added. The recommended rates are 23 kgn and 23 kgp 2 O 5 per hectare (care - these rates have probably been developed in relatively high rainfall areas: they may not be applicable to dryland areas). Growing Period - The growth period is between 100 and 150 days for oilseeds. When the crop is grown for fibre, the best time to harvest is when the plant is in full bloom. At this stage fibrous elements in the linseed plant are well developed, and the fibre can be extracted. The straw and fibre obtained at this time are greenish and of better quality. Yields - The average yield is around 3.5 to 5.0 quintals of oilseed per hectare. The yield of fibre is 500 to 900 kg finished fibre per hectare.

20 DLCP 432 Industrial Crop Production - Oil Crops - Castor Castor (Ricinus communis) A: young shoot, inflorescence and leaves; B: male flower in longitudinal section; C: female flower in longitudinal section; D: developing fruits and male flowers; E: mature fruits; F: dehiscing carpel; G: seed - front view; H: seed - side view. The castor plant belongs to Family: Euphorbiaceae Genus: Ricinus Species: Ricinus communis Castor is generally known as the castor-bean plant and the seeds as castor beans. Since the plant is not a legume, these names should not be used, and the plant should be known as the castor plant, and the seed as castor seed. Castor is a plant whose contemporary distribution in the warmer regions is world-wide. Its origin is obscured by its wide dissemination in ancient times, and the ease and rapidity with which it becomes established as a native plant. It certainly appears indigenous to Eastern Africa, especially the Ethiopian area, but elsewhere there is invariably considerable evidence indicating its introduction. Tribesmen in Africa south of the Sahara extensively use castor mixed with local pigments to paint their bodies, and women use it in hairdressing. In Africa, the plant is usually a fairly tall, much-branched perennial. When cultivated commercially, a short-lived, erect, little-branched, dwarf perennial is generally selected, which is usually treated as an annual. The oil has found wide application in modern technology, and there are many hundreds of industrial uses for castor oil and its derivatives. Castor oil is a purgative, but the whole seed a fatal poison. Even today, strict safeguards are necessary to ensure that expressed oil for medical use is not contaminated by toxic elements. The attractive seeds have caused frequent fatalities, and records of such tragedies are numerous and continuing.

21 DLCP 432 Industrial Crop Production - Oil Crops - Castor GENERAL The castor plant varies greatly in its growth habit, colour of foliage, stems, seed size, colour and oil content, so that varieties often bear little resemblance to each other. Some are large perennials often developing into small trees, others behave as short-lived dwarf annuals, and every gradation between extremes can be found. Colour differences in leaves, stems and inflorescence have resulted in the selection of these varieties as horticultural and ornamental plants. A diagrammatic representation of a castor plant is shown to the left. The period from emergence to maturity varies with variety, and is greatly influenced by environment. Giant perennial types grown locally in East Africa produce the first ripe seed suitable for picking approximately 140 days after planting, but imported dwarf types require 160 days. Quick maturity can be an asset, even when related to lower potential yield. PLANT CHARACTERISTICS Root system Giant types have a root system similar to typical woody perennials, with a large, well-developed tap-root, which can reach several metres in length, and has substantial laterals and secondary roots. Dwarf types have root systems which reflect the particular variety or cultural system (rainfed or irrigated), and the tap-root is less apparent. The well-developed secondary root system is much branched and often deeply penetrating to take maximum advantage of soil moisture, a major factor in the plant s resistance to drought. In arid areas, where the plant has only rainfall for subsistence, aerial growth tends to be slower in relation to root growth than under more favourable conditions, and the rate of root growth of local plants is faster than in other varieties. An added advantage of quick root growth is increased ability to follow the moisture front down into the subsoil, which in many dry areas is often better supplied with nutrients than in more temperate regions. Good yields from crops with deeply penetrating roots can be obtained at a lower level of added nutrients than would be required in neighbouring areas of higher rainfall. The pounded root is believed to have medicinal properties in some primitive societies, which may have some basis in scientific fact. Stem The stem is round, glabrous, frequently glaucous, and covered with a waxy bloom which gives red or green stems a bluish appearance in the field. The stem of dwarf varieties generally becomes hollow with age, but is usually solid to a considerable height in giant, tree-like types. There are well-developed nodes, from each of which a leaf arises. The node at which the first raceme appears is an

22 DLCP 432 Industrial Crop Production - Oil Crops - Castor important agronomic characteristic, since it is associated with quick maturity. In dwarf-internode hybrids, it usually occurs after the sixth to twelfth node, but in a segregating population can vary from six to forty-five. Branches Pruning to reduce the height or number of major branches has been frequently attempted, but is usually ineffective, on giant types, although it may increase yield. The cost of the operation, which must be carried out with care if it is not to cause damage to the relatively brittle plant, may be greater than the value of the resulting yield increase. Topping at cm can reduce height and increase branching, but usually decreases yield. In its natural state, castor is multi-branched, primary branches giving rise to secondary branches, a sequence that continues over the life of the plant. This is an unfavourable characteristic for commercial production, since the fewer the branches, the lower the number of racemes, and hence a shorter period of, and more even, maturity. Leaves The very large leaves, cm wide, are usually a dark glossy green, palmate, with five to eleven lobes, and prominent veins on the under-surface. There are ornamental varieties with leaves and stems which vary from light green to dark red, depending on the level of anthocyanin pigmentation. Leaves are alternate, except for two opposite leaves at the node immediately above the cotyledons. They are borne on long, stout petioles. Young leaves are mildly toxic to animals and some insects. Growth and expansion of castor leaves do not appear to be checked by prolonged sunlight, provided there is ample moisture for transpiration. It is not until a water-deficit has been built-up that growth and expansion are affected. Inflorescence The inflorescence, which forms a pyramidal raceme also known as the spike or candle, is borne terminally on main and lateral branches, and the node at which the first one originates is a varietal characteristic. The inflorescence can reach a length of 100 cm, but since there is a wide variation in distance between flowers, yield is not necessarily correlated with length. The lower portion of the raceme bears the male flowers, the upper female, the ratio between them being a varietal characteristic, but it is also strongly influenced by climate. High temperature favours maleness, as does plant age and short daylength; the opposite femaleness. Pollen is usually shed from two to three hours before sunrise until late afternoon, and there is frequently a peak at mid-morning. Pollen is shed readily between C with a relative humidity of 60%, but a temperature of 15 C delays shedding, and lower temperatures can injure grains. Pollen grains contain an allergenic compound similar to that in the seed, but the allergic reaction in susceptible persons is not so severe as to that in the seed. Normally cross-pollinated, wind being the major agent in the tropics, monoecious plants or strains occur. The plant produces flowers over an extended period, and in the wild or naturalised state, giant and perennial types may flower year-round when climatic conditions permit. The lowest flowering raceme on the plant is usually the first to mature, the others following in sequence up the stem. There is a distinct variation in yield of seed and their oil content between inflorescences, primary racemes

23 DLCP 432 Industrial Crop Production - Oil Crops - Castor generally producing the greatest number of, and largest, seeds. This is illustrated in the table overleaf by data from three dwarf varieties grown in Brazil. There is variation not only between varieties, but also between racemes, related to the various periods involved. Average seed size was less affected, although oil content and the kernel/husk ratio differed significantly between varieties. Fruits The fruit is a globular capsule, spiny to some degree, which becomes hard and brittle when ripe. The giant types and some varieties shatter at maturity, but this is not general in dwarf varieties. Cultivated varieties known as thornless have been developed, and these often have rudimentary spines. In others, the spines, although remaining on the capsule, are soft, flexible and non-irritant. Length, thickness, rigidity, and the presence or absence, of capsule spines is generally a varietal characteristic, but considerable variation can exist even on individual plants. Ripening of fruits along the raceme is uneven, the lower maturing before the upper. In wild varieties, the period between first and last mature fruits may be several weeks. Differences in development and seeds of sequential racemes. Variety Component IAC 38 Campinas Guarani Days to flowering Primary racemes Secondary racemes Tertiary racemes Days to maturity Primary racemes Secondary racemes Tertiary racemes seed weight (g) Primary racemes Secondary racemes Tertiary racemes Germination (%) Primary racemes Secondary racemes Tertiary racemes Av. seed dimensions (mm) Length Breadth Thickness Kernel/husk ratio (%) Average oil content (%) The capsule encloses three seeds, a flattened oval in shape, with a shiny brittle testa enclosing a white highly oleaginous kernel. A sectioned drawing of a castor seed, compared with bean and maize seeds, is shown overleaf. Seeds may be coloured white, brown, buff, black or red, but usually several colours occur as very attractive mottling on the testa. Seeds vary greatly in size, from a few millimetres to nearly 250 mm long in giant types, and in breadth from five to sixteen millimetres. Seed size varies not only between varieties, but from different racemes on the same plant. There is also a difference in rate of germination between seed from different racemes, the first to flower having a greater viability than the last. The

24 DLCP 432 Industrial Crop Production - Oil Crops - Castor 1000-seed weight may vary from 100 to 1000 g, but most of the dwarf-internode varieties average some 300 g. In general, the weight of individual seeds increases as the total number of seeds produced per plant decreases. However, the increase in seed weight does not fully compensate for the decrease in number, and total yield is less. Yields normally decrease after the optimum sowing period. There appears to be a correlation between seed size and oil content, for when the range of seed size is large, kernel percentage is more closely correlated with oil content than other factors. The testa is thin and often brittle, the degree of brittleness also depending to some extent on the age and oil content of the seeds. Some varieties of castor seed may have a dormancy period of several months, but freshly harvested seed of there varieties can be made to germinate by removing the caruncle, and piercing the testa at this site, leaving the endosperm intact. However, the majority of modern dwarf hybrids are not dormant, and freshly harvested seed germinates without special treatment. Germination is epigeal, the cotyledons acting as suctorial organs absorbing the endosperm, and are carried above the surface and expand as green leaves. The seed is an active poison, as both the toxic protein ricin and alkaloid ricinine occur in it, and to a minor extent in other plant parts. Oil The most important seed constituent is the oil, usually between 40 and 60% in commercial varieties. The expressed oil is high in triglycerides, principally ricinolein,

25 DLCP 432 Industrial Crop Production - Oil Crops - Castor the fatty acid component being ricinoleic acid C 17 H 32 OH.COOH, whose three hydroxyl groups confer on castor oil the unique property of being soluble in alcohol. There can be annual variation in oil content of seed produced by the same variety, and this variation has been found in successive seasons in Kenya and Tanzania. This suggests that seasonal environmental differences were responsible, but climate may also have affected the sequence of agricultural operations, and these can have a greater effect on the final result. For instance, too-early harvesting of immature or still-green capsules can drastically reduce the yield of oil per hectare. ADAPTATION Climatic requirements Basically a semi-tropical perennial, castor now grows throughout the warmtemperate and tropical regions, and flourishes under such a variety of climatic conditions that its range cannot be easily defined. As a smallholder or peasant crop, it can be grown almost anywhere land is available, and a saleable crop can be produced by the most primitive methods. In such circumstances, it can be found growing from sea-level at the coast to high on inland mountains, often depending at the limits of its range on the amount of official support it receives. It has been commercially cultivated from 40 S to 52 N, from sea-level to 2000 m, but will grow up to 3000 m, with an optimum between 300 and 1500 m, the limiting factor being frost during growth. Castor is essentially a long-day plant, but is adaptable, with some loss of yield, to a fairly wide day-length range. Castor requires a moderately high temperature, C, with low humidity throughout the growing season to produce maximum yields. Long, clear, sunny days are most suitable, and cloudy or humid days, irrespective of temperature, will reduce yields. High soil temperature decreases time from sowing to emergence, and low soil temperature extends it. Thus temperature and time of sowing are closely related, but the factors influencing both vary regionally. The effect of soil temperature, as influenced by planting dates, is shown in the table overleaf - in general, planting outside the optimum period reduces yield. There are occasions, however, when it may be necessary, as a means of avoiding high temperatures at flowering or the period when a major pest is most active. A hard frost will normally kill dwarf or annual castor at any stage of growth, young plants being most susceptible, and a frost-free growing period of days is necessary. Hail damage to foliage can be visually severe with little effect. Giant varieties are able to compensate for damage caused even fairly late in the season by prolonging the flowering period. With dwarf varieties, fairly extensive defoliation up to the flowering of the first raceme has little effect on yield, but after this period, yields may be depressed. Seedlings are extremely susceptible to hail damage, and losses caused by shattering of mature capsules by late-season storms can be serious.

26 DLCP 432 Industrial Crop Production - Oil Crops - Castor Effect of time of planting on emergence and yield - USA Number of Mean soil Adjusted Adjusted Date of days to 50% temperature mean yields mean yields planting emergence ( C) * (kg/ha) (kg/ha) 18 April May May May June * Mean soil temperature was taken at 10 cm depth at 08:00 hrs daily for 14 days after sowing. From non-irrigated trials carried out at the same time. With a reputation for drought resistance, castor produces its highest yield with a minimum rainfall of mm if this falls mainly in the early growing season, but good yields have been obtained with a rainfall of mm. For optimum yields, 100 mm distributed evenly in the first four months of growth is desirable. There should be no shortage during flowering, but protracted heavy rain during this period will reduce yield. Prolonged rain prior to planting will lower soil temperature, and in these circumstances sowing should be delayed until the soil warms up again. Effect of planting date on yield (kg/ha). East Africa * Sudan Yield Date Yield Date (a) (b) 1 June June June June July July August August August * Average of several years. Sudan yields from north (a) and south (b) of Khartoum. Where total rainfall approaches the minimum required to grow a castor crop, it is essential to plant following the first major rainfall, when soil moisture is adequate for germination, and soil temperature has not been depressed. Where rainfall is above this minimum, planting early in the rainy season will result in poor emergence due to low seed-bed temperature and fungal attack. More important, flowering will then frequently coincide with a major insect pest build-up, since the onset of the rainy season, with attendant periods of high humidity, acts as a trigger mechanism on many insect eggs and larvae. In arid regions where rainfall is barely adequate to sustain a castor crop, or where most rains fall as intense storms, moisture conservation is of major importance. Cropping in alternate years may be possible, the non-crop year being used to store moisture for the following crop. For the system to be effective, lands should be left under bare fallow, or, if there is a danger of erosion, by some crop such as teff. Castor has been successfully grown in this region for many years, averaging two crops in three years. The effects of various crops on soil moisture in sandy red loams in Tanzania are shown overleaf. The figures are equivalent to rainfall in millimetres at 1.8 metres soil depth.

27 DLCP 432 Industrial Crop Production - Oil Crops - Castor Bare fallow Teff cover Volunteer cover Sorghum crop Maize crop Year Year Soils Castor will grow and produce a crop in almost any soil, with the exception of very heavy clays and those poorly drained. In fact, provided the other major factors of suitable climate, pest control and adequate nutrients are available, soil structure appears to be of secondary importance. Since castor is often selected for growing in areas which are marginal for other crops, this adaptability is of considerable economic importance. Highly fertile soils favour excessive vegetative growth, prolong the period to maturity and greatly extend flowering, all of which adversely affect seed yield or cultural practices. Castor s ability to adapt to environmental factors should be exploited, since selection within local varieties suited to a particular soil type can greatly increase yield. Slightly acid soils, ph , are preferred, but castor will tolerate up to ph 8.0, although growth tends to be restricted to a much greater extent on alkaline clays than on other soil types. Saline soils are unsuitable. Those varieties with a pronounced tolerance of either strongly acid or alkaline soil tend to be tree-like, and are usually of little commercial value as oil producers. As castor plants have little soil-binding ability, a fairly open canopy, require efficient weed-control resulting in a relatively bare soil surface, and are often grown in dry areas with high winds and high-intensity rainstorms, practical soil conservation measures are required. Fertilisers Castor is tolerant of low rainfall, not low fertility. These are often confused, although they are completely different. Plants selected to be grown at a specific nutritional level must be adapted to produce the maximum required product at that level. In general, fertilisers have little effect on the oil content of seeds. However, oil formation is most active twenty to seventy days after flowering, and throughout this period nutrient supply must be adequate. When castor has not previously been grown on any scale, fertiliser requirements necessary to produce high maize yields will generally be suitable for high-yielding dwarf hybrids. Where indigenous castor types are to be grown, the use of fertilisers must be dependent on the results of fertiliser trials, as the response from these types tends to be unpredictable. Castor s natural adaptability can ensure adequate returns to peasant growers in those areas where climate or life-style offer few opportunities for cash crop production, or where the existing agricultural system is such that little cash is available to purchase fertilisers. The correct time of planting, and plant population then become more important then fertiliser to ensure maximum yields. But, as increased interest in a crop often precedes better standards of management, and fertiliser use, the level which maximises growers returns must be established. Castor grown in pure stands, instead of being intercropped or preserved where found growing, makes different demands on soil nutrients or moisture, and it may well be that the soil-moisture status is insufficient to sustain a higher population. In such under-developed areas the use of imported, from whatever distance, fertilisers

28 DLCP 432 Industrial Crop Production - Oil Crops - Castor should be rigorously evaluated before recommending their use, although animal manures can be a locally acceptable substitute. On a number of crops in Africa, it has been demonstrated that growth and yield were improved much more by increased frequency of weeding, and planting at the optimum time, than by application of fertiliser. Moreover, weeds often showed a much greater response to fertiliser application than did the crops themselves. These results suggest that improvement of peasant farming can more often be obtained by persuading farmers to give more care to crops cultivated by traditional methods. CULTIVATION A large proportion of castor seed from many less-developed regions is obtained from wild or semi-cultivated plants, and systematic cultivation of pure stands of castor by peasant farmers is the exception. More often, castor is interplanted with other crops, sown around the margins of fields, planted on areas unsuitable for other crops, or merely protected when found growing. When castor is deliberately sown as a cash crop. the standard of cultivation varies as widely as the regions in which it is grown. Ploughing - the term being used in its loosest sense - is usually shallow and kills few weeds. Planting may be carried out at the same time by dropping seeds into the furrow and covering them by treading down earth. Ploughing may be carried out before the rains, and when the soil is moist enough, the seeds are dibbled into the seed-bed in rough lines. In dry regions where total rainfall is barely adequate to produce a castor crop, ridge cultivation is a most suitable method. The ridge can vary in size to accommodate one or more rows of plants, should follow the contour, and ideally be tied at intervals to reduce runoff to the minimum. Seed may be planted on the ridge or in the furrow, depending on the rainfall expected and the soil type. This system has been used to successfully grow a castor crop on alluvial sandy clay with a total rainfall, somewhat unevenly spread, of 400 mm. Since rainfall is the least expensive method of watering crops, every effort should be made to conserve the maximum possible, especially where moisture is the limiting factor in plant growth. The seed-bed necessary for dwarf castor is similar to that for maize or cotton, but, for even germination, castor requires a moist seed-bed for a longer period than either, since emergence may take three weeks. The soil should be moist to cm, and seed planted at least 5 cm deep. Seedlings will emerge from a depth of 30 cm, but are usually shorter and less vigorous than those planted less than 10 cm deep. When planted 35 cm deep, seed germinated and produced hypocotyls varying in length from cm, but failed to emerge. A seed-bed temperature of 17 C is normally necessary for uniform germination. However, there are varietal differences in susceptibility to low seed-bed temperature and subsequent emergence. This means that soil conditions may be such that the optimum period for sowing a particular variety may be too short to plant the whole area to that variety. To achieve maximum yield per hectare, it will then become necessary to use other varieties selected to suit the conditions of the extended planting period. A soil moisture range of 15-20% usually ensures good germination at the optimum temperature, below 11% impairs, and above 25%

29 DLCP 432 Industrial Crop Production - Oil Crops - Castor inhibits. Heavy rain just after planting, unless followed by warm sunny days, can seriously reduce emergence. Seed rates are of little significance with giant varieties, since these are generally planted by hand, with several seeds per hill, and thinned or not as required. For dwarf castor, the one metre row width adopted for many tropical row crops can be used. A reasonably accurate rule of thumb about intra-row spacing may be used in low rainfall regions, that is those with 760 mm or less. Using a standard 100 x 30 spacing, the distance between plants should be increased by 30 cm for every 120 mm drop in average rainfall (i.e. at 500 mm rainfall, spacing would be 100 x 90 cm). A graph easily shows intermediate spacing (see below). 160 Graph showing rule of thumb intra-row spacings for castor in low-rainfall areas. Intra-row plant spacing (cm) Average annual rainfall (mm) At the wider spacings, leaving two plants together produced a similar effect as occurs with cotton - a reduction in individual plant yield, but higher total yield per hectare. With irrigated crops, row width may be predetermined by the system of watering used, and, where water is not a limiting factor, a population of 30,000-40,000 plants/ha is suitable, again dependent on variety. Castor seed is very susceptible to seed-bed fungal disease. In lessdeveloped areas, where seed of a local variety is readily available, the use of a higher seed rate is preferable and safer than chemical seed dressings. Castor, although commonly known as a bean, is not a legume, and no bacterial inoculation of the seed is necessary. Castor seedlings, especially those of dwarf varieties, are poor competitors to the often rampant weed growth in tropical countries, and weed control is essential. Mechanical methods are still the most widespread, but, owing to the seedling s long, brittle hypocotyl, and spreading shallow root system, are often extremely damaging to small plants (see below). Hand weeding is effective, especially on lands where there are patches of persistent perennial grasses. Hand weeding also produced the highest yields in replicated trials comparing various methods of weed control in India, East Africa and the USA. Controlling weed growth

30 DLCP 432 Industrial Crop Production - Oil Crops - Castor both before and after planting accounts for a very high proportion of the total labour requirements in the peasant production of crops. Inadequate weeding was given as one of the most important reasons for the failure of castor growing in Angola in areas suitable for its production. Seedling stages of the castor plant, showing the long, brittle hypocotyl, which is susceptible to damage by mechanical weeding. The seedling on the right shows root damage caused by cultivation. Because of its ability to extract water from considerable depth in the soil, castor is a natural choice for irrigation schemes where the amount of water is insufficient to allow an economically viable area of more demanding crops. Alternatively, castor can be used to extend the area of an existing scheme by utilising water available outside the normal planting dates for other crops; for instance, it can be planted several months after the optimum planting period for cotton, or it can use soil moisture remaining from the previous year. Maximum water availability in the tropics frequently does not correspond with the optimum planting dates of many crops, whereas castor can utilise moisture over a very long period. The ability to extract subsoil moisture has been demonstrated in Zimbabwe, and it can be appreciated from these data that castor used moisture more efficiently than sorghum, which is considered to be a very drought-resistant plant. Percentage moisture use by African crops. Depth (cm) Crop Castor Maize Sorghum (dwarf, grain) Sorghum (tall, forage) Moisture use = 100% available - mean of available readings on Bouyoucos meter. HARVESTING Probably the most difficult and time-consuming operations in castor growing are harvesting and hulling. Capsules can be hand harvested by any suitable method from breaking or cutting off whole racemes to some form of stripping device. Whatever method is used, it is generally unsuitable for large areas, since the spiny

31 DLCP 432 Industrial Crop Production - Oil Crops - Castor capsules make the work unpleasant and disliked, and their bulk involves frequent transport and emptying of containers. However, in some circumstances, it can be a profitable means of employing labour that would otherwise lack work. A worker using a stripping cup can harvest kg of capsules daily. Following harvest, plants should be destroyed, preferably by burning, as this can substantially reduce the severity of insect and disease infestations. However, where it is necessary to control erosion, crop residues should be left in situ, but preferable broken up to limit pest survival. Where wind erosion is a potential problem, crop residues should be contour windrowed. These windrows should be burned prior to planting, the ash being a good fertiliser and soil ameliorator. The yield of castor for selected countries/areas is shown below, and is the average seed yield (shelled seed in kg/ha) of rain-fed crops unless otherwise stated. Average High Average High Africa: Americas: West USA (Irrigated) Central Brazil South India South (Irrigated) USSR USSR (Irrigated) China Clusters reaped slightly green or with wet capsules must be dried before hulling. In the tropics, they can be spread in the sun, but overlong exposure to sun may affect the oil content of the seed, and increase the danger of insect infestation. STORAGE Storage on-farm of large quantities of castor seed should be avoided wherever possible, for seeds are large and occupy considerable space in relation to their weight. A certain amount of storage is unavoidable. Castor seed cannot be stored in the open except for short periods, as both heat and sunlight reduce oil content and quality. Bagging of seed must be carried out with care, and seed handled as little as possible. Damaged seeds and hulls can be used as fuel, or composted, after which they are approximately equal to FYM as a fertiliser. Few pests attack stored castor seed if the testa is unbroken, but damaged seeds can become infested. Common pests are the tropical warehouse beetle (Ephestia cautella), the cigarette beetle (Lasioderma serricorne) and the red flour beetle (Tribolium castaneum). PESTS Castor is attacked by a multitude of insect pests, and even those that would never encounter the plant naturally eat it. The damage caused by insects to castor may be greater than the small amount of sap lost or leaves eaten. It has been shown that the action of piercing a developing inflorescence during feeding by sucking bugs, especially the Miridae, was itself sufficient to cause die-back or premature abscission of capsules. Many of the major pests of castor also damage other tropical

32 DLCP 432 Industrial Crop Production - Oil Crops - Castor crops, and, when planted in the vicinity of large blocks of these, castor becomes liable to greatly increased levels of attack. Unprotected castor plants which lose a major proportion of their first racemes to insect attack are able to compensate to some extent by fruiting later in the season, when insect numbers have naturally decreased. The giant type is thus able to produce a crop from unprotected plants equal to that from dwarf plants that have been dusted with insecticides. In Tanzania and Kenya, when castor was planted in the vicinity of large areas of maize or sorghum, the general level of insect attack was higher than when the surrounding area was grassland. The proportion of mirids also increased in relation to other pests, and the damage was thus more severe. Under peasant farming conditions in dry regions, castor should be encouraged as a cash crop instead of cereals, especially maize, since the latter is more profitably grown elsewhere. Agrotis segetum (cutworm) may be locally common in parts of Africa. Symptoms of attack are seedlings eaten off just above surface level, or wilting. Digging near roots of such plants or those growing in their vicinity, will expose greasy, darkbrownish green or grey, sometimes yellowish, larvae up to 4 cm long curled up about 1 cm from the surface. Mole crickets (Gryllotalpa species) and other species of crickets, mainly Brachytrupes and Gryllus species, can cause damage to both seed and seedlings. Small chrysomelids of the flea beetle type have been noted in East Africa as occasionally causing serious damage to young seedlings. Outbreaks of this severity are uncommon. Aphthona whitfieldi has been recorded on young castor plants in East Africa. Grasshoppers can be troublesome in seedlings, but are seldom damaging to mature plants. Zonocerus variegatus (variegated grasshopper) occurs in East Africa and Ethiopia, where castor seedlings are often attacked by bands of nymphs or adults. Beating these bands with bushy branches is a most effective method of control for small farmers or to protect scattered plantings. In Africa, Chrotogonus, Cyrtacanthacris and Phymateus species may all cause damage to young plants, becoming serious pests locally. Stem-borers are of economic importance only where giant or other indigenous castors are grown as perennials, and damage may so weaken plants that they are unable to withstand high winds. Little control of actual infestation is possible, but the danger can be reduced by burning the stems of fallen plants and the previous crop when replanting. Since these stem-borers are not specific to castor, wide area control is not possible. In East Africa, the main stem-borer is the larvae of Xyleutes capensis. Damage usually begins in the stem near ground level. Larvae are creamy white in colour, and reach a length of 5 cm. The pupa formed protrudes outside the stem for most of its length. Heliothis armigera (bollworm) is damaging to some extent in specific seasons. Dasychira georgiana (tussock moth) occurs in East Africa where severe attack completely skeletonises leaves. Jassids (leafhoppers), particularly Empoasca flavescens, attack castor and a wide range of other tropical plants, but there is varietal resistance to this pest. Probably the most damaging pests are those attacking the inflorescence, especially mirid and pentatomid bugs, which can have devastating effects when present in large numbers. Helopeltis schoutedeni, a red, orange or yellow bug with black-winged adults, is common in north-equatorial areas across Africa and in

33 DLCP 432 Industrial Crop Production - Oil Crops - Castor Sudan, and occasionally appears in enormous numbers, when it not only causes severe damage to the flowering spike, but also seriously retards the growth of the whole plant. Lygus ricini is locally important in East Africa. Eurystylus and Adelphocoris species occur generally in Africa. Throughout East Africa, larvae of the false codling moth Cryptophlebia leucotreta feed on panicles and bore into maturing capsules and seeds. Once the larvae are inside the capsule, little control is possible, and the damage has already occurred. Delay in harvesting can result in serious loss from this pest, as well as problems with hulling due to the oil from damaged seeds. Aphids and whiteflies frequently occur in large numbers on plants, but damage is usually confined to a specific district or season. Nematodes are not considered to be a serious pest of castor, which is regarded as being resistant. DISEASES One hundred and fifty organisms that are pathogenic on castor have been recorded, but few are of economic importance. The most damaging diseases attacking seedlings are various rots, often described as damping off, which affect emerging plants. These are frequently caused by Fusarium, Rhizoetonia and Sclerotium species, with Phytophthora parasitica the most important in Africa. P. parasitica (foot or crown rot) thrives under wet conditions, and is spread by the heavy tropical storms which occur. Large raindrops carry zoospores from one plant to the next, and, should cool, wet conditions persist for a long period, extensive damage can occur, particularly among immature plants. The most common foliar disease is Melampsora ricini. It is most severe on mature leaves which are no longer contributing significantly to plant growth, so its effect on yield is generally slight. It appears that there may be local strains of giant types in Africa that have resistance to the disease. Symptoms are the presence of masses of orange spores on the undersides of the leaves. Alternaria ricini leaf spot is more damaging, and a heavy infestation will reduce yield. It also attacks seedlings, and can affect capsules. Nitrogen application can reduce the severity of the disease, as can rate and timing of irrigation. Symptoms are light brown, generally circular spots on the leaves, larger than Cercospora, which tend to become angular with age. A grey-green spore mass may sometimes be seen. In sub-saharan Africa, Cercospora ricinella has a similar effect on plants as Alternaria, but does not damage capsules so badly. In Somalia, the disease is considered to be most serious, and can defoliate plants completely in years of heavy infection. Symptoms are light brown, generally circular interveinal spots, with margins of concentric rings, the outer being broad and dark. With age, the centre may change to grey. The spore mass is blackish. Xanthomonas ricini causes severe defoliation, is of economic importance due to the difficulty of control, and, in areas of very heavy infestations, may be the limiting factor in plant growth. Symptoms are small, rounded water-soaked lesions, most numerous towards the leaf tips. It usually occurs after periods of driving rain. The pathogen travels through the xylem vessels and veins, the

34 DLCP 432 Industrial Crop Production - Oil Crops - Castor leaves becoming dark brown and dying. In severe infections, the organism may move down the leaf petiole and into the stem. Capsule diseases, of which the moulds Alternaria and Botrytis species are the most serious, may limit commercial production where they occur. The most obvious symptom is a dense woolly growth on flowers and capsules, varying in colour from pale to olive-grey, but greater loss is caused by the weakening of capsule peduncles, which subsequently break. Loss on susceptible varieties can be eighty percent of capsules, while others show considerable resistance. The diseases also affect leaves and stems by infection from the racemes. First symptoms are small blackish spots from which drops of yellow liquid may exude. Fungal threads which grow from these spots spread the infection and produce the characteristic appearance of the affected raceme. Sclerotinia ricini is a brownish grey mould that covers and shrivels capsules. Close spacing of plants, or several plants left together in hill plantings, increase the incidence of the disease. Chemical control is not practical, and wide spacing of plants is recommended to reduce the spread of the disease. In the more humid areas of West Africa, S. ricini is considered the most important disease attacking the inflorescence. IN ETHIOPIA 1996 Ethiopian production (FAO, 1997): Area Harvested: 14,000 ha Average Yield: 978 kg/ha Production: 14,000 tonnes Safflower (Carthamus tinctorius) Safflower belongs to: Order: Compositae Family: Asteraceae Genus: Carthamus Species: Carthamus tinctorius GENERAL The plant has long been domesticated, initially for the orange dye obtained from the florets, and has been positively identified as growing in Egypt 4000 years ago, to where it was probably introduced from the Euphrates region. Expression and use of oil came much later.

35 DLCP 432 Industrial Crop Production - Oil Crops - Safflower A: habit; B: capitulum; C: capitulum in longitudinal section; D: floret; E: achene. PLANT CHARACTERISTICS Safflower is a highly branched, herbaceous, thistle-like annual, varying in height from cm, generally with yellow flowers, the seeds of which contain 35-45% oil, and resemble small sunflower seeds. Root system The plant has a well-defined and frequently fleshy tap-root, and normally produces numerous thin horizontal laterals. The tap-root commonly penetrates to a depth of two to three metres, and this deep-rooting characteristic allows the plant to draw moisture and nutrients from a considerable volume of soil. In Australia, for instance, roots of safflower were traced to a depth of 220 cm, while roots of wheat on an adjoining plot only reached 40 cm. Tap-root penetration can be retarded by a layer of compacted or dry soil, or fine textured clay. Salinity may also affect the extent of root penetration and the horizons in which secondary roots proliferate. The deep-rooting habit requires that cultivation allows such growth to take place with a minimum of hindrance. Deep ploughing is seldom essential in the tropics as subsoiling and chisel ploughing are both effective alternatives, and to be recommended in areas where safflower s drought-resistant character is a major asset. Stem The stem is stiff, cylindrical, fairly thick at the base, becoming thinner as branching increases, quite smooth, glabrous and light grey or green to white, with fine longitudinal grooves, and becoming brittle when mature. Brittleness may be a genetic characteristic varying in degree and age at which it occurs. The stem girth 35

36 DLCP 432 Industrial Crop Production - Oil Crops - Safflower of mature plants at ground level can vary from three to twelve centimetres, and this characteristic has been significantly correlated with yield. Following emergence, the stem apex produces a rosette of leaves on the soil surface, which rapidly develops into a true stem. Cultivated safflower has no true rosette stage as occurs in other Carthamus species, but the rosette stage can be prolonged when the crop is sown in inimical weather conditions. In contrast to its relatively slow start, safflower grows rapidly after the stem begins to elongate. Lodging is also higher in thin-hulled safflower strains, since the main effect of the gene controlling this factor is essentially to reduce the amount of secondary wall-thickening in sclerenchyma cells. Thus, the fibre cells surrounding vascular bundles are weaker than in normal thick-hulled types. Height is a varietal characteristic, is affected by cultural techniques and climate, and can vary from 50 to 200 cm. Dwarf plants, some 35 cm in height when mature, related to the lack of a rosette stage, are known to occur. The central stem branches from 15 to 20 cm to form secondary stems, which themselves branch, each branch terminating in a flower. The angle branches form to the main stem is a varietal characteristic, but can be considerably affected by environment. Most commercial cultivars have a branch-stem angle of 30-70, but can vary between 10 and 90. Nipping out central shoots just before flowering induced increased branching, number of seed heads per plant and total seed yields in India. This is an obvious advantage when yield per plant is important, such as when safflower is grown in single lines as a border crop around fields. Leaves Leaf size and shape varies considerably between variety and on individual plants, from 2.5 to 5 cm broad and cm long. They are usually large and deeply serrated on the lower stem, short, stiff, ovate to obovate at the inflorescence, where they become superimposed as the involucral bracts. The lower leaves are generally spineless, but the number of leaves on the upper leaves is a varietal characteristic, and can vary from spineless to strongly spined. This spiny character is used to good effect by smallholders in many countries, who plant several lines of plants on bunds or the borders of their fields. This effectively repels straying stock or children. Flowering The inflorescence is typical of the Compositae, and consists of numerous florets collected closely together on a circular, somewhat flattened, receptacle. The number of florets varies with variety, and can be affected by environment, in the range The receptacle is surrounded by several layers of involucral bracts, the outer ring being heavily spined, so protecting the developing inflorescence. The individual flowers are themselves provided with bracts in the form of small hairs. The involucre is conical, with a small apical opening through which the corolla tubes of the flowers protrude. Flower colour can vary from a whitish yellow to red-orange, with deep yellow the most common. Two colouring materials can be obtained from the flowers: one a water-soluble yellow, carthamidin, the other the formerly important colouring material cartharmin. The latter is an orange-red dye, insoluble in water, but readily soluble in an alkaline solution. The capitula are borne at the end of stems or branches, that on the main branch blooming before those terminating secondary branches. When secondary branches have completed their growth and produce heads, these begin to bloom. Thus, flowering begins at the inflorescences which terminate the main axis of the plant, followed by the most mature of the main branches. The secondary and tertiary branches continue the process in regular order. Although flowering may over an extended period, heads do not easily shatter when ripe,. Flower heads can vary in diameter from 125 to 400 mm, and the number per plant from five to fifty. Large head size does not necessarily indicate more or larger seeds, and the relationship between head size and other plant characteristics is inconsistent. Close spacing directly affects the number of heads produced (see graph overleaf). However, although the number of heads can be reduced as low as approximately three heads per plant by increased planting rates, further reduction is resisted. Reduced yield from this point is due almost entirely to a reduction in the number of seeds per head. The size of an individual head also depends on its position on the plant, for primary and secondary heads are the largest, while tertiary and subsequent heads are usually smaller. Flowering normally begins at the head margin, proceeds centripetally, and requires three to five days to complete. Since plants are multi-flowered, total flowering may extend over ten to forty days. Time to flowering in a variety is essentially genetically controlled, but the actual period can be greatly influenced by environment. High temperature during early growth accelerates flowering, and, when this is due to sowing after the optimum date, time from emergence to flowering can be reduced by thirty to forty days when compared to plants sown during the optimum period. Salinity may also accelerate the onset of flowering, but reduction of the 36

37 DLCP 432 Industrial Crop Production - Oil Crops - Safflower The number of heads/safflower plant from different intra-row spacings at a standard row width No. heads/plant Intra-row spacing (cm) period from emergence to flowering also varies with the variety and type of salinity. Salinity also reduces the number of flowering heads and yield of seed per head, although the actual number of seeds per head may not be affected. Temperatures approaching 0 C at the late bud or early flowering stage will adversely affect fertility; a range of C is considered most favourable, although, after flowering, temperatures of over 40 C cause no appreciable damage when soil moisture is adequate. Safflower is essentially self- not wind-pollinated, but bees or other insects are generally necessary for optimum fertilisation and maximum yields. Large numbers of honey-bees are normally attracted to safflower fields during flowering due to the plant s abundant pollen and nectar. The efficiency of bees as pollinating agents cannot be doubted, for even in strains of safflower where only minute amounts of pollen are available, effective distribution was accomplished. Fruits The fruit, achene, resembles a small, slightly rectangular sunflower seed, but with a thicker, more fibrous hull. The testa is generally cream or off-white, but grey or mottled types occur. A black or brown testa invariably indicates crossing with wild species. Striped testa have resulted from crosses to produce thin-hulled seed. In the thin-hulled type, the melanin layer is visible through the outer sclerenchyma cells, giving the seeds a greyish or brownish colour. Seed size is a varietal characteristic, is variable, and is affected by climatic conditions. The average seed composition of white-hulled commercial types is in the range hull 33-45%, kernel 55-65%, oil 35-45%, but oil content has risen and hull content fallen in the latest commercial hybrids and varieties. Analyses of safflower seed from various sources, not necessarily indigenous varieties, are shown overleaf. Seed from heads at different positions on the plant, and similar positions on different plants, can vary considerably in composition, and oil content tends to be highest in late- and lowest in early-flowering heads. Average composition of safflower seed (%) Seed Kernel Hull Crude Whole Whole Origin Moisture Oil Protein Ash fibre seed Oil seed Oil Kenya Somalia Sudan Oil Safflower oil is normally very pale yellow, with a bland or slightly nutty flavour depending on the method of processing. It is a drying oil, intermediate between soybean and linseed oil in total unsaturation. Initially its uses were mainly industrial, but publicity concerning possible deleterious effects of high blood cholesterol content in humans increases interest in its potential as an edible oil. Industrial use was mainly in protective coatings, for which its unique high linoleic acid content, some 78%, makes it especially suitable. This high linoleic acid content, together with a small amount of saturated acids and the absence of linolenic acid, enables the oil to form a fast-drying, non-yellowing film with low wrinkling characteristics. Special industrial uses for safflower oil include urethane resins, caulks and putties, linoleum and extra-high quality oil emulsion paints for external use. Safflower seed oil, and occasionally the seed, is used for food in most of the countries in which it is produced, although sesame is usually preferred for cooking. The use of safflower oil in more sophisticated societies is recent, but it is now commonly found in many food products, including cooking oil, margarine, mayonnaise, salad dressing, frozen desserts and speciality breads. Comparison of fatty acids of safflower oil with other vegetable oils. Fatty acid Safflower Soya Sunflower Groundnut Palmitic Stearic Oleic

38 DLCP 432 Industrial Crop Production - Oil Crops - Safflower Linoleic Linolenic Eicosenoic ADAPTATION Climatic requirements Safflower is essentially a crop of the warm-temperate regions, whose range has now been greatly extended by selection and breeding. Distribution as a peasant crop is in a band approximately contained within the latitudes 40 N-20 S. Safflower is normally grown below 1000 m.a.s.l., and both seed yield and oil content fall with increasing height. In the high-altitude tropics, safflower will grow well, but yields are low as compared to yields obtained below 1000 m. There would appear to be no major reason why suitable varieties should not be bred for the very extensive highland areas. Although safflower is considered day-neutral, varieties may show adaptation to specific photoperiods, and a short photoperiod can prolong the rosette stage. It would appear that temperature is more important than day length. The most important effects of temperature on safflower are seedling tolerance of low temperature, and susceptibility to high temperatures at flowering, although there is considerable varietal variation. Seedlings can tolerate -7 C, with specific tolerance as low as - 12 C in certain varieties, but become more susceptible to frost damage at the cessation of the rosette stage. In general, varieties with a short rosette stage are more susceptible to frost damage than those with a long rosette period. Frost on maturing crops affects both yield and oil content of seeds, and so the period from stem elongation to maturity, approximately days, depending on variety, should be frost free. There can be an interaction between high temperature and soil moisture, with a shortage of the latter exacerbating the deleterious effects of the former, and adequate soil moisture ameliorating the effects of high temperature. High temperature tends to decrease seed weight and oil content, and affect oil constituents. High temperature together with high humidity can severely reduce seed yield. Safflower is considered drought resistant, but this is true only of its independence of rainfall. It is capable of obtaining moisture from levels not available to the majority of crops, and so can tap subsoil moisture or seepage. In dry areas where rainfall is scarce, and high temperature during the growing season encourages quick maturity, planting may have to be delayed in order to avoid the development of a large plant that will exhaust available soil moisture producing foliage, with subsequent meagre seed yield. In general 600 mm is the minimum rainfall necessary to produce a commercial crop, the major portion falling before flowering. In more dry windy regions, which are most suitable for safflower since the incidence of disease is lower, mm may be necessary, the larger amount when irrigated. In areas where there are no hot, dry winds, and with adequate pre-planting soil moisture levels, 300 mm of rain will produce excellent yields if this falls mainly prior to flowering. In its younger stages, particularly the rosette period, safflower is little damaged by even severe hailstorms, but, once the stem begins to elongate, it becomes more susceptible. Hail immediately prior to the formation of flowers and secondary branches can do immense damage, especially where the growing season is limited, but mature plants are resistant to all but the most severe storms. Fully grown plants are extremely wind resistant, and, even after seeds are mature, there is little loss from lodging or shattering. Soils Safflower is grown by small-scale farmers on a wide range of soil types, with a ph of 5-8, but for commercial production highest yields are obtained on fairly deep, well-drained, somewhat sandy loams of neutral reaction. Irrespective of their fertility, shallow soils seldom produce high yields, which is invariably due to insufficient moisture. Dense subsoil will retard root growth, as will a layer of impermeable clay, and the yield from rainfed crops will be substantially reduced even though the subsoil below the layer has adequate moisture. Acid soil can increase the possibility of attack by Fusarium root rot, since soil acidity is known to favour development of several biological forms of this fungus. Safflower is considered to be salt tolerant, ranking just below cotton in its ability to produce a profitable yield when grown in saline soil, and is similar to barley in its tolerance of alkalinity when rain-grown (see figure overleaf). It is especially tolerant of sodium salts, but less so of disalts and trisalts containing either calcium, magnesium or both. Salinity delays initial emergence, which subsequently tends to be irregular, while very high levels of salinity also reduce germination. The use of saline soils for crop production is becoming increasingly necessary, and trials with safflower have shown significant differences between cultivars in their reaction to salinity, which suggests that selection for resistant types is possible. 38

39 DLCP 432 Industrial Crop Production - Oil Crops - Safflower Yield reducti : : : Beans Flax Salt tolerance of field crops. Th tolerances apply to the period o growth from late seedling stage least tolerant plants appear at t the most tolerant plants at the b Broad bean Maize Padi rice Sesbania Soybean Sorghum Wheat Safflower Cotton Sugar-beet Barley ECe in milimhos per cm at 25 C Fertilisers Safflower is grown on a commercial scale in few of the countries to which it is indigenous, and little fertiliser is applied to the crop except when it is part of a mixed sowing which has been given an overall dressing. As a result, there is a lack of reliable data. The nutrient most often required is nitrogen, either in the seed-bed or as a top-dressing. Phosphate requirements are moderate, and potassium necessary only where there is a major local deficiency. The new high-yielding varieties - some specifically developed for irrigated production - have a higher nutrient requirement. When these are to be grown, it is necessary to establish the optimum nutrient level with field trials. In common with other oilseeds, placing seed and fertiliser in contact adversely affects emergence, and band placement to the side or below seed is recommended. Seed-bed placement of nitrogen generally increases the uptake of phosphorus, but the economics of so doing must be determined. Visually improved seedling growth does not necessarily result in higher seed yield. Nitrogen increases seed yield primarily through its effect on the number of heads per plant. Increase is greatest in tertiary, and to a lesser extent secondary, heads. Effect of nitrogen on yield components - Australia Ammonium Seed heads/plant Seeds/head Weight of seed/head (g) nitrate Primary Secondary Tertiary Primary Secondary Tertiary Primary Secondary Tertiary (kg/ha) head head head head head head head head head CULTIVATION Land preparation, sowing and harvesting of safflower presents few problems, and cultivation suitable for wheat or maize is also suitable for safflower. However, too much surface cultivation can lead to the pulverisation of many tropical soils, and as safflower is a deep-rooted crop, the use of chisel ploughs or subsoilers is recommended. Plough pans, clay or lateritic layers within the root zone should be fractured, as these inhibit tap-root development, severely curtailing the plant s ability to use sub-soil moisture. The seed-bed should be free from clods, but not so fine that it caps after rain. Safflower requires moist soil for germination, so, in some years it may be necessary to postpone planting of rainfed safflower until the soil moisture has reached a suitable level and depth. Where moisture is the limiting factor in crop production, cultivations should be few and aimed at retaining the maximum amount in the soil. Seed rate is only important where safflower is grown for commercial oil production on a large scale. Under smallholder conditions, it is usually interplanted, or grown in scattered clumps at a spacing most convenient to the grower. When broadcast with other crops, a seed rate of 5-12 kg/ha is common, the amount varying according to the percentage of the total crop the cultivator wishes safflower to occupy. When grown in strips alternating with other crops, a row spacing of 45 cm is commonly combined with a seed rate of kg/ha. When the crop is rainfed, a major factor determining plant population is available soil moisture. The time of planting affects seed rate; when it is necessary to plant at any time other than the optimum period, a higher population may be required to produce the same oil yield per hectare as would have been obtained from an early-planted crop. Some safflower varieties have smaller seeds than others, so more seeds for a given weight, and this must be allowed for when planting. Within a fairly wide range, safflower has the ability to compensate for spatial variation by producing more secondary and tertiary heads per plant, resulting in little effect on the final yield of seed, but a reduction in the amount of oil produced per unit area. Safflower seed germinates moderately slowly, and requires adequate moisture and fairly high soil temperature over this period. In order to ensure optimum conditions for germination, planting may have to be later or deeper than for other crops in a given area. Seeds should be sown into moist soil 3-5 cm deep. However, when the top cm of topsoil is dry and loose, safflower must be planted into moist soil even if this means that the seed is some cm deep. Where plantings are irrigated, it is considered desirable to water before 39

40 DLCP 432 Industrial Crop Production - Oil Crops - Safflower sowing to ensure that the soil is at field capacity to a depth of metres, depending on soil type. Seed-bed temperature should be in the range C for quick, even emergence of annual crops. Careful hand weeding often gives the highest yield. HARVESTING The harvesting of safflower is comparatively simple since the crop does not lodge or shatter, and there is no restricted period during which harvesting must take place to avoid incurring substantial losses. A mature crop may be left standing in the field for up to one month with small loss. For smallholder production systems, this extended harvesting period may be of small importance, because the grower is often able to collect individual heads as they ripen, but it may lighten the pressure on the farmer if there are other crops to harvest. Some varieties, however, are prone to germination in the head if there are periods of warm wet weather at maturity. In areas where there are large bird populations, such as of love-birds and various species of weaverbirds in East Africa, these quickly flock to mature safflower fields, and cause considerable damage. Safflower is ready to harvest when the plant is quite dry, but not brittle. The bracts on the heads turn brown, and the seed has a moisture content of eight percent or less, preferably nearer five percent. Harvesting can normally take place some thirty-five to forty days after maximum flowering. Seed should be tested for maturity by squeezing several heads between the fingers. If the seed separates easily from the head, it is ready for harvesting. If the seed is properly dry, it requires little attention, since it does not heat in store. STORAGE Seed should be stored in bulk wherever possible, provided the seed moisture content is approximately five percent. Small amounts of sound seed store well at a moisture content of below eight percent with little loss of viability. Storage for long periods of seed intended for crushing is uneconomic, and should be avoided wherever possible. As safflower is both edible and saleable, stores will need to be thief-proof. PESTS A variety of insect pests attack safflower, and although some are of economic importance, the majority do not warrant control measures, especially in smallholder and interplanted crops. Stem borers can cause significant damage, They are small flies, the larvae of which bore into stems and sometimes leaf ribs, and can be seen as very small, shiny white maggots or shiny black pupae in the stem. In Africa, Ophiomyia phaseoli is the most common. Depredations of foliage pests are generally of no great significance, but occasionally major outbreaks of a specific insect cause severe local damage, with leaf worms locally important. The bollworm Heliothis armigera is also a common pest, and assumes varying degrees of importance locally. Leafhoppers occur widely on safflower, but damage is minor. Aphids are common and widely distributed pests of safflower. By far the most important effect of aphids is that they are able to transmit more viruses than any other insect. Myzus persicae, the green peach aphid, is cosmopolitan and polyphagous. In some years plantings in East Africa were continually reinfested from when a few inches high to flowering, while in others there was one peak just prior to flowering. 40

41 DLCP 432 Industrial Crop Production - Oil Crops - Safflower One of the most damaging pests of safflower whenever it occurs is the safflower fly, Acanthiophilus helianthi, whose larvae feed on flower heads and buds. It is a fairly small, rather bristly fly, greyish-coloured with light brown legs. Maggots feed on florets and thalamus, infected buds rot, and an evil-smelling fluid oozes from the apical opening, giving the whole bud a bedraggled appearance. The fly can have up to three generations during the life of a crop, but an early infestation may remain in the terminal shoots prior to flower formation. It is common in Ethiopia at all altitudes. In tropical climates, its numbers are kept in check by predators and parasites; chemical control is difficult as the rate of reproduction and reinfestation is high. DISEASES A range of diseases have been recorded on safflower, and, although most are of minor economic importance, several can limit commercial production. The most economically important disease attacking safflower is the rust Puccinia carthami. Plants are attacked from pre-emergence to flowering, but it is on young plants that the most serious loss occurs, frequently with more damage on irrigated than non-irrigated crops. Symptoms on young seedlings are yellow discoloration, drooping, and wilting of cotyledons and first leaves. Seedlings may also be infected in the hypocotyl and die without exhibiting above-ground symptoms. On older plants, stem girdling can appear, roots be affected, and chestnut-brown pustules appear on leaves and bracts. Other diseases that affect safflower are: root rot caused by Phytophthera drechsleri, which is especially serious when the crop is grown under surface irrigation. wilt or stem rot caused by Sclerotinia sclerotiorum, which is widespread and often seriously damaging disease. wilt caused by Verticillium species, particularly V. albo-atrum, causes various degrees of damage. Symptoms can vary from plant to plant, with some plants being killed before flowering, others developing sterile heads, and still others bearing small or light-weight seeds. Cercospora carthami and Alternaria carthami, which are the two most widespread and important leaf spots. IN ETHIOPIA According to the FAO, the only significant producer of safflower seed in Africa is Ethiopia, which grew approximately 4% of total world production. The production figures for 1996 were estimated as: Area harvested: 69,000 ha Yield: 507 kg/ha Total production: 35,000 tonnes (FAO, 1997). 41

42 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Sesame belongs to: Order: Tubiflorae Family: Pedaliaceae Genus: Sesamum Species: Sesamum indicum syn. S. orientale Sesame (Sesamum indicum) A: flowering shoot; B: lower leaf; C: flower cut open; D: fruit in longitudinal section. GENERAL The Ethiopian area is generally accepted as the origin of cultivated sesame, S. indicum. In addition, S. alatum and S. radiatum, which occur wild throughout tropical Africa, are occasionally cultivated in that region for their edible seeds, which are rich in oil, and are used in soups and other foods, and as an adulterant of sesame. Similar to other plants that have long been domesticated, there are many hundreds of varieties and strains of Sesamum indicum, which differ considerably in form, size, growth, colour of flowers, seed size, colour and composition. It is typically an erect, branched annual, occasionally perennial, metres in height, with a developed root system, multi-flowered, whose fruit is a capsule containing a number of small oleaginous seeds. PLANT CHARACTERISTICS 42

43 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Root system Two basic sesame types are usually distinguished: long-season, also occasionally treated as perennials, which have an extensive and penetrating root system, and short-season, with less extensive, shallower roots. There is a close relationship between climate and growth of both upper plant and root systems. The same variety can behave quite differently in succeeding years of climatic variation. The short-season, usually singlestemmed, types have a more rapid rate of root elongation than the longer-season, branched types, but the latter have a faster rate of root spread. Comparative trials have shown that the initial rate of root growth of rainfed sesame is frequently less than that of groundnuts, maize or sorghum, a factor of importance when sesame is interplanted, a common practice in many countries. Soil type and available moisture influence the rate and type of root growth, and a particular variety can differ markedly from the norm when soil conditions also vary. Roots develop more profusely in sandy than in clay soils, and sesame s drought-resistant qualities are due partly to this widely ramifying root system. Root growth is inhibited by relatively low salt concentrations, much lower than, for instance, is tolerated by safflower. Stem The stem is erect, and normally square in section with definite longitudinal furrows, although rectangular and abnormally wide, flat shapes occur. It can be smooth, slightly hairy or very hairy, which three characteristics are used to differentiate the types. There is probably a correlation between stem pubescence and drought-resistance. Stem colour can range from light green to almost purple, but is most commonly a darkishgreen. Stem height is usually between cm, but can reach three metres. The extent and type of branching is a varietal characteristic, as is the height at which the first branch occurs. Some types have but few branches, or a small number arising from the axils of the lowest leaves; others form primary then secondary branches to a high level on the main stem. Short-stemmed, little-branched types are generally early-maturing; the taller, branched types, late-maturing and tending to be more drought-resistant. Long-season varieties tend to elongate more slowly as seedlings, but increase this rate at later growth stages. Single-stemmed types have relatively thicker stems as seedlings than branched types, but there is little difference at maturity. With early varieties, short photoperiods increase stem diameter; heat increases it most in medium-maturing varieties, as also do long days; in later varieties, long days have a greater influence than heat. There is a tendency for capsules to be closely appressed to the stem in single-stemmed types, producing a very compact plant. Division into the broad classes of branched and unbranched is satisfactory, and in general use. Leaves Leaves on sesame plants are most variable in shape and size, on the same plant and between varieties. Generally. lower leaves tend to be broad, sometimes lobed, margins often prominently toothed, with the teeth directed outwards. Intermediate leaves are entire, lanceolate, sometimes slightly serrate; upper leaves are more narrow and lanceolate. Leaves may be opposite or alternate in different varieties, or can be opposite below and alternate above in others. The arrangement of leaves is important since it affects the number of flowers borne in the axils, and thus optimum seed yield per plant. An opposite arrangement of leaves encourages multiple flowering. Leaf size may vary from cm in length, cm in width, with a petiole cm long. Generally of a dull darkish green, leaves can be much lighter, occasionally with a yellowish tint. Very hairy leaves often appear bluish, especially when grown on fertile soils, In all varieties leaves are mucilaginous and hairy to some degree. There is a basic difference in the rate of water conductance between leaves of indehiscent and dehiscent sesame, the former being much faster. These varieties are therefore less suited to areas with restricted water supply. Flowering Flowers arise in the axils of leaves and on the upper portion of the stem and branches. The node number on the main shoot at which the first flower is produced is a varietal characteristic and highly heritable. Flowers occur singly, but up to eight have been recorded, and may also occur singly on the lower leaf axils with multiple flowers on the upper stem or branches. Flowers are borne on very short peduncles, have a corolla of five lobes, the lower being the longest and the upper the shortest. Corolla colour is generally white or very pale pink, but can be much darker to almost purple, and the inner surfaces may have red or black spots, occasionally purple or yellow blotches. Sesame is normally self-pollinated, but insect pollination is common and wind pollination uncommon. Flowers open early in the morning, wilt after midday, and are usually shed in the evening. The stigma is receptive one day prior to flower opening and remains receptive for a further day. Under natural conditions, pollen remains viable for approximately twenty-four hours. Low temperature at flowering can result in sterile pollen or premature flower fall. Conversely, periods of high temperature, 40 C or above, at flowering will seriously affect fertilisation, and reduce the number of capsules produced. 43

44 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Fruits The fruit is a capsule, rectangular in section and deeply grooved, with a short triangular beak. Capsule size is most variable, and within the basic flat-sided, cylindrical shape occurs a wide range of types. Generally, each shape tends to be a varietal characteristic, with environment a major modifying factor. Several forms can occur on one plant. Capsule length can vary from cm, with a diameter of cm, and the number of loculi from four to twelve. Capsules are usually hairy to some degree. The capsule dehisces by splitting along septa from top to bottom, or by means of two apical pores. The degree of dehiscence is a varietal characteristic, as is the above-ground height of the first capsule. Capsules near the base of the stem normally ripen first, and those nearest the tip last. Thus, if the mature plant were allowed to stand in the field for any length of time prior to harvest, much of the seed would be lost through shattering. The number of capsules per plant is directly related to the number of flowers, and is also influenced by the plant population. High populations tend to reduce both the number of capsules and the number of seeds per capsule. Seed yield is directly related to the number of branches, but the total number of capsules has the greatest direct effect on seed yield. Sesame seeds are small, ovate, slightly flattened and somewhat thinner at the hilum than at the opposite end seed weight is usually between two and four grammes. Testa may be smooth or ribbed, and black, white, yellow, reddish-brown or grey in colour, although dark-grey, olive-green and very dark-brown seeds also occur. Light-coloured seeds are considered to yield a better-quality oil than dark, and are also preferred when roasted and eaten, so usually command a market premium over dark seeds. However, it should be noted that black-coloured sesame in India normally has a higher oil content than light-coloured seed. Oil content of average sesame seeds falls in the range 44-45%, with the protein content being between 19% and 25%. Oil content of seed can vary considerably between varieties and between seasons, and, as with many oilseed crops, the percentage of oil in seed tends to rise with increasing length of photoperiod. Oil The very large world production of sesame seed is almost wholly used for cooking, the major proportion consumed in the country of origin, and only a minor proportion of low-grade oil is used industrially. Sesame oil consists of glycerides, the chief fatty acids being oleic and linoleic, with small proportions of stearic, palmitic and arachidic acids. Crude sesame oil can vary in colour from deep to pale yellow, and is used directly in cooking wherever it is produced. It is usually the favoured oil for cooking, and its nutty flavour is appreciated. The refined oil, which is usually a clear pale yellow, is used commercially as a bland salad oil, and for purposes where an edible oil of exceptional keeping quality is required. Locally expressed oil varies widely in its characteristics and keeping quality, probably due to the seed composition of the dominant local variety or strain. Because of high local demand, there is little international movement of the oil. Due to its popularity and higher price, sesame oil is frequently adulterated with less costly oils, usually groundnut, rape or cotton-seed. ADAPTATION Climatic requirements Sesamum indicum is considered a crop of the tropics and sub-tropics. The diversity of local ecotypes well-adapted to their particular locality is an indication of the plant s potential in this respect. Sesame s main distribution is between 25 S and 25 N, but it can be found growing up to 40 N and 35 S. It is normally to be found below 1250 m.a.s.l., although some varieties may be locally adapted up to 1500 m. These high-altitude types are usually small, quick-growing and relatively unbranched, frequently with only one flower per leaf axil and low seed yields. Within varieties, yields invariably decrease with altitude. Sesame normally requires fairly hot conditions during growth to produce maximum yields. A temperature of C encourages rapid germination, initial growth and flower formation. Should the temperature fall below 20 C for any length of time, germination and seedling growth will be delayed, and below 10 C inhibited. A frost-free period of approximately 150 days is required, and a hard frost at maturity will not only kill plants, but will also reduce seed and oil quality. Sesame is essentially a short-day plant, and with a ten hour day will normally flower in days, but many varieties have become adapted to various light periods. When these varieties are introduced into other areas which have a similar day length, but dissimilar rainfall or temperature patterns, there is frequently a considerable variation in growth and yield from that in their original home. Occurrence of adaptive reactions to shade, and also changes in productivity and oil content of seed, indicate that light intensity has a significant morphogenetic effect. 44

45 DLCP 432 Industrial Crop Production - Oil Crops - Sesame The relationship between time of planting and maximum yield is generally well appreciated, if not well understood, in the main sesame-growing countries. The optimum time has been determined empirically by local growers over a long period, and more recently by trials at experimental stations. The effect of various sowing dates on yield is shown below. Country Sowing date Yield (kg/ha) Sudan Mid-June 536 Mid-July 346 Mid-August 292 Tanzania Mid-January 973 Mid-February 835 Mid-March 521 The rapid fall in yield is typical of most areas. and indicates the necessity of determining the optimum sowing period. This can vary annually, as occurs in Africa south of the Tropic of Cancer. In Africa, sesame is planted after the first rains where these are of short duration, but may be sown later where the crop is required to mature in the dry season. The actual date in any year is, naturally, mainly dependent on the onset of the rains. Sesame is reasonably drought-resistant, but this does not mean that good growth and yields can be obtained on a very low total rainfall. It does indicate that, once established, sesame is capable of withstanding a higher degree of water stress than many other cultivated plants. The seedling stage is, however, extremely susceptible to moisture shortage, and planting techniques may have to be modified where showers following emergence are likely to be scattered and erratic. Where soil moisture is adequate, sesame flourishes, and is relatively independent of rainfall; the crop can grow almost entirely on stored soil moisture, and, with only an odd shower early in growth, good yields can be obtained. It can be planted in areas where rainfall distribution is erratic, and the adaptability of the species has resulted in local varieties extremely well-suited to specific conditions. Sesame will produce an excellent crop with a rainfall of mm, but down to 300 mm and up to 1000 mm will also produce a crop under certain conditions. For maximum yields, precipitation should be distributed over the period of plant growth in approximately the following proportions: germination to first bud formation 35% first bud formation to main flowering 45% main flowering to maturity not more than 20%, falling as seeds are filling, and ceasing as the first pods begin to ripen Heavy rain at flowering will drastically reduce yield, and, if cloudy weather persists for any period at this time, yield can be meagre. Rainfall when plants are ready to harvest also reduces yield by increasing susceptibility to disease, and prolonging the period required for capsules to dry out. Sesame is extremely susceptible to waterlogging. In Sudan, sesame is grown mainly in the mm rainfall areas. At the lower end of the range, the seedling stage is susceptible to a local dry period, but at 500 mm excellent crops are produced. At the higher end of the range, soils must be well-drained - under these conditions, a rainfall of up to 850 mm will be tolerated. In East Africa, sesame is generally grown in those areas too dry for groundnuts, that is in the rainfall range of mm, or where there are likely to be local dry periods which would reduce the groundnut yield to unprofitable levels. Good rainfall distribution during the period of most active growth in January-February improves yields in Tanzania. Sesame is very susceptible to wind damage after the main stem has elongated, and, even in more sturdy types, wind can cause a high proportion of the seed can be lost through shattering in the field. The plant is also highly susceptible to hail damage at all stages of growth. Prior to flowering, stems can be badly bruised, sometimes broken, and terminal shoots so damaged that distorted growth occurs. At flowering, both buds and flowers may be stripped from plants, and damaged buds produce aborted flowers. Heavy storms can virtually strip plants of all leaves and recovery is slow. Crop production on a commercial scale in known hail belts such as occur in a number of tropical regions is likely to prove a hazardous undertaking. Soils 45

46 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Sesame grows well on a variety of soil types, but thrives best on those which are moderately fertile and free-draining. Composition and structure appear to be of secondary importance compared to water-holding capacity, as the plant is extremely susceptible to even short periods of waterlogging at any stage of growth. Shallow soils with an impervious subsoil, or those that are saline, are not suitable. Sesame is extremely sensitive to salinity, and salt concentrations that have little effect on safflower or cotton are fatal to the crop. Soils with a neutral reaction are preferred, although good results have been obtained on slightly acid and slightly alkaline soils, sesame does not thrive on acid soils. It will grow in soils of ph , but at the higher figure, soil structure becomes of increasing importance. Within these rather broad limits, sesame can be grown successfully on a very wide range of soils, but this is due more to the diversity of types well-adapted to local conditions than to the basic adaptability of any one variety. In Africa, sandy soils are often cropped with sesame, not because they are the most productive, but because sesame is the most suitable crop for this type of soil. Fertilisers Sesame, like safflower, is grown as a smallholder crop over the greater part of its range, generally under low standards of husbandry. Local sesame varieties or strains are often extremely well-adapted to specific local conditions. If these are altered, for instance by adding fertiliser, it would become necessary to select another strain more able to take advantage of the new situation. Incorporation of organic manures or plant residues into sandy soils increases their humic content and moisture-retaining ability, although their effect on subsequent sesame crops in tropical areas tends to be erratic, often depending mainly on rainfall prior to planting or the application of additional nitrogen to assist decomposition. In general, fertilisers have little effect on seed composition or oil content, except at much higher rates than are economically justified. Nutrient deficiency symptoms in sesame General chlorosis, with or without withering of plants, appearing initially on older plants and associated with the following: N deficiency P deficiency Mg deficiency Plants light green, stalks slender, branching absent and leaves erect. Lower leaves become lemon yellow, turning to orange. Discoloured leaves are shed Branching suppressed, stalks slender, lower leaves dull dark, greyish green. Necrosis of lower or majority of leaves is followed by defoliation. Lower leaves develop interveinal chlorosis, light yellow in colour, becoming orange later. Green colour persists in midrib and veins, giving a characteristic pattern. Chlorosis appearing as mottling, with or without necrosis: K deficiency Plants dwarfed. and margins of lower leaves become wavy and cupped upward. Light lemon-yellow chlorotic mottling appears, which later turns bright orange and finally copper-coloured. No defoliation. Effects localised in the growing region. Terminals die back: Ca deficiency Terminal dies out following distortion of the tips and bases of young leaves. Hooking downward of the young leaf tips followed by twisting and puckering. CULTIVATION The majority of sesame is grown by smallholders using simple methods and tools. Cultivation required for wheat, sorghum or similar small grains is suitable for sesame, together with subsoiling where a plough pan or clay stratum is present to allow free growth of roots. Cultivation methods for non-mechanised crops are as varied as the varieties planted, and, similar to other crops which have a long history of domestication, traditional methods have evolved which are well-suited to local conditions and tillage implements. In sub- Saharan Africa, sesame is almost entirely grown by manual labour. At peasant level, seed quality alone is seldom a major factor limiting yield, and it is not until the general level of husbandry is raised that it becomes important. In remote areas, or where local conditions differ markedly from elsewhere, it may be necessary to maintain local seed stocks. Such seed production plots should be isolated from main plantings, and, whenever possible, receive a higher standard of attention. Roguing is important in areas where wild sesame occurs. The possibility of a mutation appearing or plants better-adapted to local conditions must always be considered. Seed 46

47 DLCP 432 Industrial Crop Production - Oil Crops - Sesame dressing is not generally used by small cultivators, and there is normally little point in introducing it locally except in the context of a general raising of agricultural standards. Smallholder crops are invariably sown broadcast at rates varying from five to fifteen kilogrammes per hectare. When broadcast, the variety has little influence on the seeding rate within wide limits. However, when sown in rows, the variety has a much greater influence on final yield, rate and type of growth. The effect of variety on seed rate, spacing and yield also varies with the locality. The local Tanzanian sesame described in the table below is a type that branches freely, Inamar is semi-branching, and Acarigua poorly branching. The local type gave the highest yield at the widest spacing tested; Inamar at a wider inter- than intra-row spacing; and Acarigua at a square spacing of 18 x 18 cm. Effect of variety and spacing on yield (kg/ha) - Tanzania Spacing Population of Variety (cm) plants/ha Local Inamar Acarigua Mean 18 x 8 736, x 8 368, x , x , x 8 183, x , x 28 99, x 18 79, x 28 49, Local Inamar Acarigua Mean 250 Yield (kg/ha) x 8 36 x 8 18 x x x 8 36 x x x x 28 Spacing (cm) Fairly high seed rates may be necessary to compensate for loss of plants between emergence and harvest, as such loss can be greater than is realised until specific counts are taken. Losses between emergence and harvest in Tanzania over two years were found to be 25% and 34% in the local Rufiji variety. Where insect pests are also numerous and protection uneconomical, increased seed rates help to compensate for losses. Peasant plantings of sesame are invariably sown by hand, and no particular method is used if interplanted. Seed is scattered and hoed in, and the operation may also weed previously sown crops, or these may have been weeded prior to sowing sesame to provide a relatively clean seed-bed. Sesame seeds, due to their small size, are often mixed with sand, soil or ash to increase the volume handled and so assist even distribution. Sesame requires a warm, moist seed-bed and fairly high temperature for germination, and should not be planted until all danger of frost or low temperature has passed. A seed-bed temperature of C is preferable, and up to 32 C is tolerated. Cold, wet conditions following planting will seriously reduce emergence, and a temperature below 18 C will retard seedling growth, while below 10 C normally inhibits germination. When grown in areas where there is a short but intense rainy season, sesame is best planted after the main rains have fallen and when soil temperature has risen. When grown under irrigation, substantial presowing watering is to be preferred to immediate post-emergence application. Sesame germinates moderately slowly, and young seedlings also make slow initial growth. The banded application of fertilisers in the seed-bed on soils of low to moderate fertility will materially increase the rate of growth and general vigour of seedlings. Sesame seedlings make slow initial growth, and are poor competitors to many quick-growing tropical weeds. A weed-free seed-bed is most important, since cultivation of sesame seedlings is difficult as the fine, fibrous roots are easily damaged. Persistent and vigorous grasses such as Digitaria, Imperata and Sorghum species are major weeds which must be removed prior to planting. Their control in growing sesame is almost impossible, and, as their rate of growth is extremely fast, they quickly smother young sesame plants. Seeds of some of these weeds are harvested with the crop, and, as they are often of similar size and weight, are extremely difficult and expensive to remove. HARVESTING 47

48 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Sesame is usually ready for harvest days after sowing, most commonly days, but some newer cultivars mature days after sowing. At maturity, leaves and stems tend to change from green to a yellowish then reddish tint. Dehiscent types are usually stooked to allow the plants to dry off, then threshed by hand. In sub-saharan Africa, sesame is often stooked in the field, and a considerable amount of seed is lost in handling from the field to threshing site. Where it is a major crop, as in Sudan, special racks are built for drying, and great care is taken to ensure that little seed is lost. Capsules ripen irregularly from the lower stem upwards, the topmost often being only half mature at cutting, and the drying period before threshing allows the seed to ripen without loss from mature capsules. Where labour is short, staggered planting dates, or the use of several varieties with different maturity periods can markedly reduce field losses by extending the harvesting period. It is essential that plants are cut before all capsules are mature, since seed loss due to late harvesting of the shattering types can reach 75%. The optimum period for a variety should be established, since harvesting even a few days earlier or later can cause large yield reductions (see table overleaf). Shattering types are more easily threshed than indehiscent varieties, and little effort is required to remove the seed from the capsule but seed harvested from shattering varieties is always of variable quality because of the uneven ripening, and this variability may be increased by unfavourable weather at harvesting. Sesame yields vary from a few hundred to three thousand kilogrammes per hectare, depending on the system of husbandry practised. Smallholder yields seldom exceed kg/ha when planted in pure stands. Effect of time of harvesting on yield and seed-oil percentage - Venezuela. Time to Seed produced 1000-seed Seed harvest per plant weight oil Variety (days) (g) (%) (g) (%) (%) Aceitera Glauca STORAGE Bulk storage of sesame presents few problems, provided the seed is clean and dry. Seed that heats or is contaminated by extraneous material produces rancid or discoloured oil. As the seed is small and relatively heavy, it occupies a small volume for a considerable weight, and is therefore stored more economically than more bulky oilseeds. Storage methods and containers on peasant farms can be various, and often ingenious, for sesame seeds are readily attacked by a large number of insects, or eaten by vermin or domestic animals. A very common container nowadays is the ubiquitous kerosene can or grease drum, both having tight-fitting lids. In Africa, small quantities may be stored in earthenware jars, or wrapped in small banana-leaf parcels sealed with dung and hung in the smoke of the fireplace. In parts of East Africa, conical mud and wattle granaries holding about 100 kg are constructed, the narrow openings sealed with a mud bung. Several of these stores may be grouped together on a raised platform, and protected by a roughly thatched roof. Sesame seed retains its viability well under controlled conditions. When kept in storage at 50% relative humidity and 18 C, germination vigour was undiminished after one year. PESTS 48

49 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Sesame is subject to attack by a wide range of insect pests, but there is considerable variation in the relative importance of various insects in different countries. In some, those species attacking flower heads and young fruit assume the greatest importance, while in others foliage eaters cause the major loss. In East Africa, for instance, some thirty species are found feeding on sesame, but only half a dozen are of any importance. Insects are a major cause of yield reduction in sesame; an average loss of 25% of potential world-wide production may reasonably be assumed. In general, chemical control of sesame pests is uneconomic, but the extent of potential yield loss must be realised and offset as far as possible by cultural techniques. For instance, high seed rates can compensate for seed-bed losses, branching varieties produce more flowers than nonbranching types, planting dates are established to avoid the main outbreak period of a major insect pest, and the destruction of crop residues assists in the reduction of successive infestations. Screening within local varieties and strains can be very useful in selecting for resistance to a local pest. Insect attack may influence traditional planting and cultivation methods, and their control may require a change in techniques. For instance, late thinning may compensate for gaps caused by mole crickets or cutworms, but, if these pests are controlled, plant populations may be too high, and early thinning or lower seed rates become necessary. Foliage eaters are of major importance in the main sesame-growing areas, although the particular species concerned may differ from region to region. Most common of widespread occurrence in Africa is Antigastra catalaunalis. The adult moth has a wing-span of some mm, with brownish-yellow forewings decorated with indistinct zigzag lines. The hindwings are pale yellow, almost transparent. The moth looks cream-coloured in flight. Fully-grown caterpillars are green to yellowish green, with black spots and a dark brown head, being some mm in length. When newly-hatched, the larvae mine the young leaves and shoot tips; at a later stage, they fasten the leaves and shoots together with silk and feed inside. Pods and flowers may also be destroyed. On smallholder crops, hand picking is recommended. Ploughing of cropped fields after harvest will expose pupae and reduce the incidence of the pest in the following season. Aphids can be extremely damaging to sesame plantings at all stages of growth, and are of widespread occurrence. They are important not only for the damage they cause during feeding, but also for the virus diseases they transmit. Varieties of sesame vary greatly in their degree of resistance to aphids, and, in areas where the pest id prevalent and protection costs high, such resistance would be valuable. The cosmopolitan Myzus persicae is the aphid most commonly found on sesame, and the most damaging. The aphid is light green or yellowish with indefinite strips of dark colour on the abdomen, some 2 mm in length, with antennae as long as the body. Typical symptoms of attack are leaves strongly wrinkled and curled downward, with young shoots deformed. In young plants, growth may be severely impaired, and, if the infestation is not controlled, yields will be greatly reduced. Aphis gossypii is also of widespread occurrence, but generally not as common on sesame as M. persicae. It can be more damaging locally, especially in Africa, where sesame is grown interplanted with or adjacent to cotton. The aphid may be yellow, green or black, and is some 1.5 mm in length. Population increase is extremely rapid, the development period of one generation being eight to ten days. Symptoms are generally similar to those caused by M. persicae, but may often initially be confined to the growing points of plants. Pests which specifically damage the flower, fruit or seeds are often the most economically important of the complex of insects which attack any plant. Although the physical damage they do may be proportionately much less than other insects do to, for instance, leaves, their impact on final yields can be much greater when the damaged parts of the plant are those desired by the grower. Where it occurs, the sesame gall midge, Asphondylia sesami, can cause extensive damage. Eggs are laid in ovaries of flowers, and the gall begins to develop before the petals wither. Fruits may be shed after attack, or they may develop into larger galls inside which the fly maggot feeds and eventually pupates. The adult emerges through an exit hole, leaving the empty pupal case protruding. In Africa, it can cause substantial yield reduction in particular years, and is to be found in the majority of pure sesame stands, or where sesame forms a substantial portion of an intercropped sowing. The Pentatomidae, stink bugs, are also major pests, causing extensive damage to seed-pods, and may be found in almost any sesame planting visited. Nezara viridula is the most widely occurring. It is in Africa that the greatest degree of damage probably occurs, and several other species are also found on the continent. Populations as low as one or two bugs per plant can cause serious reduction in yield. Calidea nana is occasionally a serious pest in Sudan, and C. dregei in East Africa, especially Tanzania. Agonoscelis pubescens is a serious pest of sorghum in Sudan, and also attacks immature sesame pods. 49

50 DLCP 432 Industrial Crop Production - Oil Crops - Sesame Cutworms, especially Agrotis ipsilon and A. segetum, are widespread and common pests in sesame fields, causing considerable local damage to seedlings. Zonocerus variegatus, a brightly coloured grasshopper, can be most damaging when heavy local outbreaks occur. Cyrtacanthacris tatarica has been recorded as damaging crops in sub-saharan Africa. Small crysomelids, flea beetles, are common in East Africa, and may sometimes occur in very large numbers. Damage caused is directly related to the degree of infestation, but, as populations rapidly build up, control measures must be taken before major damage is caused to young seedlings. A very small bug, Aphanus sordidus, may cause substantial damage by sucking maturing seed in the field prior to harvest, when stooked, or even on the threshing floor. Damaged seed is shrivelled, stained black, and fails to germinate. The bug also attacks groundnuts and sorghum. It congregates in considerable numbers on threshing floors. No stem-borer is reported as a major pest of sesame, although several species have been recorded as of minor or local importance. DISEASES Chemical control of sesame diseases is difficult and seldom economic, and cultural methods should be used wherever possible to reduce the incidence and spread of disease. The use of resistant varieties, destruction of crop residues and alternate hosts, and rotations giving a quarantine period should all be tried. Probably the most damaging diseases, where they occur, are bacterial leaf spot, Pseudomonas sesami; stem and leaf blotch, Alternaria sesami; the leaf spots, Cercospora sesamicola and C. sesami. Fusarium wilt (Fusarium oxysporium f. sesami) can be devastating to susceptible varieties, but local strains appear to have some degree of resistance to the local race of pathogen. Charcoal rot, caused by Macrophomina phaseolina, of which the sterile stage is known as Sclerotium bataticola, attacks the stems of sesame, causing them to become characteristically black and rotten. Capsules are also affected, and seeds with small black sclerotia of the fungus can be found in these pods. Stem anthracnose, caused by Colletotrichum species, is important locally in Africa. IN ETHIOPIA Ethiopian production figures for 1996 were estimated as (FAO, 1997): Area harvested: 61,000 ha Yield: 508 kg/ha Total production: 31,000 tonnes Soya (Glycine max) 50

51 DLCP 432 Industrial Crop Production - Oil Crops - Soya A: leaf; B: flower from below; C: flower in longitudinal section; D: pod; E: seed. GENERAL It seems that the genus Glycine originated in eastern Africa, although the centre of domestication of the cultivated soya is thought top be the eastern half of north China. The soya grown for seed production is a leguminous annual, normally bushy, erect, usually less than 75 cm in height, much branched, with well-developed roots, and producing numbers of small pods containing round, usually yellow or black seeds. The various growth stages of a soya plant have been well-defined, and an international standard published, as shown overleaf. PLANT CHARACTERISTICS Root system The root system is extensive, with a tap-root which may exceed 1.5 m in length, giving rise to many lateral branches, usually in the 0-30 cm horizon. However, there is considerable variation between cultivars in respect of rate of growth, total amount, spread and degree of penetration of roots, factors which must be considered when choosing varieties to be grown in specific conditions. A cultivar with a quick-growing, deeplypenetrating tap-root should be selected as a rainfed crop, or where residual subsoil moisture is available. There are three separate phases of root development in soya, corresponding to a specific period of vegetative development: extension of the tap-root and shallow horizontal laterals accompany vegetative top-growth root development to 75 cm is related to flowering and pod formation extensive and deeper penetration of lateral roots occurs during seed maturation. Growth stages of soya. 0: Pre-emergence 6: Beginning bloom 1: Emergence 7: Full bloom 2: Unifoliate leaves 8: Pod production 3: Trifoliate leaves 9: Bean development 4: Four nodes 10: Bean full size. Physiological maturity. 5: Six nodes 11: Harvest maturity 51

52 DLCP 432 Industrial Crop Production - Oil Crops - Soya Roots initially elongate faster than above-ground growth, and in the field, under normal conditions, roots of rainfed plants will be twice as long as above-ground plant height at growth stage 5. Under irrigation, this relationship was found to extend to growth stage 8. Soil temperature affects the rate of root growth. and a range of C appears to be optimum for quick initial growth. Neutron radiography has allowed the determination that 48 hours after sowing, soya had a tap-root 14 mm in length, by 72 hours 18 mm, by 120 hours 44 mm with several laterals, and at 170 hours it had reached a length of 88 mm, and produced laterals half this length. It cam therefore be appreciated that apparently small seedlings in the field can have extensive and spreading roots, that are easily damaged mechanically. Roots carry nodules containing a species-specific strain of Rhizobium japonicum bacteria, which, when well-developed, render the plant generally independent of nitrogen application. Nodules are small, approximately spherical but occasionally lobed, smooth surfaced, and are produced in large numbers when the specific strain of bacteria are present. When these bacteria are not present in the soil, the seed must be inoculated to ensure adequate nodulation. There are differences in the ability of different strains of R. japonicum to fix nitrogen and in their symbiotic relationship to specific soya cultivars. Quick initial growth of the tap-root is important, since its nodules, which first appear some seven to ten days after planting, are main contributors to early plant development. Lateral root nodules become more important at flowering and seed formation. Stages in soya development (solid line indicates soil level). Stem The stem is normally round, often hairy, varying in colour according to the variety, usually less than 75 cm in height, the lower internodes becoming woody with age. Plants are naturally much-branched, although modern cultivars usually have less than six branches, and there are determinate and indeterminate types. Nodes which develop simultaneously on the main stem and branches tend to act similarly, in that they flower at the same time and have a similar number of flowers and pods. Tall varieties, which may reach up to 200 cm, and recumbent types are generally grown for fodder of as smallholder crops, since they are unsuitable for mechanised production. Trials indicate that plants which achieve maximum height at flowering, with minimal subsequent growth, produce higher seed yield than plants which significantly increase their height after flowering. Leaves leaves are alternate, variable in shape, hairy in some varieties, normally trifoliate, the three ovate or lanceolate leaflets borne on a long petiole, and stipulate. The most common colour is dark green, but leaves can appear tinted with shades of brown, red or blue when growing in the field. Maximum leaf area index values of 5-8 are usually attained at main flowering, and reduce to 4-6 at physiological maturity. Leaves are normally shed as the seed pods ripen. Soya leaves have characteristic Calvin cycle photosyntheses, and there is initially little variation between leaf photosynthetic rates until main flowering and pod filling. Then, new upper leaves have rates much higher than previous leaves, although the extent of this different and the general rate of 52

53 DLCP 432 Industrial Crop Production - Oil Crops - Soya photosynthesis is also directly related to the cultivar and environment. Pods and stems also contribute to CO 2 uptake to some extent, especially during seed development. Flowering Flowers are borne on short racemes originating in leaf axils, each inflorescence bearing up to twenty small purple or white flowers, which are typically leguminous in shape (see below). Longitudinal section of soya flower. Self-pollination is the rule, pollen being shed just before or when the flowers open, and normal outcrossing is estimated at %. Insects are regarded as a minor factor in soya pollination. Cool or cold periods, C, adversely affect flower development, but have little effect on yield once the seed has been formed. The flowering period can be up to six weeks, but is usually between three and four weeks. In indeterminate lines, flowering begins on the main stem at the fourth to eighth node and progresses upwards, the branches flowering some days later than the main stem. Determinate lines flower at the eighth to ninth node and proceed rapidly, so that within a few days every node flowers, including the branches and terminal raceme. The ratio between flowers produced and pods set is very low, often less than twenty-five percent, the reasons for this still being imperfectly understood. It may be that, as with groundnuts, it is an evolutionaryproduced survival mechanism. Fruits The fruit is normally a short, hairy pod, which can vary from two to ten centimetres in length, and two to four centimetres in width, according to variety, and is usually some shade of brown or black, but can have a green, red or purple tint. Pods normally shatter when ripe, releasing the seed, the rate and degree of shattering being a varietal characteristic. A method of determining the degree of shattering showed that a force of 1.72 kg was necessary to open pods of a non-shattering variety as compared to 0.68 kg for shattering varieties. Pod number per plant can vary from a few dozen to several hundred, and, although the number is essentially a varietal characteristic, it is heavily dependent on climatic conditions during growth and flowering. The pods usually contain three, occasionally more, hard round or ovoid seeds, usually between five and ten millimetres in diameter, with a smooth shiny testa and a small distinct hilum. Seed colour can be yellow, green, red, brown, black slightly mottled, or occasionally bicoloured, according to variety. There is, in fact, very great variation in size, shape and colour of pods and seeds. Pale yellow is the most commercially acceptable colour for soya seed intended for human consumption and oil production seed weight varies considerably in the range g, dependent on variety. Oil Soya differs from many other oilseeds as the seeds themselves have few direct uses. they are seldom used as beans unless previously treated in some fashion, and need to be processed to obtain maximum benefit from the crop. Seed-oil content is a varietal characteristic, which is influenced by environment and climate, within the range of 15-22%. The oil normally contains approximately 10% linolenic, 55% oleic and 30% linoleic acid, with up to 50% variation in a specific component. It is the relatively high linolenic acid content, as compared to 1% in maize oil, which is the main cause of poor flavour or flavour instability in soya oil. Protein content, of greater importance, is usually between forty and fifty percent, and contains almost the entire complex of amino-acids, including those considered essential. Protein content is inversely related to oil content, but there are also some indications that high protein content can be associated with lower seed yield. The rate 53

54 DLCP 432 Industrial Crop Production - Oil Crops - Soya of increase in, and total, seed-oil content is temperature sensitive, high temperature generally favouring high oil content. These conditions appear to have the opposite effect on protein content, and it is probable that the more rapid rate of oil accumulation reduces the assimilates available for protein conversion. Seeds are rich in digestible nutrients, have a high calcium, iron and vitamin content, and are of great value in the human diet. The chemical composition of soya seed compared with other tropical pulses is shown below. Chemical composition of tropical pulses (%). Legume Moisture Protein Fat Carbohydrate Fibre Ash Vigna mungo Cicer arietinum Vigna unguiculata Lablab purpureus Arachis hypogaea Phaseolus lunatus Cajanus cajan Glycine max Phaseolus acutifolius Edible use of soya derivatives is numberless, ranging from pure oil, blended oil products, fats, margarine, shortening, processed foods, milk and meat substitutes, and proteins. Soya oil is highly unsaturated, and classified as a semi-drying oil. Its use in the Western world was originally mainly industrial, since the high linolenic acid content and unpleasant odour when used for frying limited edible acceptance. Today, non-food use of the oil is estimated at less than ten percent. Crude soya oil is a clear yellow, with a characteristic greenbean flavour which is eliminated during processing to produce a bland, pale-yellow oil. Following storage, the odour returns to some degree, a fact which has retarded wider utilisation of the oil and its derivatives. A major cause of quality loss occurs at harvest, and is exacerbated during storage and transport. Tests have shown that crude oil extracted from consignments with a significant proportion of split or damaged beans has higher free fatty acids and iron content than oil from whole beans, and the quality falls further as storage and transit time increases. ADAPTATION Climatic requirements Soya is essentially a warm-temperature, short-day plant, that is adapted to growing from sea-level to 3000 m, with a day-length varying from twelve to sixteen hours. Smallholder strains greatly extend this range, but seldom produce a commercially profitable seed yield. The low yields often recorded from soya crops in the tropics are most often due to deficient management techniques rather than to any inherent lack of crop potential. For this potential to be realised, soya must be planted at the optimum time, correctly fertilised, adequately weeded and properly harvested. Soya is highly photoperiodic: a variation in day-length of fifteen minutes may be sufficient to inhibit flower development in a specific variety. In general, short-season varieties require longer days to flower and mature than do short season types. Temperature is probably the next most important factor, and the optimum range for most cultivars is a C day temperature, or C on a mean daily temperature basis. However, plants appear to be generally unaffected by a fairly wide variation in day temperatures prior to flowering, although maximum development occurs close to 30 C. At certain periods, night temperature has a significant effect on development. For instance, an increase in night temperature to around 24 C will decrease time to flowering. The interaction between day-length and night temperature on the time to first flowering on soya and cowpea is shown below. Effect of daylight and night temperature on time to first flowering (days from sowing) in soya and cowpea - Nigeria Day-length/ night temperature treatment combination Sensitivity to: 11 hr. 40 min. 13 hr. 20 min. Day- Cultivar 24 C 19 C 24 C 19 C length Temp. Both Soya Grant

55 DLCP 432 Industrial Crop Production - Oil Crops - Soya Hshi hshi TK 5 * Belgium Congo * Improved Pelican * Cowpea TVu TVu TVu TVu 859 * TVu 1020 * TVu 2744 * * Note the consequence of equal and opposing night temperature and day-length effects on onset of flowering A daytime temperature of 25 C or less also delays flowering, and prolonged periods of cloudy weather tend to extend the vegetative stage at the expense of seed yield. High temperature also affects seed viability and vigour. A mm rainfall is necessary to produce high seed yield, and, although soya can tolerate dry soil conditions prior to flowering, adequate soil moisture is essential once the buds have formed and until the pods have filled. High humidity during seed maturation will lower seed viability and seed vigour, and reduce storage life. Soya is slightly more drought-resistant than maize, but much less so than sesame. Waterlogging for lengthy periods at any stage is detrimental to growth and yield, but especially so at germination and emergence. Frost normally kills soya plants at any stage of growth prior to maturity, and a frost-free period of some 120 days is usually considered desirable for optimum yields. Hail is severely damaging to young seedlings, but less so at flowering. Even if a substantial number of buds and flowers were to be destroyed by hail, plants are capable of largely compensating for such loss if other conditions are favourable. High winds when the pods are ripening increase the danger of shattering. Lodging caused by termite attacks on drying roots and the stem can be severe in arid regions. Soils Soya is tolerant of a wide range of soil conditions, with the highest yields obtained on well-drained fertile loams. Highly compacted soils produce short, sturdy plants with restricted root development and few nodules. In general, soya will produce high yields in areas where maize is grown, although very sandy or heavy clay soils require skilled management when used for commercial soya production. Soil reaction can vary from fairly acid to slightly alkaline, ph , but ph is desirable. since acid soils reduce nodule bacteria activity and also magnesium and calcium availability. Soils with a boron content as low as 1 ppm (µg/g) in the soil extract will adversely affect yields, as this element is toxic to soya. Soya has a low salinity tolerance, less than half that of cotton, but slightly more than many varieties of maize. Tropical red earths can grow good soya crops, but, in general, vertisols have proved extremely difficult, as the surface can dry and cap very quickly. This crust prevents emergence, or results in the cotyledons being held in the soil while the hypocotyl continues to grow until it fractures, resulting in a fatal condition known as bald head. Fertilisers Soya has a moderately high nutritional requirement in comparison with grain crops, removing more phosphorus, potassium, magnesium and calcium than a comparable maize crop. Of the total amount of nutrients used by the plants, up to 70-80% of the nitrogen and phosphate, and 60% of the potassium is usually in the seed at harvest. Analysis of soya plants to show nutrient distribution - Brazil Component N P 2 O 5 K 2 O Mg S kg/ha % kg/ha % kg/ha % kg/ha kg/ha Grain Straw Stubble/roots Total Per 100 kg seed

56 DLCP 432 Industrial Crop Production - Oil Crops - Soya Percentage distribution of the total nutrient uptake in 120-day-old soya - Brazil Plant part Stems Leaves Pods and seeds N P K Ca Mg S B Cl Cu Fe Mn Mo Zn Al When soya is grown in rotation with other highly fertilised crops, and inoculated seed is used, little additional nutrient is needed. Phosphate is one of the most frequently required, and there is evidence to support wide dispersal through the root zone, usually by broadcasting and ploughing-in, for optimum yield. Application of lime to acid soils normally increases yield, and can be all that is necessary for profitable production. Many small farmers are unable to buy or obtain fertilisers, and use crop residues and animal manure. Provided there is sufficient soil moisture, and Rhizobium bacteria are present, good yields are obtained. CULTIVATION The pre-planting cultivation necessary for cotton, maize of beans is suitable for soya, with the qualification that, on heavy clay soils and those with a hardpan or laterite layer, deeper cultivation may be necessary to ensure free drainage or root penetration. The greater soil volume available for nutrient uptake by roots is especially valuable where plant nutrients may be too costly to apply or not readily available. Adequate soil moisture is essential for germination, since soya must reach a moisture content of about 50% before germination processes begin, compared with maize that only requires about 30%. Bold-seeded varieties can be planted deeper than small ones, but, within a variety, it appears that small, sound seed may give higher emergence percentages than large seed. Germination is epigeal, and, under optimum conditions, cotyledons can be above ground in three to five days. They are fully open one day after emergence, the primary leaves unfolding by the fifth to seventh day. The first trifoliate leaf unfolds in nine to eleven days, and reaches full expansion by the fifteenth to seventeenth day. A seed-bed temperature of C produces optimum emergence, with temperatures below 15 C and above 37 C adversely affecting it. Yields fall rapidly outside the optimum planting dates, and increased seed rates or fertiliser applications cannot compensate for the loss. The effect of sowing date and spacing on yield in East Africa is shown below; similar results can be obtained in most countries where soya is grown. Effect of sowing date and spacing on yield (kg/ha) Sowing Spacing (cm) Mean Mean date 60 x 5 60 x x 5 90 x 10 yield yield * 25 May June July July Mean * mean yield of all trials in all years on approximately similar dates - Kenya 56

57 DLCP 432 Industrial Crop Production - Oil Crops - Soya Optimum plant population is a major factor influencing yield, and should be determined locally. As a guide, seed rates of kg/ha, giving a population of 250, ,000 plants/ha, should suffice. It is not always possible to plant soya mechanically, and many smallholders prefer to plant by hand. Planting three to six seeds together, hill sowing, can produce yields averaging 80-90% of drilled crops at the same row-width, when sown in pure stands and receiving the same level of attention. There is also a substantial saving in seed cost. Inoculation of seed with a particular strain of Rhizobium is usually necessary where soya has not previously been grown, or grown in the preceding four years. On fields which have previously grown soya, or where an indigenous Rhizobium strain is present, inoculation with a different strain may be ineffective. There may also be antagonism between a specific soya cultivar and Rhizobium bacteria. Weeds Weeds in soya reduce seed yield, the degree of depression being related to the amount of weed and the growth stage of the crop. Young soya seedlings are unable to compete with many fast-growing tropical weeds, and their control at this stage is most important. Since it is difficult to cultivate soya immediately prior to and just after emergence, every effort should be made to reduce the weed population before planting. Mechanical weeding is less damaging once the plants are 5-10 cm high. After six to eight weeks, soya competes effectively with all but the most persistent weeds, which it may be necessary to remove by hand. Soya plants are more dependent on their vertical than lateral roots, so overdeep weeding operations are not as damaging in terms of yield reduction as might be expected. The sowing of soya into lands that have not been mechanically cultivated (minimum tillage) has been successful in temperate regions, but the major problem in tropical and sub-tropical regions is the subsequent greatly increased weed growth. Where there are pernicious grasses, such as Digitaria abyssinica or Imperata cylindrica, or perennial broad-leaved weeds, the technique is less successful. Soya just cannot compete with these species. HARVESTING Soya is considered ready for harvest when the majority of leaves have fallen, the lowest pods are yellowish and dry, and the seed wholly yellow. Seed should have a maximum moisture content of %; at higher levels, beans will not store without drying, and below 12% mechanical damage increases. A basic problem for growers is to decide when the soya is mature and ready to harvest, and a reliable field indication of maturity is an asset. Research has shown that soya is physiologically mature when the seed coat is completely yellow, irrespective of the pod s main colour. To determine maturity, samples of seed should be collected daily from when the first yellowish pods on any plants are seen. A sample found to contain only. or mainly, yellow seed is physiologically mature, and, when moisture content falls to an acceptable level, harvesting can begin. Seed moisture will usually be between 50-60% at physiological maturity, and days are usually necessary for it to fall to 14%. Soya should preferably be harvested when the majority of plants are mature, but in some areas it can be an advantage to harvest slightly earlier. Frost or alternating periods of rain and sun can cause extensive shattering, and to wait for full maturity may result in increased seed loss. Harvesting may be by a range of methods from wholly manual to fully mechanised. All are equally successful, provided the timing of the operation is accurate. Manual harvesting consists of pulling the plants by hand, throwing them into heaps and threshing with sticks, or pulling by hand, wind-rowing and threshing mechanically. In general, windrowing is not recommended, except in those circumstances where field conditions normally preclude natural drying, since losses from shattering are increased. Gleaning is possible. STORAGE Correct harvesting procedures which produce whole, sound beans will materially reduce subsequent storage problems. Dirty samples of sound beans are easily cleaned and require less protection than clean samples with a high proportion of damaged beans. Oil from the latter will also generally have a higher level of free fatty acids. It is possible that hard-seeded cultivars, which produce seed with a substantially harder or 57

58 DLCP 432 Industrial Crop Production - Oil Crops - Soya impermeable testa than normal, can reduce damage during harvest and deterioration in store. Clean dry beans, those with a moisture content of 10% or less, are easily moved in bulk, store well and present few problems other than pest and rodent control. Beans harvested at more than 14% moisture must be dried before bagging or bulk storage. In hot regions, standing the bags open-necked in the shade is sufficient, but where this is not possible, artificial drying is necessary. For over-season storage on the farm, a moisture of 10-12% must be maintained. Since water can migrate to the top of the bins, these must be checked regularly, and the top layer turned so that the beans do not deteriorate. If seed is dried, viability is inversely related to the initial moisture content, that is the higher the pre-drying moisture content, the lower the viability. PESTS Many of the insects that attack the various legumes commonly grown for food or forage around the world also attack soya. When the crop is introduced into a rotation, it is to be expected that local legume pests will also attack soya plants. The level of insect damage which can be tolerated in soya, or the threshold value of crop destroyed compared to the cost of controlling an infestation, must be determined locally. Insects not only reduce yield by directly damaging plant parts, they also indirectly depress yield. Bean leaf beetle larvae injury, for instance, also caused substantial reduction in the extent and development of nodulation, and thus nitrogen fixation. Among the most damaging, excluding locust or army worm outbreaks, are mites, bean fly, moth larvae, certain sucking bugs and nematodes. Termites can be a major source of crop loss in drier regions, especially in seasons of below-average rainfall when plants mature early and roots become dry and fibrous, thus more attractive to these insects. Not only are the plants weakened, but their stems fracture. Pods in contact with the ground are also eaten. The majority of storage pests which infest soya are non-specific, and also attack most stored legumes and grains. Some common soya pests in Africa Seed and seedling Sylepta derogata Leaf roller Agrotis spp. Cutworms Thrips tabaci Onion thrips Chrotogonus spp. Grasshoppers Flower and fruit Epilachna spp. Flea beetles Acanthomia spp. Bean bugs Gryllotalpa spp. Mole crickets Callosobruchus spp. Weevils Stem Epicauta spp. Blister beetles Agromyza phaseoli Stem-borer Epilachna spp. Bean beetles Melanagromyza sojae Stem-borer Hylemya platura Seed maggot Termitidae Termites Maruca testualis Mung moth Foliage Ophiomyia phaseoli Seed fly Aphis fabae Bean aphid Nematodes Cydia ptychora Soybean moth Meloidogyne spp. Root-knot nem. Heliothis spp. Bollworms Pratylenchus spp. Root-lesion nem. Pseudococcus spp. Mealy bugs Rotylenchulus sp. Reniform nem. DISEASES Some common diseases of soya in Africa Fungal Septoria glycines Brown spot Cercospora kikuchii Purple seed stain Thanatophorus cucumeris Rhizoctonia rots Cercospora sojina Frog-eye leaf spot Thielaviopsis basicola Root rot Colletotrichum truncatum Anthracnose Bacterial Corynespora cassiicola Target spot Pseudomonas syringae Bacterial blight Diaporthe phaseolorum Pod/stem blight Xanthomonas ampelina Bacterial pustule Fusarium oxysporum Blight, wilt. pod rot Viral Macrophomina phaseolina Charcoal rot Soybean mosaic virus Microsphaera diffusa Powdery mildew Tobacco ring spot virus Nematospora coryli Yeast spot Yellow mosaic virus Peronospora manshurica Downy mildew Storage Phialophora gregata Brown stem rot Aspergillus flavus Pleosphaerulina sojicola Leaf spot Aspergillus niger Pythium spp. Damping off Colletotrichum truncatum 58

59 DLCP 432 Industrial Crop Production - Oil Crops - Soya Sclerotinia sclerotiorum Stem rot Rhizopus spp. IN ETHIOPIA Recommended varieties: Jupiter; TEM 260, Altitude: higher altitudes from 1000 to 1700 m.a.s.l. Soils: very good results on such soils as reddish brown or even heavy clay. Time of sowing: mid-june to early July Recommended spacing: 5 x 40 cm Seed rate: kg/ha Rainfall: mm, well-distributed through the main growing period 59

60 DLCP 432 Industrial Crop Production - Oil Crops - Sunflower Sunflower (Helianthus annuus) A: flowering shoot; B: portion of capitulum in longitudinal section; C: ray floret; D: disc floret in longitudinal section; E: achene; F: achene in longitudinal section. GENERAL The sunflower, Helianthus annuus, is a member of the Compositae, a large and successful family of flowering plants occurring throughout the world, although few are of economic importance as cultivated plants. The genus Helianthus is named from the Greek Helios (sun) and anthos (flower). H. annuus was named by Linnaeus, to whom the only sunflower known lived but a single season. In fact there are many perennials among the sixty-seven presently recognised species in the genus. About seventeen species, mainly ornamental, can be considered as cultivated sunflowers, and identification is often difficult. Commercial varieties grown for seed are considered to be H. annuus var. macrocarpus, with H. annuus ssp. lenticularis the nearest wild relative. Most ornamentals should apparently be referred to as H. annuus ssp. annuus. Sunflowers are cultivated world-wide commercially and as ornamentals. Some are also grown for fodder or silage, and the plant is often deliberately sown to attract birds. Today, sunflower is one of the world s important oilseeds, with global production in 1996 of around twenty-five million tonnes of seed. The cultivated sunflower is a tall, erect, unbranched, coarse annual, with a distinctive large, golden head, the seeds of which are often eaten, and are commonly crushed for their oil. Easily observable changes in plant growth form the basis of the definition of the development stages of the crop. 60