Chapter 10-Foods from Roots, Tubers and Rhizomes Foods from Roots, Tubers and Rhizomes Roots and underground stems that store food are natural food sources for humans that have been eaten since prehistoric times. Food is usually stored as carbohydrate which gives higher caloric values than aerial stems and leaves.
REVIEW External root structure Internal view of the roots The last few millimeters of a root tip consists of 4 major zones: 1)Root cap 2)The root meristem, a zone of cell division 3) The elongation zone 4) The zone of maturation Eudicot Root Monocot Root pericycle endodermis cortex pith cortex phloem xylem
REVIEW Symplastic transport- Mineral passage from root hairs through the cortex and endodermis via plasmodesmata. Apoplastic transport- Minerals dissolved in water diffuse from the root s environment into epidermal cell walls, then through the walls of the cortical cells to the endodermis.
Storage roots are useful as human food http://www.gardeningclan.com/12-radishvariety-kitchen-garden.html http://www.turniprecipes.co.uk/types-of-turnip/ https://www.morningagclips.com/ sweet-potatoes-are-healthy-andtasty/
Biennial Root Crops The families of major biennial crops: The two major root crops of the mustard family: Turnips are the roots of Brassica campestris which grew wild in Europe and Asia. Indian writings ( 4000 years old) refer to a plant that was an oilseed type of turnip. Europeans also cultivated turnips for seed oil in the 13 th century. Turnips have been held in low esteem throughout history: -In Roman times, turnips were a favorite object to throw at miscreants. -Young German women would reject suitors by giving them a plate of boiled turnips. Turnips were a staple food during winter in Europe during the Middle Ages. The first Jack-O-Lantern was carved out of a turnip.
Biennial Root Crops Rutabagas or Swedish turnips, Brassica napus, are actually more nutritious than turnips. Genetic and molecular studies have shown that rutabagas resulted from polyploidy after hybridization. Brassica oleracea (cabbage) x Brassica campestris (turnip) (n=19) (n=9) Brassica napus (rutabaga) (n=10) The history of rutabaga cultivation has paralleled the history of turnips with the exception of cultivars of B. napus that produce oilseed crops, (rape seed oil or canola oil). In Europe, rutabagas are used as food for domesticated animals. In the U.S., rutabagas are yellow and larger than turnips.
Biennial Root Crops The radish, Raphanus sativa, is an important food crop worldwide. Inscriptions from Egyptian tombs ( 4000 years ago) show that radishes were important in that ancient civilization. In Japan and many other eastern Asian countries, radishes are among the most important vegetables. The large, straight-rooted types are probably similar to the wild types. The round forms were not developed until the 18 th century. The Apiaceae (carrot family) yields two important root vegetables: Carrots are more popular in the U.S. than parsnips. Like most biennials, carrots store reserves in a main taproot (cortex) during the first summer. Originally, wild carrots were probably woody and branched. Human selection led to the conical, unbranched versions of today.
Biennial Root Crops The original carrot cultivars from central Asia were purple and white. Yellow forms caused by a mutation prevented the synthesis of purple anthocyanins. Yellow carrots became the most commonly grown type in Western Europe. Later selection intensified the orange color. Parsnips (Pastinaca sativa) resemble carrots except that they are cream-colored. Parsnips are native to the eastern region of the Mediterranean. These vegetables were eaten throughout Europe during the Middle Ages. The Pilgrims brought parsnips to North America. Beta vulgaris, (Amaranthaceae, amaranth family), provides four different crop plants. -fodder beets (mangel-wurzels) --mostly composed of root tissue --used as stock feed -sugar beets --consist mostly of root tissue --processed for sugar
Biennial Root Crops Beta vulgaris, (Amaranthaceae, amaranth family), provides four different crop plants. -table beets --transition tissue between leaf and root -Swiss chard --eat petiole and leaf Jicamas, (Pachyrhizus erosus; Fabaceae), are known as yam beans and are increasingly common in U.S. supermarkets. Jicama is native to Mexico. In the U.S., the roots are eaten raw in salads and appetizers. Starchy Tubers, Rhizomes and Roots Underground stems, primarily rhizomes and tubers, serve as overwintering organs. Wild tubers were among the principle foods gathered by pre-agricultural people. Potatoes, (Solanum tuberosum; Solanaceae) The tuberous potato ranks fourth as a major food staple. Today, more than 4000 varieties of potatoes are grown in over 100 countries.
Starchy Tubers, Rhizomes and Roots Archeological evidence has shown that wild potatoes were eaten 13,000 years ago in Chile. Potatoes have been cultivated for at least the last 7000 years. In high elevation areas of the central Andes, Native Americans preserve potatoes by a primitive method of drying. The process results as a dry mass of cellulose and starch known as chuῆo. The Spanish introduced potatoes to Europe in the 1500 s. Between 1843 and 1844, potato blight caused by the oomycete (Phytophthora infestans) reached Europe. Within 5 years, virtually of the Irish (and British) potato crops were destroyed. At least 1 million people died of starvation and more than a million people emigrated to the U.S. Rowan Gillespie s Famine statues on Custom House Quay in Dublin. Photograph: John Crowley
Starchy Tubers, Rhizomes and Roots The common potato, Solanum tuberosum consists of two subspecies: -S. tuberosum subsp. tuberosum --southern Chile -S. tuberosum subsp. andigena --Columbia to northern Argentina --cultivated in the Andean highlands All the potatoes taken to Europe were S. tuberosum subsp. andigena. After the potato blight of the 1840 s, cultivars of S. tuberosum subsp. tuberosum which were more resistant to Phytophthora replaced S. tuberosum subsp. andigena in Europe. The second most important tuber in terms of world production is the yam. Although the sweet potato, Ipomoea batatas, is called a yam in the United States, true yams belong to the genus Dioscorea (Dioscoreaceae). Most authorities consider the underground storage organ of a yam to be a tuber, (modified stem). Different species of yam are native to Africa, Asia, and South America. Domestication has occurred independently on each continent. In many parts of Africa and Asia, yams are important to all aspects of culture. In New Guinea and Melanesia, yams are central to rituals and ceremonies. Propagation of yams occurs by asexual means through planting pieces of tuber with buds. Most of the cultivated species are poisonous or semi-poisonous because of the presence of oxalates. Peeling and boiling the yams will eliminate the problem.
Starchy Root Crops Most of the root crops native to temperate regions are vegetables generally used as side dishes, but the major starchy root crops of tropical regions often make up the entire meal. The most important tropical root crop, Manihot esculenta has many names: Fifty percent of the global production is in Africa. Manioc is a staple food (starch) for 800 million to 1 billion people. Molecular work indicates that domestications occurred in South Central Brazil and spread west and north to Central America. Griddles for baking manioc bread date to the year 1992 B.C. in South America. Manioc is an ideal crop for tropical regions: -grows well in arid and wet climates -produces storage roots in poor soil -relatively resistant to insect and fungal pests -requires minimum of agricultural labor -high yield per unit area Drawbacks of manioc: -contains little protein -essentially no vitamins -often contains poisonous compounds -- must be removed before consumption
Starchy Root Crops In Brazil and Venezuela, the manioc roots are shredded, pressed and drained overnight. The wet, day-old pulp is used to make a flatbread ( 1 meter in diameter) dried and powdered to produce flour toasted farofa juice from the pulp dried fermented into beer eaten raw baked into bread if heated, it gelatinizes into pellets (tapioca) The sweet potato Ipomoea batatas (Convulvolaceae) is cultivated throughout the world. In temperate areas, it is grown as an annual, and in the tropics, a perennial. Sweet potatoes are grown less extensively than manioc in the tropics because they are more susceptible to disease and insect attack. In the U.S., sweet potatoes are boiled, roasted and fried. Africa consumes 7 million tons a year. Over half of the annual crop of sweet potatoes is used for:
Starchy Root Crops Sweet potatoes are native to South America. Fossilized sweet potatoes from the Andes date from between 8,000 and 10,000 years ago. The cultivation of sweet potatoes is at the center of the hypothesis that pre-historic exchanges occurred between native peoples of Malaysia and Polynesia, as well as natives of South America.
Study outline-chapter 10-Foods from Roots, Tubers and Rhizomes Review: external and internal root structure; eudicot and monocot root; symplastic vs. apoplastic transport Biennial Root Crops What are the families of the major biennial root crops? What are the two root crops of the mustard family? Turnips (Brassica campestris; Brassicaceae) Rutabagas (Brassica napus; Brassicaceae) Radishes (Raphanus sativus; Brassicaceae) What are the two major root crops of the carrot family? Carrots (Daucus carota; Apiaceae) Parsnips (Pastinaca sativa; Apiaceae) What are the 4 different crop plants of Beta vulgaris (Amaranthaceae)? What are the different uses for each crop? What are jicamas? Name the family Starchy Tubers, Rhizomes and Roots Potato, (Solanum tuberosum; Solanaceae) What part of the plant is consumed? What plant disease caused the potato blight in Europe between 1843 and 1844? What are the 2 subspecies of Solanum tuberosum? Why did the potato blight wipe out virtually all of the Irish and British potato crop? Yam, (Dioscorea; Dioscoreaceae) What part of the plant is consumed? Starchy Root Crops Manioc; Cassava; Tapioca (Manihot esculenta; Euphorbiaceae) What part of the plant is consumed? Why is manioc an ideal crop in the tropics? What are the drawbacks of using manioc as a food crop? Sweet potato (Ipomoea batatas; Convulvolaceae) What part of the plant is consumed?