Instructor: Stephen L. Love Aberdeen R & E Center 1693 S 2700 W Aberdeen, ID Phone: Fax:

Transcription

1 Vegetable Crops PLSC 451/551 Lesson 3,,. Instructor: Stephen L. Love Aberdeen R & E Center 1693 S 2700 W Aberdeen, ID Phone: Fax: slove@uidaho.edu Origin, Evolution Nikolai Ivanovich Vavilov Most of the varietal wealth in our crop plants was concentrated in eight great centers of diversity: China, Hindustan, Central Asia, Asia Minor, the Mediterranean region, Abyssinia, Central America, westcentral S. America Fig. 2.1 Centers of Origin 1

2 Origin, Evolution Nikolai Ivanovich Vavilov Centers of origin i of species coincide id with the areas where the greatest diversity exists in the species. Origin, Evolution Nikolai Ivanovich Vavilov Secondary centers of origin i (centers of diversity) may be found far removed from the primary center of origin. These may be associated with domestication and human movement Centers of Origin Determination of centers: Botanical evidence Archeological evidence Historical evidence Linguistic evidence (Last 3 more likely to determine center of domestication) 2

3 Centers of Origin Features: Geographical location of species origin Site of maximum adaptation Site of maximum diversity Presence of related species Usually associated with site of domestication cabbage carrot celery lettuce corn, bean pumpkin, tomato pepper potato beet cantaloupe onion lettuce, turnip cucumber watermelon eggplant okra manioc sweet potato Vavilov s Centers of Diversity (origin) Centers of Origin Major Crops Lettuce Europe and Asia Cabbage Europe Beet Europe Carrot Europe and Asia Onion Asia Potato South America Sweet Potato South America Bean South America 3

4 Centers of Origin Major Crops Pea Europe and Asia Tomato Central America Pepper Central and South America Cucumber Asia and Africa Cantaloupe Asia Watermelon Africa Squash Central and North America Sweet Corn Mexico? Edible species 20,000 Species used for food 3,000 Species cultivated 200 Major crop species - 25 Crop Species Began 8-10,000 years ago Process Foraging and unintentional selection Foraging and unintentional selection Early cultivation Intensified and large scale production 4

5 Foraging Impact of foraging and plant management Selection of best food types seed distribution Selection of best adapted types in habitat region Unintentional altering of habitat to promote growth of certain plants (i.e. burning) Early Cultivation Began as man approached food production systematically Started as unintentional habitat alteration to favor desired species Led to more intense cultivation; form depended on geographical constraints Early Cultivation Favored in tropical regions: Vegetatively propagated plants re-growth from remnants no dormancy discarded propagules in refuse piles 5

6 Early Cultivation Favored in mountainous or temperate regions: Seed propagated plants collected seeds may fall, germinate (after rain) around settlements eventually seed were actively stored and systematically planted Early Cultivation Impact of early cultivation on crop species Deliberate care of preferred plants Preferential survival of edible crop plants Distribution to new areas of habitat Increased population of humans and thus populations of crop species Years BC 6

7 Characteristics of wild species: Edible parts small, fibrous, bitter Numerous seeds, rapidly dispersed Poor or non-uniform seed emergence Often contain toxic compounds Changes in plants as a result of selection: Gigantism often a result of changes in PLOIDY Where PLOIDY reflects the number of chromosomes in a SOMATIC cell (somatic versus gametic) Terms of Ploidy: monoploid has only a single complement of a basic chromosome set of the species also referred to as the haploid state (gamete cells) 7

8 Terms of Ploidy: diploid has two complete sets of the basic chromosome number of the species Terms of Ploidy: diploid has two complete sets of the basic chromosome number of the species triploid tetrapoid pentaploid hexaploid Examples of Ploidy: diploid corn, onion, lettuce, tomato triploid taro, watermelon (seedless) tetraploid cassava, potato, hexaploid yams, sweet potato 8

9 Changes in seed as a result of selection: Size Uniformity of germination # of seeds per plant Shattering Dormancy Hardness of seed coat Other morphological and physiological changes resulting from selection Loss of survival traits Loss of photoperiod response (potato) Emergence of mutant types (brassica) Absence of toxic substances (tomato) Bean Example Trait Wild Domesticated Seed dispersal present absent Pod wall fibers present absent Seed dormancy 70% germ. 100% germ Growth habit indeterminate determinate Number of pods Pod length 5.7 cm 9.3 cm Seed weight (100) 3.5g 19.5g Days to flower Harvest index Flower delay (16 hr) >60 days 0 days 9

10 Impact of on crop species Selection of useful traits within crop species Elimination of survival traits resulting in dependence on human culture Wider distribution and adaptation Intense Cultivation Defined as controlled crop production: Includes: tillage planting and transplanting weed and pest control harvest and sometimes storage Intense Cultivation Result of intensified cultivation Selection for traits resulting in economic benefit to the producer directed breeding Ease of management Storability Shipability Market specific quality traits 10

11 Intense Cultivation Age-old question I can t buy a good tomato any more! Is the complaint valid that produce has lost quality as we concentrate on economic production factors? Process of lumping numerous crop species into useful categories Classified by environmental adaptation: Warm-season (very tender) Cucumber Eggplant Lima bean Muskmelon Okra Pepper Pumpkin Squash Sweet potato Watermelon 11

12 Classified by environmental adaptation: Warm-season (tender) Cowpea Snap bean Soybean Sweet corn Tomato Classified by environmental adaptation: Cool-season (semi-hardy) Beet Carrot Cauliflower Celery Swiss chard Lettuce Parsnip Potato Classified by environmental adaptation: Cool-season (hardy) Cabbage Broccoli Brussel sprouts Califlower Onions Leeks Pea Radish Garlic Asparagus 12

13 Classified by life cycle Perennial Asparagus, rhubarb, sweet potato Biennial Beet, broccoli, carrot, onion, parsley Annual Cucumber, tomato, spinach, sweet corn Classified by edible portion: Root beet, carrot, turnip Bulb leek, onion, garlic Stem asparagus, kohlrabi Flower cauliflower, broccoli Tuber - potato Classified by edible portion: Immature fruit cucumber, sweet corn Mature fruits watermelon, tomato, squash Leaf cabbage, lettuce, spinach Petiole celery Seed beans, pumpkin seed 13