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Olericulture – Hort 320 Lesson 3, Domestication, Classification Jeremy S. Cowan WSU Spokane County Extension 222 N. Havana St. Spokane, WA 99202 Phone: 509-477-2145 Fax: 509-477-2087 Email: [email protected] 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, west-central S. America Fig. 2.1 Centers of Origin Origin, Evolution • Nikolai Ivanovich Vavilov Centers of origin of species coincide with the areas where the greatest diversity exists in the species. Video time: http://www.youtube.com/watch?v=WQz5lb72XbE Origin, Evolution • Nikolai Ivanovich Vavilov Secondary centers of origin (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: 1. Botanical evidence 2. Archeological evidence 3. Historical evidence 4. Linguistic evidence (Items 2-4 most likely to determine center of domestication (secondary centers of origin) 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 Centers of Origin Centers of Origin Centers of Origin cabbage carrot celery lettuce beet corn, bean pumpkin, tomato pepper potato watermelon okra cantaloupe lettuce, turnip onion cucumber manioc sweet potato Vavilov’s Centers of Diversity (origin) eggplant 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 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 Domestication Began 8-10,000 years ago Process Foraging and unintentional selection Early cultivation Domestication Intensified and large scale production 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 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 Domestication Domestication Domestication Video Time: https://www.youtube.com/watch?v=6odEvT-YHxE Domestication Characteristics of wild species: Edible parts small, fibrous, bitter Numerous seeds, rapidly dispersed Poor or non-uniform seed emergence Often contain toxic compounds Domestication Changes in maize Domestication North American marsh elder Domestication 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) Domestication 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) Domestication Terms of Ploidy: Diploid – has two complete sets of the basic chromosome number of the species Domestication Terms of Ploidy: Diploid – has two complete sets of the basic chromosome number of the species Triploid Tetrapoid Pentaploid Hexaploid Domestication Examples of Ploidy: Diploid – corn, onion, lettuce, tomato Triploid – taro, watermelon (seedless) Tetraploid – cassava, potato, Pentaploid – sweet potato, potato Hexaploid – yams, sweet potato Domestication Changes in seed as a result of selection: Size Uniformity of germination # of seeds per plant Shattering Dormancy Hardness of seed coat Domestication 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) Domestication – Bean Example Trait Wild Domesticated Seed dispersal Present Absent Pod wall fibers Present Absent Seed dormancy Growth habit 70% germination 90% germination Indeterminate Determinate 43.2 7.5 5.7 cm 9.3 cm 3.5 g 19.5 g Days to flower 69 46 Harvest index 0.42 0.62 >60 days 0 days Number of pods Pod length Seed weight (100) Flower delay (16 hr) Domestication – Squash Example of selected diversity in squash Domestication – Tomato Example of selected diversity in tomato Domestication – Cowpea Example of selected diversity in cowpea Domestication Impact of Domestication on crop species Selection of useful traits within crop species Elimination of survival traits resulting in dependence on human culture Wider distribution and adaptation Cultivation Defined as controlled crop production: Includes: Tillage Planting and transplanting Weed and pest control Harvest and sometimes storage Bolivian crop terraces Cultivation Result of intensified cultivation Selection for traits resulting in economic benefit to the producer – directed breeding Ease of management Storability Transportability Market specific quality traits Cultivation Age-old question: “Why can’t I buy a good tomato any more?” Is the complaint valid that produce has lost quality as we concentrate on economic production factors? Cultivation Classification Process of lumping numerous crop species into useful categories Classification Classified by: Adaptation and hardiness Classification Classified by environmental adaptation: Warm-season (very tender) Cucumber Eggplant Lima bean Muskmelon Okra Pepper Pumpkin Squash Sweet potato Watermelon Classification Classified by environmental adaptation: Warm-season (tender) Cowpea Sweet corn Tomato Snap bean Soy bean Classification Classified by environmental adaptation: Cool-season (semi-hardy) Beet Carrot Cauliflower Celery Swiss chard Lettuce Parsnip Potato Classification Classified by environmental adaptation: Cool-season (hardy) Cabbage Brussels sprouts Onions Pea Garlic Broccoli Cauliflower Leeks Radish Asparagus Classification Classified by: Adaptation and hardiness Life Cycle Classification Classified by life cycle: Annual Cucumber, tomato, spinach, sweet corn Biennial Beet, broccoli, carrot, onion, parsley Perennial Asparagus, rhubarb, sweet potato Classification Classified by: Adaptation and hardiness Life Cycle Parts used for food Classification Classified by edible portion: Root – beet, carrot, turnip Bulb – leek, onion, garlic Stem – asparagus, kohlrabi Flower – cauliflower, broccoli Tuber – potato Classification Classified by edible portion: Fruit – cucumber, tomato, squash Leaf – cabbage, lettuce, spinach Petiole – celery Seed – beans, pumpkin seed Classification Classified by: Adaptation and hardiness Life Cycle Parts used for food Taxonomic grouping (for Monday)
