vegetable crops – plsc 451/551 lesson 3, domestication, classification. instructor: stephen l....

Vegetable Crops – PLSC 451/551 Lesson 3, Domestication, Classification.

Instructor:Stephen L. LoveAberdeen R & E Center1693 S 2700 WAberdeen, ID 83210Phone: 397-4181 Fax: 397-4311Email: 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, 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.

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:

Botanical evidenceArcheological evidenceHistorical evidenceLinguistic evidence

(Last 3 more likely to determine center of domestication)

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

Vavilov’s Centers of Diversity (origin)

lettuce, turnip

cucumber

cantaloupe

cabbage

watermelon

manioc

potato

pumpkin, tomato

corn, bean

carrotcelerylettuce

onion

pepper

beet

sweet potato

okraeggplant

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 DomesticationBegan 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

Vegetatively propagated plants

re-growth from remnants

no dormancy

discarded propagules in refuse piles

Favored in tropical regions:

Early Cultivation

Seed propagated plants

collected seeds may fall, germinate (after rain) around settlements

eventually seed were actively stored and systematically planted

Favored in mountainous or temperate regions:

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

Plant/human co-development (Fuller, WorldPress.com)

Domestication

Years BC

Domestication

Domestication

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 maize

Domestication

North American marsh elder

Domestication

Gigantism

often a result of changes in PLOIDY

Where PLOIDY reflects the number of chromosomes in a SOMATIC cell

(somatic versus gametic)

Changes in plants as a result of selection:

Domestication

monoploid – has only a single complement of a basic chromosome set of the species

Terms of Ploidy:

also referred to as the haploid state(gamete cells)

Domestication

diploid – has two complete sets of the basic chromosome number of the species

Terms of Ploidy:

Domestication

diploid – has two complete sets of the basic chromosome number of the species

triploid tetrapoid pentaploid hexaploid

Terms of Ploidy:

Domestication

diploid – corn, onion, lettuce, tomato

triploid – taro, watermelon (seedless)

tetraploid – cassava, potato,

hexaploid – yams, sweet potato

Examples of Ploidy:

Domestication

Size

Uniformity of germination

# of seeds per plant

Shattering

Dormancy

Hardness of seed coat

Changes in seed as a result of selection:

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 DomesticatedSeed dispersal present absentPod wall fibers present absentSeed dormancy 70% germ. 100% germGrowth habit indeterminate determinateNumber of pods 43.2 7.5Pod length 5.7 cm 9.3 cmSeed weight (100) 3.5g 19.5gDays to flower 69 46Harvest index 0.42 0.62Flower delay (16 hr) >60 days 0 days

Example of selected diversity in squash

Example of wild species in potatoes

Example of selected diversity in potato

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

Intense Cultivation

Defined as controlled crop production:

Includes:

tillage

planting and transplanting

weed and pest control

harvest and sometimes storage

Bolivian crop terraces

From Correll, 1962

Intense Cultivation

Result of intensified cultivation

Selection for traits resulting in economic benefit to the producer – directed breeding

Ease of managementStorabilityShipabilityMarket specific quality traits

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?

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 Snap bean

Soybean Sweet corn

Tomato

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 Broccoli

Brussel sprouts Califlower

Onions Leeks

Pea Radish

Garlic Asparagus

Classification

Classified by:

Adaptation and hardiness

Life Cycle

Classification

Classified by life cycle

PerennialAsparagus, rhubarb, sweet potato

BiennialBeet, broccoli, carrot, onion, parsley

AnnualCucumber, tomato, spinach, sweet corn

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:

Immature fruit – cucumber, sweet corn

Mature fruit – watermelon, tomato, squash

Leaf – cabbage, lettuce, spinach

Petiole – celery

Seed – beans, pumpkin seed

Classification

Classified by:

Adaptation and hardiness

Method of culture

Parts used for food

Taxonomic grouping (next lecture)