NRES 700

Plant domestication is a process which occurs under cultivation in populations of early wild-type crops (sown from seed gathered from wild stands). Mutant plants that possess traits that are desirable to humans (though not necessarily advantageous for survival in the field) are selected and kept in cultivation until mutant phenotypes dominate the crop population.

The process of domestication caused organisms to undergo genetic changes that made them better suited for human use rather than for survival in the wild. In plants, domestication may involve the nonshattering seeds on grain plants. Other examples include large fruit size or seed, higher sugar content, interesting shapes, beautiful colors, lower amounts of toxic compounds (in leaf, stem or tuber ), uniform germination or ripening. The degree of domestication determines whether the plants are capable of surviving on their own without human intervention. A fully domesticated plant is one that is incapable of surviving on its own without human assistance. An example of a fully domesticated plant is corn. Corn cannot dispersed its seeds due to the morphology of the husk that had been selected. Read Domestication of crops click on The process of domestication and also click on Paul Gepts 2002 article on A comparison between crop domestication, classical plant breeding and genetic engineering.(#Both required)

Forty percent of an estimated 2,300 species of cultivated plants belong to just four families, Poaceae (grasses), Leguminosae (legumes), Rosaceae (apples; pears; etc.), and Solanaceae (potatoes). The Poaceae gave the world the most important source of staple crops that humans depend on. Rice, maize, and wheat account for roughly 60 percent of the calories and 56 percent of the protein that humans consume directly from plants.

Rice (Oryza sativa L.) is one of the worlds' most important crop because more people in the world eat rice as a staple food as compared to wheat or maize. In the Orient, the importance of rice is unequivocal because a meal is considered incomplete if rice is absent. The throwing of rice weddings is a symbol of fertility in Asian cultures.

Rice was probably domesticated in Asia. The greatest diversity of rice varieties lies in the northeastern region of India and across South East Asia. Rice was unknown to the Egyptian. Even though rice was not mentioned in the Bible, rice had been cultivated for several thousand years in Asia before the birth of Christ. It was Alexander the Great who first mentioned rice in Europe during one of his conquests at round 320 B.C. Three hundred years before Christ, rice cultivation spread across the Middle East. Spain and Italy were growing rice by the fifteenth century. Read this article on history of rice cultivation in China (#click on The Origin of Chinese Rice Cultivation and Its Spread East).

Maize (Zea mays L.) is the major domesticated cereal from the New World. Maize was the basis of the major New World civilizations, Mayans, Aztec, and Inca. Read Maize Evolution on Maize Domestication and Maize, the Staple Crop of the Americas (#Both required).

Wheat is an annual plant whose ancestors were probably perennial grasses. One of the early species grown is the diploid type called einkorn (Triticum monococcum) has 14 chromosomes. Hybridization between einkorn and a wild goat grass (Aegilops speltoides) gave rise to the tetraploid wheat called emmer (T. turgidum) which has 28 chromosomes. Triticum turgidum var. dicoccum is the free-thrashing wheat known as durum wheat. Durum wheat is primarily grown in the Mediterranean, central Russia, and the Great Plains and is used for pasta and noodle making. The common bread wheat (known botanically as T. aestivum) is hexaploid (42 chromosomes). Read Wheat Evolution (#click on History of Wheat)

Potatoes (Solanum tuberosum) is native to the Andean mountains of South America. When Spanish explorers came to South America, they found these curious starchy tubers being grown by Indians along the Andes from Colombia to Chile. The Spanish knew that these tubers now known as potatoes had a potential as a food source and subsequently introduced it to Spain. Later the rest of Europe learned about potatoes. Potato became great success in Ireland because of the Irish moist, cool climate. Ireland also adopted and became dependent on the monoculture of potatoes so that when the potato leaf blight struck in 1845, virtually all of Irish and British potato crops were devastated. Read Potato Origin (#click on Potato Conquers The World) and watch this video-stream of potato routes (# click on Potato Routes).

If you would like more general information on wheat, click on and visit the following optional links: Kansas State U Wheat Page; The Maize Page

Origins of American crop.

Tubers from the Andes: Extinction or Propagation

After completing Unit I. Section D, please click on Unit I Assignment. Complete the assignments given and then return to the course syllabus and begin reading Unit II.