Introduction of Plants

the introduction of plant species or varieties into new places or regions; the term has been used since the second half of the 19th century. The underlying theory, first substantiated in 1855 by A. de Candolle, was elaborated by N. I. Vavilov on the basis of his theory of centers of origin of cultivated plants. The primary centers contain the main gene pool of wild related species and the most ancient forms of cultivated plants, which are carriers of genes valuable for selection and breeding. The carriers of new characteristics that are promising for breeding purposes (yield capacity, high-quality production, early ripening, and so forth) are often concentrated in the secondary geographical centers of many cultivated plants (through mutations and hybridization). Man’s intervention led to the transfer of plants from these centers to new regions and the concomitant broadening of the range of various species. Thus modern cultivated wheat, barley, rice, oats, corn, soybeans, cotton, and sunflower are descendants of wild species that were frequently valuable in themselves.

The geography of the most important cultivated plants has changed; their ranges have been substantially broadened, and, as a result, their connection with the primary centers has frequently been lost. For example, the native home of the coffee bean is Ethiopia, but today its production is concentrated chiefly in Latin America. The main production of peanuts, which originated in northern Argentina, is now concentrated in equatorial Africa. According to Vavilov, there can be two sources for the introduction of plants: (1) gene centers, from which the dominant genes that determine resistance to diseases and pests and high-quality production can be drawn, and (2) remote areas of highly developed agriculture, where there is a concentration of the carriers of recessive genes that determine many valuable characteristics for breeding.

Material for the introduction of plants is primarily provided by the scientific expeditions that are sent by many countries to the primary and secondary centers of origin of cultivated plants. Botanical gardens and other botanical and breeding facilities perform the day-by-day work of introducing and acclimatizing wild species.