Origins of formation and centers of origin of global crops

The first evidence of plant domestication dates back to about 10–12 thousand years ago — to the transition between the Paleolithic and Neolithic periods, when humanity began to transition to a settled lifestyle. For the modern agronomist, understanding these origins is not just history, but a key to managing the potential of crops. Searching for wild relatives helps identify genes for resistance to diseases, pests, and drought that were lost during the selection process.

Kinship Ties and Searching for Ancestors of Cultivated Plants

Finding the direct ancestors of modern field crops is not always possible. Often, wild relatives turn out to be merely lateral related forms, while the true ancestors have long since disappeared. For example, the wild ancestors of the peach have not yet been discovered, even hypothetically. For wheat, barley, peas, faba beans, and chickpeas, modern wild relatives serve only as an indirect reference point.

In 1920, the law of homologous series in hereditary variability was presented at a breeders' congress. It proves the parallelism of variability in closely related species and genera based on the commonality of their origin. This law makes it possible to predict the existence of as-yet-undiscovered plant forms useful for breeding. Today, these classical methods are supplemented by molecular-genetic studies of wild and cultivated species.

• Number of cultivated plant species described — 247
• Found in the wild — 194
• Found in a semi-wild state — 27
• Known only in cultivation — 26

Geographical Centers of Crop Formation

To find valuable starting material for breeding, scientists study the geographical distribution of intraspecific diversity. The definition of centers of formation is based on the racial composition (variability) of a species and the geographical distribution of its diversity. The territory with the maximum diversity of forms of a specific crop is considered the center of its origin.

In 1926, five centers of formation for cultivated plants were identified for the first time; in 1935, three more were added, and in 1971, the classification expanded to 12 modern centers of origin:

• Chinese-Japanese — homeland of soybean, millet, foxtail millet, Japanese barnyard millet, common wheat, buckwheat;
• South Chinese — Indonesian — homeland of many tropical fruit and vegetable crops, some species of sugarcane, oats;
• Australian — homeland of a number of tropical woody plants, eucalyptus, tobacco, some wild species of rice and cotton;
• Hindustani — homeland of rice, club wheat, some species of cotton and sugarcane, a number of vegetable and fruit crops;
• Central Asian (Afghanistan, Turkmenistan, Uzbekistan, Tajikistan, Kyrgyzstan) — homeland of Afghan rye, peas, lentils, chickpeas, mung bean, faba beans, hemp, melon, safflower, some species of cotton;
• West Asian (Asia Minor, Caucasus, Iran, Iraq, Arabia) — homeland of most rye species, some species of wheat, barley, oats, peas, alfalfa;
• Mediterranean (Syria, Egypt, Tunisia, Italy, Greece) — homeland of some species of wheat, oats, barley, clover, most legumes, beet, cabbage, rutabaga, radish, mustard, carrot, onion, garlic, flax;
• African (Ethiopia, Sudan, and other countries) — homeland of some species of cotton, wheat, African rice, millet, sorghum, castor bean, sesame, some legumes, coffee, kola nuts, oil palm;
• European-Siberian — homeland of fiber flax, alfalfa and sickle medick, hybrid and white clover, hemp, hemp dogbane, hops, some vegetable and fruit plants;
• North American — homeland of some species of barley, sunflower, lupine, many vegetable, berry, and fruit crops;
• Central American (Mexico — Panama) — homeland of maize, some species of potato, bean, pumpkin, summer squash, pepper, sweet potato, long-staple cotton;
• South American (or Andean: Peru — Bolivia — Chile) — homeland of potato, tomato, tobacco, popping maize, some species of barley.