Basic Methods for Breeding Animals and Microorganisms
The subject of plant breeding is the theoretical development and practical breeding of new plant varieties, as well as the improvement of old varieties.
In plant breeding, a large role is played by a variety of breeding material. The works of N. I. Vavilov and his followers are devoted to the study of the diversity of the source material. The centers of origin of modern plants cultivated by man were investigated. N. I. Vavilov identified eight such centers, the most important of which are:
1) Chinese (East Asian) – soy, some varieties of barley, onion, eggplant, pears, apple trees and other plants were bred here
2) Central Asian – the birthplace of wheat and legumes –
3) Mediterranean – the birthplace of many vegetables (cabbage, parsley, turnips, onions, etc.), forage crops –
4) South American – the birthplace of potatoes, sunflowers, peanuts, cassava and other cultivated plants.
In these centers the ancestors of modern cultivated plants still grow and they can (and should) be used in plant breeding. Foundations and seed collections of the original plant forms were created, which were used by plant breeders to breed new plant varieties.
In plant breeding, organisms can be divided into two groups: one-and two-year-old herbaceous forms and perennial tree-shrub forms. Different plant breeding methods are applicable to these plant groups. For the first group, mass selection is more widely applicable and, to a lesser extent, individual selection, for the second group, individual selection is more applicable.
In breeding new plant varieties for closely related crosses, self-pollination is used and clean lines are obtained (this method is applicable to all plants).
Obtaining “clean lines” is practiced not only for the actual breeding work, but also to increase plant yields using the phenomenon of heterosis.
Heterosis is a sharp increase in the productivity of first-generation organisms obtained by crossing individuals of “clean lines”.
In plant breeding, the phenomenon of polyploidy is widely used to overcome the barrier of non-crossbreeding during interspecific hybridization and increase the yield of some plants, for example, sugar beets. Polyploidy, in addition to sugar beets, is characteristic of wheat, rye, turnip, and other plants.
The specificity of plant breeding is the use of somatic mutations, since plants are capable of vegetative propagation. Through the use of such mutations, the Antonovka apple and a half pound (six hundred grams) variety was bred. The use of somatic mutations is possible due to the widespread use of the vaccination method, a specific method possible for perennial tree-shrub forms, which include many fruit crops.