Achievements of Modern Breeding in Belarus
Selection Methods. The selection process is based on artificial selection – a person’s choice of the most economically valuable animals, plants and microorganisms to further obtain offspring from them with the desired traits and properties. There are two main types of selection: mass and individual.
Mass selection is the selection of a group of individuals that are similar in one or more of the desired characteristics (i.e., selection by phenotype), without checking their genotype. For example, out of thousands of wheat plants of a particular variety, only those plants that are resistant to lodging and have a large spike are left for further propagation. In subsequent generations, plants with the right qualities are selected again.
The main advantages of this method are its simplicity, efficiency and the ability to relatively quickly improve local varieties and breeds. The disadvantage is the impossibility of an individual assessment of the offspring, due to which the selection results are unstable (in the offspring splitting can be observed, which means that not all individuals will inherit valuable traits).
With individual selection (by genotype), the offspring of each individual organism in a series of generations is obtained and evaluated with the obligatory control of the inheritance of the traits of interest to the breeder. In the subsequent stages of selection, only those individuals that gave the greatest number of offspring with high rates are used.
Such selection is most effective among self-pollinating plants (wheat, barley, etc.), since it leads to the production of clean lines with the highest degree of homozygosity. At the same time, a large number of identical descendants can be obtained from one plant due to asexual and sexual reproduction.
In order to increase variants of the source material for selection, induced mutagenesis is used. Thus, in many cereals, mutant forms with a number of useful features were obtained using x-ray radiation. They are characterized by increased productivity, lack of awns (Fig. 114), and a shortened stem. Such plants have significant advantages in machine harvesting. In addition, short and durable straw allows for further breeding to increase the size and weight of grain without fear that increased yields will lead to lodging of plants.