Selection Methods in Plant Breeding Based On Mode of Reproduction - Mass Selection

Mass Selection

This method of selection depends mainly on selection of plants according to their phenotype and performance. The seed from selected plants are bulked for the next generation. This method is used to improve the overall population by positive or negative mass selection. Mass selection is only applied to a limited degree in self-fertilizing plants and is an effective method for the improvement of land races. This method of selection will only be effective for highly heritable traits. One shortage of mass selection are the large influence that the environment has on the development, phenotype and performance of single plants. This can also be an advantage in that varieties can be selected for local performance.

A variety developed by this method will be more uniform than those developed by mass selection because all of the plants in such a variety will have the same genotype. The seed from selected plants are not added together but are kept apart and used to perform offspring tests. This is done to study the breeding behaviour of the selected plant.

Stratified mass selection for ear size over 22 cycles has drastically altered plant phenotype in the maize population Zacatecas 58. Plants in the C22 cycle were 50 cm taller, had twice the leaf area index, reached anthesis 7 days later and had a 30% higher harvest index than C0 (Table 1) Differences in growth were detected early in ontogeny. The root growth of C22 exceeded that of C0 and the ratio of shoot dry mass to root dry mass was reduced by nearly 12%, from 8.0±0.2 to 7.1±0.1 (Table 2). Analysis of yield components revealed that C22 was superior to C0 in grain weight, number of rows per ear, number of grains per row, and total yield per unit area (Table 3). Because the two genotypes were phenologically different, planting density optima are probably different for each population.