Effects of competition in the selection
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Date
1984
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Abstract
Competition between plants interferes with the selection process: (1) by reducing genotypic differentiation and therefore progress through selection, (2) by imposing a limit on the number of environments and replicates when testing in early generations, both directly by reducing the number of seeds produced per plant, and indirectly through the establishment of field plots as experimental units, and (3) by making single-plant selection for yield unreliable, since competitive ability is usually negatively correlated with yielding ability. The detrimental effects of competition are overcome effectively by using wide spacings (i.e. 90 cm in wheat, 125 cm in maize) and the honeycomb field designs. With such designs a multisite and multireplicate screening of potential crosses and exceptional genotypes or families can be carried out in early generations. In this way annual progress will be maximized and the time needed to develop a new cultivar can be halved. Genes for adaptation and stability will be incorporated early in the programmes and both individual buffering and monoculture performance will be improved. Finally the scheme ensures a constant improvement of the cultivar, and paves the way for mechanizing and computerizing selection for yield
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honeycomb selection, competition, genotypic differentiation, yield, selection efficiency, early generation selection