Genetic variability and the application of selection indices for yield improvement in two soya bean populations

Abstract

Substantial genetic variability was found in two hybrid soya bean populations and progress in yield through selection was demonstrated. Genetic advance was restricted in those environments in which moisture stress limited the expression of genetic variation. The best F6-derived selection was 49% higher-yielding than the highest-yielding parent. However, most trials were conducted at low to moderate yield levels, and the existence of significant environmental interactions indicates the necessity for regional selection and testing. Selection indices were of greatest efficiency, relative to selection for yield alone, in those environments for which meaningful yield data were unavailable. The crosses differed substantially in the importance of different yield components in the indices. The cost of data collection for selection indices based on yield components is not justified in terms of genetic advance.