Recurrent Selection in Soybeans. I. Seed Yield1

Abstract
Three selection criteria were compared after three cycles of a recurrent selection procedure in soybeans (Glycine max (L.) Merr.). The criteria were seed yield per se, efficiency expressed as the ratio seed weight]straw weight, and an index in which the ranks of the components seed yield and efficiency were weighted equally. Selection was based on S1 progeny performance in a replicated nine‐hill plot grown at one location. Composites of S3 seeds from selected St progenies from each cycle within the three selection criteria were evaluated in four environments with 12 replications per environment to compare the effectiveness of each selection criterion for yield response. Only selection for seed yield per se was effective in significantly increasing the yield of the base population. An average yield increase of 134 ± 30 kg/ha/cyde of selection was observed for seed yield per se and 38 ± 55 kg/ha/cycle for the index. Yield decreased an average of 2 ± 47 kg/ha/cycle for selection based on efficiency.Selection for seed yield per se had no significant effect on the unselected traits of seed size, percent oil, and percent protein. The favorable yield response observed in this recurrent selection program suggests that this breeding scheme may be used to develop populations of greater diversity and productivity.