Influence of Intergenotypic Competition on Seed Yield of Heterogeneous Soybean Lines1

Abstract

Two experiments were conducted to determine if overcompensation or undercompensation due to intergenotypic competition is preferentially associated with high or low‐yielding heterogeneous soybean (Glycine max (L.) Merrill) lines. In Experiment 1, yield of 40 random F2‐derived lines, four F5‐derived lines from each F2 line, and a blend of the four F5 lines (F5 blend) were evaluated for two crosses. Linear regression was used to compare the yield of the F2 lines and F5 blends with the mean yield of the four F5 lines. In Experiment 2, four F5‐derived lines were selected from each of six high and six low‐yielding F2‐derived lines in the two crosses. The four F5 lines were evaluated for yield in pure stands, in the six possible two‐component blends, and in a four‐component blend. Yields of the blends were compared with average performance of the components in pure stands.In both experiments, overcompensation or undercompensation was not preferentially associated with high or low‐yielding heterogeneous lines. The results indicated that early generation testing for yield in soybeans should not be biased significantly by intergenotypic competition within heterogeneous lines.