Genetic Gain in Early Stages of a Soybean Breeding Program

Abstract

Multistage testing of genotypes is an essential feature in plant breeding programs. Little research is available to help breeders test efficiently. Our objective was to determine the genetic gain obtained in selected stages of a soybean [Glycine max (L.) Merr.] breeding program and to determine ways to increase the overall gain, if possible. The mean selection differential and genetic gain and their regression coefficient were determined for tests at the F3, F4, and F6 generations of the Ohio State University‐Ohio Agricultural Research and Development Center breeding program during 1985 to 1997. Genetic gain for yield averaged −1.4% in the F3 stage, 3.7% in the F4, and 9.1% in the F6 stage, where percentages are based on the mean of the common check genotypes. Overall changes in maturity were small at each stage. Improvements in lodging resistance occurred in the F4 and F6 Negative yield gains in the F3 were attributed to use of unreplicated plots and to the necessary selection pressure for early maturity. Examination of the selection differentials for individual lines indicated that selection could be intensified in the F4 and F6 generations with little risk of discarding potentially superior cultivars. The conclusion that near equality of the selection intensity across stages would be beneficial for this breeding program confirms the theoretical recommendations reported in earlier research.