Performance and Inbreeding Depression between a Synthetic and Three Improved Populations of Maize

Abstract

Effective recurrent selection for a quantitative trait will increase the frequency of favorable alleles in the maize population. As a result, fewer deleterious alleles are expressed for the quantitative trait when inbreeding. This study was conducted to compare performance and inbreeding depression in the original Iowa Stiff Stalk Synthetic (BSSSC0) maize (Zea mays L.) population, two improved Iowa Stiff Stalk populations [BSSS(R)C9 and BS13(S)C3], and the cross between the improved populations (C3 ✕ C9). The improved populations of BS13(S)C3 and BSSS(R)C9 yielded similarly to BSSSC0, whereas the S1 generation of BS13(S)C3 and BSSS(R)C9 yielded significantly greater than the S1 of BSSSC0. The C3 ✕ C9 population showed high‐parent heterosis at the S0 and S1 generation levels. Only the BS13(S)C3 population showed significantly less inbreeding depression than did BSSS. Differences among the three improved populations for inbreeding depression of grain yield were not significant.