Effect of Recurrent Selection on Combining Ability in Maize Breeding Populations

Abstract

Recurrent selection (RS) is a population improvement method that increases the frequency of favorable alleles while maintaining genetic variation in breeding populations. Twelve University of Guelph RS maize (Zea mays L.) populations selected via reciprocal recurrent selection (RRS), selfed‐progeny recurrent selection (S), or a method combining RRS and S (COM), were assessed for changes in the genetic structure of grain yield, grain moisture, and broken stalks, and two associated selection indices. Partitioning of the entry sums of squares from diallel matings of the original (C0) and advanced (CA) cycle populations using Gardner and Eberhart's Analysis II and Analysis III indicated genetic improvement occurred for the per se and cross performance of most populations. Accompanying the favorable changes in population performance were less favorable shifts from predominantly additive genetic effects in C0 to greater nonadditive genetic effects in CA This shift did not substantially change the general combining ability estimates (gi) of most populations. However, for grain yield, the underlying components of gi effects were altered in their relative importance. General combining ability (GCA) effects in the C0 were caused primarily by the population per se effects (vi), while in CA the GCA effects were caused predominately by parental heterotic effects (hi).