Component analysis of complex characters in plant breeding

Abstract

Component analysis provides the necessary data for the exploitation of recombinative heterosis in plant breeding. Recombinative heterosis is the phenomenon that the progeny value of a complex character exceeds the mid-parent value as a result of the multiplicative relationship between the complex character and its component traits. It is suggested that this form of heterosis may be an important cause of specific combining ability. As such, it may be involved in the heterosis of complex characters in F1 hybrids and in the hybrid vigour encountered in interspecific hybrid populations. It is demonstrated how recombinative heterosis may be explained by a quantitative genetical model involving additive inheritance of the component traits. A simple procedure is proposed to predict progeny performance for the complex character from parental data for the components. This requires regression of individual components on the preceding primary character. The predicted values can serve as a basis for the selection of promising parent combinations. The importance of component analysis and recombinative heterosis for modern forms of plant breeding, based on molecular genetics, is stressed.