Optimum exploitation of heterosis utilizing the concept of heterotic groups and patterns in hybrid breeding

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For a systematic exploitation of heterosis the concept of heterotic groups and patterns has been advocated. However, until today, the theoretical proof for the necessity of heterotic groups in hybrid breeding has not been presented. Therefore, our objectives are to (1) examine the advantages and disadvantages of the concept of heterotic groups and patterns in hybrid breeding, (2) evaluate different methods for the identification, establishment, and management of heterotic groups, and (3) explore methods to broaden available heterotic groups. The influence of the genetic divergence between heterotic groups on the ratio of the variances due to specific (2scA) and general combining ability (2GCA) was examined applying quantitative genetic theory. These theoretical results will in the following be compared to experimental data (Experiment 1). For identifying heterotic patterns in germplasm with a complex population structure novel model-based clustering methods will be adopted and tested in experimental data in triticale (Experiment 2). In addition, various scenarios for the management of heterotic groups will be compared based on computer simulations and optimal strategies will be suggested. In Experiment 3 we examine methods for an efficient broadening of the genetic basis of established heterotic patterns using molecular markers. We expect that our investigations provide valuable information for an efficient identification, establishment, management, and broadening of heterotic patterns for autogamous and allogamous crops thus guaranteeing an optimal exploitation of heterosis.