Improving Breeding Efficiency Of A Hybrid Maize Breeding Program Using A Three Heterotic-Group Classification

Heterotic group classification has a crucial impact on maize (Zea mays L.) breeding efficiency in a hybrid-based breeding program. The objectives of this study were to: (i) investigate whether or not breeding efficiency could be improved using a three heterotic-group (TriHG) classification (Reid and non-Reid, and Suwan1 heterotic groups) system instead of a usual two heterotic-group (DiHG) classification (Reid and non-Reid heterotic groups) system; and (ii) estimate the impact of TriHG and DiHG systems on breeding efficiency, utilizing the same data in computing specific breeding efficiency (SBE) and general breeding efficiency (GBE) in a subtropical breeding program in southern China. Twenty-five adapted tropical and subtropical lines were crossed to six testers using a line x tester mating design. Data on grain yield were used to calculate SBE and GBE for comparing DiHG- and TriHG-based strategies. The TriHG classification system increased GBE by 77.8% over the DiHG system without a significant loss in SBE. We concluded that the TriHG system was better than the DiHG system for improving maize-breeding efficiency. Therefore, maize breeders may re-think their breeding strategy for improving breeding efficiency in long-term breeding programs by adopting the suggested TriHG system. Hybrid maize improvement programs, especially in the early stages of breeding for identifying hybrids with high yield potential, can be become more efficient by using three testers with one from each of Reid, nonReid, and Suwan1 heterotic groups. This would improve the chances of developing high-yielding hybrids in a breeding program with the available, diverse germplasm.