Development of Heterotic Groups in Triticale

Heterotic groups are an essential prerequisite for efficient hybrid breeding. The present study in winter triticale (xTriticosecale Wittmack) was performed to (i) evaluate the magnitude of heterosis, (ii) investigate the efficiency of the prediction of hybrid performance based on midparent value or general combining ability (GCA) effects, and (iii) identify two heterotic groups by employing principle coordinate analysis and an enumeration algorithm for maximizing F-1 performance, midparent heterosis, and sigma(2)(GCA)/sigma(2)(SCA) ratio for grain yield. Twenty-one inbred lines and their 210 diallel crosses were field-evaluated for grain yield at five agroecologically diverse locations in Germany. On average, the hybrids yielded 8.6% higher than the midparent performance, and the maximum superiority was 12.4%. Hybrid performance was predicted more reliably with GCA effects rather than with midparent performance. An enumeration algorithm based on optimum allocation of parents to heterotic groups, improved all three criteria. F, performance, midparent heterosis, and sigma(2)(GCA)/sigma(2)(SCA) ratio increased by about 3, 24, and 70%, respectively, as compared with the base situation of having no heterotic groups. These improvements substantiate the potential advantages, when heterotic groups are developed in hybrid breeding.