Heterosis and combining ability in winter wheat (Triticum aestivum L.)

A diallel cross involving seven parents and 21 hybrids was adopted to study heterosis and combining ability in wheat. F₁ hybrids and parents were compared in space planted experiments in two years. Ten hybrids gave significantly higher yield than the highest parent in the cross. The range for all hybrids was 13.8 to 75.9 per cent over the highest parent. Heterosis was obtained from hybrids within the soft red winter wheat group as well as from hybrids derived from hard red and soft white winter wheats. Heterosis was observed for all characters measured in some of the crosses. Greatest heterosis was observed in hybrids derived from crossing late and early maturity parents, a fact that could be important for the commercial utilization of hybrid wheat since it will be difficult to produce hybrid seed from parents that differ in time of anthesis. Heterosis was not observed in hybrids involving closely related parents indicating that genetic diversity is required for the expression of significant heterosis.

Significant general and specific combining ability effects were obtained for yield and agronomically important traits. Tenn. 9, an experimental line, contributed positive general and specific combining ability effects for most characters. This study indicated that certain hybrids should be studied for heterosis under conditions of commercial production.