Gene effects and heterosis for grain iron and zinc concentration in sorghum [Sorghum bicolor (L.) Moench]

The aim of this study was to understand the inheritance of grain iron (Fe) and zinc (Zn) concentrations in sorghum [Sorghum bicolor (L.) Moench] and to assess the possibility of exploiting heterosis to improve these micronutrients. Three sets of full diallel crosses were made, one set using five parents contrasting for both grain Fe and Zn concentrations; the second set using six parents contrasting only for Fe, and the third set with four parents contrasting only for Zn. The crosses and parents were evaluated in replicated trials for two years. The results indicated that both additive and non-additive gene action play a role in conditioning grain Fe and Zn concentration in sorghum. However, non-additive gene action is predominant in conditioning grain Fe; and additive gene action in conditioning grain Zn. Some of the crosses showed significant heterosis for grain Fe concentration without yield penalty and some crosses showed targeted grain Zn concentration (40 mg kg−1) coupled with higher grain yields. The results also showed that it is possible to improve grain Fe concentration through exploiting heterosis, but there would be little opportunity if any for improving grain Zn through heterosis breeding. To develop hybrids with high grain Fe and Zn concentration in sorghum both parents needs to be improved for these micronutrients. Combining higher grain Fe and Zn with high yield is feasible.