Genetic control and heterosis for grain iron and zinc contents in sorghum [Sorghum bicolor (L.) Moench]

For formulating an appropriate breeding strategy, genetic control of grain iron (Fe) and zinc (Zn) in sorghum was studied in a half-diallel mating design with nine parents. Both additive and non-additive gene actions were important in the genetic control but dominant gene action was predominant in case of Fe. In case of grain Zn additive gene action was more important with a σ2 gca/σ2 sca ratio of 0.94. Predictability ratio was 0.14 for grain Fe and 0.65 for Zn. Significant correlation between mean parental performance and GCA effects (r = 0.86 for Zn, r = 0.67 for Fe) indicated that selection of genotypes with high mean Zn and/or Fe levels would be highly effective in selecting for high GCA. The results suggest the scope for heterosis breeding to improve grain Fe, while for improving grain Zn progeny selection in pedigree breeding will be effective. High Fe and Zn levels in both of the parental lines would be required to develop heterotic hybrids with high grain micronutrient contents.