Genetic improvement of sorghum for grain mould resistance: I. Performance of sorghum recombinant inbred lines for grain mould reactions across environments

► Grain mould in sorghum is an important disease worldwide for which success in breeding for resistance has been limited. In this study an attempt has been made to understand why source of grain mould resistance is rare. ► The study included characterization of grain mould reactions of 200 recombinant inbred lines (RILs) (296 B × B 58586) at physiological maturity (PM) and at harvest maturity (HM) across 6 environments. ► For the first time this study showed that nature of genetic control on grain mould at PM and at HM were different. At PM it is controlled by both host genetics and environment and that at HM it is entirely controlled by environment. Therefore, genetic resistance for grain mould would be better assessed at PM than at HM. ► It is suggested that identification of QTL(s) against the pathogenic fungi that infect before PM will be more fruitful than against grain mould complex observed at HM. ► New grain mould resistant sources (RILs) were identified which were distinct from the available resistant source (B58586) for many useful traits.