Grain mould resistance and associated characters of sorghum genotypes

Twenty-two sorghum genotypes were evaluated for grain mould response, 13 morphological and biochemical traits thought to contribute to resistance, and 3 agronomic traits related to utilization. Measurements of grain mould (field grade score, threshed grade score, ergosterol content, and percentage germination) were strongly correlated with one another. Highly significant correlations between measures of grain mould and seed hardness, seed phenol content in acid methanol extract, and glume colour indicated that they strongly affected grain mould response. Harder grain, higher levels of seed phenols, and darker glumes contributed to grain mould resistance. Weaker and less consistent correlations between measures of grain mould and seed colour, seed flavan-4-ol content, glume phenol and flavan-4-ol contents, and glume cover indicated relatively less effect of these traits on grain mould response. Genotype means indicated that combinations of several traits are required to achieve resistance. Germplasm lines, including coloured-seeded lines IS 14375, IS 14387, IS 18144, and IS 18528, and white-seeded lines IS 21443, IS 24495 and IS 25017, showed greatest grain mould resistance. Improved lines generally had poorer grain mould resistance than these landraces. However, the best improved lines were comparable in resistance to white-seeded landraces. B58586, IS 14375 and IS 14387 are hard-seeded guinea sorghum lines that can be used as sources of grain mould resistance for West Africa. SP 33316, SP 33349 and GM 15018 are agronomically elite lines that can be used as sources of grain mould resistance for further improvement of white-seeded sorghum for South Asia and other regions.