Reaction of Sorghum to Grain Mould in Relation to Its Biochemical and Morphological Traits

Abstract

Seeds of eight sorghum cultivars from Ethiopia and South Africa were evaluated for factors that might relate to grain mould resistance. Ergosterol content and extent of discoloration of seeds were used to measure seed invasion by the mould fungi. Ergosterol content of seeds was compared with their chemical and morphological characters to establish relationships between
them. Cultivars Gambellal 107, NK286, Buster and SNK3939 showed significantly low ergosterol concentration (< 24 pg/g seed) suggesting low colonization of the cultivars by grain mould fungi. NK283 and Seredo contained high ergosterol level (> 100 pg/g) indicating an increased development of grain mould on these cultivars. PAN8446 and IS9302 had ergosterol content of 48 and 63 pg/g seed, respectively, which indicated moderate level of grain mould development on the two cultivars. NK283 and Seredo also showed significantly higher seed discoloration (55 and 35%, respectively) than others (< 15%). Cultivars with relatively low levels of ergosterol contained significantly great amount of glume proanthocyanidin (tannins), seed flavan-4-ol, apigeninidin and/or luteolinidin than those cultivars with higher ergosterol. Among the cultivars with low ergosterol, most had colored seed pericarps and glumes, while some had white seeds. The cultivars varied in number of days to flowering (65-68). However, there was no significant correlation between ergosterol concentration and days to flowering.