Inheritance of sugar concentration in stalk (brix), sucrose content, stalk and juice yield in sorghum

Sweet sorghum is gaining importance as a raw material for ethanol production. Information on genetics of sugar content in stalk is required to facilitate the breeding of cultivars with high ethanol yield. Generation mean analysis and frequency distribution studies were carried out in crosses 27 B × kellar, and 27 B × BJ 204 for sweet stalk during 2006 and 2007. Kellar (a US sweet sorghum line) and BJ 204 (a Chinese line) are high brix (sweet stalk) lines. The traits studied were: brix, sucrose, stalk, and juice yield and plant height. The mean performance of families showed that the F1 in crosses for high brix and sucrose percentage were tending towards P2 (higher sugar percentage parent) implying these traits to be dominant for higher brix and sucrose content. However, the mean values of F1 for stalk and juice yields and plant height showed over-dominance for the traits. Frequency distribution of F2 showed that brix and sucrose percentage are polygenic traits, and stalk and juice yields are oligogenic traits. Generation mean analysis showed that both additive and dominant gene actions for traits, sucrose and brix in stalk juice were significant. Since the plant traits important for high stalk sugar percentage show dominance and over-dominance inheritance, hybrid breeding will be useful. Selection for pure lines with high brix is to be practised in later generations.