Abstract

                                Generation mean analysis was carried out to estimate the nature and magnitude of gene effects for sugar content, green cane yield and its component traits in sweet sorghum [Sorghum bicolor (L.) Moench]. Six generations viz., P1, P2, F1, F2, BC1 and BC2 of a cross derived from two parents viz., 27 B and NSSV 13, which are contrasting for the trait of interest i.e., grain quality and yield traits of grain sorghum and juiciness of sweet sorghum were evaluated in summer 2012. The scaling tests as well as chi square test from joint scaling test were highly significant for all the fourteen quantitative characters, indicating inadequacy of simple additive - dominance model and justifying the use of six parameter model for the detection of gene interactions. Both additive and dominance gene effects were highly significant for all the traits barring stem girth, grain yield, total biomass and fresh stalk yield where only dominance component is predominant in first two traits, while additive in later two traits. Among non allelic interactions, dominance × dominance (l) gene interaction was of greater magnitude than main gene effects for all the characters under study indicating the importance of heterosis breeding to utilize non additive gene effects.

Key words : Sweet sorghum, Generation mean analysis, Scaling test, Additive - dominance model, Sugar yield.