Generation mean analysis of water stress tolerance parameters in Indian mustard [Brassica juncea (L.) Czern & Coss] crosses.

Little information is available on the genetics of physiological traits for drought tolerance in Indian mustard. Generation mean analysis was performed using two crosses (Maya x BPR543-2) and (BPR543-2 x BPR2) to study the nature and magnitude of gene effects on seed yield and physiological characters in Indian mustard. The F1, F2, BC1 and BC2 of these crosses, along with P1 and P2, were studied for eight physiological traits. As to the water use efficiency, the dominance (h) and dominance x dominance (l) non-allelic interactions were found to be the most important in BPR543-2 x BPR2 cross. In Maya x BPR543-2, negative significant values of h and l were observed. Water use efficiency also showed duplicate-type epistasis in both crosses; indicating that l gene interaction effect or other types of digenic complementary gene interaction could be exploited effectively by selection for improvement of this character. The seed yield per plant in the cross Maya x BPR-543-2 showed d, h, and additive x additive (i) types of gene interaction, which means that this trait is under the control of fixable and nonfixable gene effects. The i gene interaction and duplicate epistasis seen in this trait suggest possibilities of obtaining transgressive segregants in later generations.