Deciphering the combining ability and gene action for root yield and related traits in ashwagandha [Withania somnifera (L.) Dunal]

Genetics and crop improvement aspects of medicinal plants in Ashwagandha should be taken consideration to meet the accelerating pharmaceutical demands. For a better understanding of the genetic basis of root yield and related traits, a 9 x 9 diallel analysis excluding the reciprocals was carried out using SKA 27, SKA 11, SKA 6, SKA 24, SKA 10, SKA 26, JA 20, JA 134 and AWS 1 as parents. The a²gca/a²sca denotes that the majority of the traits considered except plant height and the number of secondary branches were governed by non-additive gene action. The fresh root yield was governed by almost equal proportions of additive and non-additive gene actions with a slight increment in additive proportion. Even though none of the parents was a good general combiner for all the traits considered, SKA 27 and SKA 11 appeared to be the best general combiners for root traits. The crosses JA 20 x AWS 1, SKA 24 x SKA 26 and JA 134 x AWS 1 were found to be appropriate for the heterosis breeding on the basis of the estimates of SCA effects.