Delineating G x E interactions by AMMI method for root attributes in ashwagandha [Withania somnifera (L.) Dunal]

In the present study, additive main effects and multiplicative interactions (AMMI) biplot analyses was used to dissect genotype x environment interaction (GEI) and to identify location specific and widely adapted genotypes for root branches, diameter and length in ashwagandha [Withania somnifera (L.) Dunal]. Trials were conducted in randomized complete block design (RCBD) with two replications over three consecutive years at three different locations. ANOVA analysis revealed environment, GxE interaction and genotype effects to contribute significantly (p<0.001) towards total sum of squares for root branches (61.00%, 22.18% and 14.00%); root diameter (51.06%, 24.26% and 15.34%) and root length (65.67%, 20.82% and 11.39%). Further, the GEI for these traits was mostly explained by the first, second and third principal component axis (IPCA1, IPCA2 and IPCA3). AMMI1 and AMMI2 biplot analyses showed differential stability of genotypes for root branches, diameter and length with few exceptions. Environmental contribution towards the genotypic performance from AMMI1 and AMMI2 analysis for root traits except environment Bhi16 contribution for root diameter and root length. AMMI1 biplots and simultaneous selection index (SSI) statistics identified SKA-11 as the most desirable genotype for root branches and length while SKA-26 and SKA-27 for root diameter. The ashwagandha genotypes identified for root attributes could be advocated either for varietal recommendation or in varietal development program.