Drought tolerance and stability of native Iranian and foreign tall fescue genotypes: Comparison of AMMI and GGE biplot analyses

Evaluation of drought tolerance in tall fescue (Festuca arundinacea Schreb.) native Iranian landraces, and estimation of the genotype x environment interaction via advanced multivariate methods has rarely been studied. Here, 24 genotypes of tall fescue, including 17 native landraces and seven foreign accessions, were evaluated during 5 yr at two locations and under two irrigation regimes of normal and severe water stress conditions. Water stress had a negative effect on dry forage yield and reduced genetic variation. However, this decline was greater in foreign genotypes than in the native ones. The superior genotypes were identified with stress tolerance index. The additive main effects and multiplicative interactions (AMMI) and genotype x genotype-environment (GGE) biplot analyses identified the most stable and high-yielding genotypes that were also classified as more drought-tolerant group. Moreover, although it was revealed that the GGE biplot method is more efficient than AMMI model for stability analyses, our results indicated high overlap between the results of these two methods.