A multi-season analysis for GxE interactions and identification of resistant grape genotypes for powdery mildew (Erysiphe necator (Schw.) Burrill.) using AMMI, GGE and MTSI analysis

Powdery mildew (PM) caused by Erysiphe necator (Schw.) Burrill is one of the most important constraints in enhancing grapevine productivity. The study focused on identifying stable and highly resistant grapevine genotypes against PM across multiple environments, while assessing conditions favouring optimal trait expression. Forty-two genotypes were evaluated over three consecutive seasons (2021–2023) using disease severity index (DSI), morphological and biochemical analysis. Resistant genotypes, such as Vitis parviflora, Pusa Navrang and V. jacquemontii exhibited lower stomatal density, increased leaf thickness and enhanced antioxidant activities. Significant G × S interactions were employed using additive main effects and multiplicative interaction and genotype (AMMI) and genotype-environment interaction (GGE) biplot analysis based on disease severity index data. The estimation of stability indices, i.e. WAASB is used for selecting highly resistant genotypes. The multi-trait stability index (MTSI) method in evaluating 18 traits highlighted V. parviflora, Chardonnay, 110 Richter, Pusa Navrang and Male hybrid as the most promising genotypes. These genotypes exhibited lower DSI and no notable changes in photosynthetic pigments in diseased leaves. High heritability of PAL, PPO and total phenols underscores their potential as key targets for selection. Similarly, high heritability of the DSI (81–93 %) confirms a strong genetic basis, with V. parviflora, 110 Richter, Pusa Navrang and Male Hybrid emerging as the most stable resistant genotypes. These genotypes were identified as stable performers under natural PM pressure and could serve as candidates for breeding programs, enabling the development of resistant grape cultivars and thus reducing the need for fungicide use in disease-prone regions.