Response of selected scion and rootstock grape (Vitis spp.) genotypes to induced drought stress

Climate change is expected to elevate drought frequency, straining agricultural freshwater resources. Developing drought-tolerant grapevine varieties is crucial. This study examined grape scion and rootstock genotypes under well-watered (WW) and induced-drought (ID) conditions. ID treatment reduced vine length by 11.34-35.15%, with Vitis parviflora, 110R, and Male Hybrid rootstocks showing superior growth. Root length increased under ID, indicating an adaptive moisture-seeking response. The ID treatment led to substantial reduction in leaf count and average leaf area, especially in Flame Seedless (27.71 and 19.07 cm2, respectively). Drought stress elevated chlorophyll a:b ratio, affecting chlorophyll degradation in different genotypes. Significant variations were observed in leaf and root iron (Fe) and zinc (Zn) contents. Enzyme activities particularly peroxidase and polyphenol oxidase especially rose under drought, particularly in V. parviflora (3.39 mu M guaiacol min-1 mg-1 protein and 1.33EU/ml/min respectively) likely to be contributing in drought tolerance mechanism. Principal component analysis (PCA) highlighted impact of traits on genotypes, emphasizing V. parviflora, Male Hybrid and Pusa Navrang as superior drought stress tolerant genotypes. Genotype clustering confirmed distinct groupings, while, correlation analysis unveiled intricate trait interactions.