Rootstock mediated modulation of growth, flowering and nutrient content in Apple (Malus × domestica Borkh.) scion cultivars in high density planting system in north-west Himalayas

This research highlights the complex interplay between growth, flowering fruit yield, nutrient dynamics, physiological responses and overall tree health in determining the performance of different apple scion-rootstock combinations in high-density plating system. Among these, 'Gala Schniga Schnico' budded on EMLA 111 rootstock exhibited exhibited the most vigorous vegetative growth which recorded the highest values for plant height, shoot growth, tree girth, leaf area, trunk cross-sectional area (TCSA), canopy diameter and tree canopy volume (TCV). In contrast, Jeromine/EMLA 111 combination showed the earliest phenological development, including pink bud stage, first flower opening, and full bloom, suggesting its potential for early harvest. Gala Schniga Schnico/EMLA 111 also recorded the longest flowering duration, which may enhance fruit set through prolonged pollination opportunities. Highest spur density was observed in Schlect Spur/EMLA 111, whereas the highest fruit set was exhibited in Gala Schniga Schnico/EMLA 9. Furthermore, Gala Schniga Schnico on both EMLA 111 and EMLA 9 consistently produced the highest fruit yield followed by Jeromine and Red Velox cultivars. Total carbohydrate partitioning revealed that non-fruiting shoots contained higher total carbohydrate concentrations compared to fruiting shoots, reflecting the metabolic demands of reproductive growth. Notably, the cultivar King Roat accumulated the highest total carbohydrate content among the cultivars tested. Leaf nutrient analysis indicated Gala Schniga Schnico/EMLA 111 had superior nutrient status, suggesting more efficient nutrient uptake and utilization. Among the rootstocks, EMLA 111 consistently supported better vegetative growth, yield performance and physiological efficiency. Based on the evaluation of agro-morphometric traits, it can be concluded that the cultivars, 'Gala Schniga Schnico', 'Jeromine' and 'Red Velox' on EMLA 111 and EMLA 9 combinations offer promising alternatives for enhancing productivity, fruit quality and adaptability in high-altitude orchard high density systems in Himalayan ecosystem.