Coordination of leaf function and carbohydrate reserves is associated with cultivar differences in mango ( <i>Mangifera indica)</i> fruit productivity

BACKGROUND AND AIMS: Optimising fruit tree productivity largely depends on physiological traits that regulate carbon acquisition and non-structural carbohydrate (NSC) partitioning. In mango (Mangifera indica), the contribution of NSC reserves and leaf functionality to fruit development under intensified orchard systems remains poorly understood. This study provides the first integrated, seasonally resolved comparison of leaf function and NSC dynamics between mango cultivars differing in productivity, identifying physiological traits associated with yield and NSC use efficiency. METHODS: 'Keitt' (higher yielding) and 'Yess!' (lower yielding) trees, previously established under both, lower (208 trees ha-1) and higher (1250 trees ha-1) planting densities, were monitored over two consecutive fruiting seasons. Leaf carbon assimilation associated traits were measured, including stomatal conductance, stomatal morphology, chlorophyll content, stable carbon isotopes (δ13C), and NSC concentrations. Additionally, NSC reserves in roots and trunks were quantified across key phenological stages to evaluate patterns of reserve replenishment and mobilisation. These physiological metrics were then related to fruit yield and yield efficiency. KEY RESULTS: 'Keitt' consistently outperformed 'Yess!' in yield efficiency, especially under higher planting density. This advantage was associated with differences in leaf physiological traits (higher stomatal conductance, chlorophyll content, and stomatal density) and more dynamic NSC reserve turnover, particularly in trunk tissues. In contrast, 'Yess!' maintained larger NSC pools but mobilised reserves less extensively. NSC reserve dynamics aligned with cultivar-specific patterns in carbon allocation and reproductive output. CONCLUSIONS: These findings demonstrate that genotypic variation in NSC regulation is associated with variation in productivity in mango. Higher productivity in 'Keitt' was associated with greater seasonal NSC turnover, suggesting stronger source-sink coupling under intensive orchard systems. By integrating measurements of leaf function and NSC reserve mobilisation, this study highlights coordinated traits associated with productivity differences among mango cultivars and provides insights relevant to cultivar selection and orchard design.