Girdling-induced hormonal and metabolic changes in mango cv. Dashehari: implications for flowering and fruit quality

Background Girdling influences flowering and fruiting in perennial fruit trees by altering assimilate partitioning and hormonal signaling. However, its mechanistic basis in mango, including the widely grown cultivar ‘Dashehari,’ remains elusive. In this study, the effects of branch girdling on hormonal regulation, metabolic changes, phenolic regulation, nutrient dynamics influencing flowering, and fruit quality were investigated in 20-year-old mango trees. Results Girdling significantly enhanced flower induction, panicle length, and fruit set. Girdled branches produced more than twice the number of panicles (14.90 vs. 6.50 per branch) with longer inflorescences (27.99 vs. 22.18 cm) and nearly doubled the fruit set (10.79% vs. 5.60%) compared to non-girdled controls. Hormonal profiling revealed localized increases in IAA, 2iP, and ABA, and a marked reduction in GA₃ in response to girdling. Girdling increased the levels of epicatechin, caffeic acid, ellagic acid, and p-coumaric acid, which were strongly correlated with floral traits and hormone dynamics. Metabolite analyses further indicated enhanced accumulation of sucrose, glucose, fructose, organic acids, and stress-related compounds in girdled branches. Girdling also reduced the concentrations of P, K, Mg, Zn, Cu, and Mn, while Ca and Fe were maintained or slightly increased. Fruits from girdled branches were heavier, had higher pulp weight and firmness, and showed higher TSS and acidity. Significant increases in phenols, flavonoids, and carotenoids indicated improved nutritional and functional quality of fruits from girdled branches. Overall, these findings demonstrate that girdling modulates hormonal, metabolic, and nutritional pathways to improve the flowering, fruit set, and fruit quality in mango cv. Dashehari. Conclusions The study provides new insights into the physiological underpinnings of girdling in ‘Dashehari’ mango and highlights its potential as a practical orchard management tool to regulate flowering, enhance fruit yield, and fruit quality. Future work should focus on cultivar-specific responses and molecular mechanisms underlying these regulatory shifts in girdled branches and fruits.