Responses of pruning and paclobutrazol in mango (Mangifera indica L.): changes in tree vigour, flowering and phenols

Abstract: Dominant vegetative phase, if not regulated, can adversely affect the mango production particularly under high density planting systems. Pruning after fruit harvest and use of paclobutrazol (PBZ) have been identified as common strategies for tree vigour regulation and productivity enhancement in mango. The objective of the present study was to investigate the effects of 50% pruning of current and previous season vegetative growth and PBZ (3 mL/ m canopy diameter) on tree vigour, flowering and phenol contents in three mango cvs. Raspuri, Dashehari and Amrapali. Suppression of plant height, tree girth, canopy spread, shoot length and girth was witnessed with PBZ application in trees pruned to 50% of current season growth followed by trees pruned to 50% of previous season growth and unpruned trees. Early flowering witnessed as a result of PBZ application led to advanced fruit harvest by 20.4, 13.0 and 14.7 days in trees pruned to 50% of current season growth and 18.7, 13.7 and 15 days in trees pruned to 50% previous season growth in the cvs Raspuri, Dashehari and Amrapali, respectively. Drastic increase in total phenols, total flavonoids and phenolic acid contents were observed at 75 days after PBZ application in PBZ treated unpruned trees and in trees pruned to 50% of current season growth followed by in trees pruned to 50% of previous season growth. The high levels of o-coumaric acid, 4-hydroxy benzoic acid and salicylic acid and low levels of caffeic acid and t-cinnamic acid were observed following PBZ application in tree pruned to 50% of current season growth and unpruned trees compared to control. From the study it was apparent that the pruning of trees to 50% of current season growth and PBZ application are vital for regulating tree size, early flowering and advancing fruit harvest in mango and such beneficial effects of treatments were mediated through increases in phenols and flavonoids contents.