Manipulation of vegetative growth and improvement of yield potential of cashew (Anacardium occidentale L.) by Paclobutrazol

Abstract

Cashew (Anacardium occidentale L.) is a perennial tree crop that realizes yield after several years of planting due to its long gestation period. Therefore, canopy management by pruning in later stages of growth often affects orchard life and performance of trees. High density planting system (HDP) has been attempted in cashew to obtain early benefits in terms of yield during initial years of planting. Under HDP, maintenance of tree and canopy growth becomes important due to closer spacing and shading of canopy of trees. In cashew, due to non availability of dwarf clones and dwarfing rootstocks, use of growth retardants, paclobutrazol (PBZ), assumes importance. Hence, this study was aimed to evaluate the morpho-physiological responses of cashew to PBZ treatments under field trials. PBZ treatments resulted in reduced vegetative growth and enhanced reproductive growth with most striking responses at PBZ 3 g a.i./tree treatment. PBZ treatments altered cashew tree physiology by modifying tree size, canopy growth, internodal length, branching pattern and overall ground coverage of the tree. Higher total leaf chlorophyll content, better photo assimilation and enhanced leaf photosynthesis contributed in inducing early flowering and development of more flowering panicles with perfect flowers. Enhanced fruit set and increased number of nuts/m2 canopy contributed in yield increment. Regression analysis showed leaf pigments, nut number and number of inflorescence as the most contributing traits for yield enhancement under PBZ. These findings may highlight the exploitation of morpho-physiological traits for better canopy growth and yield maximization by PBZ in cashew under the HDP.