CHEMICAL-REGULATION OF TREE SIZE IN MANGO (MANGIFERA-INDICA L) CV ALPHONSO .1. EFFECTS OF GROWTH-RETARDANTS ON VEGETATIVE GROWTH AND TREE VIGOR

Effects of soil drenching with paclobutrazol and foliar sprays of Cycocel and Alar were assessed over two successive years as a means of chemically dwarfing young mango trees. Treatments were imposed either once or twice, just prior to vegetative flushing. All treatments suppressed vegetative flushing, shoot length and leaf number and area. Paclobutrazol was the most effective; the highest dose (10.0 g per tree) practically arrested tree growth but had some phytotoxic effects. At 2.5 or 5.0 g per tree there was more than 50% reduction in tree volume expansion, with no phytotoxicity. Higher doses of Cycocel and Alar also checked tree volume but the effects persisted only for one season.