FRUIT SET, RETENTION AND YIELD OF MANGO IN RELATION TO ETHYLENE

The role of ethylene in fruit set and retention of 'Kensington Pride' mango was investigated employing exogenous applications of ethylene and its biosynthesis and action inhibitors including aminoethoxyvinylglycine (AVG), and aminooxyacetic acid (AOA) and cobalt sulphate (CoSO₄) and ethylene action silver thiosulphate (STS). A spray application of ethylene biosynthesis inhibitors was more effective at increasing initial, final fruit set and fruit retention (120, 42 and 1.8 fruits/panicle), when compared with the ethylene action inhibitor STS (104, 38.9 and 1.7 fruits/panicle) respectively, when applied to fully-grown panicles before anthesis. Significant direct positive linear correlations were observed between both initial and final fruit set and fruit retention, in all weeks after initial fruit. Exogenous application of ethrel significantly reduced fruit set (up to 76%). Fruit yield was significantly improved with all ethylene biosynthesis and action inhibitors. However, the results indicate that increasing initial or final fruit set has no effect on fruit yield, although, there was a significant direct correlation between final fruit retention and fruit yield. The increase in fruit yield with treatments of ethylene biosynthesis and action inhibitors may be due to their effects on improving fruit retention. No deleterious effects on quality were observed with the single spray application of ethylene biosynthesis and action inhibitors before anthesis. The promotion of fruit set with the inhibitors of endogenous ethylene biosynthesis and it’s action and reduction in fruit set with the exogenous application of ethrel showed that endogenous ethylene plays an important role in the fruit set of mango. In conclusion, single exogenous spray applications of CoSO₄ (200mg/L) to fully-grown panicles before anthesis, was most effective for improving fruit set, retention and yield.