The role of ethylene in mango (Mangifera indica L.) fruitlet abscission was investigated by determining endogenous ethylene concentrations in intact and about-to-abscise fruitlets and their pedicels, and the effects of exogenous applications of ethephon and inhibitors of ethylene biosynthesis. About-to-abscise fruitlets and pedicels at pinhead, pea and marble stages had higher endogenous ethylene production than intact tissues in 'Kensington Pride' and 'Glen' (191 percent and 66 percent more ethylene in 'Kensington Pride' in 2001, 53.5 percent and 101 percent in 'Glen' in 2000, and 135 percent and 93 percent in 2001). Exogenous application of ethephon at fruit set, accelerated fruitlet abscission compared with control. Fruitlet abscission was increased with increased rates of ethephon applied during 1999 and 2000. Exogenous spray of ethylene inhibitors at pre-anthesis stage increased fruitlet retention. Spray of STS or CoSO_4 (200 mg l~(-1)) resulted in the highest fruitlet retention (7.7 and 7.6fruit per panicle) compared with control (4.9 fruit per panicle). These results suggested that ethylene is involved in mango fruitlet abscission.
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