Stress-induced fruit abscission in cotton and role of ethylene

This study explores the relationship between endogenous ethylene levels in stress-induced fruit abscission in different cotton cultivars. The plants were exposed to soil waterlogging or high temperature (45C) stress during early reproductive phase. Ethylene synthesis was also modified using chemical ethylene regulators e.g. aminoethoxyvinylglycine (AVG) and 1-aminocyclopropane-1-carboxlic acid (ACC), and a lintless mutant line 5B (ethylene insensitive). The number of fruit produced and ethylene concentrations released from leaf tissue were estimated after one week of waterlogging and heat treatments. Both waterlogging and high temperature stress increased loss of young fruit in all the cotton cultivars studied, except 5B, which showed a degreea of tolerance to waterlogging. In contrast, ethylene production from cotton leaf tissues was increased only in response to soil waterlogging, suggesting a variable mechanism of fruit loss in waterlogged compared with heat-stressed cotton plants. This was further confirmed by no significant effect of ethylene regulators AVG and ACC on the fruit production in heat-stressed cotton plants. We concluded that endogenous ethylene plays a key role in regulating abscission of fruit mainly in waterlogged cotton but not in heat-stressed cotton crop. Thus, ethylene management techniques may not be useful for future heat-stressed cotton.