Role of abscisic acid in the phenomena of abscission of flower buds and bolls of cotton (Gossypium hirsutum L.) and its reversal with other plant regulators

Abstract

The investigations carried out to find the role of abscisic acid in the phenomena of abscission of flower buds and bolls of cotton (Gossypium hirsutum L. cv. ‘H-14’) have shown abscisic acid content to be low in retained bolls as compared to that in the abscising ones of the same age, suggesting that relatively higher endogenous abscisic acid content to be promotive of abscission. Abscisic acid applied exogenously either to intact flower buds/bolls or boll explants promoted their abscission. Naphthalene acetic acid not only reduced abscission but also could erase completely the promotive effect of abscisic acid on abscission. Gibberellic acid promoted abscission in intact buds and boll explants but applied to intact bolls it reduced their shedding even more than naphthalene acetic acid. Gibberellic acid could also counteract the promotive effect of abscisic acid in the case of intact bolls but enhanced that of boll explants. All the cytokinin-furfurylamino-purine treatments given other than at the abscission zone promoted abscission. Furfurylaminopurine applied in combination with abscisic acid showed some antagonistic effect in the case of intact bolls and boll explants abscission zone treatments. Ascorbic acid applied at a relatively lower dose (0.025 mM) reduced shedding but applied at a higher dose it showed promotion. Ascorbic acid could erase the promotive effect of abscisic acid on abscission to a significant extent.