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Studies were conducted on alternate bearer mango cv. Dashehari.
Dashehari produced a major vegetative flush in March-April followed by 2
minor flushes in June-July and September-October. The major vegetative
flush fruited, whereas the other 2 minor flushes did not. Shoots which
fruited rarely produced a new vegetative flush soon after crop harvest
and also did not flower and fruit in the following season. To promote
vigour and productivity, such shoots were forced to produce vegetative
growth soon after crop harvest by pruning and application of 1-2% urea.
Such treatments failed to induce flowering and fruiting. The
concentrations of endogenous growth regulators were determined in
shoots. Shoot-tips contained 3 auxins, 8 gibberellins, 11 cytokinins, 11
steroids and an ABA-like inhibitor. High concentrations of auxins,
inhibitors, cytokinins and steroids were observed in shoot-tips just
prior to or during the period of flower bud differentiation, whereas low
concentrations of gibberellins were observed. Gibberellins were
identified as inhibitors of flowering in Dashehar. The application of
paclobutrazol to soil antagonised gibberellin production in new shoots
and induced flowering and fruiting. |
