Neem: Azadirachta indica A. Juss. reproductive studies in relation to polyamine application

The in vivo morpho-physiological responses to polyamine application in Neem (Azadirachta indica) were studied during three consecutive annual reproductive flushes from bud development onwards to seed set (prior standardization with endogenous levels). The number of buds and flowers per inflorescence was higher in treated branches as compared to the control. Physiological responses were observed to be polyamine-specific. Sample protein, total sugar and reducing sugar measured higher following spermidine and putrescene as compared to spermine. The response was significant in 0.2 mM spermidine samples. Spermine treatments produced poor flowering response, longer juvenility and low contents of the above compounds as compared to the control. The enzyme assay measuring the activities of invertase, protease, acid- and alkaline phosphatases was consistent with the biochemical responses to the polyamine treatments. In control, a shorter regeneration phase seems to lead to lower productivity in terms of floral inflorescence and fruit set. Therefore, it is suggested that the application of spermidine and putrescene may regulate the reproductive phase resulting in improved organ/biomolecule production.