Abstract
A comprehensive analysis of neem seed samples for azadirachtin-A (aza) was carried out from trees growing in different agro-ecological zones of India.The aza content varied from 0.3 to 0.9% on kernel dry weight basis. The variation in other parameters like oil per cent, 100 seed wt. and kernel to seed ratio was also high among samples, but relatively lower than the variation for azadirachtin. None of the factors like soil type, rainfall, tree age and fruit ripening stage had direct influence on the aza per cent kernels. Seeds from trees of comparable age growing at same location showed 10 fold variation in the aza content. The data revealed that azadirachtin content of neem ecotypes could be a genetically controlled trait and the wide variation among individual trees may be due to cross pollination in neem. Selection of plus trees and production of saplings from them through vegetative propagation might help in establishing seed orchards or clonal plantations for producing quality seed with high azadirachtin for the biopesticide industry.
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