Flowering Biology and Phenology of Aonla (Emblica officinalis Gaertn.) in the Semi-arid Environment of North-West India

Background and Objective: Aonla (Emblica officinalis Gaertn.) is a new introduction in the semi-arid environment of North-west India.This study is conducted for gaining knowledge about the factors affecting the floral biology and flowering phenology of this fruit plant under such environments.Material and Methods: The floral parameters like inflorescence and flower structure; months and time of anthesis, anther dehiscence and nectar production and floral longevity of Aonla were recorded.The stigma receptivity was determined by pollinating the female flowers at different intervals.Results: Inflorescences of Aonla bore unisexual flowers; sex ratio was male-biased.The flowering period of Aonla lasted for about 30 days.Anthesis started at about 1500 h and continued till 1800 h.Dehiscence of anthers started with the opening of the flowers and this too continued till 1800 h.The female flowers opened gradually in different stages and took about 72 h to open completely.Stigma was receptive from the second day of anthesis until the fifth day (for about 85 h); maximal stigma receptivity was recorded on the 3rd day of anthesis.The longevity of a male flower was about 2.5 days (about 60 h) and that of a female flower it was about 5 days (120 h).Conclusion: Aonla carried unisexual flowers with male-biased sex ratio, peak flower anthesis and anther dehiscence took place in the evening in March-April.The longevity of a male flower was about 60 h and of a female flower, it was 120 h.Pollination by the biotic pollen vectors seemed to be an essential requirement for the successful fruit set in the flowers of this plant.