Abstract

                                A knowledge of the natural pollination and fertilisation in cultivated crops is of extreme importance to the plant breeder in the matter of evolving successful techniques of artificial hybridisa- tion for crop improvement. In most of the crop plants, which are self fertilised, natural pollination occurs at the time of flower opening. when the anthers dehisce and shed their pollen on the stigma, which is receptive then, enabling the pollen to germinate and fertilise the ovule. In plants where cross fertilisation is the rule, self fertilisation is pre- vented in nature by the different times of maturity of the anther and the stigma i. e., the pollen is shed either long before (protandry) or long after the stigma is receptive (protogyny). In grasses protandry is more common than protogyny. A study of the period of pollen viabi- lity and the receptivity of the stigma forms an important preliminary work in crop improvement. The present paper deals with the studies on the period of receptivity of the rice stigma.

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