Panicle water relations during water stress

Abstract Although the importance of water stress-induced sterility during reproductive stages of cereal development is obvious, little is known about the tissue water relations of the panicle. The water potential and water content of rice panicles were found to be linearly related. Newly emerged panicles of rice apparently lack active mechanisms to impede water loss if water deficits coincide with flowering since they transpired at rates that were independent of panicle water potential. Overt symptoms such as desiccated white areas on the spikelets develop at water potentials and water contents of about −25 to −30 bars and 50–60%, respectively, after which spikelet desiccation progresses exponentially with further change in water status. Decrease in panicle water potential below −13 to −17 bars was also associated with decreased anthesis. These results indicate that water relations of reproductive organs may vary significantly from those of leaves and warrant further study.