| In the paper, the physiological and water-saving effects of Regulated Deficit Irrigation (RDI) on cotton were studied with pot-planting test under glasshouse. Controlled soil water deficit was applied with three moisture contents (low, moderate, high) at late seedling stage, budding stage or both stages. The results showed that, under appropriate water deficit in right stage, the excess vegetative growth was significantly inhibited, and the plant frame and root-shoot ratio were more ideal. During the water deficit period, the transpiration rate (ET) and stomatal conductance (gs) of cotton leaves decreased obviously, but the diminution of photosynthesis rate (Pn) was not obvious. After re-watering, the Pn and gs were significantly recovered to the level of the controls. In addition, the water deficit not only affected fruit numbers, but also affected per fruit dry weight. The final results showed that the yield of the proper RDI treatments was close to or higher than that of the controls, and that more than 20% of the irrigated water was saved. |