Physiological response and water-saving effect of regulated deficit irrigation in cotton

The physiological response and water-saving effects of Regulated Deficit Irrigation (RDI) were studied with pot-grown cotton in a glasshouse. Controlled soil water deficits were applied using low, moderate or high soil water contents at either or both of the late seedling and budding stages. Results showed that, for an appropriate amount of water deficit at a specific stage, the excess vegetative growth was significantly inhibited, so that an ideal plant frame and root-shoot ratio was obtained. During the water deficit period, the transpiration rate and stomatal conductance (g(s)) of cotton leaves obviously decreased. After re-watering, P-h and g(s) significantly recovered. In addition, the water deficit not only affected fruit numbers, but also affected dried fruit weight. Some RDI plants had less vegetative growth and similar or higher yield efficiency than those having high water content during both stages, so more than 20% of the irrigation water could have been saved.