Effects of water-saving irrigation on water consumption and photosynthetic characteristics of winter wheat in Huang-Huai-Hai area of China

Field experiments were conducted during 2008-2009. The objective of the research was to find effects of water-saving irrigation on water consumption, photosynthetic characteristic, grain yield and water use efficiency(WUE) of winter wheat. The results showed that, during sowing to jointing stages, under 42 mm precipitation condition, available water content of 0-40 cm soil layer decreased significantly, 0-40 cm soil layer of all treatments(except wintering and jointing treatment）was under serious water stress, while wintering and jointing treatment only under light water stress. Serious water stress before jointing stages remarkably affected root to absorb water in deep soil layer and photosynthetic rate of wheat in late stages. With increase of irrigation times, total water consumption increased, but the percentage of soil-water consumption and precipitation consumption decreased. Under light water stress condition, stomatal-conductivity decreased, consequently reduced transpiration rate, but preserved the net photosynthetic rate, so WUE of leaves increased. There was a conic relationship between grain yield, WUE and water consumption, but the two conics did not have the same variation tendency. A point of intersection at 360 mm water consumption was found which indicated the best combining site of grain yield and WUE. Grain yield of wintering and jointing treatment was 7753 kg/ha, which increased 40.2% compared to no irrigation treatment(W0). WUE of wintering and jointing treatment was 1.9 kg/m3, which did not differ with W0. To this effect, wintering and jointing treatment was the best water-saving and high yielding treatment under experimental conditions.