Photosynthesis and Drymass Production of Winter Wheat in Response to Micro‐Sprinkling Irrigation

Water-saving irrigation techniques are critical for winter wheat (Triticum aestivum L.) development in the Huang-Huai-Hai Plain of China and assist in coping with increasingly serious water shortages. A micro-sprinkling irrigation experiment was conducted from 2010 to 2012 to investigate how soil water distribution, photosynthesis, drymass accumulation, and grain yield responded to different sprinkling angles. Five treatments were designed: Rainfed, W35, W50, W65, and W80. The Rainfed treatment consisted of no irrigation throughout the growing season. The W35 to W80 treatments involved irrigation applied through micro-sprinkling hoses with sprinkling angles of 35°, 50°, 65°, and 80°, respectively. Micro-sprinkling irrigation could regulate soil water content to the target level of previous designs. After irrigation, distribution of soil water across the four inter-rows was the most uniform in W80. Following the intermediate stage of grain filling, when increasing sprinkling angle from 35° to 80°, the mean actual photochemical efficiency, maximum quantum yield of the PSII, flag leaf photosynthetic rate, and canopy apparent photosynthetic rate (CAP) significantly increased. A high sprinkling angle is favorable in improving the grain-filling rate as well as lengthening its duration. At maturity, the W80 treatment produced the highest dry matter (DM) in the stem plus sheath and the highest grain weight and total DM, leading to the highest 1000-grain weight, grain yield, and water-use efficiency (WUE). Overall, the optimum sprinkling angle of the micro-sprinkling hose for supplemental irrigation (SI) of winter wheat after jointing is 80°, and the benefits are hypothesized to arise from an increased uniformity of soil water conditions.