Effects of Irrigation Stage and Amount on Water Consumption Characteristics, Flag Leaf Photosynthesis, and Grain Yield in Wheat

Abstract

Shortage of water resource has become one of the major factors limiting wheat (Triticum aestivum L.) production in North China. Irrigation plays an important role to obtain high grain yield. Currently, studies on water consumption characteristics and the physiological basis of yield formation in wheat are seldom reported. In this study, three wide planted cultivars, Jimai 20, Taishan 23, and Taishan 22 were used in two independent experiments in 2004–2005 and 2005–2006 growing seasons. There were four irrigation treatments in both experiments, i.e., no irrigation (W0), soil water plus one irrigation at jointing stage (W1), soil water plus two irrigations at jointing and anthesis stage (W2), soil water plus three irrigations at jointing, anthesis, and grain-filling stage (W3). Each irrigation supplied water of 60 mm. In the 2004–2005 growing season, the highest grain yields of Jimai 20 and Taishan 23 were obtained in W2 treatment with water consumptions of 429.8 and 453.0 mm, respectively, which were higher than those of W1 treatment (402.9 and 416.6 mm). However, the irrigation efficiency of W2 treatment was lower than that of W1 treatment. The water use efficiencies (WUE) of W1 and W2 treatments were both higher than those of other treatments in the two cultivars. In Jimai 20, there was no significant difference between W1 and W2 treatments, whereas in Taishan 23, W1 had higher WUE than W2. In the 2005–2006 growing season, Jimai 20 yield the highest in W1 treatment, and Taishan 22 in W2 treatment, with water consumptions of 451.3 and 459.2 mm, respectively. The highest and the lowest WUE were in W0 and W3 treatments in both Jimai 20 and Taishan 22, respectively. In Jimai 20, the WUE was higher in W1 than in W2, whereas there was no significant difference between W1 and W2 in Taishan 22. With the increase of irrigation amount, the percentage of soil water supply amount and precipitation to total water consumption amount decreased and the percentage of irrigation amount to total water consumption amount increased. Compared with W1, W2, and W3 treatments, W0 treatment had lower flag leaf photosyn-thetic rate and sucrose phosphate synthase activity at medium and late grain-filling, but at early grain-filling, there was no signifi- cant difference between W0 and W1, W2, W3, and the transfer of sucrose from flag leaf to grain was more favorable in W0 than in W1, W2, and W3, thus, Jimai 20 obtained the highest grain weight in W0 treatment. In wheat production under conditions similar to this study, the optimal irrigation regimes are suggested as 60–120 mm for Jimai 20 and Taishan 23 at jointing or at jointing and anthesis stages without irrigating base water, and 60 mm for Jimai 20 at jointing or 60–120 mm for Taishan 22 at jointing or at jointing and anthesis stages with irrigating base water 60 mm .