Effects Of Different Irrigation Regimes On Grain Yield, Water Use Efficiency And Nitrogen Use Efficiency Of Winter Wheat

The experiment was conducted in the field at the Agricultural Experimental Station. (latitude 36°09′N, longitude 117°E) of Shandong Agricultural University (Taian, Shandong Province, China) from Oct 12, 2009 to Jun 19, 2010. Tainong18, a widely grown winter wheat cultivar, was selected as experimental material and applied the following five irrigation regimes: irrigated before sowing (represented as CK); irrigated at sowing and jointing stages (represented as W1); irrigated at sowing , jointing with alternative irrigation at over-wintering and milking (represented as W2); irrigated at sowing, jointing, flowering stages (represented as W3); irrigated at sowing, jointing, over-wintering, and milking stages (represented as W4). Effects of different irrigation regimes on yield, water use efficiency, and nitrogen use efficiency of winter wheat were investigated in dry years. The main results are shown as follows:1 The effects of different irrigation regimes on grain yieldWith increasing amount of irrigation, the grain yield of the treatments present the trend of increase. Under the condition of 119.7 mm rainfall in the growth season of winter wheat, no significant difference in grain yield was observed between W4 and W2. Compared with W3, the grain yield W2 was significantly higher. Analyse the components of TN18, W2 was significantly higher than W3 at kernel numbers. With increasing amount of irrigation, the weight per 1000 kernels decrease, and W3 was significantly higher than both W2 and W42 The effects of different irrigation regimes on water use efficiencyWith increasing amount of irrigation, the amount of soil water was decreased. Irrigation regime effects wheat absorption and utilization of soil water, and W3 was lower than W2 significantly. The water consumption amount of different treatments increased with the amount of irrigation. Under the same irrigation amount, W3 was significantly higher than W2 at the amount of irrigation. With increasing amount of irrigation, WUE increased first and then decreased.At the 202.5mm amount of irrigation, the wheat got the highest WUE, compared with W1, there was no significant difference in the water use efficiency between them was found. With increasing amount of irrigation, the irrigation use efficiency decreased. W2 is no significant difference with W3, which has the same amount of irrigation as W2.3 The effects of different irrigation regimes on nitrogen use efficiencyThe results showed that, under the same irrigation amount,W2 was low at total nitrogen uptake amount,while its high at NUE, so it can increase the grain yield.With the increasing amount of irrigation,the uptake both from fertilizer nitrogen and soil nitrogen increased.W2 was higher than W3 at the proportion of fertilizer nitrogen accumulation in total nitrogen accumulation,it increased the fertilizer nitrogen utilization.With increasing amount of irrigation,the Tnue,NPFP, NRE increased significantly,while the NUE reduced significantly.W2 has the highest NPFP,but it is no significant difference with W3.With increasing amount of irrigation, the soil NO₃^--N content of irrigation treatments in 0²00 cm soil layer gradually reduces with increasing the soil depth. With increasing amount of irrigation, the soil NO₃^--N content of irrigation treatments in 0¹00 cm soil layer significantly reduces with increasing amount of irrigation, but increases in varying degrees in 100²00 cm.It showed that, alternating irrigation can reduce the content of soil NO₃^--N leaching from 0¹00cm soil layer to 100²00cm soil layer.4 The effects of different irrigation regimes on partial physiological and biochemical indexesCompared with W3, W2 was significantly higher at leaf water potential and osmatic potential. Compared with W4, W2 was significantly lower at leaf water potential and osmatic potential, but no significant difference between them was found.5 The soil water movement of alternating irrigationWater from irrigated filed can move 70cm to the no irrigated filed at horizontal direction. Water can move 60cm at vertical direction in irrigated filed. The soil water content of no irrigated filed was increased significantly in 0⁶0cm soil layer. While the soil water content of no irrigated filed was no significant difference in 60¹00cm soil layer.