Effects Of Irrigation And Nitrogen Application On Nitrogen Supply Characteristics Of Soil And Grain Yield And Quality Traits Of Winter Wheat In High-yielding Area

The studies were conducted at the Scientific&Educational Station of Henan AgriculturalUniversity (Zhengzhou) and in Wenxian in Henan province during the2012-2013growingseasons. A high-yielding winter wheat (T. aestivum L.) cultivar, Yumai49-198, was used in bothsites of the experiment. The experiment was designed with three irrigation regimes with watersupply75mm each time (W0, no irrigation; W1, irrigation once at jointing stage; W2, irrigationtwice at jointing and anthesis stage), and four N fertilizer rates (N0,0kg/hm2; N1,180kg/hm2; N2,240kg/hm2; N3,300kg/hm2), to evaluate the effect of different irrigation and nitrogen regimes onthe nitrogen characteristic in the soil profile and yield formation and quality traits of winter wheat.The main results were as follows:1. Effects of different irrigation and nitrogen application on grain yield and its componentsThe results indicated that irrigation significantly increased the grain number per spike andgrain yield, while nitrogen application increased spike number and grain yield at bothexperimental sites. Some differences existed between the two sites: the spike number wassignificantly improved with irrigation increasing in Zhengzhou, while no significant changes wereobserved in Wenxian. The maximum grain yield was obtained at the nitrogen rate of180kg/hm2,which was significantly higher than N240, N300in Zhengzhou. While in Wenxian, the maximumgrain yield was obtained at the nitrogen rate of300kghm2, and no notable difference betweendifferent nitrogen rates was found in Wenxian. The interaction of irrigation and nitrogen on spikesnumber, grains per spike, thousand kernel weight and grain yield reached a significant level atZhengzhou. While no significant interaction of irrigation and nitrogen was found on grain yieldand yield components in Wenxian. The highest yields were obtained at treatments of W2N300intwo years in Wenxian and W2N180in Zhengzhou, respectively. The grain yields in Wenxian were26%higher than in Zhengzhou.2. Effects of different irrigation and nitrogen application on nitrogen utilization efficiencyThe effects of different irrigation and nitrogen on the nitrogen agronomy efficiency (NAE)and partial factor productivity of applied (PFP) were basically the same in Wenxian andZhengzhou. The NAE and PFP declined with the increase of N application rate. Increasingirrigation to alleviate decreasing the NUE which because of increasing the more nitrogen to someextent to improve the NAE and PFP. The highest NAE and PFP values were obtained at W2N180 at the experiment.3. Effects of different irrigation and nitrogen on protein qualities of winter wheatThe grain protein, globulin and prolamin were highest in W0treatments. The protein contentwas lowest in W2irrigation condition. The protein content and compositions increasedsignificantly with N application rate increase in the year of2011-2012. The protein content and itscomponents and the GMP content of flour were highest in W1treatments at two sites in the yearof2012-2013. In Wenxian, the protein content and its components and the GMP content of flourwere lowest in W0treatments, while in W2treatment in Zhengzhou. Compared with no nitrogen,the nitrogen application increased the protein and its components content and GMP content inwheat grain and improved the protein yields significantly, while there was no obvious differenceon most traits among the nitrogen treatments at two sites. The interaction between irrigation andnitrogen also affected the protein and GMP content and other traits significantly. The grain proteincontent and GMP content highest values were obtained at W1N300and W1N240combination atWenxian and Zhengzhou, respectively. And the protein yields highest values were acquired atW2N300and W2N240combination at Wenxian and Zhengzhou, respectively. Applying180～240kg·hm-2of N combined with irrigation at jointing stages was the ideal management regime forthe high protein content and GMP content. The highest grain yields were obtained at W2condition,while it had a diluting effect on protein.4. Effects of different irrigation and nitrogen on the flour colorThe a*-value declined significantly with irrigation times increase, while L*-value increasedsignificantly with the irrigation times increase at Zhengzhou. The results indicated that irrigationimproved the flour color at Zhengzhou. There was no obvious effect of irrigation regimes onL*-value and a*-value, while b*-value was markedly increased at Wenxian. The results indicatedthat no improvement effect of irrigation regimes at Wenxian. The L*-value decreased to someextent with N application rate increase at Wenxian, while b*-value increased significantly atZhengzhou. These results showed that there were no improvement effects of too much nitrogen onthe flour color. Applying less than180kg·hm-2of N combined with irrigation at jointing stages wasthe ideal management combination for the flour color. The correlation analysis of the flour colorwith protein content and compositions showed that a negatively significant correlation existed inL*-value with protein content and compositions, yet a positive correlation existed in a*-value andb*-value with that. The correlation at Wenxian was higher than that at Zhengzhou.5. Effects of different irrigation and nitrogen on processing qualityThe irrigation at jointing stage might extend stability time, enhanced FQN andSDS-sedimentation value, reduced softening degree. And the development time was longest at W1 condition at Wenxian, while the development time decreased with increasing of irrigation atZhengzhou. The nitrogen application extended the development time and stability time, enhancedFQN and SDS-sedimentation value, reduced softening degree significantly, while there was noobvious difference on most traits among the nitrogen treatments at two sites. The correlationanalysis showed that there was a correlation between processing quality and protein quality traits.And the correlation at Zhengzhou was higher than that at Wenxian.6. Effects of different irrigation and nitrogen on characteristic of soil nitrogenThe nitrate nitrogen content was higher at jointing stage, and significantly decreased atmature stage. Soil nitrate nitrogen content decreased with the deepening of soil layer at two sites,while the contents at Wenxian were higher than that at Zhengzhou. There were some differenteffect of irrigation regimes on nitrate nitrogen content between Wenxian and Zhengzhou. Thenitrate nitrogen content lower was obtained at W1condition at Wenxian, while the lowest valuewas acquired at W2condition at Zhengzhou. These indicated that irrigation promoted nutrientsuptake and utilization for crop. The effect of different nitrogen on nitrate nitrogen content wassimilar at two sites, that was N300＞N240＞N180＞N0. The nitrate nitrogen moved to the deepsoil layer with the increasing of nitrogen application and the rate of increase which nitrate nitrogenat deep soil layer was higher than surface layer.7. The correlationship of nitrogen supply characteristic of soil with grain yield and protein contentand its componentsThe correlation analysis results showed that with protein content and its componentspositively correlated with the soil nitrate nitrogen content of0-100cm soil layers in significant orextremely significant level at two sites. At Wenxian, a positively significant correlation existed inthe grain yield with nitrate nitrogen of different soil layers, while the correlationship did notachieve to significant level at Zhengzhou. This was related to the partial sand soil at in Zhengzhou,which led to the lower dependency of grain yield on the soil nitrate nitrogen.