Regulating Effects Of Nitrogen Application Rates On Grain Yield And Quality Formation In Winter Wheat

To evaluate the effects of nitrogen application rates on nitrogen metabolismand translocation, grain yield and yield components, nutritional quality and processing qualityof wheat grain, two wheat cultivars with different gluten-strengths, Zhengmai366(astrong-gluten cultivar) and Aikang58(a medium-gluten cultivar) were studied under the fieldcondition. The experiment was carried out at Henan Agricultural University Research farm,Zhengzhou (34°N latitude,113°E longitude), in wheat growing-season of2009-2010and2010-2011. At the same time,2aided experiments were studied. One was carried out withAikang58at Wenxian and Xunxian of Henan province in growing-season of2009-2010toevaluate the effects of nitrogen application rates on protein content and its components.Another was carried out with Zhengmai9023, a strong-gluten wheat cultivar, at six locationsof Henan Province (Anyang, Sanmenxia, Shangqiu, Luohe, Nanyang, Xinyang) ingrowing-season of2007-2008, to evaluate the effects of different ratios of nitrogen andphosphorus on protein content and processing quality.The main results were as follows:1. Effects of N application rates on grain yield and nitrogen translocationThe results indicated that nitrogen increased grain yield and protein yield of wheatsignificantly. N application rate of225Kg/hm~2got the highest grain yield and protein yield ofwheat at Zhengzhou, Wenxian and Xunxian. And the average value of grain yield and proteinyield in Zhengmai366were higher than that of Aikang58at Zhengzhou. This was mainly dutto more kernels per ear and more TGW of Zhengmai366. And the effects of N application onears per hectare and TGW led to the difference of grain yield in this field condition. Fornitrogen translocation, translocation amount of pre-anthesis stored nitrogen in different organsand nitrogen accumulation in grains at maturity of Zhengmai366and Aikang58wereincreased with N application increased. But N application had no effects on translocation ratioof pre-anthesis stored nitrogen in different organs, contribution rates of pre-anthesis and post-anthesis assimilated nitrogen to grain nitrogen2. Effects of N application on the key enzymes activity of protein metabolism and dynamic accumulation of proteinN application affected the activity of NR and GS in flag leaf, and increased GS activity ingrain significantly. Nitrogen increased GS activity of superior grain on each grain position ofwheat in the early filling stage and mid-filling stage. And this promoted the synthesis andaccumulation of nitrogen.The performance of three ear positions was consistent. The tendencyof protein content of superior kernel in Zhengmai366presented the type of “V”. And the rateof decline in early stage of filling stage was faster than the rate of increase in post stage.Among all treatments, protein content increased with N application rate increased. Theprotein content in all spikelets got the highest value at basal spikelets except15days and30days post-anthesis. And N application promoted the protein content of central spikeletsmainly.3. Effects of N application rates on protein content, protein components and percentageof each protein component to total protein content of wheat grainN application rates affected protein content and its components of wheat grain significantly.The performances of protein components were different among three locations. Globulin,gliadin and glutenin of Zhengmai366and Aikang58were affected by N applicationsignificantly at Zhengzhou. N application rates effected gliadin and glutenin of Aikang58atXunxian significantly, and glutenin of Aikang58at Wenxian.According to the effects of Napplication rates on protein content and its components, the N application rate of225Kg/hm~2got the highest value of protein content and its components in Zhengmai366and Aikang58atZhengzhou. And the best N application rate for Aikang58was300Kg/hm~2at Wenxian andXunxian. IN the experiment of combined application of nitrogen and phosphorus, proteincontent of Zhengmai9023got the highest value with the treatment N application rate of240Kg/hm~2, P application rate of60Kg/hm~2.Percentage of each protein component to total protein content varied among differentcultivar and different sites. The percentage of albumin and globulin decreased with Napplication increased, while gliadin and glutenin increased. So, N application increasedpercentage of storage protein to total protein content, and then enhanced processing quality.4. Effects of N application on processing quality of winter wheatTest weight of grain declined with N application increased, while SDS-sedimentation valueincreased. Test weight of Aikang58was more sensitive to nitrogen than Zhengmai366, whileSDS-sedimentation value of Zhengmai366was more sensitive to nitrogen than Aikang58.The more of N application amount extended development time and stability time, reducedsoftening degree, enhanced FQN, increased extension area and resistance to extension, added extensibility and extension ratio. And N application rate of225Kg/hm~2got the bestprocessing quality of Zhengmai366and Aikang58. At the same time, Zhengmai366hadlonger development time and stability time, lower softening degree, higher FQN, largerextension area and extensibility, bigger resistance to extension and smaller extension ratiocompared with Aikang58.5. The correlation between protein quality and processing quality and flour colorTest weight was significant negatively correlated with protein content and its component,excepted albumin (P≤0.01). While SDS-sedimentation value was significant positivelycorrelated with protein content and its compositions, excepted albumin and globulin(P≤0.01).Protein content had significant negatively correlation with softening degree (P≤0.01), but hadsignificant positively correlation with other farinaceous parameters and extensible parameters(P≤0.01).Protein components had significant correlation with processing quality as well, but theywere various among each protein component. At the same time, there was significantcorrelation among all processing parameters and between processing parameters and the mainagronomy characters.6. Effects of N application on flour color and the correlation between protein quality andflour colorN application affected flour color significantly. L*-value of Zhengmai366and Aikang58declinde with N application rate increase, while a*-value increased significantly with Napplication rate increase. And b*-value of Zhengmai366inceased significantly with Napplication rate increase, while b*-value of Aikang58was not affected by N application rates.Between two cultivars, Zhengmai366had higher a*-value and b*-value, while Aikang58hadhigher L*-value. Flour color had close relations with protein content and its components, andthe storage protein had closer connection than soluble protein.In conclusion, Nitrogen application rates affected the formation of grain yield and qualityin winter wheat significantly. The proper N application could increase grain yield, advancedquality of grain and improved the flour color. And combined application of nitrogen andphosphorus increased protein content and improved processing quality of wheat grain on acertain degree. The nitrogen application rate of225Kg/hm~2got the highest grian yield and thehighest protein content. And protein content of Zhengmai9023got the highest value with thetreatment N application rate of240Kg/hm~2, P application rate of60Kg/hm~2in the experimentof combined application of nitrogen and phosphorus.Protein content and its components wassignificant corrected with processing quality and flour color, but different among cultivar and location. So, we should choice excellent cultivar with proper nitrogen fertilizer application,give full play to cultivar potential by rational cultivation measures, and achieve the goal ofhigh yield and high quality at last.