Nitrogen Regulation Technology Of Medium-gluten Wheat Yangfumai4for High-quality And Grain Yield

This study, consisted of one experiment done in the light-textured loam on the Experimental Farm of Jiangsu Provincial Key Lab of Crop Genetics and Physiology and another experiment done in the yellow clay on the Experimental Farm of Yangzhou University, was conducted during the two wheat growing seasons from2008to2010. Yangfumai4, a medium-gluten wheat variety, was used as the testing variety. The effects of nitrogen application amount and the ratios of nitrogen application on grain yield, grain quality, and physiological parameters of plant leaves were studied to provide a solid base for obtaining high grain yield and quality in Yangfumai4. The main results were as follows:1. For the treatments with the grain yield of7500kg/ha and above, the nitrogen application amount was different, but the ratio of nitrogen application was the same. The content of grain protein in these treatments was in line with the standard of medium-gluten wheat quality. Specifically, the nitrogen application amount was225kg/ha in the light-textured soil and263kg/ha in the yellow clay soil. And the ratio of nitrogen application was the ratio of5:1:2:2at the growth stages of basal, tillering: elongation, and booting.2. At the same ratio of nitrogen application within a reasonable range of nitrogen application amount, the grain yield, number of spikes, kernel number per spike and1000-grain weight increased with the increase of nitrogen application amount. However, when the nitrogen application amount was increased to a level higher than the optimum level, the grain yield was increased insignificantly or decreased. At the same level of nitrogen application amount, the grain yield was increased with the increasing ratio of fertilizer at the stages of elongation and booting.3. The nitrogen application amount and the ratio of nitrogen application produced significant effects on the total number of culms and tillers, leaf area index (LAI), dry matter accumulation, and the spike rate at different growth stages. At the same ratio of nitrogen application within a reasonable range of nitrogen application amount, the indexes of population quality increased with the increased nitrogen application amount. However, when the nitrogen application amount was increased to a level higher than the optimum nitrogen level, the spike rate and dry matter accumulation began to decrease. At the same level of nitrogen application amount, the increased ratio of nitrogen application at the early growth stages increased the number of ineffective tillers and decreased the spike rate. The LAI of the treatments at the ratio of7:1:2:0increased at wintering stage. At jointing stage, the LAI of the treatments at the ratios of5:1:2:2and3:1:3:3increased significantly till the stages of booting and flowering. Compared with the treatment of7:1:2:0, the dry matter accumulation was significantly higher from wintering, elongation to booting in the treatments of5:1:2:2and3:1:3:3. Statistical analysis indicated that the dry accumulation after flowering was positively correlated to grain yield and the postponement of nitrogen application was beneficial to the increase of grain yield.4. At the same nitrogen application amount, the increased ratio of nitrogen from elongation to booting slowed the descending trend of the net photosynthesis rate of flag leaf after flowering, stomatal conductance, transpiration rate, chlorophyll content and the ascending rate of intercellular carbon dioxide concentration, the activity of SOD, CAT, and POD, indicating the capability of flag leaf of eliminating free radicals was decreased. The MDA content was decreased and the senescence of plant was delayed.5. At the same ratio of nitrogen application within a reasonable range of nitrogen application amount, the nitrogen accumulation, nitrogen productivity, nitrogen harvest index, nitrogen use efficiency, and nitrogen agronomic efficiceny increased with the increase of nitrogen application amount within a reasonable range. However, when the nitrogen application amount was higher than the optimum nitrogen level, these parameters decreased. At the same nitrogen application amount, the highest nitrogen use efficiency was observed in the ratio5:1:2:2, followed by3:1:3:3and7:1:2:0. The treatment of7:1:2:0increased the nitrogen accumulation from emergence to jointing. However, an opposite trend was observed under the treatments of5:1:2:2and3:1:3:3. At the nitrogen levels of188kg/ha and225kg/ha, the nitrogen harvest index was higher at the ratio of3:1:3:3; nitrogen agronomic efficiency was significantly higher at the ratios of5:1:2:2and3:1:3:3than at the ratio of7:1:2:0. When the nitrogen application amount was increased to263kg/ha, the nitrogen harvest index at the ratio of7:1:2:0was highest. And the nitrogen agronomic efficiency was highest at the ratio of7:1:2:0, followed by5:1:2:2and3:1:3:3.6. In the case of this experiment, the grain yield of Yangfumai4was higher than7500kg/ha and the grain protein content was in line with the standard of medium-gluten wheat. At this yield level, the number of spikes was450-530million/ha; the number of kernel per spike was38-40; the weight of1000kernels was40-43g; the basic seedling number was1.5million/ha; the maximum number of tillers was twice the number of the spike and the rate of tillers was45-48%; the maximum LAI of6.0-7.0appeared at booting stage; the dry matter production after anthesis was6500kg/ha accounting for85-90%of dry weight of grain and the economic index was demanded above0.4. High yield was obtained when the nitrogen application amount was225kg/ha in the light-textured loam and263kg/ha in the yellow clay, both at the ratio of5:1:2:2at basal, tillering, elongation and booting.