Effect Of Nitrogen Application On Physiological Characteristic And Yield Formation Of Super-High-Yielding Winter Wheat

The results of this experimen indicated that fewer amounts of nitrogen application at sowing period satisfied the growing and developing needs of Super-High-Yielding winter wheat (.YUMAI49) in the early stage of the wheat development. Properly postponing nitrogen application and increasing the rates of nitrogen application could increase Chi contents of the flag leaves , raise RUBPcase activity and Pn rates, alleviate the degradation of photosynthetic areas (LAI)and rates (CAP) of plant groups during the late periods, improve SOD activity of leaves, reduce the accumulation of MDA so that NR activity, soluble protein and sugar contents in leaves were in properly high levels ,carbon and nitrogen metabolism developed reasonably, and the plants were in health. During the ten treatments, 5:5 and 7:3 proportions of nitrogen application at sowing and booting periods (A3B2 , AjBj), and 5:5 at the sowing and jointing periods (A2B2) had high protecting enzymes activity, strongly photosynthetic organs and reasonable carbon and nitrogen metabolism in the late growing period. Less application of nitrogen or applying it too early42could be able to reduce SOD activity, increase MDA accumulation, quicken degradation of photosynthetic characteristics, unbalance the carbon and nitrogen metabolism, which made plants decline early. Excessive nitrogen applied at the jointing period (A2B3) could result in a big plant group and its single plants was in bad states and low ability. Excessive nitrogen at the booting period (A3B3), however, could restrain photosynthetic characteristics (RUBPcase, Pn) in flag leaves, strengthen nitrogen metabolism that lengthened the whole growing period and made the plant maturation postponed.By analysing effects of different nitrogen treatments on yield and its components, treatment 5:5 nitrogen application at jointing period (A2B2) had reasonable yielding components result in the highest yield in the experiment; 5:5 and 7:3 nitrogen application at the booting period (A3B2, A3B1) greatly improved the 1000-kernel weight and kernel number per ear, but the yield was not so high as that of A2B2 for their fewer spikes ; Treatment A^ had also a good effect of increasing yield for its more spikes; other treatments' s effects were low because of their unsuitable yield components.