Effects Of Application Nitrogen Level On Yield And Quality For "Nongda1108" In The Guanzhong Plain

Nongda 1108 is a new medium-strength gluten wheat variety with outstanding comprehensive characteristics.It has the characteristics of high yield,stable yield,and multi-resistance.A field experiment was conducted at the Wugong Experimental Station of Northwest A&F University in 2017-2018,to clarify its suitable nitrogen application rate.There were five treatments of 90 kg/hm²?N3?,120 kg/hm²?N4?,150 kg/hm²?CK;N?,180kg/hm²?N1?and 210 kg/hm²?N2?in the experiment.This study will provide theoretical support for the large-scale promotion of this variety in Guanzhong area.Our results showed that the suitable nitrogen application rate is 120 kg/hm² for Nongda1108.The specific results were as follows:1.Different nitrogen levels have some effects on the growth and lodging resistance of Nongda 1108 wheat.A significant change was observed in plant height,biomass per plant,leaf area of flag leaf during flowering,height of plant center of gravity,and mechanical strength between the first node of the base.The plant height is gradually increased with the increase of nitrogen application rate.The nitrogen application rate is from low to high in the range of 150 kg/hm²to 210 kg/hm²,and the plant height is gradually reduced.The dry weight of the individual plants treated with 40%?N2?and 40%?N4?nitrogen application decreased significantly,with the booting and maturity periods decreasing by 13.3%and4.8%.The dry weight of single plants and the leaf area of flowering leaves were significantly decreased by 40%?N2?and 40%?N4?.Respectively,as compared with CK,the dry weight per plant decreased by 13.3%and 4.8%at the booting stage and maturity stage,the flag leaf area decreased by 15.9%and 10.5%in the flowering period.The treatment of nitrogen application increased by 40%?N2?and 40%?N4?significantly affected the lodging resistance of plants,respectively,compared to the CK,the mechanical strength between the first sections of the base was reduced by 3.0%and 3.3%,the center of gravity of the nitrogen reduction 20%?N3?treatment was reduced by 9.0%,the mechanical strength of the first internode was increased by 0.4%,and the lodging resistance was enhanced.2.Propriate reduction of nitrogen application rate had little effect on the chlorophyll content and net photosynthetic rate of flag leaf of Nongda 1108 wheat at flowering stage,and the chlorophyll content and net photosynthetic rate of flag leaf treated with nitrogen reduction of 20%?N3?were 55.87 SPAD and 17.27?molCO₂·m^-2·s^-1,respectively,compared with CK,which decreased by 0.1%and 3.0%,but the difference is not significant from the CK.While excessive nitrogen and nitrogen increased significantly affected the chlorophyll content and net photosynthetic rate of flag leaf,when reducing nitrogen by 40%?N4?and increasing nitrogen by 40%?N2?,respectively,compared with CK,the chlorophyll content of flag leaves decreased by 5.5%and 4.5%,the net photosynthetic rate of flag leaves decreased by 20.0%and 19.0%,which is not conducive to the accumulation of photosynthetic materials.3.Different nitrogen levels have significant effects on the yield and composition of the1108 wheat,and the water and nitrogen use efficiency.Nitrogen reduction of 20%can significantly increase its yield,the yield is 8969.62 kg/hm²,compared with CK,the yield increased by 1660.92 kg/hm²,an increase of 22.7%,the grain number per spike,1000-grain weight and harvest index are also increased by 2.5%,1.7%and 1.7%.Respectively,as compared with CK,the water use efficiency and nitrogen fertilizer partial productivity increased by 24.5%and 53.4%.4.The nitrogen levels had significant effects on the grain protein content of Nongda1108 wheat,but had little effect on milling quality and food processing quality.The grain protein content of 20%?N1?nitrogen treatment increased significantly by 3.4%compared with the control.