Study On High-efficient Nitrogen Fertilization Planning Techniques Of Machine Harvest Summer Maize In Dongting Lake Area

In recent years,the planting area of summer maize in Dongting Lake area has gradually increased,but its supporting fertilization technology is not yet perfect.In order to explore the high-efficiency nitrogen application method of summer maize in Dongting Lake area,field experiment was carried out in Mutangyuan Town,Taoyuan County,Hunan Province in 2019.The effects of nitrogen application rate(0,N0;150kg N/hm~2,N1;225kg N/hm~2,N2)and nitrogen fertilizerplanning method(ratio of base fertilizer,jointing fertilizer and ear fertilizer,7:0:3,Y1;5:0:5,Y2;7:1.5:1.5,Y3;5:2.5:2.5,Y4)on yield formation characteristics,nitrogen utilization efficiency and lodging resistance of machine harvest summer maize were studied under high densitycondition(90000 plants/hm~2)with Zhengdan 958 as material.The main results are as follows:The yield of summer maize was affected by nitrogen rate and nitrogen fertilizer planning method.The yield of Y1 treatment was the lowest under N1 condition,the yield of Y2 treatment was the lowest under N2 condition,and the yield of Y4 treatment was the highest under both nitrogen application rates.Under the same nitrogen fertilizer planning method,the yield showed a trend of N2>N1>N0,and the yield of N0 treatment decreased by more than 35%compared with nitrogen treatment.The dry matter accumulation,distribution and transfer of summer maize were affected by nitrogen rate and nitrogen fertilizer planning method.The dry matter accumulation,transport rate and its contribution to grain yield in N0 treatment were lower than nitrogen application treatment.Under the same nitrogen application rate,the population dry matter accumulation and dry matter transport rate of Y4 treatment were the largest.Under the same nitrogen fertilizer planning method,the dry matter accumulation was increased with the increase of nitrogen rate,and the dry matter transport rate and its contribution to grain yield under Y1 treatment showed the trend of N1>N2,and the other treatments showed the opposite.Nitrogen application could significantly increase the nitrogen accumulation of summer maize.The nitrogen use efficiency and the partial productivity of nitrogen fertilizer in summer maize generally decreased significantly with the increase of nitrogen application rate,while the nitrogen application rate and nitrogen fertilizer planning method had significant interaction effects on the nitrogen utilization efficiency of maize.Nitrogen harvest index showed a trend of N1>N2 and Y4>Y1>Y2>Y3.Nitrogen transport efficiency was obviously affected by nitrogen fertilizer planning method,showed a trend of Y4>Y3>Y2>Y1,but not greatly affected by nitrogen rate.The contribution rate of nitrogen transport to grain increased with the increase of nitrogen application rate,which showed the trend of Y3>Y2>Y1>Y4under N1 condition,while there was not much difference between the treatments under N2 condition.It could be seen that Y4 treatment was beneficial to improve the nitrogen utilization efficiency.When the nitrogen application rate was the same,the ear position coefficient of summer maize was the smallest,the stalk was the thickest,and the lodging risk was the smallest in Y3 treatment,and Y4 treatment was the second and the difference was not big.When thenitrogen fertilizer planning method was the same,the ear position coefficient was smaller and the stem was thicker in N2 treatment compared to N1,that is to say,the lodging risk of N2 treatment was smaller.The stempuncture strength and pulling force of summer maize increased significantly with the increase of nitrogen application rate,and there existed the trend of Y3>Y4>Y1>Y2among treatments of nitrogen fertilizer planning method.Taken together,N2Y3 treatment had the strongest lodging resistance,and followed by N2Y4treatment.Comprehensively consider yield,nitrogen utilization efficiency and lodging resistance,the suitable nitrogen application rate and nitrogen fertilizer planning method for machine harvest summer maize in Dongting Lake area was nitrogen application rate 225 kg N/hm~2,base fertilizer:joint fertilizer:ear fertilizer ratio 5:2.5:2.5,respectively.