| In order to rationally close planting and balanced fertilization,improve the utilization rate of nitrogen fertilizer and increase maize yield,this paper takes Maize in Chaoyang village,Hanzhang Township,Dunhua City,Yanbian Korean Autonomous Prefecture,Jilin Province as the research object.Through field experiments and indoor analysis,the interaction effect of planting density and nitrogen application rate on maize growth characteristics,yield,nutrient migration and nutrient transfer under mulching conditions was studied.The results show that:1.The interaction between density and nitrogen fertilizer had a significant effect on Maize growth.Increasing planting density and appropriate amount of nitrogen application could significantly increase plant height,leaf area index and dry matter accumulation,but stem diameter,chlorophyll content,root volume,root dry weight,soluble sugar concentration of ear leaf and 100-grain weight of maize decreased significantly with increasing density and reducing nitrogen.The plant height,leaf area index and dry matter accumulation of maize population reached the maximum value under M3D3 treatment in each growth period.The stem diameter,leaf chlorophyll content,root volume and dry weight of spike position were treated with density of 60,000 plants hm*2,nitrogen application rate of 360 kg hm-2,soluble sugar of spike leaf was treated with 60,000 plants hm-2 and nitrogen application rate of 160 kg hm-2.2.The interaction between density and nitrogen fertilizer had a significant effect on Maize yield.The maximum yield could be obtained by increasing planting density and appropriate alount of nitrogen application.The grain yield was 15 641.8 kg·hm-2 under the treatment of 900,000 plants hm-2 and 240 kg hm-2,and the yield decreased with the increase of nitrogen application.The conditions of high planting density and high nitrogen application had significant effects on grain number per row and grain number per ear of maize,which reached the maximum under the treatment of density of 90,000 plants hm-2 and nitrogen application of 360 kg·hm-2.Reducing planting density and properly applying nitrogen fertilizer could increase 100-grain weight.The maximum value was obtained when the density was 60,000 plants hm-2 and the amount of nitrogen applied was 80 kg·hm-2.Increasing plaLting density and applying nitrogen properly could significantly increase the number of panicles harvested in flat rice,with a density of 90.000 plants·hm-2 and a nitrogen application rate of 160 kg·hm-2 being the maximum.3.Mathematical model was established and analyzed.The optimum planting density was 6.381 million plants·hm-2,the optimum nitrogen application rate was 208.332 kg·hm-2,and the maximum grain yield was 14456.34 kg·hm-2.4.The interaction between density and nitrogen fertilizer had a significant effect on nitrogen accumulation in maize.Nitrogen accumulation also increased with the increase of density and nitrogen application.The maximum nitrogen accumulation was 90,000 plants·hm-2 at male-setting stage,80 kg·hm-2 at nitrogen application rate and 114.34 km·hm-2 at male-setting stage.The maximum nitrogen accumulation during grain filling was 293.91 kg·hm-2 under M3D5 treatment.The maximum nitrogen accumulation at maturity stage was 90,000 plants·hm-2,360 kg·hm-2 and 317.07 kg·hm-2 Under all treatments,nitrogen in maize was gradually transferred to grains along with the growth period.At grain filling stage and ripening stage,the average grain nitrogen percentage was 21.0%and 47.0%respectively.5.The interaction between density and nitrogen fertilizer had a significant effect on phosphorus accumulation in maize.Increasing planting density and proper application of nitrogen fertilizer could significantly increase phosphorus accumulation in maize.The maximum phosphorus accumulation was in the treatment of 900,000 plants ·hm-2 density and 360 kg· hm-2 nitrogen application.The phosphorus accuiulation was 56.07 kg ·hm-2 at the stage of tasseling,kg·hm-2 at the stage of filling and 80.73 kg hm’2 at the stage of maturity.Under all treatments,phosphorus in maize was gradually transferred to grains along with the growth period.The average phosphorus content in grains at grain filling stage and maturity stage was 15.8%and 42.3%respectively.6.The interaction between density and nitrogen fertilizer had a significant effect on potassium accumulation in maize.Increasing planting density and proper application of nitrogen fertilizer could significantly increase potassium accumulation in maize.Potassium accumulation was the highest in the treatments with density of 90,000 plants ·hm-2 and nitrogen application of 240 kg ·hm-2.Potassium accumulation was 310.51 kg ·hm-2 at the stage of tasseling,324.23 kg ·hm-2 at the stage of filling and 263.34 kg ·hm-2 at the stage of maturity.Under different treatments,potassiul in maize mainly existed in the stems and leaves of maize.The average percentage of potassium in grain was 8.4%at filling stage and I8.6%at ripening stage.7.Through the analysis of nitrogen efficiency of different dense nitrogen treatments,it was found that the partial productivity of nitrogen fertilizer,the apparent utilization rate of nitrogen fertilizer,the agronomic utilization rate of nitrogen fertilizer and the physiological utilization rate of nitrogen fertilizer decreased with the increase of nitrogen application rate.Nitrogen harvest index decreased with the increase of density.In conclusion,it is considered that increasing planting density and nitrogen application rate can optimize maize biological characteristics and increase maize yield under mulching conditions.The optimum planting density was 6.381 million plants·hm-2,the optimum nitrogen application rate was 208.332 kg·hm-2,and the maximum grain yield was 14456.34 kg ·hm-2. |
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