| 【Objective】under the conditions of quantitative management by drop perfusion and water fertilization integration under the membranes,in order to study the effects of the number of nitrogen tracing times on maize yield,plant morphology,leaf area,dry matter accumulation,nitrogen accumulation and nitrogen use efficiency,to clarify the most suitable mode of nitrogen application management in the main production area of Maize in North Xinjiang,and to provide a theoretical reference and practical basis for the construction of a precise regulation technology mode for high-yield cultivation of Maize in dense regions.【Methods】The experiment was carried out at qitai Farm test site of the Sixth Division of Xinjiang from 2020 to 2021.A single factor random block design was adopted,using maize variety Denghai 618(DH618)as material,with a planting density of 120,000 plants/hm~2.Based on the optimal nitrogen application level of 360kg/hm~2 recommended by the team in the previous study,5 times of nitrogen application were set during the whole growth period of maize,namely 2 times,4 times,6 times,8 times and10 times.The amount of single nitrogen application was 162,81,54,40.5 and 32.4 kg/hm~2,respectively.The proportions of nitrogen fertilizer distribution before and after silking were 55%:45%,77.5%:22.3%,55%:45%,44%:56%,37%:63%,respectively.The leaf area,dry matter accumulation in aboveground and nitrogen accumulation in 6 key growth stages of maize under different treatments were measured using local farmers’four times of nitrogen fertilization as control.【Results】1.At the high yield(≥15000 kg/hm~2)level of dense planting(120 000 plants/hm~2),Increase nitrogen chase times and appropriate number of nitrogen dressing(8 times)was beneficial to the improvement of maize yield and nitrogen use efficiency,significantly optimized grain number per ear of maize,and promoted maize high yield and high nitrogen use efficiency.Compared with 4 treatments,the yield of 6 treatments,8 treatments and 10 treatments increased by 1.07～2.69%,4.53～6.89%and 0.50～0.92%,and nitrogen partial productivity increased by 1.33～2.35%,3.02～9.17%and 0.61-2.47%,respectively.Nue increased by 4.93～10.57%,11.24～52.71%,2.29～8.51%,and NUE increased by 43.04～58.09%,70.60～73.27%,30.58～49.43%,respectively.Yield increased by 0.50～0.92%,nitrogen partial productivity increased by 1.77～8.44%,agronomic use efficiency increased by 19.07～36.86%,and nitrogen use efficiency increased by 38.52～42.61%.2.The appropriate number of nitrogen dressing(8 times)was beneficial to the growth and matter accumulation of maize,and the 8 times treatment effectively extended the photosynthetic time of maize leaves,kept the higher photosynthetic potential of maize population from silking 30 days to physiological maturity stage,and significantly promoted the leaf area index and dry matter accumulation of maize at maturity stage.Compared with 4 treatments,leaf area index of 6,8 and 10 treatments increased by5.21～5.74%,9.96～14.15%and 8.80～9.31%at maturity stage,and total dry matter accumulation increased by 5.94～13.75%,9.94～17.68%and 0.37～3.19%,respectively.Leaf area index(LAI)and dry matter increased by 9.31～13.46%and 2.94～11.73%in 4 treatments compared with 2 treatments in other areas of China.At the same time,increasing the number of nitrogen dressing decreased the dry matter translocation and translocation rate before silking and the contribution rate of matter translocation before silking,but significantly increased the dry matter accumulation after silking.3.The appropriate number of nitrogen topdressing(8 times)promoted the synchronization of nitrogen supply and nitrogen demand in maize growth,which was beneficial to the absorption,transport and accumulation of nitrogen.Compared with 4 treatments,nitrogen accumulation in 6,8 and 10 treatments increased by12.47～19.57%,28.28～30.27%and 5.81～9.01%at physiological maturity stage,respectively,and average nitrogen accumulation in grains increased by 26.71%,44.54%and 6.47%in two growing seasons,respectively.Compared with the second treatment,the nitrogen accumulation in plants increased by4.89～6.17%,and the nitrogen accumulation in grains increased by 4.83%.【conclusion】Under the condition of dense planting(120,000 plants/hm~2)and high yield(≥15000kg/hm~2),The suitable nitrogen application times before spinning is 3 times,and the suitable nitrogen application times after spinning is 5 times.which could significantly optimize maize plant morphology,delay leaf senescence,guarantee leaf area index and photosynthetic potential for a long time after silking,and facilitate dry matter accumulation in the upper part of maize field,thus promoting yield improvement.At the same time,8 times of nitrogen dressing promoted nitrogen supply matching with nitrogen absorption of maize,which was beneficial to nitrogen accumulation and distribution,reduced the contribution rate of nitrogen transport to grains before silking,increased the contribution rate of nitrogen accumulation to grains after silking,and significantly improved the nitrogen use efficiency of maize.Therefore,under the conditions of this experiment,the high yield and high efficiency production target could be achieved by applying 36 kg/hm~2nitrogen fertilizer at the base of nine leaves spreading,twelve leaves spreading,5 days before spinning,5days after spinning,15 days,25 days,35 days and 45 days,respectively. |
