Effects Of Nitrogen Fertilizer Management On Nitrogen Absorption And Utilization,Photosynthetic Characteristics And Yield Of Maize Soil

Heilongjiang province is situated in the northeast of China.Meanwhile,Heilongjiang province is the largest grain-producing province in the country and the largest corn growing area in China.Maize?Zea mays L.?is a major food crop which has the largest planting area and the highest yield in China.Nitrogen fertilizer application has a very significant influence on maize growth and yield formation,however,nitrogen fertilizer will be affected by volatilization and leaching,which limit its utilization efficiency.In this study,the main maize varieties Xianyu 335 and Tiannong 9 of Heilongjiang Province were used as materials to explore the yield and dry matter accumulation of maize,the characteristics of plant nitrogen accumulation,and the inorganic nitrogen content of the soil profile under different nitrogen fertilizer application methods changes,soil-crop nitrogen balance,leaf chlorophyll content,and photosynthesis characteristics,in order to provide a more suitable nitrogen fertilizer migration scheme for maize cultivation in the northeast of China.The major results are as follows:1.Under the same nitrogen fertilizer application rate,with the increasing of proportion in top dressing,maize yield and yield components increase first and then decrease.Xianyu 335 nitrogen fertilizer treatments increased by 4.93%?6.87%compared to the customary nitrogen application,and Tiannong 9 nitrogen fertilizer treatment increased by 1.99%?5.45%compared to the customary nitrogen application.Xianyu 335 and Tiannong 9 showed the best yield of 20%of base fertilizer+60%of joint fertilizer+20%of flowering fertilizer in different nitrogen fertilizer treatments.2.Under the same nitrogen fertilizer application rate,after increasing the proportion of top dressing,the two maize varieties reduced the dry matter accumulation before the big trumpet period and increased the dry matter accumulation after the big trumpet period compared with the traditional nitrogen treatment.In different nitrogen fertilizer treatments,Xianyu 335 and Tiannong 9 showed that the dry matter accumulation of maize at maturity was the highest under the treatment of base fertilizer 20%+jointing fertilizer 60%+flowering fertilizer 20%,which increased by 4.55%and3.59%compared with the conventional nitrogen application treatment.3.Under the same nitrogen fertilizer application rate,after increasing the proportion of top dressing,the two maize varieties increased the chlorophyll content of the corn after the trumpet stage and promoted the photosynthesis of corn leaves compared with the traditional nitrogen application.As the proportion of top dressing increased,the transpiration rate and stomatal conductance of corn increased first and then decreased.The intercellular CO₂ concentration decreased with the increase of top dressing ratio,and the leaf photosynthetic rate increased and increased with the proportion of top dressing.The treatment of 20%basal fertilizer+60%jointing fertilizer+20%flowering fertilizer had the best effect on promoting post-anthesis photosynthesis of corn.4.Under the same nitrogen fertilizer application rate,increasing the proportion of top dressing reduced the inorganic nitrogen content in the soil tillage layer of the corn before the trumpet stage,and increased the inorganic nitrogen content in the soil after anthesis.At the same time,increasing the proportion of top dressing significantly increased the residual inorganic nitrogen in the soil and the nitrogen carried out by the crop,reducing the apparent nitrogen loss.Base fertilizer 20%+jointing fertilizer 60%+flowering fertilizer 20%has the best optimization effect on corn soil-crop nitrogen balance system.5.Under the same nitrogen fertilizer application rate,increasing the proportion of top dressing reduced the amount of nitrogen accumulation before the big trumpet stage of corn,increased the amount of nitrogen accumulation after maize flowering,and improved the rate of nitrogen absorption and utilization,nitrogen agronomic utilization and Nitrogen partial productivity.Base fertilizer 20%+jointing fertilizer 60%+flowering fertilizer 20%at maturity had the best effect on optimizing the nitrogen accumulation and nitrogen utilization efficiency at every growth stage of maize.6.Among different nitrogen fertilizer treatments,20%basal fertilizer+60%joint fertilizer+20%flowering fertilizer performed the best in improving corn yield and nitrogen utilization,reducing apparent nitrogen loss,and leaf photosynthesis.Therefore,when the nitrogen application rate is 210kg/hm²,20%basal fertilizer+60%joint fertilizer+20%flowering fertilizer is the best nitrogen fertilizer treatment in this area.