Effects Of Nitrogen Application On Agronomic Characters,Yield And Nitrogen Uptake And Utilization Of Spring Maize

The suitable nitrogen application rate was helpful to increase the yield of maize.the high nitrogen efficiency maize variety Xianyu‘335’and the low-nitrogen high-efficiency maize variety Jingnongke‘728’were used as test materials.five nitrogen application treatments were adopted:N1(120kg·hm^-2,66.66%less nitrogen than NCK),N2(180 kg·hm^-2,50%less nitrogen than NCK),N3(240 kg·hm^-2,33.33%less nitrogen than NCK),N4(300 kg·hm^-2,16.66%less nitrogen than NCK),and NCK(360 kg·hm^-2,local production nitrogen application).In this paper,the effects of nitrogen application on agronomic characters,yield and nitrogen absorption and utilization of maize under the condition of nitrogen reduction were studied.In order to provide a theoretical basis for rational regulation of nitrogen application in spring maize in eastern Hebei,China.The results are as follows:1.With the increase of nitrogen application rate,the plant height,ear height,stem thickness,ear length,ear thickness,bald tip length and axillary thickness of the two varieties increased to varying degrees.Jingnongke‘728’performed better under low nitrogen conditions,and Xianyu‘335’performed better under high nitrogen conditions.With the increase of nitrogen application,the yield increased first and then decreased.The highest yield of Jingnongke‘728’was 11180.04 kg·hm^-22 under N2treatment,and the highest yield of Xianyu‘335’under N4 treatment was 12309.14kg·hm^-2,Secondly,the yield under N2 treatment was 11712.85 kg·hm^-2,the differences between treatments were not significant.There was a positive correlation between yield and constituent factors.2.With the increase of nitrogen application rate,the net photosynthetic rate,transpiration rate,stomatal conductance,and intercellular CO₂ concentration tended to increase first and then decrease.During the filling stage,Jingnongke‘728’reached the maximum photosynthetic rate and transpiration rate under N1 treatment.Xianyu‘335’reached the highest photosynthetic rate under N4 treatment.3.With the increase of the amount of nitrogen application,the amount of dry matter accumulation increased continuously,reaching the highest in the mature period;The dry matter accumulation of Xianyu‘335’was 10.79%higher than that of Jingnongke‘728’during maturity.the nitrogen accumulation increased first and then decreased.Nitrogen distribution ratios of the above-ground organs of the two varieties at the maturity stage were kernels>leaf>stalk>stem>cob>leaf sheath>bud leaf>stamen.Under N2 treatment,the nitrogen content of grains,stems and cobs of Jingnongke‘728’and nitrogen accumulation at maturity reached the highest values,Under the N4 treatment of Xianyu‘335’,the nitrogen content of stems,leaves and grains and the nitrogen accumulation at maturity reached the maximum,the differences between treatments were not significant;Nitrogen partial productivity and nitrogen demand per hundred kilograms of grain gradually decreased.4.With the increase of nitrogen application rate,the grouting rate and duration of each stage increased to varying degrees;Jingnongke‘728’had the lowest water content during physiological maturity under low nitrogen condition N2 treatment,the moisture content of grains was the lowest when harvested under N1 treatment,highest average dehydration rate;Xianyu‘335’had the lowest physiological maturity and high moisture content under high nitrogen NCK treatment and the highest dehydration rate under N3 level.grain moisture content was extremely significantly positively correlated with bract leaf moisture content and dehydration rate,and positively correlated with stem moisture content and dehydration rate,but did not reach significant levels.Based on the above analysis,this experiment considered that the suitable nitrogen application rate of low-nitrogen and high-efficiency variety Jingnongke‘728’was 180kg·hm^-22 in eastern Hebei,China.The suitable nitrogen application rate of Xianyu‘335’with high nitrogen and high efficiency was 180kg·hm^-2.