Effects Of Interaction Of Density And Nitrogen Fertilizer On Growth Characters Of Maize And Rules Of Nitrogen And Phosphorus Nutrient Transport And Accumulation

In order to explore the optimum density and nitrogen application rate of maize planting in Dunhua area of Yanbian,a field plot experiment was designed.The planting density was set at three levels:Ml?6.0×104 plants hm-2?,M2?7.5×104 plants hm-2?,M3?9.0×104 plants hm'2?.Five levels of nitrogen application were set,namely D1?0 kg·hm-2?,D2?80 kg·hm-2?,D3?160 kg·hm-2?,D4?240 kg·hm'2?and D5?360 kg·hm-2?.The growth and physiological indexes,nitrogen uptake and utilization,and root system status and yield of Maize at seedling stage,jointing stage,flowering stage and maturity stage were measured and analyzed.The main results were as follows:?1?With the increase of density,plant height stem diameter,dry matter accumulation,chlorophyll content and root morphology index of maize decreased gradually from seedling to maturity stage.Leaf area index,soluble sugar,soluble protein and root nitrogen and phosphorus content gradually increased.With the increase of nitrogen application rate,most indexes of maize growth and development showed a trend of first increasing and then decreasing,and reached the maximum when nitrogen application rate was D2.When the density is M1?6.0 ×104 plants hm-2?and the nitrogen application rate is D2?80 kg·hm-2?,the growth of maize reaches the optimum state;?2?With the increase of density,the yield and panicle number per hectare increase,while the number of grains per panicle and 1000-grain weight decrease.With the increase of nitrogen application,the yield and its components increased first and then decreased.The maximum yield was 8254 kg·hm-2 under M3D2 treatment.The results also showed that the number of ears per hectare and the number of grains per ear had a great decisive effect on Maize yield;?3?With the increase of density,the content of nitrogen and phosphorus in soil and the accumulation of nitrogen and phosphorus in maize plant increased.With the increase of nitrogen application,the content of nitrogen and phosphorus in soil and the accumulation of nitrogen and phosphorus in maize plant increased first and then decreased.There was no significant difference in nitrogen and phosphorus concentration and accumulation between above-ground treatments.Different nitrogen application rates changed the content of nitrogen and phosphorus in soil and indirectly changed the shape of root system;?4?Under the interaction of density and nitrogen fertilizer,the yield of maize reached its maximum value under the density of M3?9 ×104 plants hm-2?and nitrogen application rate of D2?80 kg·hm-2?,but the growth and development of maize were inhibited by high density,and the number of grains per ear and 1000-grain weight decreased,Which reduced the contribution efficiency of nitrogen transfer to grain nitrogen.Therefore,considering the optimum density and nitrogen application rate for maize growth and high yield,this study suggests that the suitable planting density of bare early-maturing Maize in Dunhua area is M2?7.5 ×104 plants hm-2?,and the nitrogen application rate is D2(80 kg hm^-2).