Effects Of Nitrogen And Density Interaction On Canopy Photosynthetic Characteristics And Yield Of Winter Wheat In Huaibei Lime Concretion Black-soil Region

In order to provide a theoretical basis for stable production and high quality cultivation of wheat in Lime Concretion Black Soil Region of Huaibei Pn and select a reasonable nitrogen-density configuration for local wheat planting,under the field conditions,we used winter wheat varieties Annong 0711(AN0711)and Yannong 19(YN19)as experimental materials and used the split zone design,set the planting density of 150×104,210×104,270×104 and 330×104 plants·hm-2(represented by D1,D2,D3,D4),and 4 nitrogen application rates:135,180,225 and 270kg·hm-2(represented by N1,N2,N3,N4).Therefore,the effects of nitrogen-density interaction on canopy structure,photosynthetic characteristics grain filling characteristics and grain yield of winter wheat were analyzed.The results showed that Nitrogen-density interaction improved wheat canopy structure and had a significant effect on canopy photosynthetic characteristics.plantt height and ear length increased with the increase of planting density and nitrogen application rate.The Pn and SPAD values of flag leaves decreased with increased planting density,but increased significantly with increased nitrogen application rate(P<0.05),but there was no significant difference between treatments when nitrogen application exceeded 225kg·hm-2.From a population perspective,the increase in planting density and nitrogen application significantly increased LAI and IPAR,reduced DIFN.At the booting stage and flowering stage,LAI and IPAR of D4N4 were the largest,DIFN minimum,while in the middle stage of filling,D3N3 had the largest LAI and IPAR,DIFN minimum.Nitrogen density interaction mainly affects the formation of grain weight by affecting grain filling speed of wheat.The grain filling speed at fast growth stage,slow growth stage and average grain filling speed are positively correlated with grain weight.Nitrogen fertilizer and density had significant interaction effects on grain yield.Both varieties had the highest yield at D3N3,and the highest yields were 7866.67kg·hm-2 and 7400.00kg·hm-2,respectively.Nitrogen-density interaction on the photosynthetic characteristics and grain yield of winter wheat canopy showed that D3N3 treatment significantly enhanced the photosynthetic characteristics of winter wheat canopy,increase yield and improving quality.Based on the nitrogen-tight configuration,the regression analysis of nitrogen-density interaction and yield is considered that in the Black Soil Region of Huaibei,the two varieties are appropriately added with nitrogen fertilizer,and the proper reduction of density of YN19 is an important cultivation method for stable production and high quality.