| Increasing planting density and reduce nitrogen fertilizer input is coordinated the measures to improve yield and nitrogen efficiency but under nitrogen limited investment increase efficiency was achieved by density cultivation,need to fully tap the corn light nitrogen utilization potential,by optimizing the layout control canopy light distribution of nitrogen and matching degree,displays the corn canopy units N photosynthetic efficiency.Synergistic approaches to improve maize yield and nitrogen efficiency.High-density maize varieties resistant to this study material,layout control mainly by means of density cultivation,system to study the different nitrogen density cultivation mode of corn canopy light distribution and matching characteristics,the influence of different nitrogen metabolism parse the blade light changes the response of the nitrogen distribution,and discusses its relationship with the canopy light nitrogen use efficiency,the main results were as follows:(1)Maize yield and n efficiency were significantly increased under two and three plant sections,and the effect of increasing yield and increasing efficiency was more obvious under high density.Under HD,the yield of two and three subplots increased by 14.0%and 13.5%,respectively,but only 5.8%and 5.7%under LD.NUE was significantly increased by increasing NIE,and increased by 73.4%and 71.2%under HD,but only 37.1%and 37.4%under LD,respectively.(2)Under the high density planting condition,the leaf PAR and SLN of each layer of maize canopy were significantly increased under two and three plant sections,and the canopy extinction coefficient and nitrogen reduction coefficient were decreased.PAR in the middle canopy increased by 61.6%and 57.0%compared with conventional planting,respectively.SLN increased by 17.1%and 18.4%compared with conventional planting,respectively.The deviation between K_L/K_b under HD and ideal state was significantly reduced,and the matching degree of light and nitrogen in maize canopy under high density was optimized.Under the high density condition,the photosynthetic nitrogen efficiency and nitrogen physiological efficiency of the two plants were increased by 18.1%and 25.9%,respectively.(3)Under the condition of high density,the red light intensity and R/FR of each layer of the canopy were significantly increased and the far-red light intensity of each layer of the canopy was decreased under the condition of two and three plant sections.The intensity of red light in the middle of the canopy under two and three sections increased by 37.6%and40.9%,respectively,compared with conventional planting.R/FR increased by 72.6%and75.7%,respectively.The far-red light intensity decreased by 20.2%and 19.7%,respectively.The increase of red light intensity and R/FR and the decrease of far-red light intensity in the canopy increased the proportion of photosynthetic enzyme and thylakoid nitrogen in total nitrogen,reduced nitrogen redundancy,and significantly increased PNUE and NIE,which were the fundamental internal cause of promoting the degree of light-nitrogen matching and improving population NIE.(4)The main physiological mechanism of dense planting was as follows:(1)Dense planting increased intra-canopy PAR and drove the increase of intra-canopy leaf SLN and the decrease of intra-canopy nitrogen reduction coefficient,thereby improving the light-nitrogen matching coefficient and making the intra-canopy light-nitrogen matching better.(2)Higher red light intensity and R/FR and lower far-red light intensity in the canopy increased the proportion of Rubisco,PEPC,PPDK and thylakoid nitrogen,and the canopy PNUE was significantly increased.(3)The photosynthetic productivity of maize per unit of nitrogen accumulation was significantly increased by better light-nitrogen matching degree and larger proportion of photosynthetic nitrogen component allocation in leaves,and the yield and NIE were increased synergistically. |
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