| The main objective of this research was to analysis the high-yield population structure, functional characteristics and yield capability analysis of maize (Zea mays L.). Field experiments were conducted in Gongzhuling, Jilin Province in 2006,2008-2009. Three corn hybrids were cultivated at 60000 plants ha-1, 75000 plants ha-1, 90000 plants ha-1, 105000 plants ha-1.Treatments were arranged in a split-plot design with three replications. Plant population density was the main-plot and hybrids the subplot. The experiment was carried out to study the dynamic changes of the chlorophyll content, photosynthetic rate, soluble sugar content, nitrogen content, carbon-nitrogen ratio in corn leaf at different stages, especially after silking. The experiment was carried out to study the changes of the LAI, LAD, NAR, MLAI, MNAR,, HI, EN, GN, GW. And the main results were as follows:(1) This research indicate plant height, ear height, ear height/plant height, SLA, LAR, grain number to leaf area ratio increased and grain weight to leaf area, base circumference, MTA, transmittance rate decreased in all hybrids as plant density intensified. It showed that morphology structure was affected by density.(2) The dry matter distribution changes with the growth center transporting. The dry matter of different organ and its contribution to grains were different during the process of yield formation. It indicated that competition after silking was more detrimental to grain yield. And about 85-93% of grain yield was attributable to assimilates formed after silking. The dry matter proportion of different organ was changed as plant density intensified. Dry matter accumulation, dry matter accumulation after silking and grain-filling rate accorded with the logistic equation y=a/(1+be-cx).The dry matter accumulation of leaf, sheath, stem, bract conformed to Polynomial fitting y=a+bx+cx2+dx3.The dry matter accumulation of cob accorded with the Rational equation y=(a+bx)/(1+cx+dx2).(3) The soluble sugar content, nitrogen content, carbon-nitrogen ratio decreased in all hybrids as plant density intensified. The peak appeared at filling stage. The range of nitrogen uptake per 100kg grain were 2.03-2.34 kg. The soluble content, nitrogen content, carbon-nitrogen ratio of different organ decreased as plant density intensified, and were different in each growth stage. Nitrogen level of different organ is quite important in determining the final nitrogen content of grain, which ranged from 59.2 to 63.29% in different hybrids and experimental sites. Metabolism of carbon due to crowding stress was generally greater in high densities than low densities.(4) This research indicates the chlorophyll content, the photosynthetic rate in grain filling stage, soluble sugar content, leaf total nitrogen decreased in all hybrids increased competition pressure. It showed that transmission rate reduce, the leaf senescence accelerated, physical activity declined as plant density intensified. During the growth period, the changes chlorophyll content were single peak curve.The peak of chlorophyll content appeared at grain filling and the peak of Carbon-nitrogen Ratio appeared at silking and ripening respectively. The chlorophyll content, photosynthetic characteristics, soluble sugar content, carbon and nitrogen in corn leaf indicated a quadratic relationship with increasing days after silking. Total nitrogen in corn leaf decreased linearly in all hybrids as days after silking increased. High densities had great effect on carbon metabolism. The chlorophyll content had no or little effect on the photosynthetic rate after silking. The results showed the dynamic changes of photosynthetic characteristics, carbon and nitrogen were different as plant density intensified.(5) This research indicate LAI,LAD,MLAI,EN increased and NAR,MLAI,HI,GN,GW decreased in all hybrids as plant density intensified. It showed that transmission rate reduce, the leaf senescence accelerated, physical activity declined as plant density intensified. During the growth period, the changes of LAI, LAD were single peak curve. The peak of LAI appeared at silking, the peak of chlorophyll content appeared at grain filling and peak of high value duration of LAD appeared from full-grown to milky maturity. The peak of NAR appeared from seeding stage to jointing and from silking to grain filling respectively. The results showed the dynamics of photosynthetic characteristics were different as plant density intensified. The highest grain yield of xianyu335, zhengdan958, jidan209 was obtained from 90000 plants ha-1, 75000 plants ha-1, 90000 plants ha-1 respectively. Kernel yield per plant decreased in all hybrids as plant density intensified. The order of dense planting hybrid was xianyu335>zhendan958>jidan209.The suitable planting density range of xianyu335 is 90000plants ha-1-105000 plants ha-1, zhengdan958 and jidan209 were 75000plants ha-1-90000 plants ha-1.
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