| The studies were conducted in the Yangzhou University experimental farm of key laboratory of crop cultivation and physiology of Jiangsu province. Screening and identifying two super higher yield normal maize varieties and their ptimum planting density, Suyu20and Jundan20, which have potential (12000～13500kg·hm-2) yield as materials in2008. The study of different nitrogen (N) levels was conducted in2009. Based on this study,Suyu29was added in2010to continue to do experiments with different N application. Dry matter accumulation, leaf area index, photosynthetic rate, soluble sugar content, N accumulation and carbon and N ratio and other indicators of population quality in the treated of high or super high-yield were analyzed. The main results were as follows:1.The components components of high yield population it’s nutrient requiremenThe experimental results showed that yield,total grain number and grain weight at different Napplication treatments were significantly different.All of the three varieties in450kg·hm-2(N treatment level) reached the maximum yield. Different N treatments closely related to total grains and yield,and total production increased from an increase of total grain number. The total production, total grain number,grain weight of the maximum yield of three varieties,Suyu20were16691kg·hm-2,4.3163million·hm-2,386.7g;Jundan20were14342kg·hm-2,4.3237million-hm"2,331.7g; Suyu29were13365kg·hm-2,4.3169million-hm"2,309.6g.According to the regression equations between N application rate and yield of three varieties,we can know that the optimalNapplication amount was450.2kg·hm-2,the range of optimum N was415.3～485.1kg·hm-2,The range of N when super-high yield was378.4-521.9kg·hm-2Jundan20were439.9kg·hm-2,374.9～504.9kg·hm-2,413.0～466.8kg·hm-2respectively (The range of N when high yi eld);Suyu29were427.8kg·hm-2,366.3～489.3kg·hm-2,401.1～454.5kg·hm-2respectively.2. Dry matter accumulation of high yield populationDry matter accumulation of the three varieties in jointing and filling revealed two accumulation peaks. The amount of different varieties of the same period dry matter accumulationand yield was closely related, showed that the Suyu20had more dry matter accumulation relatively, followed by Suyu29, Jun20was the least one. Dry matter accumulation of the three varieties in450kg·hm-2reached the maximum. The regression equation between dry matter accumulation and yield of Various growth stages of three varieties showed that, Increasing dry matter accumulation of12-leaf to flowering can significantly contribute to the formation of Suyu20and Jun20high orsuper-high yield, the dry matter accumulation of the maximum capacity were3203kg·hm-2,2481kg·hm-2,followed by flowering to25days after flowering period in Suyu29, its matter accumulation of the maximum capacity was25675kg·hm-23.Photosynthetic rate of high yield populationPhotosynthetic rate of three varieties were advancing with the growth process firstand then decreased,which appeared a single peak curve,maximum flowering filling stage gradually decreased at450kg·hm-2Napplication level,The photosynthetic rate of thethree species were showed maximum value and the minimum rate of photosynthes was decline with different N application level. These showed that a higher yield of photo synthetic rate under optimum N application rate was conducive to the formation of high or super-high yield. The regression equation between photosynthetic rate of Various growth stages of three species showed increasing the photosynthetic rate by12-leaf of Suyu29and Jundan20can significantly contribute to the formation of high or super-high yield,the photosynthetic rate of the maximum capacity were43.1μmol m-2s-1、35.5μmol m-2s-1, followed by25days after flowering period in Jundan20,its photosynthetic rate of the maximum capacity was29.3μmolm-2s-1. 4. The LAI of high yield populationThe LAI of three varieties were all increased along with the advance of growth stages first and then decreased,and the Maximum values were all in the flowering period. There were the same trend along with the advance of N treatment level. The largest LAI of Jun20shows at the450kgN·hm-2, and the maximum was6.2. Followed by Suyu20and Suyu29in the495kgN·hm-2,7.4,6.8. Effect of Grain fertilizer to slow down the rate of decrease LAI was significant.The regression equa-tion between flowering LAI ofthe three varieties and N treatment level were,respective-ly,Suyu20was Y=-0.0002x2+0.1777x-34.04(R2=0.9646); Jundan20was Y=-0.00008x2+0.0763x-12.08(R2=0.9915); Suyu29was Y=-0.00006x2+0.0634x-9.08(R2=0.9878). These show that the regulation of flowering LAI throngh N was one of the important measures.5. Carbon and N metabolism of high yield populationThe soluble sugar content and N accumulation of plants and various organs of the three varieties in the process of promoting present different variation. But they were all increased along with the advance of N treatment level first and then decreased. Which The peak values of soluble sugar content of plants and leaves showed at the450kgN·hm-2. Known by the accumulation of Carbon and N, the extent of the transfer of soluble sugar and the larger ransfer rate of leaf in filling period were conducive to the formation of high yeild of groups. The regression equations between the accumulation of soluble sugar of maturity and yield showed that soluble sugar content of grain of Suyu29and Jundan20can significantly contribute to the formation of high or super-high yield,the soluble sugar content of the maximum capacity were207.26kg·hm-2,140.83kg·hm-2, followed by Leaves in Jundan20,its N content of the maximum capacity was42.07kg·hm-2.The regression equations between the N accumulation of maturity and yield showed that N content of grain of Suyu29and Jundan20can significantly contribute to the formation of high or super-high yield,the N content of the maximum capacity were373.71kg·hm-2337.33kg·hm-2, followed by Leaves in Jundan20,its N of the maximum capacity was55.39kg·hm-2.The regression equations between the C/N values of different stages of the three varieties and yield showed that regulating well the C/N value of the period of flowering was very important guarantee for high yields Suyu20and Jundan20, the C/N value ofthe maximum capacity were1.85,1.67, followed Suyu29in12-leaf period. its C/N value of the maximum capacity was1.73. |
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