| Nitrogen fertilizer has played a essential role in the growth of grain yield and stability, and made important contribution to ensure food security in china. Nitrogen fertilizer excessive application and methods of extensive application have been leading to massive nitrogen lost and nitrogen fertilizer use efficiency is low, and then the lost nitrogen caused massive economic cost and brought huge pressure on the ecological environment. More and more people pay more attention to the problem. Maize and wheat are the main food crops in China and those yield and quality have an important influence to china food security. Screening and breeding of maize and wheat with high NUE is an important way to improve NUE and reduce environmental risk.There is a great significance to ensure food security and sustainable development of agriculture.The system of evaluation indexes of maize and wheat with high NUE is established by studying on maize and wheat growth status and biological indicators at the seedling stage. Maize and wheat varieties in different types of NUE were screened by the subordinate function and the clustering analysis method. Researching of maize and wheat varieties with different NUE of nitrogen absorption and utilization efficiency and those biological characteristics were conducted at the field experiments, in order to provide scientific basis and improve NUE for maize and wheat. The main results are as follows:1 Analysis of the traits of the Anhui province 23 maize varieties at normal nitrogen level (5 mmol/L) and high nitrogen level(45 mmol/L) at the seedling stage were found stem dry weight, total dry weight, leaf area, stem nitrogen accumulation and total nitrogen accumulation had the greater variability and the amount of traits variation coefficient respectively were between 34% to 58% and 35% to 48%, and reached the extremely significant positive correlation, the establishment system of evaluation index for screening of maize varieties with high NUE at the seedling stage. Analysis of the traits of the 44 wheat varieties at normal nitrogen level (5 mmol/L) and high nitrogen level(45 mmol/L) at seedling Stage were found stem nitrogen accumulation.stem dry weight,root nitrogen accumulation,root dry weight,and leaf area had the greater variability and the amount of variation coefficients were between 27.9% to 33.7% and 21.5% to 32.8%, the establishment system of evaluation index for screening of wheat varieties with high NUE at the seedling stage.2 The efficient evaluation index of maize and wheat were standardized by subordinate function method and then The integrated nitrogen use efficiency values were calculated. The integrated nitrogen use efficiency values results show that:The integrated nitrogen use efficiency values at normal and high nitrogen levels at seedling stage were from 0.199 to 1.113 and from 0.216 to 1.128, respectively. The integrated nitrogen use efficiency values of Jundan 20 at normal nitrogen level and high nitrogen level are greater than 90%. The integrated nitrogen use efficiency values at normal and high nitrogen levels at wheat seedling stage were 0.053 to 0.920 and 0.001 to 0.853, respectively. The integrated nitrogen use efficiency values Jian 76 wheat variety was greater than 80% at both normal and high nitrogen levels.3 Based on the integrated nitrogen use efficiency values and the clustering analysis of integrated nitrogen use efficiency values,23 maize varieties varieties were divided into three categories, which were high, middle and low nitrogen use efficiency. Hua yu 15、 Feng le 21 and Jun dan 20 belong to high NUE maize varieties at normal nitrogen level; Zheng dan 18 and Jun dan 20 belong to high NUE maize varieties at high nitrogen level. Based on the integrated nitrogen use efficiency values and the clustering analysis of integrated nitrogen use efficiency values, forty four wheat varieties were divided into three categories, which were high, middle and low nitrogen use efficiency. The Yang mai 16 and Jian 76 belong to high NUE wheat varieties at both the normal and high nitrogen levels; Wan mai 68, F60501-4, Jian 62 and An nong 1026 belong to high NUE wheat varieties only at high nitrogen level.4 Field conditions, high NUE maize variety Jun dan 20 at unsupplied nitrogen region, middle nitrogen region and high nitrogen region total root length were higher 4.11,4.86 and 8.57 times than low NUE maize variety Nong da 108,respectively; Root surface area of Jun dan 20 were higher 3.32,3.49 and 4.85 times than Nong da 108; Root volume of Jun dan 20 were higher 2.71,2.25 and 2.23 times than Nong da 108. At the same nitrogen level, high NUE maize variety the total root length, root surface area, root volume, root number and root furcation number of Jun dan 20 were significantly higher than low NUE maize variety Nong da 108,respectively.High NUE maize variety biological characteristics of root were better than low NUE maize variety at the seedling stage.5 Yield of Jun dan 20 with high NUE at unsupplied nitrogen region, middle nitrogen region and high nitrogen region were 2657.34 kg/hm2,8811.19 kg/hm2 and 9790.21 kg/hm2;Yield of Nong da 108 with low NUE at unsupplied nitrogen region, middle nitrogen region and high nitrogen region were only 1351.98 kg/hm2,6200.47 kg/hm2, 8041.96 kg/hm2. At unsupplied nitrogen region, middle nitrogen region and high nitrogen region,yield of Jun dan 20 were higher 96.55%,42.11% and 21.74% than Nong da 108, all reached the significant level respectively.6 NUE, NHI of maize variety with high NUE were significantly higher than low NUE maize variety. At unsupplied nitrogen region, middle nitrogen region and high nitrogen region,NUE of Jun dan 20 were higher 96.56%.42.09% and 21.73% than Nong da 108; NU,E of Jun dan 20 were higher 71.48%,32.68% and 37.60% than Nong da 108 respectively; NHI of Jun dan 20 were higher 46.94%,20.59% and 22.06% than Nong da 108.7 At unsupplied nitrogen region, middle nitrogen region and high nitrogen region, aboveground dry weight of Yan nong 19 were significantly higher 13.02%,43.31% and 51.67% than Zhou mai 22, respectively (p<0.05); Grain nitrogen accumulation of Yan nong 19 were significantly higher 38.61%,26.67% and 28.87% than Zhou mai 22 (p< 0.05); Aboveground nitrogen accumulation of Yan nong 19 were significantly higher 17.10%, 26.01% and 31.12% than Zhou mai 22, all reached the significant level (p<0.05).8 At unsupplied nitrogen region, middle nitrogen region and high nitrogen region, NUE of Yan nong 19 were higher 54.84%,45.85% and 48.59% than Zhou mai 22; NUPE of Yan nong 19 were higher 17.31%,26.87% and 30.43% than Zhou mai 22; NUtE of Yan nong 19 were higher 32.23%,15.72% and 13.38% than Zhou mai 22. At middle nitrogen region and high nitrogen region, NPFP of Yan nong 19 were higher 45.84% and 48.61% than Zhoumai 22; NAUE of Yan nong 19 were higher 99.67% and 89.82%. |
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