| This experiment was carried out in Lankao County in 2008～2010. The root sample , by artificial digging from different soil layer of the field, was scanned and analysed by the system of WinRHIZO Pro 2008 scanner with computer. The effects of nitrogen application rates on the morphologic, physiology characteristics and the distribution of root of high-yield winter wheat with two different spike-shapes, and the correlation between root and the above ground and grain yield was studied to provide a theory basis of root regulation in high yield, high efficiency cultivation. The main results were as follows.1. In the condition of high-yield wheat field, the root weight density, root length density, root diameter, root volume and root surface area of winter wheat all increased with different growing stages progressing, and reached a maximum at heading stage, then declined slowly till the maturity stage. The soluble sugar, sucrose and total nitrogen content in root were the highest at over-wintering stage in the high-yield field, while the C/N reached the highest at anthesis stage. With the passing of growth stage, the content of soluble sugar and sucrose in root declined to minimum at heading stage, and increased greatly at anthesis, then continued decreasing. At the same time, the total nitrogen content in root decreased to the lowest at jointing stage or heading stage, and then continued increasing with small-amplitude. And the C/N in root was declined to the lowest at heading stage with two wheat cultivars, and increased to the highest at anthesis, then declined until maturity. The parameter referred above, sugar content, total nitrogen content and C/N in the root were greatest in the surface soil layer, and they vertically decreased with the increasing of soil depth.2. The nitrogen application rates affected the distribution of root weight density, root length density, root diameter, root volume and root surface area. The treatments were: N180>N360>N0. Compared with N0, the parameters referred above of the N180 with LKAZ 8 increased by 13.10%,34.34%,1.31%,19.36% and 17.58%, and the N180 with YM49-198 increased by 19.22%,24.51%,2.94%,27.47% and 23.75%, respectively. Viewed from different soil depths, the root parameters of surface layer in adding nitrogen fertilizer treatment were obviously higher than that of low nitrogen treatment. Compared with N0, among which of N180 with LKAZ 8 increased by 8.68%,47.98%,1.83%,24.73% and 25.48%, and the N180 with YM49-198 increased by 19.22%,24.51%,1.08%,27.47% and 23.75%, respectively. The sugar, total nitrogen content and the C/N in root were all highest in the treatment of N180 with two cultivars.3. Effects of nitrogen rate on yield and yield components with winter wheat were analyzed in this experiment. The results showed that the grain yield, the grain number per spike and 1000-grain weight all reached the highest in the treatment of N180 with two wheat cultivars. Compared with N0 and N360, the grain yield in the treatment of N180 with LKAZ 8 increased by 14.28% and 7.69%, and that with YM 49-198 increased by 18.30% and 1.43%, respectively, and there were significant differences among the treatments. The spike number of N180 and N360 in two cultivars were significantly greater than N0 in 2008～2009. And the spike number and 1000-grain weight between N180 and N0 with two cultivars were significantly different at the level of 0.05% in 2009～2010. And the grain yield i n the treatment of N180 of YM 49-198 was higher than that of LKAZ 8 by 12.98%. And the correlations between root morphology distribution and grain yield were analysed. The research results showed that there were significant correlation between root morphology distribution and grain yield in the whole growing stage. The root morphology distribution of LKAZ 8 with large-spike type cultivar in the middle growth stages, had significant correlation with the grain yield, especially in jointing stage. While for YM 49-198, the correlation between root morphology distribution and the grain yield was significant in the late growth stage, and more significant in anthesis stage. In the whole growing stage, the root surface area had the most significant correlation with the grain yield. And the correlation between root surface area and volume and the grain yield of LKAZ 8 in the surface layer was more significant, while as for YM 49-198, the root volume in the surface layer had more significant correlation than others with the grain yield.4. The results indicated that, in the soil layer of 0～100cm, when the grain yield of LKAZ 8 with large-spike cultivar reached about 8000kg/hm~2, the root weight density, root length density and root surface area should have reached at 99.81～102.49g/m~3, 3.6358～3.6394×103m/m~3 and 0.5619～0.5731m~2 in jointing stage, and reached 280.24～289.46g/m~3, 8.6195～8.6346×103m/m~3 and 0.9086～0.9122m~2 in heading stage, respectively. While the grain yield of YM 49-198 with multi-spike cultivar reached about 8500kg/hm~2, the root weight density, root length density and root surface area reached at 253.22～276.09g/m~3, 7.3483～7.4854×103m/m~3 and 0.9779～1.1129m~2 in heading stage, and reached 219.49～228.19g/m~3, 5.5124～5.8468×103m/m~3 and 0.6622～0.7119m~2 in anthesis, respectively. The results provided theoretical basis and controlling parameters for realizing stable and high yields cultivation of winter wheat with different spike-type cultivars. |
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