Variation of nitrogen uptake and utilization efficiency in mid-season hybrid rice at different ecological sites under different nitrogen application levels | 浜や腑绋诲ㄤ板芥爱姘村钩涓姘告跺╃ㄦ寮

[Objective] The study aimed at investigating the effects of different geographic sites, soil chemical characteristics and nitrogen application levels on nitrogen accumulation and distribution in different organs and utilization efficiency for mid-season hybrid rice. [Method] By using mid-season rice varieties II-you 7 and Yuxiangyou203 as the experimental materials, field experiment was conducted at seven ecological sites in four provinces or cities in Southwestern China in 2009. A total of four nitrogen application levels were set as follows: by using 75 kg/hm2 of P2O5 and 75 kg/hm2 of K2O as the base fertilizer, extra 0, 90, 150 and 210 kg/hm2 of nitrogen fertilizer (in which, base fertilizer, base-tillering fertilizer and base-earing fertilizer respectively accounted for 60%, 20% and 20%.) was applied, respectively. In the split-plot design, fertilizer was considered as the main factor while rice variety was taken as the secondary factor. A total of eight treatments were set with three replications. [Result] Highly significant differences of grain yield were found among seven locations, two varieties, four nitrogen application levels, interactions of site variety and site nitrogen application level, but the interaction of variety nitrogen application level had no significant influence on rice yield. There were highly significant effects of site, varieties and nitrogen application level on dry matter production, nitrogen content, nitrogen utilization efficiency. Highly significant negative correlations between uptake efficiency and utilization efficiency for nitrogen were found; and multiple stepwise regression analysis showed that nitrogen uptake-utilization efficiency were significantly influenced by different ecological sites, chemical quality of soil and the levels of nitrogen application. [Conclusion] The research will provide theoretical and practical basis for the highly efficient application of nitrogen in mid-season hybrid rice cultivation.