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Effects of nitrogen rate and ratio of base fertilizer and topdressing on uptake, translocation of nitrogen and yield in wheat |
| SHI Yu1, YU Zhenwen1, WANG Dong1, LI Yanqi2, WANG Xue2 |
| 1.Key Laboratory of Wheat Physiology and Genetics Improvement, Ministry of Agriculture, Shandong Agricultural University, Tai′an 271018, China; 2.Center of Agricultural Technique Extension of Longkou City, Longkou 265701, China; |
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Abstract Application of nitrogen (N) fertilizer is one of the most important measures to increase grain yield and protein content in winter wheat (Triticum aestivum L.) production. However, misuse of N fertilizer will not only affect grain yield and quality, but also cause the decline of economic benefits and related negative environmental effects. It is essential to study reasonable N application regimes for profitable yields, efficient N utilization and reduction in possible environmental pollution. The objective of this study was to determine the N uptake and translocation in wheat plants by using 15N isotope tracers in PVC cylinders (2.05 m long, &Phi 0.2 m, without bottom) in seven treatments: without N fertilizer application (N0); N application rate of 168 kg/hm2 (0.527 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N1), 1:2 (N2) and 0:1 (N3); N application rate of 240 kg/hm2 (0.753 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N4), 1:2 (N5) and 0:1 (N6). The 15N tracer experiment showed that the main basal N absorbed by plant from sowing to jointing stage accounted for 78.04% 89.67%; fertilizer N use efficiency (FNUE, N fertilizer accumulation in plant/N supplied) of topdressing was significantly higher than that of basal N; reducing basal N amount and increasing topdressing N amount could appropriately promote the plant s absorption of more N fertilizer and enhance FNUE, of which treatment N2 had the highest values. Under the high-yield condition, when N fertilizer rate was increased from 168 to 240 kg/hm2, there were no significant differences in the amount of N accumulation in plants and in grains between treatments with the same ratio of base fertilizer to topdressing; by reducing basal N amount and increasing topdressing N amount accordingly, the translocation efficiency (TE, accumulation amount from vegetative organs to grain/N accumulation in vegetative organs during anthesis) increased, and the amount of N assimilation to grains after anthesis and its contribution proportion (the amount of N assimilation to grains after anthesis/N accumulation in grain) also increased. In other words, grain N accumulation amount increased with increasing amount of topdressing N at the same N fertilizer rate. There were no significant differences among treatments N2, N3, N5 and N6 in grain N accumulation. Appropriate N fertilizer rate with a reduction in basal N amount and an increase in topdressing N amount such as in N2, N5 and N6 increased grain yield and protein content. In conclusion, under conditions used in this experiment, as far as grain yield, protein content and FNUE are concerned, the recommended appropriate N fertilizer application regime is treatment N2, with a N fertilizer rate of 168 kg/hm2 and a ratio of base fertilizer to topdressing of 1:2.
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Issue Date: 05 June 2007
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