以杂交稻“天优998”为材料, 设置覆盖还田和不还田2种稻草还田处理, 4种氮肥处理, 进行了连续2年的田间试验, 研究稻草还田对水稻氮素吸收和氮肥利用率的影响。结果表明: 稻草还田显著促进了水稻对氮素的吸收, 其总吸氮量比稻草不还田处理增加13.7%~20.3%, 但对不同生育阶段吸氮量占总吸氮量的比例影响不大。与稻草不还田处理相比, 稻草还田处理的水稻在分蘖中期(MT)、穗分化始期(PI)和抽穗期(HD)叶片叶绿素含量显著提高[实地养分管理(N1)的MT时期除外]。稻草还田可提高氮肥吸收利用率(RE)、农学利用率(AE)和氮肥偏生产力(PFP)。两年平均, 稻草还田处理的RE比稻草不还田处理提高8.23个百分点, 相对提高23.4%, 达极显著水平。AE、RE、PFP与MT~PI期间的吸氮量呈正相关, 其中AE和PFP达极显著水平。RE与HD~MA期间的吸氮量呈极显著正相关。在MT施氮、促进MT~PI期间的氮素吸收对提高AE、RE和PFP有重要意义。创造条件增加抽穗后的氮素吸收, 对于提高RE、减少氮肥损失和面源污染至关重要。
The objective of this study was to determine the effect of straw incorporation through mulching on nitrogen uptake and N-fertilizer use efficiency of rice. Two field experiments were conducted at the Baiyun Experimental Station, Guangdong Academy of Agricultural Sciences using “Tianyou998” hybrid rice in split plot design experiments with straw incorporation and N treatment as the main and split factors respectively. The results are as follows: (1) Straw incorporation enhances rice nitrogen uptake by 13.7%~20.3%. However, the percentage of N uptake at different growth stages to total N uptake remains unchanged. (2) Chlorophyll content (SPAD value) of rice leaves is significantly greater in straw incorporation than in non-straw incorporation treatments at mid-tillering (MT), panicle initiation (PI) and heading (HD) stages, except for the SSNM (site-specific nutrient management) treatment at MT stage. (3) Recovery efficiency (RE) of N-fertilizer is 8.23% (relatively 23.4%) higher in straw incorporation than in non-straw incorporation treatments (P<0.01). Agronomic efficiency (AE) and partial factor productivity (PFP) are also higher for straw incorporation treatments. (4) AE, RE and PFP are positively significantly correlated with N uptake from MT to PI. RE is positively significantly correlated with N uptake after heading. Application of N-fertilizer at MT to enhance N uptake from MT to PI is important for increasing AE, RE and PFP. Increasing N uptake at grain-filling stage is crucial for improving RE.