【目的】再生稻是头季稻生长的延续。本研究尝试从根际微生态系统的变化来阐明机械化栽培下头季稻氮肥管理对头季-再生季水稻产量形成的影响,为再生稻高产高效栽培提供参考。【方法】以“甬优1540”为材料,通过2年的田间试验,在头季总施氮量(225.00 kg/hm²)不变的前提下,设置头季不同氮肥运筹处理,分析了机械化栽培下再生稻产量、根系伤流强度、根际土壤酶活性及其微生物多样性的变化特点。【结果】头季前氮后移施肥处理(N1、N2)有助于根系保持较高活力,尤其在头季生长中后期N1处理(基肥∶一次分蘖肥∶二次分蘖肥∶孕穗肥=3∶1∶2∶4)根系伤流强度比对照(N0)和当地常规施肥处理(N4)显著提高;N1处理两季总产量最高,2年平均达17 351.23 kg/hm²,比当地常规施肥处理(N4)提高了23.00%。土壤酶活性分析表明,蔗糖酶活性在头季齐穗期表现为N2>N1>N3>N4>N0,之后则表现为N1>N2>N3>N4>N0;过氧化氢酶与硝酸还原酶活性在头季生长期均表现为N1>N2>N3>N4>N0;脲酶活性从头季齐穗期至再生季齐穗始终表现为N1>N2>N3>N4>N0;各生育时期土壤酶活性与根系伤流强度间均呈显著或极显著正相关。细菌 16S rDNA 测序表明,施肥与不施肥处理细菌群落结构多样性差异显著,N1处理细菌 Chao1 指数和香农指数显著高于其他处理。菌群结构分析表明,施肥处理增加了与土壤碳氮循环、有机质含量及抗逆性密切相关的细菌数量,尤其是N1、N2处理硝化螺旋菌属相对丰度较高,有利土壤氮素循环。【结论】机械化栽培下,头季氮肥适当后移有利于再生稻根际微生态系统的改善,从而提高根系活力,促进水稻生长,获得两季水稻的高产。

【Objective】 Ratoon rice is the continuation of the main crop. We attempt to elucidate the effect of mechanical transplanting of main crop together with nitrogen fertilizer management on the yield of the main crop and ratoon rice from the perspective of rhizosphere microecosystem, which may provide a reference for the high-yielding and efficient cultivation of ratoon rice. 【Method】 The rice genotype of Yongyou 1540 was used as the material. At a total nitrogen application level of 225.00 kg/hm² in the main crop, different nitrogen fertilizer treatments were designed to analyze the effects of mechanical cultivation on the yield, root bleeding intensity, enzyme activities and microbial diversity in rhizosphere soil in two consecutive years in paddy field. 【Result】 In N1 and N2 treatments, the root system maintained higher vigor, especially in the late growing period of the main season in the N1 treatment (basal fertilizer : primary fertilizer for tillering : secondary fertilizer for tillering : fertilizer for panicle initiation= 3 : 1 : 2 : 4) showed a significant increase in root bleeding intensity as compared with the control N0 and the local conventional treatment of N4. The total yield of the N1 treatment was the highest in the two growing seasons, reaching an average of 17 351.23 kg/hm², 23.00% higher than that of N4. Soil enzyme activity analysis showed that the activities of sucrase followed the trend of N2>N1>N3>N4>N0 in the full heading stage during the main season, but N1>N2> N3>N3>N4>N0 for ratoon rice; the activities of catalase and nitrate reductase both followed a trend of N1>N2> N3>N4>N0 in the full heading stage during the main season; the activities of urease, N1>N2> N3>N4>N0 from the heading stage of the main crop to the heading stage of ratoon rice. Highly significant positive correlations were observed between soil enzyme activities and root bleeding intensity at all growing stages. Bacterial 16S rDNA sequencing showed that the structural diversity of bacterial communities differed significantly between the fertilized and non-fertilized treatments, and the Chao1 index and Shannon index of N1 treatment were significantly higher than those of other treatments. Function analysis of rhizospheric bacterial community showed that fertilization increased the number of bacteria closely related to soil carbon and nitrogen cycle, soil organic matter content and soil stress resistance, especially the N1 and N2 treatment with higher relative abundance of nitrospira, which were favorable to soil nitrogen cycle. 【Conclusion】 Under mechanical cultivation, the treatment with properly postponed nitrogen fertilizer application in the main crop is beneficial to the improvement of the rhizosphere microecosystem of ratoon rice, thus improving root vigor, promoting rice growth, and obtaining high yield of rice in both growing seasons.