Abstract:

【Objective】 It is of great significance to elucidate the effects of different rice-straw returning techniques on soil properties and the underlying mechanisms of rhizosphere microbial remediation and soil improvement, and to find an efficient straw returning technology suitable for the tobacco-rice rotation area in Fujian, so as to lay a basis for high-quality and efficient crop cultivation.【Method】 Using flue-cured tobacco Yunyan 87 and late rice Yongyou 1540 as materials, a 2-year field experiment was carried out to reveal changes in soil nutrient properties and microbial communities in tobacco-rice rotation system and their relationships under various straw returning modes.【Results】 With rice straw returning for two consecutive years, grain yield of each treatment was significantly increased, among which, T₂ treatment with lime and urea was the best. The yield of tobacco and rice under T₂ treatment increased by 25.67% and 11.49% respectively compared with T₀, followed by T₃ treatment with Fuganlin and urea, and T₁ treatment with straw returning. In the first year, the yield of tobacco in T₁ treatment was not significantly different from that of the control, but in the second year, the yields of tobacco and rice were 3.77% and 5.90% higher than those of the control, respectively. After two consecutive years of straw returning, the nutrient and organic carbon contents of topsoil in each treatment were significantly increased, T₂ treatment ranked first, followed by T₃ treatment. The contents of alkali-hydrolyzed nitrogen, available phosphorus, available potassium, soil organic carbon and dissolved organic carbon in T₂ treatment increased by 7.09%, 5.97%, 3.01%, 11.32% and 5.47%, respectively compared with the control. The rhizosphere microbial community analysis showed that the relative abundance of HSB_OF53-F07 related to carbon source metabolism, Arthrobacter related to the degradation of toxic substances and Pseudeurotium related to cellulolysis increased significantly in T₂ and T₃ treatments compared with the control, while the abundance of Humicola and Penicillium associated with pathogenesis decreased significantly. Further correlation analysis found that the increase of beneficial bacteria in the rhizosphere were positively correlated with soil nutrients, while the abundance of pathogenic bacteria were negatively correlated with soil nutrients.【Conclusion】 Rice-straw returning with lime or Fuganlin and appropriate amount of urea is conducive to increasing the nutrient contents in the topsoil, promoting the growth of beneficial microorganisms such as nitrogen-fixing bacteria, inhibiting pathogenic bacteria, and creating a good soil environment for tobacco-rice rotation, and thus improving crop yield.

Key words: straw returning, tobacco-rice rotation, soil nutrients, rhizosphere microbes, community diversity

摘要：

【目的】 探讨不同稻草还田技术措施对土壤特性的影响及根际微生物修复和改良土壤的内在机制，探索适合福建烟-稻轮作区的稻草高效还田技术，以期为烟-稻轮作区作物优质高效栽培提供依据。【方法】 以烤烟“云烟87”和晚稻“甬优1540”为材料，通过不同的稻草还田配施技术处理，进行了2年的田间定位试验，分析比较了烟-稻轮作系统耕层土壤养分、根际微生物和作物产量的变化规律以及根际微生物与土壤环境因子间的内在关系。【结果】 产量分析表明，连续2年稻草还田后，各处理产量均比对照显著增加，其中配施石灰和尿素的T₂处理最显著，其烟草和水稻产量分别比对照提高25.67%、11.49%；其次是配施腐秆灵和尿素的T₃处理，纯稻草T₁还田处理效果最差；T₁处理第1年稻草还田后烟草产量与对照差异不显著，第2年烟草和水稻产量分别比对照提高3.77%和5.90%。耕层土壤养分特性分析表明，经连续2年的稻草还田处理后，耕层土壤养分与有机碳含量均显著增加，其中T₂处理效果最好，其次是T₃处理。T₂处理碱解氮、有效磷、速效钾、有机碳和可溶性有机碳含量分别比对照提高了7.09%、5.97%、3.01%、11.32%和5.47%。根际微生物群落分析表明，与对照相比，T₂、T₃处理下碳源代谢相关的HSB_OF53-F07、自毒物质降解有关的节杆菌属（Arthrobacter）和纤维素分解有关的假散囊菌属（Pseudeurotium）丰度均显著上升，而与发病相关的腐质霉属（Humicola）和青霉菌属（Penicillium）相对丰度则显著下降。相关分析表明，根际有益菌丰度与土壤养分因子多为正相关，而致病菌的丰度则与土壤养分因子负相关。【结论】 稻草还田配施石灰或腐秆灵和适量速效氮肥，有利于提高耕层养分含量，促进固氮等有益微生物生长，抑制病原菌，为烟-稻轮作提供良好的土壤环境，进而提高作物产量。

关键词: 稻草还田, 烟-稻轮作, 土壤养分, 根际微生物, 群落多样性