臭氧浓度升高条件下大豆残茬—土壤反馈对大豆生理生态特性的影响

With the rapid urbanization of our country, O3 pollution has become an increasing serious problem in many cities, where obvious degradation of urban forest caused by high level O3 has been observed. Clarifying the effects of elevated O3 on plant growth is of great significance to O3 risk evaluation and plant protection. Residue recycling is the important cultivation measure in agriculture. The residue decomposition can be affected by elevated ozone, which results in the change of soil microbial. But the feedback mechanism on soil microbial to plant is not distinct. In this project, an environment with elevated O3 will be simulated using the open-top chamber system with the residue recycling. And photosynthesis characteristics, active oxygen metabolism, secondary metabolism and biomass or yield of soybean and the change of residue decomposition, soil microbial will be analyzed, which can reveal the influence mechanism of elevated O3 on soybean. Then the experiments on residue feedback and soil microbial feedback will be utilized for further analysis of the mechanisms involving sol feedback to address the lack of knowledge and understand the effects of increasing ozone on interaction between plant and soil, we will study the effects of soybean on soil biota and its feedback effects on soybean from the view of plant-soil feedback under elevated O3 concentration. The objectives of this study are to clarify the effects of soil feedback mediated by residue decaying on soybean under elevated ozone, with an attempt to provide more information on influences of increasing O3 on ecosystem due to altered plant secondary metabolites. Based on this project, it can perfect the mechanism of plant-soil feedback and a scientific basis could be provided to sustainable development of agriculture coping global climate change in the future.

由人类活动导致的近地层臭氧浓度持续升高，已造成全球许多地区作物减产和林木衰退，科学开展O3风险评价并采取有效措施缓解O3对植物体的胁迫已成为全球气候变化研究的热点问题之一。残茬还田是农业生产重要的耕作措施，臭氧浓度升高影响了作物残茬分解过程，其成分的改变能够引起土壤微生物群落发生变化，但土壤微生物群落的变化对作物生长发育的反馈作用尚不清楚。本项目拟以重要经济作物大豆为研究对象，利用开顶式熏气系统模拟O3 浓度升高的生长环境，通过残茬还田试验，从植物-土壤反馈角度，分析臭氧浓度升高对大豆生物量、次生代谢物质、光合特征、活性氧代谢的影响，以及大豆残茬分解和土壤理化性质、土壤微生物群落变化。结合残茬添加反馈试验和土壤反馈试验，重点探讨臭氧胁迫下残茬还田对大豆生长发育的土壤反馈作用，有助于进一步揭示农作物对O3浓度升高的响应及适应机制，为完善全球气候变化下植物-土壤反馈机制研究奠定理论基础。

由人类活动导致的近地层臭氧浓度持续升高，科学开展臭氧风险评价并采取有效措施缓解O3对植物体的胁迫已成为全球大气污染研究的热点问题之一。残茬还田是农业生产重要的耕作措施，本项目以重要经济作物大豆为研究对象，利用开顶式熏气系统，从植物—土壤反馈角度，探讨臭氧胁迫下残茬还田对大豆生长发育的土壤反馈作用，进一步揭示作物对臭氧浓度升高的响应及适应机制，为全球气候变化下农业可持续发展提供科学依据。. 研究表明，臭氧浓度升高条件下，大豆叶片光合作用限制的主要因素由气孔因素转化为非气孔因素，大豆生物量及产量下降，由于残茬还田直接影响大豆根系活性，在一定程度上缓解了这种效应。. 大豆植株及土壤的生态化学计量特征表明，残茬还田措施显著提高了土壤含水量、土壤有机碳、全氮、碳氮比、土壤易提取有机碳和土壤无机态氮含量等指标。残茬还田能够使臭氧胁迫下大豆根系和茎秆氮、磷、钾利用率降低，提高叶片的氮素利用率和有机碳和全钾含量。大豆生长主要受氮素限制。残茬还田还显著影响土壤蔗糖酶活性、多酚氧化酶活性、脲酶、淀粉酶及酸性磷酸酶活性。. 臭氧浓度升高影响了作物残茬分解过程，从而引起土壤微生物群落发生变化。残茬还田增加了革兰氏阳性菌和丛枝菌根真菌等生物碳含量。高通量测序结果表明，在大豆分枝期残茬还田降低了土壤微生物chao1多样性指数和shannon多样性指数。而结荚期高浓度臭氧熏蒸下残茬还田促进了土壤微生物shannon多样性指数。.针对土壤线虫富集指数和结构指数进行分析研究发现，随着臭氧浓度增加，土壤微食物网由原来的未受干扰结构化趋于胁迫、退化状态，残茬还田措施显著影响土壤线虫功能代谢足迹。. 臭氧浓度升高条件下土壤微生物群落的变化对大豆生长发育的影响表现为负反馈（土壤微生物群落的改变导致植物净的生长降低），而残茬还田在一定程度上可以缓解负效应。