基于土壤病原菌与重金属生态效应的再生水分根区交替灌溉调控机制

Growing water shortages pose a growing threat to agricultural production safety, and rapid urbanization and industrialization releases enormous volumes of reclaimed wastewater, which is increasingly utilized as a valuable resource for irrigation in agriculture. The impact of distribution of soil pathogens and transfers and transformations of heavy metals on the food safety and soil ecological safety under the effect of treated municipal wastewater becomes one of hot topics of the safe use of reclaimed wastewater in agriculture. The alternate partial root-zone drip irrigation has a significant impact on the distribution of soil pathogens and transfers and transformations of heavy metals irrigated with reclaimed wastewater, but the mechanism has yet to be completely defined and there is a need for further study on the regulatory mechanism. Our previous research had suggested that the alternate partial root-zone drip irrigation technology is an effective water-saving irrigation technology, and can keep the crop yield, but the exact mechanisms are still unclear. Micro field plot experiment and soil column will be used to study the effect of different alternate partial root-zone drip irrigation on distribution of soil pathogens and transfers and transformations of heavy metals, micro-ecological environment, using tomato as the research object. As the object of study, focuses on the research of impact of alternate partial root-zone drip irrigation with reclaimed water on water physiological status of crop growth and development, and affect the quality of products, in order to expound the yield and safety of physiological mechanism, and through the study of effect of alternate partial root-zone drip irrigation with reclaimed water to the characteristics of soil heavy metal migration, soil microbial community and soil enzyme activity, to explore the influence of physicochemical properties and safety of the mechanism of soil. Then from the theory to clarify the mechanism of alternate partial root-zone drip irrigation with reclaimed water on crop growth and soil environment safety regulation. This study will provide a solid new theoretical foundation for the safe use of reclaimed wastewater in agriculture and eco-environmental protection and the food safety.

随着水资源短缺矛盾不断加剧，作为替代水资源的再生水农业利用将日益受到重视。再生水灌溉病原菌与重金属对食品和土壤生态安全的影响已成为研究热点。再生水分根区交替灌溉影响到土壤病原菌的分布与重金属迁移转化，但其机理尚未明确，影响及调控机制也有待于深入研究。申请者前期研究发现分根区交替灌溉是一种有效的节水灌溉技术，但有关分根区交替灌溉对再生水灌溉土壤病原菌与重金属运移特性的影响机制尚不清楚。本研究将利用大田微区试验与土柱试验相结合的方法，以西红柿为研究对象，重点研究分根区交替灌溉对作物生理及品质的影响，揭示其安全利用的生理机制，并通过研究再生水分根区交替灌溉土壤病原菌分布特征与重金属运移特性，探索其对土壤理化特性与安全性的影响机理，构建再生水分根区交替安全灌溉指标阈值，进而从理论上阐明再生水分根区交替灌溉调控机制。该研究将为再生水农业安全利用、生态环境保护及食品安全提供新的理论基础。

随着水资源短缺矛盾的不断加剧，作为替代水资源的再生水农业利用日益受到重视。再生水如果利用不当，其中含有的一些危害物质尤其是病原菌和重金属，不仅会导致土壤环境恶化、农业生产力下降，而且会影响生态环境和食品安全。.本项目重点研究分根区交替灌溉对再生水灌溉作物生理响应过程和农产品品质的影响、再生水灌溉土壤病原菌迁移和代谢特性对不同分根区交替灌溉的响应、再生水灌溉重金属Cd迁移转化对分根区交替灌溉的响应特征、基于土壤病原菌与重金属Cd互作效应的再生水分根区交替灌溉调控机制。研究发现再生水灌溉不同技术模式对土壤理化性质影响差异显著，交替灌溉处理不同土层土壤含水率均低于充分灌溉处理，但再生水非充分灌溉处理表层盐分累积高于充分灌溉处理。与清水灌溉相比，再生水灌溉显著提高了番茄果实糖酸比和可溶性糖含量，表明再生水灌溉处理提高了番茄营养品质（Vc和可溶性蛋白），同时显著提高了其风味品质（糖酸比）；短期再生水灌溉下鲜果符合食用标准，但是随着再生水灌溉年限的增加，番茄鲜果中重金属Cd的含量（P＜0.05）增加明显，长期灌溉下重金属残留风险不容忽视；分根区交替灌溉对番茄鲜果重金属Cd累积具有一定的阻控作用。随着灌溉年限的增加，再生水灌溉下根层土壤重金属Zn、Cd含量提高显著，但远低于国标GB15618-2018]中重金属含量限值；土壤重金属与致病菌之间的相关性分析表明，土壤镉、铅、锌含量与土壤细菌、真菌总数及大肠菌群、大肠埃希氏菌数量之间呈正相关，说明较低含量重金属含量刺激土壤活性微生物的生长繁殖。再生水灌溉显著增加了表层土壤病原菌（大肠菌群、粪大肠菌群）的数量，土壤病原菌随土壤深度的增加呈下降的趋势，特别是分根区交替灌溉通过调控土壤水分状况，降低了土壤中病原菌的存活率，减少了病原微生物污染风险。.本项目研究成果，为再生水农业安全利用、生态环境保护及保障食品安全提供新的理论基础。具有广阔的应用前景。

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