设施黄瓜连作土壤氨氧化微生物群落特征及其对氨水熏蒸-生物有机肥联用的响应研究

Greenhouse vegetable production is an important branch of modern agriculture, meanwhile, is of strategic significance to enhance utilization efficiency of natural resources and increase economic payoffs of farmers. With the rapid expansion of the scale of production, continuous cropping obstacle has become an important bottleneck restricting the sustainable development of greenhouse vegetable industry in China. A lot of studies have been carried out by previous researchers to explore the mechanisms of continuous cropping obstacle, however, little attention is paid to the relationship between the function group of soil microbes and continuous cropping obstacle. Ammonia oxidizers including AOA and AOB are important players in soil ecosystem since they drive soil N cycle, which are also the potential indicators for soil quality. In this proposal, with the help of Real-time PCR and high throughput sequencing, we make an attempt to evaluate the effects of continuous cucumber cropping on quantities, community composition and structure of AOA and AOB under greenhouse cultivation, compare the differences in AOA and AOB in response to continuous cropping practice, and identify the critical soil variables driving the shifts in AOA and AOB communities. In addition, we investigate the effects of combination of ammonia fumigation and bio-organic fertilizer application on AOA and AOB communities through pot experiment. This project will be very important to provide new understanding involved in continuous cropping obstacle and develop the effective approach to control continuous cropping obstacle during greenhouse vegetable production.

设施蔬菜生产是提高自然资源利用效率和促进农民增收的重要途径。随着种植规模不断扩大, 连作障碍已成为限制设施蔬菜产业可持续发展的重要瓶颈。早前的学者对连作障碍机理进行了大量研究, 但对于土壤功能组微生物与连作障碍发生的关系尚不明确。氨氧化微生物是驱动土壤生态系统氮素循环的关键因子, 也是表征土壤质量的重要指标。本项目基于设施黄瓜连作生产系统, 拟以氨氧化微生物(AOA和AOB)为研究对象, 结合Real-time PCR和高通量测序等方法, 研究连作对设施土壤AOA和AOB数量、群落组成结构的影响, 比较二者对连作种植的响应异同, 探索设施环境下驱动氨氧化微生物群落变化的主导性土壤因子; 同时布置盆栽试验, 试图揭示“氨水熏蒸-生物有机肥联用”这一新型连作障碍防控策略对设施黄瓜连作土壤AOA和AOB群落组成结构的影响。旨在为进一步阐明设施蔬菜连作障碍机理和建立高效的连作障碍防控体系提供帮助。

设施蔬菜生产是我国重要的农业生产类型之一, 设施蔬菜行业健康发展对于地方经济发展和解决三农问题具有重要意义。然而, 由于长期集约化种植导致的连作障碍问题已经严重限制设施蔬菜行业的可持续发展。理解设施蔬菜连作土壤的一些关键生物学过程对于加深连作障碍机理的理解十分必要。氨氧化微生物是驱动农业土壤氮循环的关键功能微生物, 也是表征土壤质量的重要指标。本项目分析了设施黄瓜不同连作年限下土壤AOA和AOB数量和群落结构变化及其驱动因子。结果表明, 设施黄瓜连作显著降低了土壤硝化潜势, 但AOA和AOB数量随着连作年限延长相对稳定。设施黄瓜连作不改变AOA和AOB多样性和丰富度, 但显著改变二者群落结构。具体来看, AOA群落中Nitrososphaerales Clade B4的相对丰度随连作年限延长显著增加, 而Nitrososphaerales Clade Nitrososphaera恰好与之相反; 对于AOB群落, Nitrosospira Cluster 3a和3b的平均相对丰度均随连作显著降低, 但Nitrosomonas sp.显著增加。多元逐步线性回归分析显示, AOA群落结构更多的受土壤含水量和全氮含量调节，而AOB群落结构则受土壤有机质含量和电导率显著影响。通过盆栽试验, 本研究进一步评估了土壤氨水熏蒸-生物有机肥联用对设施黄瓜连作土壤AOA和AOB群落组成结构的影响。盆栽试验设置四个处理: 对照, 不氨水熏蒸(NAF); 单独氨水熏蒸(AF); 单独生物有机肥(NAF+BOF); 氨水熏蒸+生物有机肥(AF+BOF)。氨水熏蒸和生物有机肥联用显著降低AOA和AOB群落的丰富度和多样性，改变AOA和AOB的群落结构。较NAF相比，AF+BOF处理下土壤Nitrosospira multiformis Clade平均相对丰度显著增加约2倍, 但Nitrososphaerales Clade A平均相对丰度显著降低约84.978%。氨水熏蒸和生物有机肥联用对土壤氨氧化微生物的影响更多地受氨水熏蒸而非生物有机肥施用所决定。总的来看, 我们的结果能够从土壤生态功能变化角度加深对设施蔬菜连作障碍机理的认识, 并能够帮助指导改善设施连作土壤氮素管理策略。