环境二氧化碳浓度升高、亏缺灌溉和接种根际促生菌（PGPR）的节水效应和养分利用效应已有些报道，但对于二氧化碳浓度升高下接种PGPR和亏缺灌溉综合效应对根际环境养分平衡、作物水分和养分吸收利用的调节机理仍然不清楚。本申请项目拟以番茄为研究对象，采用人工气候室盆栽试验和理论分析相结合的方法，在明确PGPR发挥效应的土壤含水率阈值基础上，探究二氧化碳浓度升高条件下接种PGPR和亏缺灌溉对番茄叶片气孔形态、气体交换速率与水分利用的调控机理，揭示土壤微生物群落结构和土壤酶活性对土壤氮素生物有效性的影响规律，阐明根系形态变化与根际理化、生物学环境对氮素吸收、转运及分配的内在关系。在此基础上进一步阐明二氧化碳浓度升高下接种PGPR和亏缺灌溉对果实品质的调节机制，从而为PGPR和亏缺灌溉在二氧化碳浓度升高情况下的节水机理和氮素的高效利用提供更深层次的机理解释与理论支撑。

The individual effect of elevated carbon dioxide (e[CO2]), deficit irrigation (DI) and plant growth promoting rhizobacteria (PGPR) on plant water use and nutrient uptake has been intensively researched, however, the combined effects of these three factors and the underlying mechanism on rhizosphere environment, water and nitrogen dynamics, and crop water and nitrogen uptake and utilization are largely elusive. In this project, tomato plants will be used and pot experiments in phytotrons will be conducted. The objectives are: to estimate the threshold of soil mositure when PGPR effective; to explore the potential mechanism of PGPR and DI effect on stomatal morphology, leaf gas exchange, and water and nitrogen use efficiency under e[CO2]; to reveal the influence of soil microbial community structure and soil enzyme activity on soil nitrogen bioavailability; to elucidate the relationship between plant root morphology, rhizosphere bio-physiochemical environment and nitrogen uptake; and to analyze the regulation mechanism of PGPR and DI effect on tomato fruit quality under e[CO2]. These findings will provide a deeper mechanistic understanding and theoretical support for development of the water-saving strategy and the efficient utilization of water and nitrogen in a drier and CO2-enriched environment.