在设施土壤硝酸盐大量盈余的情况下，仍需持续高量投入氮素来保证蔬菜高产，进而又加剧了硝酸盐累积，威胁设施蔬菜的可持续发展。研究表明，高湿和盐胁迫等抑制养分的吸收、转运和累积，集约化种植易导致土壤微生物种群退化。我们推测设施菜地特殊的高湿环境导致硝酸盐积累，产生盐胁迫，抑制根系生长和土壤氮循环关键微生物调控的供氮能力；且受根系-土壤微生物互作影响进一步降低根系对氮的吸收利用和土壤供氮潜力，这可能是导致设施菜地氮素高投入低利用率机制之一。为验证此科学假设，设计了室内模拟和田间试验，从湿度、硝酸盐供应水平对番茄养分吸收、根系生长及根系-土壤微生物互作、氮循环关键微生物数量和结构变化的影响等开展深入研究。以期初步阐明设施菜地高湿条件是导致氮素向地上部转运下降的环境影响机制之一，并进一步揭示其根系响应和根系-土壤微生物互作的机制。研究成果可为设施菜地提高氮肥利用率、保障设施土壤可持续利用提供科学依据。

The continuous and higher rates of nitrogen applied to the vegetable soil to maintain the high yields even if in the soil with high nitrate concentration. Some previous studies indicated that, the absorption, transport and accumulation of the soil nutrients were inhibited by high humidity and salt stress, and lead to the degradation of the soil microbial population in intensive cultivation. It has been speculated that the special growing environment of high humidity, the response of nitrate stress on root structure and the effects of nitrate stress on key microbial functional diversity in nitrogen cycling may be the one of the mechanisms of low nitrogen use efficiency in high nitrogen input and high nitrate residual soil of greenhouse vegetable production system. To test the hypothesis, the laboratory simulation experiment and field experiment were conducted to study the effects of humidity and salt stress on nutrients uptake and accumulation, root growth and the change of the key microbial functional diversity in nitrogen cycling. So as to preliminary clarified one of the environmental impact mechanisms of high humidity lead to the decrease of nitrogen transport toward aboveground, to further reveal the root biology mechanism and soil microbiology mechanism of the low nitrogen use efficiency in high nitrogen input and high nitrate residual soil of greenhouse vegetable production system. The research achievements would provide a scientific basis for improving the nitrogen use efficiency, maintain the soil microbial function diversity and ensured the sustainable utilization of greenhouse soil.