延迟栽培葡萄根际促生菌与土壤氮素转化对水分调控的协同响应机制

Plant growth-promoting rhizobacteria (PGPR) are a kind of beneficial bacteria which colonize in the rhizosphere of plant. They can enhance soil nitrogen uptake and utilization by dissolving soil nutrients and fixing atmospheric nitrogen. Recently, how to promote the growth of PGPR through water regulation in order to improve the efficiency of transformation and utilization of soil nitrogen has been a hot topic. In this project, delay-cultured grape will be used as research object. The PGPR groups will be selected by rDNA technique. Based on the study of the synergistic effects of root exudates and PGPR on water regulation, the mechanism for regulating water to control PGPR communities in root-rhizosphere system will be revealed. Meanwhile, by investigating the effects of water regulation on the relationships among nitrogen physiological regulation and soil nitrogen transformation, the mechanism for regulating water to control nitrogen status in root-rhizosphere system will also be confirmed. On this basis, the root zone, rhizosphere and root system will be integrated into a system. The interaction for water regulation with root physiological activities, root exudates, PGPR, and nitrogen transformation will be studied in order to reveal the physiological mechanism of W-B-N (i.e. water regulation drives bacterial growth and nitrogen transformation and supply). The results of this project can provide scientific evidences for PGPR control in delay-cultured grape and the effective transformation and utilization of soil nitrogen, and simultaneously be used for some further hot issue studies based on soil microbiology, such as water saving for grape and other fruit trees, soil bacteria control and nitrites increase.

植物根际促生菌是一类定殖于植物根际的有益细菌，能通过与土壤水分协作增强土壤氮等营养元素的吸收和利用。如何通过水分调控等措施促进根际促生菌生长，达到提高土壤氮素高效转化利用，是近年来关注的热点问题。项目以延迟栽培葡萄为研究对象，利用rDNA技术测序筛选葡萄根际优势促生菌，并分析其与根系分泌物等协同应对水分调控的规律，明确根系-根际层“控水调菌”机理。同时研究水分调控对根际-根区层土壤氮素生理群及氮素转化过程的交互影响，揭示“控水调氮”机理。在此基础上，以根区-根际-根系为整体系统，通过根系生理活性及其分泌物、根际促生菌、土壤氮素转化等对水分调控的交互响应关系研究，明确水分调控驱动促生菌生长及氮素转化和有效供给的“W-B-N”协同作用机制。其研究结果可为我国延迟栽培葡萄根际促生菌调控及土壤氮素高效转化利用提供依据，同时也可为土壤微生物学研究葡萄及其他果树节水、控菌、增养等热点问题积累经验。

如何通过水分调控等措施促进根际促生菌生长，达到提高土壤氮素高效转化利用，是近年来关注的热点问题。该项目以西北地区设施延迟栽培葡萄主栽品种‘红地球(Red Globe)’为研究对象，利用rDNA技术测序筛选葡萄根际优势促生菌。在此基础上，设置全生育期水分调控、单个生育期水分调控、水菌耦合调控3组试验，分析葡萄根际优势促生菌对水分调控的响应规律，研究水分调控对土壤氮素生理群及氮素组分的交互影响，揭示水分调控驱动促生菌生长及氮素转化和有效供给的协同作用机制。研究结果表明：（1）设施延迟栽培葡萄根际存在许多本土促生菌，其中在属水平上促生菌群有假单胞菌属、寡养单胞菌属、溶杆菌属、亚硝化螺菌属、热单胞菌属、酸杆菌属、鞘氨醇单胞菌属、粪杆菌属等。（2）水分调控对葡萄根际土壤优势微生物群落有重要影响，最优势菌门、菌纲、菌目、菌科、菌属都能适应葡萄生长前期（开花期前中短期）的水分胁迫，从而迅速巩固和提高群落的竞争优势；随着胁迫的持续，在葡萄生长发育中后期水分胁迫对其影响减弱。（3）与充分供水处理相比，全生育期轻度和中度水分胁迫均能提高葡萄根际土壤酸解总氮、酸解未知态氮含量；在萌芽期—果实膨大期前轻度水分胁迫也能显著提高氨基酸态氮含量，但却显著抑制未知酸解氮含量的积累，且胁迫程度越高，其抑制效果愈加明显。（4）水菌调控下各生育期土壤全氮含量基本保持稳定；充分供水多量菌肥水平能提高生长中后期有机质、有机碳和水溶性碳含量，促进葡萄后期土壤硝态氮含量的增加。轻度水分胁迫能提高酸解氨基酸态氮、酸解氨基糖态氮、酸解铵态氮、酸解未知态氮占全氮百分比，而轻度水分胁迫少量促生菌添加可达到节水、增产、提质和改善土壤微生物环境的效果，是设施延迟栽培葡萄最佳的水菌调控模式。上述研究结果可为我国设施延迟栽培葡萄根际促生菌调控及土壤氮素高效转化利用提供依据，同时也可为其他果树节水、控菌、增养等热点问题研究积累经验。