基于植物-土壤反馈的不同绿肥驯化微生物对玉米生长的影响

Microorganisms domesticated with different green manures regulate maize growth via plant-soil feedback

摘要:

【背景】在农田生态系统中，土壤微生物与植物互作的机制仍不清楚。【目的】进一步加强对植物-微生物互作的认识，筛选出引起不同反馈作用的关键微生物或微生物类群。【方法】采集豆科绿肥救荒野豌豆(Vicia sativa, V)、十字花科绿肥油菜(Brassica napus, N)和荒坡土壤(remnant prairie, R)驯化的田块土壤0-20 cm作为菌剂在温室进行植物-土壤反馈(plant-soil feedback, PSF)试验。土壤菌剂的接种量为10%，即有90%理化性质一致的灭菌土壤作为背景土，同时设置灭菌土壤菌剂作为对照(CK)，种植玉米。每组土壤菌剂处理均分为50 mg/kg高磷(high phosphorus, HP)和5 mg/kg低磷(low phosphorus, LP)两个磷浓度处理。玉米收获后，测定产量和植株地上部磷含量，并取土壤样品进行高通量测序，解析不同养分供给情况下微生物对作物生长的反馈效应。【结果】高磷和土壤反馈效应均促进了玉米的生长。在低磷水平下，V、N和R处理的玉米地上部生物量均高于CK处理，但N处理的玉米地上部生物量增加最多(38%)，且增幅显著高于V处理(28%)和R处理(16%)；在高磷条件下，V、N和R处理的玉米生物量与CK之间无明显区别。低磷条件下，3种土壤菌剂处理的玉米地上部磷含量显著高于对照处理；高磷条件下，各处理的玉米地上部磷含量并无显著差异。各处理门水平主要物种组成存在差异，N处理富集更多的变形菌门(Proteobacteria)和拟杆菌门(Bacteroidota)。KEGG代谢通路分析表明，N处理中磷养分活化相关的功能基因phoB、phoA、phoR、phnA和glpR含量显著上升。【结论】土壤反馈实验表明，十字花科绿肥驯化的土壤微生物能够提高玉米的吸磷能力，促进其生长；十字花科绿肥富集更多和解磷相关的微生物和功能基因。

关键词:植物-土壤反馈(PSF);土壤养分;土壤微生物;果园绿肥

Abstract:

[Background] In agricultural ecosystems, the mechanisms of interactions between soil microorganisms and plants remain unclear. [Objective] To strengthen the understanding of plant-microorganism interactions and screen out the key microorganisms or microbial groups that cause different feedback effects. [Methods] The soil in the 0-20 cm layer of the fields domesticated with leguminous green manure Vicia sativa (V) or cruciferous green manure Brassica napus (N) and the remnant prairie (R) were collected as inoculants in the greenhouse for plant-soil feedback (PSF) test. Maize was planted in the substrate containing 10% inoculant and 90% sterilized soil with the same physical and chemical properties. The sterilized soil inoculum was set as the control (CK). For each inoculation treatment, two phosphorus levels, 50 mg/kg (high phosphorus, HP) and 5 mg/kg (low phosphorus, LP), were designed. After maize was harvested, we measured the yield and phosphorus content in the shoots and sequenced the soil samples to analyze feedback effects of microorganisms on crop growth under different nutrient supply conditions. [Results] High phosphorus and soil feedback both promoted the growth of maize. In the case of LP, the aboveground biomass of maize in the V, N, and R treatments all increased compared with that in the CK. Moreover, the increase in the N treatment (38%) was significantly higher than that in the V treatment (28%) and R treatment (16%). The V, N, and R treatments showed no significant difference in maize aboveground biomass compared with CK under the HP condition. The phosphorus content in the shoots of maize treated with the three soil inoculants was significantly higher than that of CK in the case of LP, while it showed no significant difference between treatments in the case of HP. There are differences in the composition of main species at each treatment phylum level, N treatment enriched more Proteobacteria and Bacteroidetes. KEGG pathway enrichment analysis showed that the abundance of functional genes phoB, phoA, phoR, phnA and glpR involved in phosphorus activation significantly increased in N treatment. [Conclusion] The soil microorganisms domesticated with cruciferous green manure could improve the phosphorus absorption ability and promote the growth of maize cruciferous green manure enriched more microorganisms and functional genes associated with phosphorus dissolution.

Key words:plant-soil feedback (PSF);soil nutrients;soil microorganisms;orchard green manure