干旱对燕麦早期根际土壤微生物群落功能多样性的影响

Effects of drought stress on functional diversity of soil microbial communities in the rhizosphere at oat early stage

[目的]研究干旱胁迫及复水下燕麦早期根际土壤微生物群落碳源代谢特征,揭示土壤微生物对干旱胁迫及复水的响应和适应规律。[方法]试验采用盆栽控水,设置正常供水(75%土壤相对含水量,CK)、适度干旱(55%土壤相对含水量,MS)、极端干旱(35%土壤相对含水量,ES)3个供水梯度,以及2个干旱-复水-干旱-复水交替胁迫处理(干旱,复水各为7 d,MS-CK;ES-CK),共5个处理。利用Biolog-ECO法,分析各处理燕麦早期根际土壤微生物群落对六类碳源的代谢利用特征。[结果]干旱胁迫有降低燕麦早期根际土壤微生物群落对总碳源和各类碳源利用能力的趋势,使土壤微生物群落各功能多样性指数均降低。适度干旱胁迫下复水可使燕麦早期根际土壤微生物群落各功能多样性指数达到或超过对照水平,微生物群落对糖类、氨基酸类、羧酸类、聚合物类和胺类碳源利用的提高幅度分别达58.22%、55.19%、11.11%、1.84%和61.14%,且对部分碳源的利用能达到对照水平。极端干旱胁迫下复水仅使燕麦早期根际土壤微生物群落对糖类碳源利用提高113.82%。[结论]适度干旱胁迫期间进行阶段性复水可使燕麦早期根际土壤微生物群落对部分碳源的利用和各功能多样性指数恢复到对照水平。氨基酸类和聚合物类碳源可被作为研究干旱胁迫及复水处理燕麦早期根际土壤微生物群落碳源代谢差异的代表性碳源。

[Objective]The carbon source metabolism characteristics of soil microbial communities in rhizosphere were evaluated at oat early stage under drought stress and rehydration.The aim was to reveal the response and adaptation rule of soil microorganisms to drought stress and rehydration.[Methods]The experiment was conducted in pots and a total of five treatments were setup,including three water supply treatments:normal water supply(75%soil relative water content,CK),moderate drought stress(55%soil relative water content,MS)and extreme drought stress(35%soil relative water content,ES),and two alternating treatments(MS-CK and ES-CK)as drought-rehydration-drought-rehydration cycle(drought stress and rehydration were at 7 days interval).Biolog-ECO method was used to analyze the metabolic utilization characteristics of six types of carbon sources in the early rhizosphere soil microbial communities of oats in each treatment.[Results]Drought stress tended to reduce the utilization capacity of soil microbial communities in the early rhizosphere of oats for total carbon sources and various carbon sources,and reduced the various functional diversity indices of soil microbial community.Rehydration under moderate drought stress made the functional diversity indices of the early rhizosphere soil microbial community of oats reached or exceeded CK level,and the utilization of carbohydrate,amino acid,carboxylic acid,polymer and amine carbon sources by microbial community were increased by 58.22%,55.19%,11.11%,1.84%and 61.14%,respectively,and the utilization of some carbon sources reached CK level.Rehydration under extreme drought stress only increased the utilization of carbohydrate carbon source by microbial community in the early rhizosphere soil of oats by 113.82%.[Conclusion]Periodic rehydration during moderate drought stress could restore the utilization of some carbon sources and various functional diversity indices of the early rhizosphere soil microbial communities of oats to CK level.Amino acid and polymer carbon sources could be used as representative carbon sources to study the difference of carbon source metabolism in the early rhizosphere soil microbial community of oats under drought stress and rehydration.