Abstract: To study the effect of copper and nickel stress on the rhizosphere of Medicago sativa 'Qingshui',this paper took the soil contaminated with copper and nickel (the contents of Cu²⁺and Ni²⁺ are 324.1,and 271.1 mg·kg^-1,respectively) in Jinchang area of Gansu as the study object,the effects of different copper and nickel concentrations (0,100,200,400,800,1 600 mg·kg^-1,respectively) on the physicochemical and biological properties and bacterial communities in the rhizosphere soil of alfalfa were investigated by the pot experiment with the material of alfalfa 'Qingshui' tolerant to the contamination of copper and nickel. The results showed that with the increase of copper and nickel concentration,the contents of soil moisture,Cu²⁺,and Ni²⁺ in the rhizosphere soil increased;the contents of available nitrogen,available phosphorus,available potassium,microbial biomass carbon,microbial biomass nitrogen,microbial biomass phosphorus,and organic matter in the rhizosphere soil increased first and then decreased;the pH value and soil enzyme activity in the rhizosphere soil decreased. The richness and diversity index of bacterial communities first increase and then decrease,reaching to the peak level under copper and nickel concentration of 800 mg·kg^-1. Proteobacteria,Actinobacteria,Acidobacteria,Bacteroidota,and Gemmatimonadetes were the dominant bacterial groups in the different samples. Through redundancy analysis and Monte Carlo permutation tests,it was found out that soil moisture content,available potassium,and catalase were the dominant factors affecting the changes in bacterial community structure in the rhizosphere of Medicago sativa 'Qingshui' under copper and nickel stress.

Key words: Copper and nickel stress, Rhizosphere soil, Bacterial community, Soil microbial biomass carbon

摘要： 为研究铜镍胁迫对'清水'紫花苜蓿(Medicago sativa 'Qingshui')根际的影响，本文以甘肃金昌市金川区农田铜镍污染的土壤(Cu 324.1 mg·kg^-1、Ni 271.1 mg·kg^-1)为研究对象，以耐铜镍植物'清水'紫花苜蓿为供试材料，采用温室盆栽试验法，研究了不同浓度的铜镍复合溶液(0，100，200，400，800，1 600 mg·kg^-1)处理对根际土壤理化、生物学性质及细菌群落的影响。结果表明：随铜镍胁迫浓度增大，紫花苜蓿根际土壤水分含量、Cu²⁺、Ni²⁺含量均升高；根际土壤速效氮、磷、钾、微生物量碳、氮、磷及有机质含量均先升后降；根际土壤pH值和土壤酶活性下降；细菌群落丰富度与多样性指数先增后降，当铜镍胁迫浓度为800 mg·kg^-1时增至最大；变形菌门、放线菌门、酸杆菌门、拟杆菌门和芽单胞菌门为优势菌门，且变形菌门和拟杆菌门的相对丰度显著增加，放线菌门和酸杆菌门的相对丰度显著降低。通过冗余分析和Monte Carlo置换检验表明，土壤水分含量、速效钾和过氧化氢酶是铜镍胁迫环境下'清水'紫花苜蓿根际细菌群落结构变化的主导因子。

关键词: 铜镍胁迫, 根际土壤, 细菌群落, 土壤微生物生物量碳