Abstract: Six rhizobia strains were isolated from the alfalfa root of two soil types in Heilongjiang province. The salt-resistant, acid-alkali resistant and acid-alkali secreting ability of each strain were studied using GGE method. Result showed that alfalfa rhizobia strain numbered as Hmx-c from black soil type had the strongest salt-resistant ability, and regularly grew in 10% NaCl medium. Alfalfa rhizobia strain numbered as Lmx-a from saline-alkali soil type and Hmx-b from black soil type had the strongest acid-resistant ability, and regularly grew in medium with pH value of 4.0. The strain numbered as Hmx-c from saline-alkali soil type possessed the strongest alkali-resistant ability, and regularly grew in medium with pH value of 12.0. A further experiment indicated that strain numbered as Hmx-a resisted both acid stress with pH value of 4.0 and alkali stress with pH value of 11.0. Meanwhile, the ability of alkali resistance was interrelated to the ability of acid secreting.

Key words: Rhizobia, Saline tolerance, Acid resistance and alkali tolerance

摘要： 为准确评价紫花苜蓿（Medicago sativa L.）根瘤菌的抗盐性，采用 GGE 双标图对来自盐碱土和黑土的6个紫花苜蓿根瘤菌（Rhizobium）菌株分别进行耐盐性、耐酸碱及其泌酸碱能力的评价研究。结果表明：黑土土壤紫花苜蓿根瘤菌株Hmx-c耐盐性极强，在10% NaCl培养基上生长正常；盐碱土壤紫花苜蓿根瘤菌株Lmx-a和黑土土壤紫花苜蓿根瘤菌株Hmx-b耐酸性最强，能在pH 4.0的培养基上正常生长；耐碱性最强的是盐碱土壤菌株Hmx-c，可以在pH 12.0的培养基上正常生长。进一步试验表明，菌株Hmx-a既能抗pH 4.0的酸逆境，又能抗pH 11.0的碱逆境。根瘤菌菌株耐碱性的强弱与其泌酸能力相关。

关键词: 根瘤菌, 耐盐性, 耐酸碱性