JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2021, Vol. 45 ›› Issue (6): 99-110.doi: 10.12302/j.issn.1000-2006.202012040

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Induced growth and salt tolerance of alfalfa by rhizobium strains from the rhizosphere of Haloxylon ammodendron

CHEN Jia(), GOU Jingyi, ZHAO Qi, HAN Qingqing, LI Huiping, YAO Dan, ZHANG Jinlin*()   

  1. (State Key Laboratory of Grassland Agro-ecosystems,Center for Grassland Microbiome, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China
  • Received:2020-12-27 Accepted:2021-03-01 Online:2021-11-30 Published:2021-12-02
  • Contact: ZHANG Jinlin E-mail:jchen19@lzu.edu.cn;jlzhang@lzu.edu.cn

Abstract:

【Objective】Soil salinity is one of major abiotic stress factors that reduce plant productivity and restrict agricultural development. Symbiotic nitrogen fixation of legume-rhizobium is very sensitive to soil salinity. Haloxylon ammodendron is a desert shrub species with high drought and salt tolerance. Therefore, deeply exploring the effects of rhizobium strains from the rhizosphere of H. ammodendron on the growth and salt tolerance of Medicago sativa(alfalfa) would provide theoretical basis and excellent rhizobium resources for developing new compound microbial fertilizers and improving the salt tolerance of alfalfa.【Method】The effects of three rhizobium strains (WAW-10, WA30-5 and WM30-21) isolated from the rhizosphere of H. ammodendron on the growth promotion and salt tolerance of alfalfa were investigated. Sinorhizobium meliloti Sm1021 was used as the reference strain.【Result】Under normal conditions or salt stress (300 mmol/L NaCl), WAW-10, WA30-5 and WM30-21 significantly increased plant height, root length, biomass, leaf chlorophyll content, root activity, and the carbon and nitrogen contents of alfalfa; three strains all induced the nodulation of alfalfa. Under 300 mmol/L NaCl, WAW-10, WA30-5 and WM30-21 significantly improved catalase activity and reduced relative membrane permeability and malondialdehyde content, therefore increased relative membrane integrity; WAW-10, WA30-5 and WM30-21 significantly increased leaf-soluble sugar and proline contents with increased osmotic regulation ability; WAW-10, WA30-5 and WM30-21 significantly decreased Na+ content in the shoots and roots of alfalfa and maintained the relative stability of the K+ content, resulting in an increased tissue K+/Na+ molar ratio (P < 0.05).【Conclusion】The inoculation of three rhizobium strains isolated from the rhizosphere of H. ammodendron all promoted the growth of alfalfa and improved its salt tolerance through maintaining relative membrane integrity, improving osmotic regulation ability and increasing tissue K+/Na+ molar ratio; WM30-21 had the optimal effects.

Key words: Haloxylon ammodendron, rhizosphere, rhizobium, Medicago sativa, growth promotion, salt tolerance

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