Interactions of four PGPRs isolated from pasture rhizosphere Isolation and identification of endogenic nitrogen-fixing bacteria in the roots of Jerusalem artichoke (Helianthus tuberosus) Study on chemical behavior of root exudates with heavy metals Screening of Phosphate-solubilizing Bacteria and Their Acting Mechanisms in the Rhizosphere of Red Clover The Relationship between Organic Acid Secreted from Phosphorus-solubilizing Bacteria and The Phosphate-solubilizing Ability Screening and identification of phosphate-solubilizing bacteria from reclaimed soil in Shanxi mining area