This study conducted a preliminary investigation on the rhizosphere fungi diversity of Kobresia humilis in the source region of the Yellow River， aiming to screen plant growth-promoting strains and provide basic materials for the future development of microbial fertilizers. Rhizosphere soil samples of K. humilis were collected from five different altitude sites in the source region of the Yellow River. Fungal strains were isolated and purified， then identified based on morphological and molecular biological methods. The plant growth-promoting activities of the dominant species Trichoderma paraviridescens were evaluated. A total of 207 fungal strains belonging to 18 genera were isolated. Among them， Fusarium and Trichoderma were the dominant genera， with 67 and 55 strains isolated， respectively， corresponding to isolation frequencies of 32% and 27%. Diversity index analysis revealed that the fungal diversity was the highest in Gonghe County （3208 m； H'=0.9381） and lowest in Maduo County （4512 m； H'=0.3378）. The overall fungal diversity in the study area was relatively low （H'=2.0809）. Both the diversity index and evenness index of rhizosphere fungi showed a trend of initial decrease followed by an increase with rising altitude. Analysis of the plant growth-promoting activities of the 55 T. paraviridescens strains indicated that 53 strains had the ability to produce cellulase， 51 strains possessed ability to produce protease， 32 strains had the ability to dissolve phosphorous， 6 strains had the ability to produce siderophores， and 4 strains had the ability to release potassium. These findings provide a theoretical basis and microbial resources for the exploitation of rhizosphere fungal resources of K. humilis and the development of microbial fertilizers in the source region of the Yellow River.

the Source Region of the Yellow River  /  Kobresia humili  /  Fungal diversity  /  Trichoderma paraviridescens