To screen plant growth-promoting rhizobacteria （PGPR） that are capable of stably colonizing the rhizosphere of Stipa purpurea， four PGPR strains previously isolated from this alpine grass were evaluated. Rifampicin-resistant derivatives were generated to monitor root-zone colonization dynamics， and the effects of bacterial inoculation on seed germination， seedling morphology， and physiological indices were assessed under the culture of 15℃， 20℃， and 25℃. Serratia proteamaculans GD-1-1 and Paenarthrobacter nitroguajacolicus YD-2-4 established stable populations in the S. purpurea rhizosphere， and the colonization amounts were 1.22×10⁸ and 0.06×10⁸ CFU·g^-1 at 20 d， respectively. Dilutions of YD-2-4 （1×10¹ and 1×10² CFU·mL^-1） significantly enhanced germination and seedling growth across 15℃-25℃， concurrently increasing antioxidant enzyme activities and lowering malondialdehyde content. In contrast， the stimulatory effect of GD-1-1 （1×10² and 1×10³ CFU·mL^-1） declined with temperature and disappeared at 15℃. These results indicated that YD-2-4 possessed robust colonization ability and broad temperature adaptability， making it an excellent candidate for the development of microbial inoculants for alpine grasslands.

Alpine grassland  /  Stipa purpurea  /  Plant growth-promoting rhizobacteria  /  Rifampicin resistance selection  /  Growth-promoting effect