Abstract: Massilia strain is widely distributed in the rhizosphere of plants;however,there is still a lack of research on its effect on promoting seedling. To analyze the effect of Massilia strain B260 on promoting seedling growth is aimed to provide theoretical basis for its practical application. Coating and scribing was used to isolate the rhizosphere bacteria. The homology analysis of 16S rRNA gene sequence was based to preliminarily classify and identify the strains. The selective medium was used to analyze the characters and abilities of strains fixing nitrogen,dissolving phosphorus phytic acid and inorganic phosphorus,producing ACC deaminase,iron carrier and IAA. Two groups of treatments（including pB260 of adding strain B260 in the matrix,CK without adding B260）were set up. The seedling growth characters of tomato,cucumber,licorice root and astragalus under 2 treatments in hole plate seedling raising were compared and analyzed. The 16S rRNA of strain B260 had the highest similarity（99.85%）with Massilia plicata 76^T,which was preliminarily identified as Massilia. B260 demonstrated the plant growth-promoting character including nitrogen fixation,phosphorus release,hormone production,iron carrier production and ACC deaminase production,among which nitrogen fixation and inorganic phosphorus decomposition were the strongest. Compared with CK,pB260 increased the germination rate,plant height,root length,dry weight and fresh weight of tomato,cucumber,licorice and astragalus,especially root length increased by 6.71%,5.41%,12.28% and 15.79%,respectively. The B260 strain is Massilia,which has traits of plant growth-promoting,and can be used as seedling substrate.

Key words: nursing seedling, Massilia, rhizosphere-promoting bacteria, promoting effect