根际促生菌对石漠化地区造林苗木的促生效应.

Extensive soil erosion and vegetation degradation are common in karst rocky desertified area, and presenting a serious challenge of restoration of degraded habitats. In order to explore the promoting effect of PGPR(plant growth promoting rhizobacteria)on the growth of afforestation seedlings, seedlings of Cinnamomum camphora, Zenia insignis, Camptotheca acuminata and Acacia confusa which are common in Guangxi rocky desertified region were used as experimental materials. The plate dilution method was used to screen nitrogen-fixing bacteria from rhizosphere soil of rocky desertification native plants. The strains with higher nitrogenase activities were selected and inoculated into experimental seedlings for pot experiment. The results were as follows: Six strains of nitrogen-fixing bacteria from rhizosphere soil were obtained, and the 16S rDNA sequence analysis showed that the tested strains belong to Rhizobium, Sinorhizobium and Flavobacterium. Among them, the nitrogenase activity of three strains of Rhizobium was the highest. Pot experiment showed that inoculating nitrogen fixing bacteria could promote the growth of afforestation seedlings. Plant height, leaf area, leaf dry weight and chlorophyll content increased significantly compared to control. Nitrogen content of Cinnamomum camphora, Zenia insignis, Camptotheca acuminate and Acacia confusa seedlings significantly increased by 28.9%, 53.1%, 37.0% and 31.6%, respectively. Phosphorus contents of Cinnamomum camphora and Acacia confusa was increased significantly by 25.6% and 42.5%, respectively, while the potassium contents of Zenia insignis and Acacia confusa was increased significantly by 57.5% and 49.7%, respectively. The nitrogen-fixing bacterial strains of karst rocky decertified areas in Guangxi have growth promoting effect on local tree seedings used for afforestation. They provide a strong potential for forest restoration through seedling inoculation. [ABSTRACT FROM AUTHOR]