[Effects of exogenous microorganisms on seedling growth and soil microbial community of Casuarina equisetifolia]

With a pot experiment, the Biolog microplate and phospholipid fatty acid (PLFA) technology were used to explore whether the application of bacteria, Bacillus amyloliquefaciens (YB706) and Burkholderia (BK8), could improve the soil nutrient, microbial community and growth of Casuarina equisetifolia. The results showed that the concentrations of soil alkali-hydrolyzed nitrogen and available phosphorus of C. equisetifolia treated with YB706 and BK8 increased significantly compared with the control (CK), but the concentrations of total nitrogen, total phosphorus, total potassium and available potassium changed little, plant height increased by 59.1% and 63.9%, respectively, and the chlorophyll content of plant treated with BK8 increased by 81.9%. The average well color development values showed a pattern of YB706>CK>BK8. The utilization rate of different carbon sources showed the same trend except the amino acids. Both YB706 and BK8 treatments significantly increased the richness and quantity of soil microorganisms. The PLFA of all kinds of microorganisms was BK8>YB706>CK except actinomycetes. The ratio of soil fungi to bacteria was increased compared with CK. The Simpson, Shannon, Brillouin and McIntosh indices of rhizosphere soil microbial community in YB706 and BK8 treatments were significantly increased. Our results suggested that application of YB706 and BK8 could improve the growth rate of C. equisetifolia seedlings, effectively increase the contents of soil available nutrients, increase soil microbial diversity, and improve soil microbial environment.