Isolation and characterization of Plant Growth-Promoting Rhizobacteria from Cenchrus fungigraminus and their potential role in plant growth promotion

AbstractAims To understand the species composition, the relative content, and diversity of nitrogen fixing bacteria inCenchrus fungigraminusrhizophere, and to screen nitrogen-fixing bacteria to study their potential role in plant growth promotion. Methods Soil samples were collected from 4 depth (G1, G2, G3 and G4) ofC. fungigraminusrhizophere and physical and chemical properties were determined. The diversity and abundance of nitrogen-fixing bacteria andnifH gene copy were analyzed. Nitrogen-fixing bacteria were screened and selected for studying theC. fungigraminusseedlings growth promotion. Results The highest diversity and abundance of nitrogen-fixing bacteria were observed inC. fungigraminusrhizosphere (G2), which mainly included Proteobacteria (93.91%), Actinobacteria (0.42%), Firmicutes (0.18%) and significantly effected by total nitrogen, available nitrogen and depth. ThenifH gene copy was also highest (1.56 ± 0.17×107copies/g) in G2.Rhizobium pusenseNO.8 and NO.28 were isolated in G1 and G2, respectively, with nitrogenase activity of 1.45 ± 0.04 and 2.00 ± 0.07 U/g. The promotion experiment revealed that plant height, root length, leaf length ofC. fungigramminusseedlings treated with both strains were significantly increased 56.79%, 76.99% and 55.71%, and significantly increased on moisture and total nitrogen of planting soil compare with control (P < 0.05). The available nitrogen, organic matter and organic carbon in soil withR. pusenseNO.28 have significantly increased 3.09, 5.77 and 5.77 times. Conclusion Nitrogen-fixing bacteria inC. fungigraminusrhizosphere soil is rich and play a significant role in promoting its seedlings growth. The study provides the development of PGPRs fromC. fungigraminusrhizosphere to be biological fertilizers.