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

Abstract

Abstract Aims To understand the species composition, the relative content, and diversity of nitrogen fixing bacteria in Cenchrus fungigraminus rhizophere, 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) of C. fungigraminus rhizophere and physical and chemical properties were determined. The diversity and abundance of nitrogen-fixing bacteria and nifH gene copy were analyzed. Nitrogen-fixing bacteria were screened and selected for studying the C. fungigraminus seedlings growth promotion. Results The highest diversity and abundance of nitrogen-fixing bacteria were observed in C. fungigraminus rhizosphere (G2), which mainly included Proteobacteria (93.91%), Actinobacteria (0.42%), Firmicutes (0.18%) and significantly effected by total nitrogen, available nitrogen and depth. The nifH gene copy was also highest (1.56 ± 0.17×107 copies/g) in G2. Rhizobium pusense NO.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 of C. fungigramminus seedlings 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 with R. pusense NO.28 have significantly increased 3.09, 5.77 and 5.77 times. Conclusion Nitrogen-fixing bacteria in C. fungigraminus rhizosphere soil is rich and play a significant role in promoting its seedlings growth. The study provides the development of PGPRs from C. fungigraminus rhizosphere to be biological fertilizers.