Effect of plant growth promoting rhizobacteria, Bacillus cereus and Pseudomonas aeruginosa on early seedling growth and seed germination of Cinnamomum tamala

The slow germination and seedling growth of Cinnamomum tamala under natural conditions are one of the problems associated with the mass production of seedlings in nurseries. The present study was designed to investigate the plant growth-promoting rhizobacterial (PGPR) activities of Pseudomonas aeruginosa and Bacillus cereus alone and in combination on C. tamala seed germination and early seedling growth. All treatments on seeds with the test bacterial culture showed a significant increase in germination percentage. However, the maximum germination was reported in autoclaved soil with Ps. aeruginosa (ASP), followed by garden soil with Ps. aeruginosa (GS+P), and autoclaved soil with B. cereus (AS+P). The mean germination time (MGT) of autoclaved soil (AS) had the highest MGT. However, the lowest MGT was reported in Garden Soil with Forest litter (GS+FL) (24.3 ± 3.65), followed by garden soil with B. cereus and Ps. aeruginosa (GS+B+P) (26.5 ± 4.33). These results suggest that Ps. aeruginosa can be considered an effective bioinoculant to promote C. tamala seed germination as compared to B. cereus, whereas, for growth, the inoculation of seedlings with the tested bacterial strains resulted in significant enhancement in growth and biomass accumulation. The combination of both strains reduced the generation time but showed a lower germination percentage compared to individual treatments. The use of Ps. aeruginosa isolate showed superior activity in terms of germination percentage and other growth parameters, it can be utilized for the treatment of C. tamala for enhancing germination as well as for the growth of seedlings.