Selective screening and characterization of plant growth promoting bacteria for growth enhancement of tomato, .

BACKGROUND AND OBJECTIVES

Plant Growth-promoting Bacteria (PGPB) can replace the dangerous chemical fertilizers and pesticides. The aim of this study was to isolate the PGPBs for plant and to determine the appropriate volume for inoculation.

MATERIALS AND METHODS

Plants samples were collected from tomato fields. Nitrogen fixing-PGPBs were isolated from rhizoplane and rhizosphere. Five isolates were screened based on their growth abilities and examined for PGPB traits including phosphate solubilization, and IAA, ammonia and HCN production. After high cell density cultivation, the cells were separated by centrifugation and freeze dried after resuspension in cryoprotectant. The powders were inoculated into sterile soil with a dose of 10, 10 and 10 CFUs/g. Tomato seeds were sown in soil and after 42 days the shoot length was measured.

RESULTS

Most of the potent PGPBs with high growth capacity were isolated from rhizoplane. Maximum phosphate solubilization was 289.7 μg/ml by NFB12 which isolated from rhizoplane. This strain produced the maximum level of IAA. NFB12 produced ammonia without the ability of production of HCN. This strain enhanced shoot length in dosed dependent manner. Surprisingly, inoculation of soil with 10 CFUs/g dramatically decreased the shoot length by 21%. Based on molecular approach NFB12 was identified as

CONCLUSION

Isolation of specific PGPBS is recommended for sustainable plant production. Our results showed that NBF12 improves tomato plant growth and its effect on tomato plant growth is does dependent. Maximum growth rate of tomato was observed with 10 CFUs/g soil inoculation of NFB12 while higher inoculation showed negative effect.