Plant Growth-promoting and Biocontrol Potential of Selected Cyanobacteria from Stress Environment

Cyanobacteria are photosynthetic microorganisms and produce large number of diverse bioactive compounds. In the present study plant growth promotion and antifungal activities of fourteen cyanobacteria strains have been studied against selected phytopathogens. Among screened isolates highest production of IAA was found in Chroococcidiopsis cubana HC1 (102.9 µg/ml) when supplemented with 0.3 mg/mL tryptophan. Co-inoculation of C. cubana (HC1) and Tolypothrix sp. (RC1) were evaluated for plant growth promoting potential on rice (Rajendra Sweta) plant which showed enhanced root (20.7±1.0 cm) and shoot length (11.4±1.3 cm) as well as increased number of forks (36.0±1.0) as compared to control seedlings. Among fourteen isolates eight cyanobacterial isolates showed zone of inhibition against selected phytopathogens. Tolypothrix sp RC1 and Nostoc sp. SK1 showed highest rate of inhibition (50%) against Ralstonia solanaceram while Pseudoanabaena sp. RD1 showed highest inhibition rate (52%) against Sclerotium rolfsi. Nostoc sp. HC2 found to be highest inhibition (61%) against Fusarium oxysporum. The cyanobacteria reported in this study have immense potential for biocontrol against fungal plant pathogens and plant growth promoting ability which enhances crop growth. Cyanobacterial isolates obtained from the study could be worthy in sustainable agriculture due to dual advantages of biocontrol as well as plant growth promotion.