IN VITRO ANTIFUNGAL ACTIVITY OF TRICHODERMA HARZIANUM RIFAI AND PGPR STRAINS AS BIOCONTROL AGENTS AGAINST GRAY MOLD AND WHITE MOLD IN EGGPLANT

The in vitro efficiency of Trichoderma harzianum (T16 and T23), PGPR strains Pseudomonas aeruginosa (P07-1) and Bacillus subtilis subsp. subtills (B379c) as potential biocontrol agents against eggplant pathogens, gray mold (Botrytis cinerea) and white mold (Sclerotinia sclerotiorum) were determined. As compared to the control, both Trichoderma and PGPR strains showed inhibitory effect on the mycelial growth of pathogenic strains of B. cinerea (Bc-TR07) and S. sclerotiorum (Ss-TR07). P07-1 and B379c performed better than T16 and T23 in dual culture tests with inhibition rates of between 66-77% for both pathogens. As compared to volatile compounds, non-volatile compounds of T16 and T23 suppressed colony development of Bc-TR07 and Ss-TR07 significantly. Mycelial dry weight measurements revealed that there was no lytic activity between the antagonist and the pathogen. There were no hyper-parasitic reactions, therefore it was concluded that primary biocontrol mechanism mostly relied on antibiosis. The in vitro root colonization study demonstrated that P07-1 and B379c were quite effective as root colonizers. Germination rates for seeds treated with P07-1 and B379c rhizobacteria were recorded as 90% and 80%, respectively, while control germination rate was 65%. Vigor index of rhizobacteria treatments was almost twice as much of the control group. This study revealed that the promising T. harzianum and PGPR strains could potentially be used for the biocontrol of grey and white mold in eggplant plants.