Potential of Trichoderma viride spores as a bio-control agent against Ralstonia solanacearum in Lycopersicon esculentuni (var. Apollo)

Abstract

The potential of the fungus, Trichoderma viride spores as a bio-control agent was observed by determining its ability to protect against bacterial wilt and/or ability to revive Rsolanacearum infected tomato plants (var. Apollo). Currently, there are only a few studies concerning the antibacterial properties of T. viride done in vivo. Seven-week-old plants were grouped into five with 10 replicates each: (1) No Treatment Group - not inoculated with bacteria or fungi; (2) Control Group - bacteria only; (3) Group A - fungi before bacteria; (4) Group B - fungi simultaneous with bacteria. Both served as the Protective groups; (5) Group C - fungi after bacteria, which served as the Restorative Group. Plants were ranked according to a disease index scale of 0-4. After 14 days, the No Treatment Group had zero mean rank since it exhibited no signs of wilting while the Control Group had the highest mean rank (35.56). Among treatment groups, Protective Group B had the lowest mean rank (23.44) and is most similar to the No Treatment Group, followed by Protective Group A (28.61), and Restorative Group C (30.71). Two statistical tests were used to analyze data gathered. Based on the mean ranks, Kruskal-Wallis Test showed that except for days 1 and 2, there are considerable differences on the degree of wilting among the plant groups per day, while Friedman Test demonstrated that along the 14 days experimentation period, each plant group exhibited considerable progressive wilting, except for the No Treatment group. A higher mean rank indicates higher degree of wilting, and in turn, greater R. solanacearum infection. Previous studies suggest that the potential of T. viride to protect and revive infected tomato plants is due to: (1) its ability to produce antibacterial metabolites which may have worked against the bacteria; (2) its ability to interact with the host plant which can induce metabolic changes that increase resistance of the plants to a wide range of plant-pathogenic microorganisms; (3) T. viride could have utilized R. solanacearum as its substrate for growth such that it was used as the fungi’s carbon source. Based on the results, Trichoderma viride spores is a potential biocontrol agent against R. solanacearum since it was able to show potential protective and restorative ability for bacterial wilt infected tomato plants. However, T. viride spores showed more protective than restorative ability.