ISOLATION AND EVALUATION OF ANTAGONISTIC SOIL BACTERIAL CONSORTIA AGAINST FUNGAL PATHOGENS, ROOT-KNOT NEMATODE AND PLANT GROWTH PROMOTION

Parasitic nematodes and fungal pathogens are identified as emerging threat for agroindustry, causing huge economic loss in global scenario. Several fungal pathogens and the nematode Meloidogyne javanica have wide host range and damage various cash crops. This study focused on isolation and evaluation of antagonistic bacteria against soil borne fungal and the plant parasitic nematode M. javanica. The study included developing consortia of effective bacterial isolates and their impact on control of root-knot under laboratory and greenhouse conditions. Under in-vitro conditions, consortium #3 showed significant reduction (88%) of hatching rate of nematode eggs and increased mortality (90%) of the second stage juvenile (J2). In greenhouse conditions, we observed reduced gall formation (61%), and egg mass (52%) in tomato when applying consortium #3 compared to saline control. Concomitantly, this consortium was found to be an effective fungicidal, as well as nematacidial agent. Additionally, a different consortium (#1) was obtained against the fungal pathogen Sclerotium rolfsii and showed promising antagonistic effect as compared to control. In this study, while vigorous growth of hyphae and 100% sclerotia germination was observed after 5 days in saline (control) none germinated in the presence of the consortium. In greenhouse condition, consortium #1 was applied to bean plants (Phaseolus vulgaris) and was shown to increase shoot length (53%), chlorophyll contents (35%) and dry biomass (50%), as compared to control treatments of dead consortium #1 bacteria and saline. The microbiome structure associated with treated tomato roots and soil are being analyzed for identifying the bacterial mechanism of action. This study provides tools for an eco-friendly alternative to control combined effects of fungal and nematode mediated plant diseases and for plant growth promotion.