Pollution Research Paper

ANTAGONISTIC ACTIVITY OF PLANT GROWTH PROMOTING NATIVE PSEUDOMONAS ISOLATES AGAINST SOIL BORNE FUNGAL PATHOGENS

BHARATHULA SARVANI AND RAVULA SUBHASH REDDY

Abstract

Plant growth promoting Rhizobacteria (PGPR) are beneficial bacteria that associate plant roots and enhance the plant growth by various mechanisms. Several bacteria thrive on abundant nutrients in the rhizosphere and some of these possess antagonistic action which safeguard the plant from pathogens and stimulate growth. In this context, it is important to investigate the natural presence of these microorganisms in the legumes viz., Groundnut and Red gram rhizosphere soils and propose a selective screening to find promising PGP strains. In this study, rhizosphere soils were obtained from different areas of Groundnut and Red gram crops in Rangareddy district. Fifteen bacteria were successfully characterized and identified as fluorescent Pseudomonas, based on their cultural, morphological and biochemical characteristics. The study was further preceded for in vitro screening of Plant growth promoting traits of the bacterial isolates viz., production of Indole Acetic acid (IAA), Ammonia, Hydrogen cyanide, Siderophores and Phosphate solubilization. All the isolates produced Ammonia and majority of the isolates showed positive results for the production of IAA, Siderophores and phosphorus solubilization. Few of the isolates displayed HCN (40%) production. The PGPR strains were also tested for in vitro antagonism against Rhizoctonia solani, Sclerotium rolfsii and Fusarium solani. Results revealed that all the Pseudomonas isolates inhibited Fusarium solani and 80% of the isolates controlled the mycelium growth of Rhizoctonia solani and Sclerotium rolfsii.