RAM GOPAL, S.K. DWIVEDI AND SANGEETA
Abstract
Plant Growth Promoting Rhizobacteria colonize plant root and promote plant growth by direct or indirect means. Biological control of fungal plant pathogens via PGPR is an ecofriendly alternative for the chemical control. The present study is an effort to determine new biocontrol agents having broadspectrum activity against the seed-borne fungal diseases. This investigation completely focuses on the antagonistic activity of some PGPR (including nitrogen fixers) collected from Sitapur and Kanpur districts. They limit density of the pathogen at minimum level, thereby control the disease. The PGPR species Bradyrhizobium (PGPB-K1, PGPB-S1), Bacillus (PGPR-L1) and Pseudomonas (PGPR-S2, PGPR-K1) were tested for their biocontrol efficiency against some fungi isolated from soybean seeds, i.e. Penicillium citrinum, Aspergillus niger, Fusarium longipes and Humicola. Our main objective was to compare the PGPR (including nitrogen fixers) isolates related to production of secondary antifungal metabolites and suppression of seed-borne fungi through colony interaction and competition for nutrition. Colonization assays revealed that PGPR isolates rapidly colonized and significantly reduced the growth of the seed-borne fungi of soybean. Amongst them Bradyrhizobium sp. (PGPB-K1) was highly antagonistic inhibiting the growth of P. citrinum, A. niger, F. longipes and Humicola by 68.85%, 64.97%, 55.82% and 62.50% respectively.