Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici is a serious problem limiting tomato production worldwide. The intent of the study was to evaluate potential of bacterial antagonists to suppress fusarium wilt disease development and evaluate the role of the strains as plant growth-promoting rhizobacteria (PGPR) in tomato. Among fifty-two bacterial strains isolated from rhizoplane and rhizosphere of healthy tomato roots, five isolates viz. isolate-01, isolate-17, isolate-23, isolate-24 and isolate-32 were found highly inhibitory against mycelial growth of Fusarium sp., in dual cultures.  Highest inhibition of radial mycelial growth of pathogen in dual culture was induced by isolate-24 (72.2%) followed by isolate-32 (71.9%). In greenhouse experiments percent disease incidence (PDI) was lower in artificially inoculated tomato plants treated with isolate-32 (7.8%) and isolate-24 (8.9%), with percent disease reduction over control of 85.6% and 83.6%, respectively. These isolates also exhibited significant difference in seed germination percentage under artificial inoculation along with pathogen, highest germination percentage was recorded by isolate-32 (91%) followed by isolate-24 (89%) as compared to pathogen inoculated control (24%). The study concluded that the two native rhizobacteria isolated from root zone of healthy tomato plants could successfully protect the tomato plants from the lethal infection by Fusarium sp. while enhancing the germination of the treated plants.

Tomato is affected by a large number of diseases. Among these, collars rot disease of tomato cause by S. rolfsii is a threatening disease in eastern coastal regions of Odisha. Since, this disease is soil borne in nature, it is very difficult to control by chemical fungicides. The native rhizosphere soil of tomato was used for isolation and screening of bacterial antagonists for their efficacy and growth promotion potential. A total of 54 bacterial isolates were isolated from rhizosphere of tomato of which five isolates viz. Iso-01, Iso-17, Iso-23, Iso-24 and Iso-32 were found effective for inhibition of the mycelial growth of S. rolfsii in dual culture. Highest inhibition of radial mycelial growth of pathogen in dual culture was induced by Iso-32 (75.6%) and Iso-24 (71.1%). In greenhouse experiment to manage collar rot in artificially inoculated tomato plants in portrays, the percent disease incidence (PDI) was minimum in treatment by Iso-32 (8.8%) and Iso-24 (9.8%), respectively. Similarly, percent disease reduction over control was highest with treatment with Iso-32 (85.1%) followed by Iso-24 (83.4%). Plant length, fresh and dry weight was also enhanced significantly due to the treatment of various isolates. The higher vigour index recorded with Iso-32 (1419) followed by Iso-24 (1387.3) as compared to vigour index (680) in non-treated control. It is concluded that native rhizobacterial strains can be successfully used for managing soil borne Sclerotium sp. affecting tomato crop while enhancing the growth of the treated plants.

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