Vol. 12, Issue 6 (2023)

Author(s):
Gurpreet Kaur Bhamra, PK Borah, LC Bora and Popy Bora

Abstract:
The study was made to assess the PGPR and endophytic microbial population of two different species of tomato plants [Solanum pimpinellifolium (kon bilahi) and Solanum lycopericum] and develop a biocontrol strategy using these microbes for managing bacterial wilt (BW) of tomato caused by Ralstonia solanacearum. In this study, we observed greater microbial diversity of PGPR and endophytic microbes in S. pimpinellifolium compared to S. lycopericum. By performing the in-vitro antagonistic and compatibility studies, it was revealed that a few promising PGPR (RKB7) and endophytic (EKA4 and EKB6) microbes could effectively inhibit the bacterial wilt pathogen. Combination of these isolates (RKB7+EKA4+EKB6) showed the highest inhibition of BW pathogen in tomato crops. Molecular characterization and nucleotide analysis revealed that RKB7, EKA4 and EKB6 isolates were found to be Bacillus subtilis (ON261568.1), Streptomyces virginiae (ON223266.1) and Pseudomonas aeruginosa (ON248938.1) respectively. Effective growth-promoting characteristics such as the production of ammonia, IAA, HCN, siderophore and zinc and phosphorus solubilisation were recorded for these isolates. Best PGPR and endophytic microbes and their combination along with an antibiotic check, streptocycline @ 200 ppm was tested in vivo for their efficacy in managing BW of tomato. The lowest disease incidence (31.11%) and highest yield (340.67 g/plant) were recorded in the plants treated with combination of these isolates (RKB7+EKA4+EKB6). Similarly, other yield attributing characters viz., plant height, root length, no. of leaves, etc., were found to be high in the plants treated with the combination of the isolates.