Abstract
BackgroundSclerotium rolfsii is a soil-borne fungal pathogen causing diseases in more than 500 plant species. It causes southern blight disease in chili. Chemical fungicides are used to control this disease, which also pollute the environment. The present study was designed to assess the potential of two species of plant-growth-promoting rhizobacteria (PGPR) viz. Bacillus megaterium and Pseudomonas fluorescence, and an allelopathic weed, Anagallis arvensis L., for the control of southern blight disease of chili.ResultsInitially, three PGPR strains, viz. B. megaterium OSR3, B. megaterium ZMR6, and P. fluorescence PF-097, were selected for their in vitro antagonistic assessment against S. rolfsii by dual culture technique on potato dextrose agar medium. OSR3 showed the highest antagonistic potential (68%), followed by PF-097 (54%) and ZMR6 (33%). In a pot experiment, the two best strains of PGPR, namely OSR3 and PF-097, and dried biomass of A. arvensis (DBA) in different concentrations (1, 2 and 3%) were used to manage southern blight disease of chili. In positive control treatment (S. rolfsii only), plant survival was low (73%) than the negative control (100%). OSR3, PF-097, OSR3 + 2% DBA, and PF-097 + 2% DBA significantly enhanced plant survival over positive control. The highest increase in chili growth over positive control was recorded due to OSR3, followed by PF-097 inoculations. Contents of carotenoid and chlorophyll were significantly decreased due to the fungal pathogen and improved due to PGPR strains. Application of the two PGPR strains and different concentrations of A. arvensis distinctly increased the catalase (CAT), peroxidase (POX), and polyphenol peroxidase (PPO) activities over positive control.ConclusionsThe present study concluded that PGPR strains B. megaterium OSR3 and P. fluorescence PF-097 can control southern blight disease effectively and increase growth and yield of chili.
Highlights
Sclerotium rolfsii is a soil-borne fungal pathogen causing diseases in more than 500 plant species
PF-097 proved a very promising antagonistic plant-growth-promoting rhizobacteria (PGPR) strain as it inhibited the growth of the fungal pathogen by (54%)
On the basis of their highly pronounced in vitro inhibitory activity against the fungal pathogen, PGPR strains OSR3 and PF-097 were selected for pot trial
Summary
Sclerotium rolfsii is a soil-borne fungal pathogen causing diseases in more than 500 plant species. It causes southern blight disease in chili. The observed disease symptoms are yellowing of plant leaves and the formation of dark brown lesions at collar region near the soil line which further lead to wilting of the whole plant (Mahadevakumar et al 2018). It produces enormous sclerotia, which persist in soil for many years in the form of infected plant debris.
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