Growth Promotion and Biological Control of Fungal Dry Rot in Potato by Potential Bacillus Rhizobacterium
Background: Dry rot of potato (Solanum tuberosum L.) is often caused by Fusarium sambucinum and is a major factor accounting for loss of productivity of this economically important food crop. Repeated use of synthetic fungicides has led to worries about pollution risk and emergence of fungicide resistant populations of the pathogen, underscoring the importance of using biological methods as alternatives to chemistry. Both Bacillus subtilis MGM123 and its lipopeptides were tested in the present study for management of potato dry rot disease condition under green house. Methods: A greenhouse experiment was conducted during 2025-2026 using potato variety Kufri Khyati in a completely randomized design with seven treatments comprising untreated control, F. sambucinum, B. subtilis MGM123, Fusarium + Bacillus, Fusarium + Trichoderma, Fusarium + Mancozeb and Fusarium + lipopeptides. Vegetative growth, defence-related enzymes (PAL, POD and PPO), total chlorophyll content, disease severity index (DSI) and tuber yield were recorded. Data were analysed using analysis of variance and treatment means were separated by Tukey’s HSD test at P≤0.05. Result: Significant differences were observed among treatments for vegetative growth, defence-related biochemical responses, disease severity and tuber yield. Bacillus subtilis MGM123 recorded the highest plant height (64.01 cm), shoot length (13.09 cm), root length (14.91 cm) and tuber yield (140.00 g plant-1). Among the pathogen-challenged treatments, lipopeptides effectively reduced disease severity from a Disease Severity Index (DSI) of 4.67 in pathogen-inoculated plants to 1.67 at 28 DAT while increasing tuber yield to 129.00 g plant-1. Biological treatments also enhanced phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities and maintained higher chlorophyll content than the pathogen-inoculated treatment. These findings demonstrate that B. subtilis MGM123 and its lipopeptides are promising environment-friendly alternatives to chemical fungicides for the sustainable management of potato dry rot.