Biological management of cumin Fusarium wilt caused by Fusarium oxysporum f.sp. cumini using antagonistic rhizospheric bacteria Bacillus licheniformis

Abstract

The field survey conducted in Rajasthan, India, unveiled the widespread occurrence of Fusarium wilt in cumin fields that have been continuously cultivated for approximately 4 to 5 years. The incidence of this disease exceeded 30%, affecting cumin plants at all stages of growth, with severe symptoms ultimately resulting in the complete mortality of the plants. In laboratory studies, a bacterial isolate known as Bacillus licheniformis (CSR-D4) exhibited remarkable in vitro effectiveness, significantly inhibiting Fusarium oxysporum f.sp. cumnini (FOC) mycelial growth by an impressive 79.85%. In controlled pot experiments, cumin plants treated with B. licheniformis (CSR-D4) displayed milder symptoms than untreated plants, demonstrating a notably higher tolerance level, with only a 15% disease incidence as opposed to 90% in untreated plants. Further analysis of defense enzymes revealed elevated chlorophyll, carotenoid, peroxidase activity levels, and proline content in cumin plants treated with B. licheniformis (CSR-D4). Field assessments confirmed the efficacy of this bacterial isolate, as it successfully suppressed wilt incidence by 60%, significantly increased crop yield by 71.16%, and promoted root and shoot growth. Notably, applying B. licheniformis (CSR-D4) did not negatively impact beneficial microorganisms, and no adverse phytotoxic symptoms were observed. This study underscores the considerable potential of B. licheniformis (CSR-D4) in managing Fusarium wilt, offering an environmentally friendly and highly effective solution to enhance the health and productivity of pea plants.