Combined effect of cauliflower intercropping and Pseudomonas fluorescens seed biopriming on the suppression of fusarium wilt in okra

Use of chemical pesticides and fertilizers impart negative impact on human health and environment. There is a need to develop alternate strategies for the management of phyto-pathogens. Intercropping offers a sustainable solution for plant disease management by modulating microbial population in rhizosphere and reducing pathogen load. In this study, we examined the protective impact of cauliflower (Brassica oleracea) and Pseudomonas fluorescens (Pfl) as seed priming agent against Fusarium oxysporum f. sp. vasinfectum (FOV) induced wilt in okra (Abelmoschus esculentus). Intercropping cauliflower with okra resulted in reduction of disease incidence and severity (44% and 67%, respectively) compared to okra cultivated with okra. Okra plants intercropped with cauliflower maintained higher growth in terms of root and shoot dry weight (10.94% and 7.50%, respectively) as well as root and shoot length (2.2% and 33.7%, respectively) compared to okra grown in combination with okra under fusarium wilt stress. Maximum content of leaf nitrogen, phosphorus and potassium (5.52, 1.14, and 1.98%, respectively) was recorded in P. fluorescens primed okra co-cultivated with cauliflower under wilt stress. Root exudates extracted from okra intercropped with cauliflower reduced FOV microconidia germination by 23.58% compared to exudates from okra cultivated with okra. Higher activity of peroxidase, glucanase and polyphenol oxidase (3.54, 5.01 and 3.01 Units /min/g FW, respectively) was recorded in okra intercropped with cauliflower and inoculated with P. fluorescens compared to unprimed okra intercropped with cauliflower (2.92, 4.56 and 2.27 Units /min/g FW, respectively) under FOV infection. In the presence of fusarium infection, okra companioned with cauliflower and primed with P. fluorescens successfully maintained higher photosynthetic activity and leaf chlorophyll content (3.93 mg/g FW) compared to okra cultivated with cauliflower in the absence of P. fluorescens (3.78 mg/g FW). Overall, our findings revealed that the synergy of cauliflower intercropping and priming okra with P. fluorescens not only reduced the impact of fusarium induced infection but also enhanced growth parameters of okra.