Enabling Seawater Farming of Cabbage Using Indole-3-Acetic Acid Producing Bacteria as a Fungicide Alternative

Fungicides are crucial for enhancing agricultural production to meet global food demands. Seawater farming offers a sustainable alternative by utilizing seawater to control fungal growth, potentially reducing reliance on chemical fungicides and preventing water pollution. However, salt stress limits its application by compromising yields. We explored optimal conditions for crop growth by treating plants with Rhodobacter capsulatus, which produces indole-3-acetic acid (IAA) to mitigate plant stress, in seawater farming. We cultured R. capsulatus under 1% w/v NaCl and sea salt to assess IAA production and salt tolerance. Cabbage plants were treated with varying concentrations of R. capsulatus, NaCl, sea salt, and IAA, and growth metrics such as root and stem length, chlorophyll content, and fungal inhibition were measured. Our findings showed that 1% w/v of NaCl and sea salt supported R. capsulatus survival and IAA production, reducing salt stress and enhancing cabbage growth. Compared with Fusarium graminearum treatment, NaCl and sea salt solutions, combined with R. capsulatus, considerably enhanced cabbage growth. R. capsulatus’s IAA effectively reduced salt stress in cabbage, and 1% w/v sea salt served as a natural fungicide while promoting growth. This approach provides a sustainable solution to enhance food production and reduce environmental impacts.