Physiological response induced by biostimulants on plantain plants (Musa AAB) under Ralstonia solanacearum race 2 stress

Abstract

Ralstonia solanacearum race 2 (Rs) is the causal agent of Moko, one of the most limiting diseases of plantain. This study aimed to determine if the preventive application of salicylic acid (SA), silicon dioxide (Si), Bacillus amyloliquefaciens (Ba), and Bacillus subtilis (Bs) reduce the disease development and mitigate the plant physiological damage caused by Rs. For this, plantain plants cv. Hartón (Musa AAB) at nursery stage were established in a split-plot design and treated with biostimulants before the inoculation with Rs. Disease development and plant physiological variables were evaluated post-inoculation. Application of SA and Si on inoculated plants improved the relative water content, quantic yield of the photosystem II, electrons transport rate, gas exchange, and promoted dry biomass partition to the roots and a higher roots elongation. Plants treated with these biostimulants showed the lowest disease degree in comparison to inoculated control plants. Moreover, non-inoculated plants treated with Si and Bs significantly improved their photosynthetic capacity, biomass accumulation, and root elongation compared to non-inoculated control plants. Results suggest that preventive application of SA and Si reduces the Moko disease development whereas Si and Bs improve the physiological features of the plants.