Impact Of Individual And Synergistic Application Of Seaweed Extract And PGPR On Growth And Physiology Of Tomato (Solanum Lycopersicum L.) Under Salinity Stress

Abstract

In this study, we investigated the individual and combined effects of a liquid extract from the brown seaweed Cystoseira compressa and a plant growth-promoting rhizobacterial strain Bacillus cereus MR64 on the growth and physiological responses of tomato plants (Solanum lycopersicum L.) under salt stress. The bacterial strain Bacillus cereus MR64 was selected for its remarkable NaCl tolerance and plant growth-promoting traits. A greenhouse pot trial was conducted, wherein tomato plants were treated with either a bacterial suspension, three concentrations (5%, 10%, and 15%) of the seaweed extract, or their combinations applied to the soil. The plants were subjected to 150 mM NaCl. Growth parameters, photosynthetic pigments, leaf relative water content, and leaf electrolyte leakage were measured. Results indicated that the extract was more effective than the bacterial strain alone in enhancing shoot growth, photosynthetic pigments, and membrane integrity. When applied alone, the bacterial strain notably increased root length and biomass compared to the extract and the control. Significant improvements in growth parameters, chlorophyll content, and electrolyte leakage were observed when the bacterial strain was combined with the extract at concentrations of 10% and 15%, showing notable synergistic effects.