Rhizobial plant probiotics enhance yield, heavy metal resistance, and impact the rhizosphere bacterial community in tomato (Solanum lycopersicum) under conventional agriculture system

Background and Aims This study investigates the potential of native elite rhizobial strains Rhizobium sp. ACO-34A, Sinorhizobium mexicanum ITTG-R7 ^T , and S. chiapasense ITTG-S70 ^T to enhance tomato crop productivity under conventional open-field agricultural management. It evaluates their effects on yield, plant growth, nutrient uptake, and rhizosphere bacterial community dynamics. Methods Tomato plants were inoculated with rhizobial strains under conventional cultivation practices and compared to a control group treated with chemical fertilizers. Agronomic and biological parameters, nutrient content in plant tissue, and rhizosphere bacterial diversity (alpha and beta) were assessed. Soil properties were analyzed to determine their influence on plant and microbial performance. Results Inoculation with Rhizobium sp. ACO-34A resulted in a significant 2.6-fold increase in tomato yield compared to chemically fertilized controls. Enhanced fruit size, plant height, stem width, and dry weight were also observed. Additionally, inoculated plants showed a statistically significant reduction in Fe and Cu content in plant tissue. However, no substantial changes were detected in rhizosphere bacterial alpha or beta diversity, nor a significant association between soil properties and crop performance. Conclusions The findings suggest that the observed improvements in tomato productivity are primarily due to inoculation with native elite strains, particularly ACO-34A, rather than soil characteristics. This study underscores the potential of native rhizobial strains as sustainable biotechnological tools to boost crop productivity and support global sustainable agriculture.