Mechanisms of plant growth enhancement and drought tolerance induced by micro-carbon™-based phosphorus (MCT-P)
Plant biostimulants encompass diverse biologically active substances that enhance growth and stress tolerance through mechanisms beyond direct mineral nutrition. This study aimed to elucidate the mode of action of a phosphorus-based biostimulant (MCT-P) and its effects under drought stress in corn (Zea mays), lettuce (Lactuca sativa), and Arabidopsis thaliana. Standardized bioassays evaluated root morphology, biomass, nutrient uptake, sugar metabolism, gene expression (TOR, H+-ATPase, LAX3), photosynthetic pigments, and chlorophyll fluorescence under optimal and drought conditions. MCT-P significantly improved root architecture, biomass accumulation, nutrient acquisition, leaf sugar content, and root sugar exudation, while modulating growth-related gene expression and enhancing photosynthetic performance and drought tolerance. These results suggest that MCT-P acts as a biostimulant by integrating humic-like bioactivity with phosphorus-mediated metabolic regulation, promoting coordinated carbon–nutrient–energy responses that support plant growth and resilience under water-limited conditions.