Humic Acids as Drivers of Plant Growth: Regulating Root Development and Photobiology Through Redox Modulation

This study explores the role of humic acids (HA) in enhancing plant growth by modulating redox processes, which affect root development and photobiology. HA, derived from oxidized sub-bituminous coal, were found to improve plant biomass, stress tolerance, and nutrient uptake. A concentration of 20 mg/L of carbon from HA was optimal for corn, leading to significant improvements in root morphology, photosynthetic efficiency, and enzyme activities. HA treatment increased reactive oxygen species (ROS) and antioxidant enzyme activities, suggesting a transient oxidative stress followed by enhanced antioxidant responses. The study highlights HA's potential as biostimulants in sustainable agriculture, although further research is needed to fully understand their mechanisms of action.