Exogenous Soil Drenching Supplementation of Fluvic Acid Enhances Growth Promotion in Maize (Zea mays L.)

The pursuit for sustainable crop improvement approaches has led to growing interest in natural biostimulants such as fulvic acid (FA), a low molecular weight, water-soluble component of humic substances known for its multifaceted roles in plant development. This study explores the impact of exogenous FA supplementation through soil drenching on the growth performance of maize (Zea mays L.), a globally significant cereal crop. Five treatments were assessed: T1 (control), and FA at concentrations of 25 mg/L (T2), 50 mg/L (T3), 75 mg/L (T4), and 100 mg/L (T5). Among them, T3 (50 mg/L) displayed the most pronounced improvements in morphology, physiology, and biochemistry. Specifically, chlorophyll a, total chlorophyll, and carotenoids increased by 3.16-, 2.92-, and 12.92-fold respectively, while relative water content and superoxide dismutase activity were elevated by 3.07- and 2.04-fold. Moreover, total proline content rose nearly 3-fold. These results confirm that reasonable FA application significantly increases the morphological changes, photosynthetic efficiency, antioxidant defense, and overall vigor in maize. Fulvic acid thus holds promise as a sustainable, eco-friendly alternative to synthetic agrochemicals for boosting crop productivity under diverse field conditions.