Revitalizing cowpea growth and physiological parameters through foliar applications of nanoparticles and biostimulants

A field experiment was conducted at SRM College of Agricultural Sciences, Baburayanpettai, Chengalpattu, Tamil Nadu, during Summer of 2025 to study the effects of zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles combined with biostimulants on cowpea growth and yield. The experiment used a Randomized Block Design with seven treatments replicated thrice. Foliar application of seaweed extract @ 2% with ZnO NPs @ 0.01% and MgO NPs @ 0.02% at 30 and 45 days after sowing (DAS) recorded the highest plant height at harvest (59.46 cm), leaf area index at 45 DAS (4.34), dry matter production (4417 kg ha⁻¹), number of branches (7.6), number of nodules (17.79), crop growth rate (12.55), relative growth rate (0.077), relative water content (65.3%), and chlorophyll stability index at 30 DAS (78.6). The second-best performance was observed by the treatment of humic acid @ 2% combined with ZnO and MgO nanoparticles applied at the same intervals. These findings suggest that combining seaweed extract with ZnO and MgO nanoparticles significantly improves cowpea’s vegetative and physiological traits by improving the nutrient uptake, nodulation and physiological resilience. Integrating nanotechnology with eco-friendly biostimulants offers a sustainable approach to enhancing crop productivity under semi-arid conditions, offering the potential for adoption in resource-limited farming systems.