Abstract
Green approach is one of eco-benign synthesis techniques and in the current investigation, manganese dioxide (MnO2) NPs are prepared using potato leaf extract and as a nanofertilizer, their effects were evaluated on photosynthetic pigments, growth, and antioxidant properties of cowpea (Vigna unguiculata) cultivar. The green-synthesized NPs were characterized for surface morphology and structure using SEM and XRD techniques. The functional groups were monitored by FTIR (Fourier transform infrared) spectroscopy analysis, which reveals that nanoparticles were of variable shapes, uniformly distributed with average particle size of 26 nm. The MnO2 NPs were applied as nanofertilizer to cowpea via soil and foliar applications. For both applications, five treatments were used, including control, salt, and three concentrations of MnO2 NPs (25, 50, and 75 mg/kg). The NPs after sonication were applied directly through soil and a spraying bottle was used for foliar application. A significant increase in plant growth by 67.1 and 45.3 (%), photosynthetic pigments by 52.8 and 39.2 (%), and non-enzymatic antioxidant activity by 56.25 and 49.6 (%) were observed for soil and foliar application, respectively. The effect of soil application was better versus foliar application to enhance the chlorophyll, growth characteristics, and non-antioxidant enzymes. Findings revealed that the MnO2 (nanofertilizer) increased the growth and yield of cowpea cultivars and has the potential to be used as a nanofertilizer for crops grown in Mn-deficient soils to increase crop productivity and yield.