Green synthesized ZnO nanoparticles for sustainable production and nutritional biofortification of green gram

Abstract

Zinc oxide (ZnO) nanoparticles were synthesized using green and conventional approaches and characterized using XRD, SEM-EDX, UV–VIS spectroscopy, particle-size analyzer. Green ZnO nanoparticles were found to have 57% lesser mean diameter, more uniform size distribution and consumed 29.3% less NaOH than standard ZnO nanoparticles. To investigate the efficiency of both types of nanoparticles on the green gram (Vigna radiata (L.) Wilczek), a pot experiment was carried out in a completely randomized design with two levels of foliar-applied nanoparticles and four levels of concentrations and three replications. The foliar application of green ZnO nanoparticles was found to perform better than standard ZnO nanoparticles based on improvement in the growth and yield parameters of green gram. Green nanoparticles resulted in 13.3% higher seed yield, 5.6% higher protein content and 3.2% higher zinc (Zn) content in seed than standard ZnO nanoparticles. The 1000-seed weight, seed yield, root biomass, active nodule content, leaf area index, seed protein content were recorded to be significantly improved up to 20 mg L−1 concentration of ZnO nanoparticles and beyond that no significant improvement was recorded. Seed protein and Zn content were increased by 15.6 and 25.2%, respectively and the seed yield was increased by 56.2% with the application of ZnO nanoparticles at a concentration of 20 mg L−1 in comparison to control. Current results show a great potentiality of synthesis and application of green ZnO nanoparticles at a concentration of 20 mg L−1 for the improvement in yield and quality of green gram with higher nutrient use efficiencies at a reduced environmental cost.