Nano-micronutrients [γ-Fe2O3 (iron) and ZnO (zinc)]: green preparation, characterization, agro-morphological characteristics and crop productivity studies in two crops (rice and maize)

Nanotechnology based fertilizer production possessing the desired chemical composition, can improve plant nutrition and may reduce the environmental impact and enhance the plant productivity. In this work, we have demonstrated the green preparation and characterization of nano iron (γ-Fe2O3) and zinc (ZnO), and the subsequent agro-morphological modification (germination, shoot length, root length, seedling length, vigor index and dry matter production (DMP) (fresh and dry weight), the effect on the crop productivity (1000 grain weight, seed length, seed thickness, seed width) and the mechanism of uptake in rice (Oryza sativa) and maize (Zea mays L.). The highest seed germination percentage (100%) and seedling vigor index values (27 500 and 36 500) were observed after using 500 ppm of nanoscale γ-Fe2O3 treatment in rice and maize, respectively. In the case of nanoscale ZnO, the highest seed germination percentages (100% and 99%) and seedling vigor index values (32 400 and 33 660) were observed at 1000 and 2000 ppm in rice and maize seeds, respectively. The results of the micro plot field studies revealed that yield attributes such as the total grain weight (g m−2), 1000 grain weight, seed length, seed thickness, seed width and yield (kg ha−1) were also highly influenced by the foliar application of nanoscale γ-Fe2O3 (500 ppm) and ZnO (750 ppm) in rice and maize, respectively.