Biofortification with ZnO NPs as nanofertilizers to improve sustainable commercial and phytochemical quality in basil plants

Biofortification is the process of developing a crop with bioavailable micronutrients in its edible parts. This has been done using nanofertilizers, since they can be used to feed plants in a gradual and controlled manner. Therefore, the aim of this work was to evaluate the effect of foliar application of ZnO NPs in different concentrations on the commercial and phytochemical quality of the basil (Ocimum basilicum L.) crop, as it is one of the most important aromatic plants used for chemical and pharmacological properties. Four concentrations of ZnO NPs (5, 10, 15 and 20 mg L-1) and a control treatment under a completely randomized design, were evaluated. The results show statistical differences in morphological parameters (leaf and stem fresh weight, height, number of leaves, leaf area and dry weight) with a slight tendency to increase on the treated basil plants mainly at concentration of 20 mg L-1. The highest chlorophyll content (5.54 µg g-1 FW) was obtained for the control treatment, whereas the lowest one (4.14 µg g-1 FW) was observed for the 20 mg L-1 treatment. However, carotenoid content in the leaves was markedly higher than the control, the control had the concentration of 0.84 µg g-1 FW, while the treatment with 20 mg L-1 ZnO NPs registered a value of 1.08 µg g-1 FW. The highest total phenolic, flavonoid, antioxidant capacity and vitamin C content was obtained for 20 mg L-1 ZnO NPs. Finally, basil plants treated with ZnO NPs could stimulate enzymatic activity, as demonstrated in this study. Detailed studies are suggested to understand the mechanism of action of nanoscale materials.