Abstract
The aim of this study is to synthesize composite micro-nutrient nanoparticles (NPs) composed of four essential nutrient elements (Ni, Cu, Zn, and Fe) for plants as well as to investigate the incorporation of these micro-nutrients into the plant tissues. For these purposes, Ni0.4Cu0.2Zn0.4Nd0.05Y0.05Fe1.9O4 NPs were synthesized by sol-gel auto combustion method and characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The NPs were applied to barley (Hordeum vulgare L.) in varying concentrations (62.5, 125, 250, and 500 mg L-1) for 21 days. Hydroponically grown seedlings were harvested and the element content of the root and leaf parts was analyzed by using an inductively coupled plasma optical emission spectrometer (ICP-OES). Results showed that NPs have a spherical structure with an average crystallite size of 18 nm. Raising NP doses gradually increased the amount of the elements found in the composition of NPs (Ni, Cu, Zn, Nd, Y, and Fe) both in root and leaf tissues. In addition, compared with the untreated control, 500 mg L-1 of NP treatment increased the abundance of some macro-elements (K, Ca, Mg, and P) in roots, while the amount of these elements except for Ca significantly decreased in the leaves (p < 0.05). This study is the first to show that Zn, Ni, Cu, and Fe can be incorporated into the plant body by the inclusion of NPs. This finding suggests that NPs with micro-nutrients can be used to heal the plants suffering from single or multiple nutrient deficiencies. New nano-formulations can be designed and applied to plants according to their nutritional requirement.