Synthesis of nano-selenium and its effects on germination and early seedling growth of four crop plants

In this work, nano-selenium (NSe) with different shapes (wires, rods, and spherical particles) was synthesized by a wet chemical method. These synthesized products were characterized by x-ray powder diffraction (XRD) analysis, a field emission scanning electron microscope (FE-SEM) with an energy dispersive x-ray analyzer, and Raman spectroscopy. FE-SEM images revealed that nanowires with an average diameter of 30–50 nm and length of 3–5 µm, nanorods with lengths of 400–800 nm and diameters of about 20–50 nm, and spherical-shaped nanoparticles (NPs) with diameters ranging from 40 to 60 nm were successfully synthesized. The XRD and Raman analysis confirmed that all the produced NSe samples exhibited hexagonal single-phase crystalline structure with no impurity phase. All three NSe products (SeNWs, SeNRs, and SeNPs) with a concentration range of 25–150 mg/l were used to investigate the impact of shape and concentration on seed germination and seedling vigor of four different crop species, namely, green bean, okra, wheat, and radish. The results revealed that NSe at low concentrations (≤50 mg/l for SeNWs and ≤100 mg/l for SeNRs and SeNPs) can promote seed germination, plant growth, and development of all the studied crop species. However, NSe can adversely affect the growth of plants at higher concentrations (≥75 mg/l for SeNWs).