Effect of zinc oxide nanoparticles and salinity on anatomical traits of Datura stramonium

This study aimed to evaluate the anatomical response of Datura stramonium to long-term exposure to zinc oxide nanoparticles (0, 100, and 500 mgl-1) and salinity (0 and 300 mM). Salinity treatment reduced leaf length and width compared to the control, while treatment of 100 mgl-1 nano-zinc oxide increased the leaf length and width relative to the control. Furthermore, 100 mgl-1 nano-zinc oxide treatment alleviated adverse effects of salinity. However, the treatment of 500 mgl-1 nano zinc oxide had a negative effect on those characteristics. Salinity decreased leaf thickness and vascular development, whereas 100 mgl-1 treatment increased leaf thickness and vascular system development compared to the control. 100 mgl-1 Zinc nano oxide treatment also reduced the signs of salinity stress in the plant. In the cross-section of the stem, salinity treatment reduced vascular differentiation, while 100 mgl-1 zinc nanoparticle treatment reinforced development of conducting tissues and the development of collenchyma. In the simultaneous treatment of salinity and 100 mgl-1 nanozinc oxide, the development of the vascular system was higher than the salinity control, thereby reducing the symptoms of salinity toxicity in the plant. The results showed that the treatment of 500 mgl-1 limited the differentiation of xylem tissue. Therefore, it seems that nano-zinc at low dose can mitigate the risk of salinity through the modification in differentiation of xylem tissue and collenchyma.