Nanosilver particles are among the potentially candidates for modulating the redox status and changing the growth, performance and quality of plants because of their physicochemical features. This study was carried out to elucidate the potential effects of nanosilver (5-20 nm) particles application on variations of plastid pigments and essential oil constituents of Pelargonium graveolens. A transmission electron microscope (TEM) image of spherical nanosilver particles was also provided. Various nanosilver particles concentrations (0, 20, 40, and 80 mg.L-1) were used as foliar application. The essential oils were isolated from aerial flowering parts of the plants by hydro-distillation method and then subjected to GC and GC-MS apparatus to determine the oil constituents. Pigments including chlorophyll and carotenoids content increased in leaves of nanosilver treated plants compared to control. Nanosilver application at 40 mg.L-1 were the most effective treatments in pigments and essential oil content. Also, results showed that citronellol was the major component under all employed treatments. Maximum citronellol/geraniol ratio was obtained at 80 mg. l-1 nanosilver treatment, indicating the positive effect of nanosilver particles on essential oil quality of geranium plant.
