J. Sharifi-Rad - Zabol Medicinal Plants Research Center, Zabol University of Medical Science, P. O. Box: ۶۱۶۱۵-۵۸۵, Zabol, Islamic Republic of Iran.
M. Sharifi-Rad - Department of Range and Watershed Management, Faculty of Natural Resources, University of Zabol, Islamic Republic of Iran.
Jaime A. Teixeira da Silva - P. O. Box ۷, Miki-cho post office Retired, Ikenobe ۳۰۱۱-۲, Kagawa-ken, ۷۶۱-۰۷۹۹, Japan

In this research, two field crops(Zea mays L. and Phaseolus vulgaris L.), two medicinal plants(Hyssopus officinalis L. and Nigella sativa L.)and two weeds(Amaranthus retroflexus L. and Taraxacum officinale F. H. Wigg) were separately treated with three concentrations of SiO۲ nanoparticles (۴۰۰, ۲,۰۰۰, and ۴,۰۰۰ mg L-۱). The effects of these treatments on morphological and biochemical characteristics of the plants were assessed, including germination, root and shoot length, root and shoot fresh weight, root and shoot dry weight, photosynthetic pigments, total carbohydrates, total protein, total amino acid, and proline content. In the crops and medicinal plants, ۴۰۰ mg L-۱ SiO۲ NPs significantly increased seed germination, root and shoot lengths, fresh weights (except for H. officinalis) and dry weights, photosynthetic pigments, total protein, and total amino acid (except for H. officinalis). In weeds, as SiO۲ NP concentration increased from ۴۰۰ to ۴,۰۰۰ mg L-۱, germination, root and shoot lengths, fresh and dry weights, and photosynthetic pigments as well as total protein decreased. Total carbohydrates in all plants decreased significantly, except for A. retroflexus at ۴۰۰ mg L-۱ SiO۲ NPs. In all plant species, with increasing SiO۲ NP concentration, proline content increased significantly. According to these results, a lower concentration of SiO۲ NPs can have beneficial effects on morphological, physiological, and biochemical characteristics of plants.

Germination, Photosynthetic pigments, Total amino acid, Total carbohydrates, Total protein