Morphological, physiological and biochemical responses of crops (Zea mays L., Phaseolus vulgaris L.), medicinal plants (Hyssopus officinalis L., Nigella sativa L.), and weeds (Amaranthus retroflexus L., Taraxacum officinale F. H. Wigg) exposed to SiO₂ nanoparticles

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 SiO₂ nanoparticles (400, 2,000, and 4,000 mg L^-1). 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, 400 mg L^-1 SiO₂ 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 SiO₂ NP concentration increased from 400 to 4,000 mg L^-1, 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 400 mg L^-1 SiO₂ NPs. In all plant species, with increasing SiO₂ NP concentration, proline content increased significantly. According to these results, a lower concentration of SiO₂ NPs can have beneficial effects on morphological, physiological, and biochemical characteristics of plants.