Early plant growth and bacterial community in rhizoplane of wheat and flax exposed to silver and titanium dioxide nanoparticles.

Silver and titanium dioxide nanoparticles (AgNPs and TiO2NPs) are highly useful, but they are also a significant reason for concern as they exert toxicity. The goal of research was to assess the role of three kinds of NPs in concentrations of 100 mg L-1 on early growth plants (wheat, flax) and bacterial community in rhizoplane. Titanium (IV) oxide anatase (TiO2NPs1) and titanium (IV) oxide nanopowder (TiO2NPs2) are commercial products. A suspension of AgNPs was prepared via a procedure of reduction with tannic acid. The response of Monocot and Dicot growth form plants to the tested NPs was different. Germination and seedling growth of wheat treated with TiO2NPs1 was better. The response of flax to NPs was noted as an increase of chlorophyll content. The bacterial community in wheat rhizoplane was not significantly modified, but there was a declining trend. In turn, a difference in the surface charge of NPs had an influence on the total bacterial community in Dicot rhizoplane. Positively charged TiO2NPs2 significantly decreased the quantity of total bacteria in contrast to negatively charged AgNPs and TiO2NPs1 which increased it. A qualitative analysis did not confirm the influence of the surface charge of NPs on an increase/decrease in the quantity of Pseudomonas and Bacillus bacteria, but did show that there was no toxicity of the tested NPs to the plant growth-promoting bacteria community. The rhizoplane microbiome was dependent on the species of plant, and the bacteria found in the communities are sensitive to NPs to a varying degree.