The influence of nanoparticles (n-TiO2 and n-Ag) on germination and plant growth

Background/Question/Methods

The use of nanoparticles in manufacturing is becoming more prevalent due to the unique properties of these compounds. Consequently, nanoparticles are introduced into ecosystems from industry, wastewater treatment facilities, and agricultural uses. Despite this, the effects of these compounds on soil communities and plant growth is largely unknown. This study evaluates the individual and combined effect of titanium dioxide (TiO­₂) and silver nanoparticles on plant growth. These are commonly found in surface waters used for water crop land, as  they are not removed by most waste water treatment plants.  We used 3 different environmental relevant concentrations (1mg/L – 16mg/L) of TiO₂and nano-silver, and a combination of the two. Plants were grown in a greenhouse and dosed weekly for 8 weeks. Germination, biomass, and above and belowground dry weight was measured.  To evaluate where the plant stores these compounds, concentrations of titanium and silver were analyzed in the leaf and root tissues.

Results/Conclusions

We found nanoparticles significantly affect apical meristem height, root length, and root and shoot dry weight. Nano-silver and the combination of TiO₂/silver negatively affected growth, particularly in the apical meristem and reduced dry weight of treated plants by 20 mg. TiO₂ alone increased root length by 4-6 cm, but final biomass decreased, suggesting long and thin roots. Concentration of nanoparticles in roots and shoots were below detection limits. Previous studies have also reported inhibition of seed germination and decreases in root growth, likely a response to the more adverse effects on synergistic microbes that aid in plant growth patterns. Our results contribute to the growing body of knowledge that nanoparticle exposure may have unintended consequences such as stunted roots and lower germination in crop plants.