carbon nanotubes, photosynthesis, gas exchange, Arabidopsis thaliana
There has been increasing interest in the biological and biomedical applications of carbon nanotube. We addressed the novel question: Are pure CNTs produced for distribution to manufacturers “toxic” to plants through their effects on physiological processes? We germinated and grew Arabidopsis thaliana seedlings on basal salt medium in Petri plates with or without pure CNTs and polyhydroxy fullerenes [C60(OH)24] at a concentration of 25 µg/mL. We measured physiological parameters after 7, 15, and 26 days of growth. Biomass was determined and also effects of an aged CNTs on chlorophyll fluorescence. We found that photosynthesis, stomatal conducatance or transpiration in Arabidopsis thaliana grown in CNTs was significantly reduced compared to controls and positive controls. Carbon gain was reduced by 15% in plants grown in CNTs versus control plants. The carbon dioxide compensation point was significantly higher in CNT grown plants than control plants. Dry weight was not significantly affected in CNTs or control plants and the dry weight of plants grown in aged CNTs were significantly lower than control plants. A significant reduction in chlorophyll fluorescence ( 11% reduction) between plants grown in aged CNTs versus control media. The pure CNTs we examined appear to not be “toxic” to plants at the whole plant level.