Multi-walled carbon nanotubes can enhance root elongation of wheat (Triticum aestivum) plants

The potential effects of oxidized multi- walled carbon nanotubes (o-MWCNTs) with a length ranging from 50 to 630 nm on the development and physiology of wheat plants were evaluated by exam- ining their effects on seed germination, root elonga- tion, stem length, and vegetative biomass at a concentration ranging from 10 to 160 lg/mL in the plant. Results indicated that after 7 days of exposure to the o-MWCNTs medium, faster root growth and higher vegetative biomass were observed, but seed germination and stem length did not show any difference as compared with controls. Moreover, a physiological study was conducted at cellular level using a traditional physiological approach to evidence the possible alterations in morphology, the cell length of root zone, and the dehydrogenase activity of seedlings. Transmission electron microscopy images revealed that o-MWCNTs could penetrate the cell wall and enter the cytoplasm after being taken up by roots. The cell length of root zone for the seedlings germinated and grown in the o-MWCNTs (80 lg/ mL) medium increased by 1.4-fold and a significant concentration-dependent increase in the dehydroge- nase activity for the o-MWCNT-treated wheat seed- lings was detected. These findings suggest that o-MWCNTs can significantly promote cell elongation in the root system and increase the dehydrogenase activity, resulting in faster root growth and higher biomass production.