effects of tio2 nanoparticles and water-deficit stress on morpho-physiological characteristics of dragonhead (dracocephalum moldavica l.) plants

Water-deficit stress is the most important environmental factors limiting plant growth, and production. Nano-titanium dioxide (nano anataseTiO₂) can have various profound effects on the crop physiological, biochemical and morphological characteristics. In the present research, the influences of different concentrations ofTiO₂ nanoparticles (NPs) (0, 10 and 40 ppm) and water-deficit stress on Dragonhead (Dracocephalum moldavica L.) were investigated in a factorial experiment based on randomized complete block design with three replications. Results showed that under normal irrigation, foliar application of 10 ppm TiO₂ NPs increased plant shoot dry mass and essential oils content. Under water-deficit stress condition, plants treated with 10 ppm TiO₂ NPs had more proline and much less H₂O₂ and malondialdehyde content as compared to untreated plants. Therefore, it can be concluded that proper concentration of TiO₂ NPs probably can be used as an exogenous stimuli for improvement of shoot growth and essential oil content in plants. Furthermore, water-deficit stress-induced damages such as oxidative stress and membrane damage can be ameliorated by foliar application of TiO₂ NPs at appropriate concentrations.