Effects of TiO2 NPs on alleviation of drought negative effects in wild pear seedlings

The present Research used TiO2 NPs for alleviating the negative effects of drought stress in wild pear seedlings. Different concentrations of TiO2 NPs including 20, 40, 80 and 100 ppm were sprayed on the aerial compartments of seedling immediately after the last irrigation. Our experiment design was a completely randomized design with 6 repeats for each treatment. Biomass allocation, growth, physiological-biochemical parameters and microscopic analysis were surveyed as index. Repeated measure ANOVA and surveying of trend showed that photosynthesis performance was less affected by drought. ANOVA results showed that there were significant differences (at 5% level) between the treatments in aspect of stem and root biomass, height growth and root length parameters. On the other hand, sprayed seedlings by nanoparticles had the better biomass allocation compared to non-sprayed seedlings when subjected to drought stress. In contrast with control, xylem water potential has declined more than three times while TiO2 NPs improved the xylem water potential. The spraying of nanoparticles on seedlings improved the relative water content (RWC) till 100% in comparison to the drought stressed plants. A considerable increasing was observed for electrolyte leakage in stressed seedlings. Although proline content is increased in stressed leaf (around 20%) but TiO2 NPs could not increase the parameters. All the treatments increased peroxidase enzyme in leaves but the higher value was for TiO2 NPs 100 ppm. The higher content of catalase enzyme was recorded for drought treatments.