Effect of Titanium Dioxide Nanoparticles on Essential Oil Quantity and Quality in Thymus vulgaris under Water Deficit

The aim of this study was to evaluate effect of foliar application of titanium dioxide nanoparticles on quantitative traits and essential oil, thymol and carvacrol percent of thyme under different levels of water stress. Factorial experiment was used based on a completely randomized design with four replications. Factors included water stress (50, 70 and 90% of field capacity) and titanium dioxide nanoparticles (0, 1 and 3 mg/l). Plant height, number of branches, fresh and dry weight of shoot, fresh and dry weight of root and also essential oils (thymol and carvacrol) content were measured using standard compounds by GC-Mass. Results showed that the water deficit affects significantly (P 0.01) on all studied traits. The greatest amount of essence (0.42% per dry matter), thymol (82.302%) and carvacrol (12.33%) at 70% field capacity and the lowest essence (0.30% per dry matter), thymol (77.53%) and carvacrol (11.62%) approached with 50% of field capacity. Analysis of variance showed significant effect (P 0.05) of titanium dioxide concentration on plant height and shoot fresh and dry weights and root dry weight (P 0.01). It was concluded that use of titanium dioxide nanoparticles as spraying under water deficit stress has incremental effect on plant growth characteristics of thyme but had no effect on essential oil components.