Effect of titanium dioxide spraying on physiological characteristics of sage (Salvia officinalis L.) under water stress

The Salvia is a large genus with about 58 species from Lamiaceae family in Iran. It has been well-known in pharmacopeia that has been used with special attention in the ancient era. The Essential oils, terpenoids, derivatives of phenolics acids and flavonoids are the main secondary metabolite constituents in Salvia species. The Pharmaceutical properties of the Salvia plants are mainly due to antioxidant activities of their secondary metabolites. It has various applications in Pharmaceutical, foods, hygienic-cosmetics and perfume industries as well as utilized in beverages as flavor.
The species of Salvia officinalis is a perennial medicinal herb from Lamiaceae family. The origin of salvia species has been reported in the northern Mediterranean and North Africa zones. The most important constituents of the essential oil are included: Tujan (30-50%), Cineol (10-15%), Camphor (6-10%) and Borneol (6 to 14%). Recently, it has been reported that the essential oil of the S. officinalis, especially some of its compounds, including Cineol, Tujan, Camphor, have an antimicrobial, antioxidant and anti-cancer properties. Drought is the most harmful factor of crops and medicinal plants production in the arid and semi-arid eras which has a negative impact on all aspects of plant growth and production. Also, in the plants exposed to severe soil dry the photosynthetic apparatus activities were damaged or impaired, leading to a decrease of photosynthetic capacity and lipid oxidation is increased in these conditions. Therefore, the use of mechanisms that lead to losses of this tension can be useful. One way to deal with the devastating effects of drought is the use of up to date and modern technologies such as Nano science.Nano-titanium dioxide has beneficial effects on the growth, physiological processes and activities of the plant metabolism.This study was to evaluate the effect of titanium dioxide spray on some physiological characteristics and activities of antioxidant enzymes sage was conducted under drought stress. This study was conducted in 2017 at the Faculty of Agriculture, University of Zabol a factorial in a completely randomized design with three replications. The experimental treatments was included drought stress (irrigated in Field capacity, depletion of soil water content up to 50% and 75% of FC condition) and foliar Nano Titanium dioxide spray (Control, 50 and 100 mg.l-1). Physiological traits (Chlorophyll a, b and T. chlorophyll, Total phenol, Proline) and activities of antioxidant enzymes (Peroxidase (POD), Ascorbate peroxidase (APX), Guaiacol peroxidase (GPX), Superoxide dismutase (SOD) and Catalase (CAT) were estimated in this experiment. Based on the results, increasing of stress severity reduced some traits, So that the soil’s water content lose to the 75% of the field capacity led to decrease in dry matter, Chlorophyll a, b and T.Chlorophyll of the plant’s leaf. However, total phenolic content, Proline concentration, the Peroxidase (POD), Ascorbate peroxidase (APX), Guaiacol peroxidase (GPX), Superoxide dismutase (SOD) and Catalase (CAT) activities were increased. Also, the results of simple effects of foliar application levels showed that by increasing the concentration of foliar application, the traits were increased, so that The highest Chlorophyll a and relative water content of leaf was obtained in plants treated with 100 mg.l-1 TiO2 and on the other hand, the results of reciprocal effects showed The highest phenolic content, Proline concentration, and the activities of POD, APX, GPX, SOD and CAT were obtained in plants subtended in depletion of soil water content up to 75% of FC and sprayed with 100 and mg.l-1 TiO2. According to the results it could be stated that due to the small size of TiO2 particles and easier penetration into the leaf it can affects growth and photosynthetic properties of sage and by reduced the lipid peroxidation, through increasing the antioxidant defense system activities and the content of osmotic regulators (Proline) of the plant and consequently, leads to cells’ structures stability against water stress.