Abstract

Thymus plant is well known as medicinal plants because of their biological and pharmacological properties. In recent years, some effects of nano-silver solution on some of the plants have been studied. This study investigated the effect of different levels of nano-silver on some of the plant growth profiles and essential oil ofThymus kotschyanus. The study was carried out in a randomized block design with 15 replications in six levels of nano-silver ion (0, 20, 40, 60, 80, and 100 ppm). Different parameters such as survival rate, plant height, diameter of canopy area, days to flowering, yield, the amount and compositions of essential oil were determined. Moderate levels of nano-silver (20, 40, 60 ppm) had the highest positive impact on survival rate, diameter of canopy area, days to flowering, yield and essential oil amount; however 100 ppm had the minimal positive impact on them. One of the interesting results in this study was the increase in one of the compositions of essential oil, α-terpinyl acetate (14.2%) in 60 ppm level of nano-silver, however in 100 ppm treatment there was a significant reduction of thymol in comparison with other treatments. In conclusion, nano-silver can be used to change the stages of plant growth and the amount of secondary metabolites; however, the effect of nano-silver on plants needs more researches. These particles can be harmful to the environment if an exceedingly high amount is used.

Key words: Nano-silver, Thymus kotschyanus, survival rate, plant height, diameter of canopy area, days to flowering, essential oil.