Salicylic Acid and Fulvic Acid foliar application influence the Growth, Some Physiological re-sponses and Essential Oil Content of Thymus vulgaris L.

This study aimed to investigate the effect of salicylic acid and fulvic acid foli-ar use on some growth responses and essential oil content of thyme.

A factorial experiment as completely randomized design with three replications was conducted. The first and second factors included: fulvic acid (0,1,1.5,2 mg/l) and salicylic acid (0,10,50,100 µM). After spray-ing and harvesting, the following factors were evaluated; fresh and dry weight, photosynthetic pigments, flavonoids, total antioxidants activity, and essential oil content of the aerial parts.

Foliar treatments significantly influenced plant height, fresh and dry weight biomass as well as chlorophyll b content. Also, salicylic acid had a significant effect on yield traits such as fresh weight, total antioxidant activity, flavonoids and essential oil content. The interactions of salicylic acid and fulvic acid on fresh and dry weight also showed a significant effect. The highest total antioxidants activity and flavo-noids were obtained at 100 µM salicylic acid. The highest essential oil content was obtained at of 50 µM salicylic acid.

In order to produce the highest yield of the plant, the application of 50 μM concentrations of salicylic acid and fulvic acid with a concentration of 1.5 mg/l seems appropriate. Also, to achieve the highest essential oil content of shoots and leaves, a concentration of 50 μM salicylic acid is recommend-ed.