The effect of drought stress on the morphological characteristics, yield and composition of essential oils of three thyme species

The aims of this research is to evaluate the effect of drought stress on the characteristics of three species of Thymus thyme. T. daenensis,, T. transcaucasicus and T. lancifolius was carried out at Pardisan Agricultural Research Station of Qom under greenhouse conditions. The experiment was conducted in the completely randomized design (CRD) and as a factorial with five replications (pots). The first factor included the seeds of three types of thyme and the second factor included irrigation treatments at 80 (normal irrigation), 60 and 40 percent of soil moisture capacity. The results of variance analysis of the data showed that the application of drought stress had a significant effect on all morphological traits, yield and essential oil composition. The highest amount of essential oil with the amount of 1.1% and the highest yield of essential oil with the amount of 0.9 grams per plant was in the irrigation treatment at 60% of the crop capacity. The species T. lancifolius with the value of 0.73 g had the highest and the species T. transcaucasicus with the value of 0.54 g per plant had the lowest yield of essential oil. The highest composition in T. daenensis species was thymol (normal irrigation) and geraniol (irrigation at 60% of crop capacity). The most compound in T. transcaucasicus species included thymol (in normal irrigation and 60% of crop capacity). The most compound in T. lancifolius species also included thymol (in normal irrigation and at 40% of crop capacity).