Effects of Different Treatments on Improving Seed Germination Characteristics in Medicinal Species of Origanum vulgare L. and Thymus transcaspicus Klokov

Seed dormancy is a serious limiting factor in revenue of an economically important species to its fullest. Because of the importance of medicinal plants in curing diseases and the shortage of natural habitats, little reproduction rate and mass cutting of trees, it is necessary to program cultivation and naturalization of medicinal plants. The objectives of this study were to investigate the effects of different treatments on seed germination in two medicinal species (Oregano and Khorasan thyme). Both species are known to have low seed germination. An experiment was performed with 9 treatments and 4 replications in a completely randomized design in the Seed Laboratory of Agriculture Faculty, Higher Education Complex of Shirvan in 2016. The treatments applied are: (1) Three concentrations of gibberellic acid (100, 500 and 1000ppm), (2) Potassium nitrate (KNO3 (0.2%)), (3) Thiourea 1 Molar, (4) Three prechilling periods (10, 20 and 30 days at 2 °C) and (5) distilled water as control. The seeds were sown in Petridishes for 15 days. Results of the analysis indicated that the effect of various treatments on the percentages of Thymus transcaspicus Klokov and Origanum vulgare L. seeds germination were highly significant (p<0.01). Treatments of 100 ppm gibberellic acid and cold (10 and 20 days) have the highest effect on seeds germination percentage of T. transcaspicus and KNO3 and cold (10 and 20 days) on O. vulgare seeds. The highest and lowest vigor indices in T. transcaspicus were seen under treatment of 100 ppm gibberellic acid (16.2) and KNO3 (2.4), and were also seen in O. vulgare under treatment of 1 M thiourea (10.9) and cold for 20 days (1.37).