Creating optimal conditions for germination of medicinal plants seed is essential for their cultivation. Therefore, to evaluate the effect of different treatments on seed germination of two medicinal species, Descurainia sophia and Plantago ovata collected in 2009 from Tehran Province, an experiment with a factorial randomized complete block design in 6 treatments with 4 replications was conducted. Treatments included KNO3 with concentrations of 0.1, 0.2 and 0.3%, acetylsalicylic acid with levels of 50 and 100 mg/l, prechilling (4°C for 10 days), thiourea with levels of 0.1 and 0.2%, boiling water for 5 and 10 min. To compare, distilled water was used as control. Results showed that the effect of different treatments on germination percentage of two medicinal species was significantly different (p < 0.05). It was shown that prechilling was the most effective treatment on seed germination of both species.Key words: Descurainia sophia, Plantago ovata, germination, acetylsalicylic acid, prechilling, thiourea and KNO3
