Effect of drought and salinity stresses on germination and seedling growth of (Dracocephalum moldavica L.) under pre-treatment of salicylic acid

This experiment was conducted to study the effect of seed pretreatment by salicylic acid under drought and salinity stress conditions on germination and growth characteristics of Badrashbo seedlings in 1400 at Islamic Azad University, Khorramabad branch. This study was conducted as two separate experiments with common pretreatment of salicylic acid and separate treatments of drought and salinity stress. Both experiments were conducted as a factorial in a completely randomized design with three replications. The treatments of the first experiment included salicylic acid at 3 levels (0, 0.1 and 0.5 mM) and drought at 4 levels (0, -0.1, -0.3 and -0.5 MPa). The treatments of the second experiment included salicylic acid at 3 levels (0, 0.1 and 0.5 mM) and salinity at 4 levels (0, -0.2, -0.4 and -0.8 MPa). At the end of 12 days of counting, germination and growth characteristics of seedlings were evaluated. The results showed that in both experiments, the effects of the factors on the characteristics of percentage and speed of germination, length of root and shoot, and seed germ were significant. Among the levels of salicylic acid, pretreatment with 0.5 mM concentration had the highest percentage and germination rate, root length, shoot length and seed germ. In the non-drought treatment, pre-treatment with salicylic acid did not lead to a significant increase in the examined traits compared to no pre-treatment, and in the drought stress treatment, the pre-treatment caused a significant increase in all the examined traits. Also, among the levels of salicylic acid, pretreatment with a concentration of 0.5 mM produced the highest percentage and germination rate. In the absence of salinity and drought stress, salicylic acid with a concentration of 0.1 mM had the longest root and shoot length, and the increase in salinity and drought caused the increase in the concentration of salicylic acid to have a negative effect on root length. In general, the results showed that pretreatment of seeds with salicylic acid in areas prone to drought and salt stress can accelerate the germination of fennel seeds and lead to an increase in the percentage of seed germination .