effect of drought and salinity tensions on germination and seedling growth of common yarrow (achillea millefolium l.) in laboratory conditions

a major problem of arid and semi-arid regions is environmental stresses like salinity and drought. to study the effect of artichoke germination under different levels of salinity and drought, two separate experiments were performed. the experimental treatments included different salinity levels of nacl (0, 50, 100, 150 mm) and five drought levels by peg (0, 10%, 15%, 20% and 25%) with three replications that used based on completely randomized design. results showed that drought and salinity stresses reduced significantly germination rate, germination percent, and shoot length. in both conditions, there was insignificant difference between treatments for dry weight of root and shoot. there was insignificant difference between treatments for root length in salinity condition, but in drought condition, there was significant difference for this trait. moisture range optimum for germination was determined from non-stress to 20% peg concentration (in this study). it seemed that among traits, shoot length was more sensitive than others to salinity and drought stresses. it was observed that common yarrow fairly tolerated salinity better than drought conditions. it can be concluded that common yarrow can tolerate salinity up to 150 mm, but in drought conditions it cannot germinate in 25% peg.