Response of Achillea species to drought stress induce by polyethylene glycol in germination stage

Achillea (Yarrow) is one of the most important genera of the Asteraceae family and different species grow wild in different parts of Iran. These species have ornamental and medicinal potential for use in drought area. The aim of this study was evaluating the effect of drought stress induce by Poly Ethylene Glycol 6000 (PEG) on germination percentage and rate of Achillea species. An experiment in randomized complete block design (RCBD) with two factors in three replications was conducted. The first factor included 5 drought level (0, -5, -7, -9 and -20 bar that zero bar as control) and second factor included 6 species of Achillea (A. eriophora, A. millefolium, A. filipendula, A. nobilis, A. wilhelmsii and A. biebersteinii). The seed were collected from Shiraz, Mashhad and Karaj area. According to the results of statistical analysis, different levels of drought stress and type of species had significant effect (p<0.01) on measured characteristics (germination percentage, germination rate and radicle length). In this species radicle length affected by drought stress less than other traits and germination percentage was the best trait for drought stress evaluation. Finally, A. millefolium and A. eriophora have the highest drought tolerance and the lowest drought tolerance belongs to A. biebesteinii and A. nobilis. The A. wilhelmsii and A. filipendula have relative drought tolerance in germination stage.