عنوان مقاله [English]
Chamomile (Matricaria recutita) is a highly valuable medicinal and aromatic plant of Asteraceae family and its anthodia used frequently in pharmaceutical and cosmetic industries. The aim of this study was the evaluation the effect of drought stress induced by Polyethylene Glycol 6000 (PEG) on germination percentage, germination rate, plumule and radicle length of four improved cultivars of German chamomile. The experiment in completely randomized design with two factors in three replications was conducted. The first factor included 10 drought levels (0, -1, -2, -3, -4, -5, -6, -8, -10 and -12 bar that zero bar as control) and second factor included 4 improved cultivars of chamomile. Seeds of Bona (diploid), Germania (diploid), Goral (tetraploid) and Lutea (tetraploid) cultivars were prepared. According to the results, different levels of drought stress and type of cultivar had significant effect on measured characteristics (P<0.01). Results also showed that all the measured characteristics were decreased significantly. Germination percentage in -4 and -6 water potentials decreased to 48 and 16 percent and germination rate decreased to 5.7 and 1.8 and in -8, -10 and -12 bar no seeds germinated. Plumule length decreased more than radicle length in drought stress. Different cultivars of chamomile with diversity in genotype have different responses to drought stress. It seems that Lutea and Bona cultivars have the highest drought tolerance in germination stage.