effects of drought stress induced by polyethylene glycol on germination and morphophysiological characteristics of dill (anethum graveolens l.)

abstract in order to study the effect of different water potential on anethum graveolens two experiments were conducted for germination and vegetative stages. this study was carried out as a factorial experiment based on completely randomized design with three replications. in the first experiment, response of dill seeds germination to levels of drought stress including to drought potentials zero(control), -1.5, -2, -2.5 and -3 bar that were obtained by polyethylene glycol 6000 were investigated. in the second experiment, similar to first, influence of drought stress on dill morphophysiological parameters were investigated. the results showed that effect of drought stress on germination characteristics including to germination percentage, germination rate, radicle and plumule length , radicle and plumule dry weight , plumule to radicle dry weight ratio was significant (p≤ 0.01). mean camparison of treatments showed that with increasing drought stress, all parameters decreased. effect of drought stress on amount of proline and soluble carbohydrates in shoot and root was significant (p≤ 0.01). mean camparison of treatments showed that with increasing stress, amount of proline and soluble carbohydrates in shoot and root, shoot to root proline and soluble carbohydrates ratio increased. shoot to root proline and soluble carbohydrates ratio were not influenced by drought stress (p≤0.05).