effects of some environment factors on wild lettuce (lactuca serriola) germination

abstract wild lettuce (lactuca serriola) is an annual weed with seed reproduction. an experiment was conducted to evaluate some environmental effects on germination and emergence of this weed. the type of design was completely randomized with four replications in which factors were arranged as factorial. the experiment was carried out with 11 cm petri dishes in a germinator (10 °c) and without light. treatments were ph= 4 to 10, drought strought stress in polyethylene glycol-6000(peg) solutions (0 to -0.9) and salinity stress in 7 nacl solutions (0 to 300 mm). analysis of variances showed that the effect of ph was not significant on seed germination. but it was significant on mean germination time (mgt), hypocotyle and radicle length. in drought stress treatments, germination percent decreased from 0.55 mpa and was 0 percent in 0.9 mpa. similar effects were observed about hypocotyle and radicle length. effect of this treatment on mgt was significant and by increasing in drought stress, mgt increased at first and then decreased. in salinity stress germination was reduced linearly from 50 mm and reached to 0 percent in 200 mm. reduction of radicle length by increasing nacl solution followed a second grade function. in contrast hypocotyle length reduced as a linear function.