Short Communication: Effects of drought stress on germination characteristics of purslane)Portulaca oleracea L.)

In order to study the effect of different drought levels on germination of purslane)Portulaca oleracea L.) seeds, an experiment was conducted under eight negative water potentials (0, -0,25, -0,5, -0,75, -0,1, -1,25, -1,5 and -17,5 MPa) using a completely randomized design with five replications. Increasing water potential significantly decreased percentage and rate of germination, length and dry weight of radicle and plumule, ratio of root to shoot length and seedling vigor index and increased the mean germination time. But these changes occurred after a threshold, e.g. negative potential more than -0.75 MPa negatively affected germination percentage and ratio of root to shoot length. In addition rate of germination and average germination duration decreased after in potentials more than -0.5 MPa. Ratio of root to shoot length was not significant different up to -1.25 MPa, and then significantly decreased. As a result, purslane germination can be extremely tolerable to drought conditions so it seems that this plant can be established in arid and semi-arid regions.