Effects of drought stresses induced by polyethylene glycol (PEG) on germination of Mongolian pine (Pinus sylvestris

Environmental stress, especially drought stress, can play an important role in the reduction of the plant growth stage, specifically duringgermination in arid and semi arid regions in Iran.. In order to study the effects of drought stress on germination indices in wheat cultivars, an experiment was conducted in factorial form, using a completely randomized design of four replications. In this experiment, seven wheat cultivars (azar,omid,dorom,tabaci ,keraceharvand,arvand, Gv 3-20) were evaluated in six levels of drought treatment(distilled water,-3,-6,-9,-12,-15 bar).Results indicated significant differences among cultivars, and drought stress levels. In all traits, a significant decrease was observed with increase in stress level. It seems that the length of stem among the other traits has more sensitivity to drought stress. Drought stress reduces the radical length at more than -6 bars. keraceharvand variety has the longest length of root with 63.58 mm. Azar had the longest length of plumule. The highest germination percentage belonged to Gv 3-20 (78%). The lowest germination percentage belonged to Arvand with (36%).The percentage of germination and the velocity of germination lessened when drought stress exceeded more than -12bars. Gv 320,tabaci had the highest velocity of germination. The highest coefficient of velocity of germination belonged to tabaci. Traits in tolerant cultivars did not show a significant decline up to -3 bars. The most tolerant cultivar was Gv-3-20,tabaci. Considering all germination indices, Arvand was the susceptible cultivar. Keywords—Wheat, water stress, germination indices.