Allelopathic Effect of Two Cynanchum acutum L. Populations on Emergence and Shoot Development of Barley

Experimental study is carried out in order to assess the potential allelopathic effect of leaf, stalk and root of two Cynanchum acutum L. populations (Karaj and Kerman) on germination percentage, radicle and shoot length of barley (Hordeum vulgare L.). Polyethylene glycol solvable (PEG) is utilized to distinguish the osmotic and allelopathic effects of distillate extracted from C. acutum. Result showed the watery distillate of before mentioned organs in two populations had allelopathic effects on germination trait and crops development; so that by increasing the concentration rate of distillate, the germination percentage, radicle and shoot length of aforementioned crop decreased. Kerman?s population showed rather osmotic potential compared to Karaj ones. H. vulgare germination traits respectively presented the highest sensitivity to distillate extracted from C. acutum. The watery distillate extracted from leaf and root had a drastic allelopathic effect compared to those that released from C. acutum stalks, which was dedicated the lowest allelopathic effect. Different PEG concentrations had no significant effect on germination trait. Thus, the whole inhibitor effects observed in distillates is pertained to their available allelo-chemical substance.