ارزیابی توان دگرآسیبی شش گیاه دارویی بر برخی ویژگیهای فیزیولو‍ژیک و بیوشیمیایی چغندرقند و دو علف هرز مهم آن

In order to study the allelopathic potential of six medicinal plants Valeriana officinalis, Rosmarinus officinalis, Artemisia absinthium, Melissa officinalis, Juglans regia, Dracocephalum kotschyi on Beta vulgaris and its two important weeds (Convolvolus arvensis and Avena fatua) and also to find a model of natural herbicides, a factorial experiment was conducted based on randomized complete block design. Shoots of B. vulgaris, C. arvensis and A. fatua were sprayed with water extracts (0 and 100 percent) of the allelopathic plants twice in 48h. Two days after spraying, the changes of dry weights, total water content, electrolyte leakage, concentrations of malondialdehyde (MDA), hydrogen peroxide, chlorophyll a, b, total chlorophyll and carotenoids were assessed in the target plants. Results of mean comparisons showed the water extracts of all studies medicinal plants had allelopathic effects on the target plants, but in different degrees. Amongst, D. kotschyi caused to make the least level of MDA (+%11.6), H2O2 (+%42), electrolyte leakage (+%8.5) and the least reduction of total chlorophyll (-%13.1) in B. vulgaris. These values were –in turn- (+%32.3, +2.6 folds, +%50 and -%48.4) in C. arvensis and (+%34.8, +3 folds, +%70.8 and -%56) in A. fatua. Generally, it is concluded that utilization of allelopathic ability of D. kotschyi would be a promising model to produce natural herbicide for sugar beet farms.