Abstract The mint family contains a large number of important medicinal species whose medicinal properties are due to their high essential oil content. The yield and quality of commercially grown examples of these species can be affected by weed infestation . In light of which the presented research was conducted to eva‎luate the tolerance of mint plants to bentazone herbicide, in combination with the foliar application of ascorbic acid (AsA). A pot experiment was performed based upon a completely randomized design, with three replications of each treatment. The treatments included three levels of AsA (0, 200, and 400 mg kg-1), and four levels of bentazone (0, 2.5, 3.5 and 5 l ha-1) on two mint species (Mentha piperita and Mentha longifolia). Traits including relative water content (RWC), malondialdehyde (MDA), antioxidant enzyme activities such as catalase (CAT), ascorbate peroxidase (APX), and guiacol peroxidase (GPX), chlorophyll and carotenoid content, plant height, shoot and root fresh and dry weight, root volume, crop injury, and essential oil percentage were determined. The result obtained showed that the relative water content of the plants decreased significantly when treated with high levels of bentazone herbicide, and that the MDA content of these plants increased. However, the foliar application of ascorbic acid at 200 mg kg-1 was shown to decrease the peroxidation of membrane lipids, by increasing the activity of antioxidant enzymes and improved the reduction of photosynthetic pigments under bentazone herbicide stress. Although high doses of bentazon herbicide caused damage to the two mint species, the foliar application of ascorbic acid at a concentration of 200 mg kg-1 improved the morphological characteristics and improved the health of the herbicide treated plants. In contrast, the combined application of bentazon herbicide at a high level (5 l ha-1) with ascorbic acid at a concentration of 400 mg kg-1 caused a significant decrease in all physiological and biochemical parameters of the plants. The highest extent of damage was observed in this treatment. These data indicate that , M. longifolia is more tolerant to herbicide treatment as compared to M. piperita . The results suggest that the application of ascorbic acid at a concentration of 200 mg kg-1 can partially negate the negative effects of treatment with the bentazon herbicide (especially at low levels) in the tested species..

حسن كريم مجني

پرويز احسان زاده , محمدرضا سبزعليان دستجردي

محمدحسين اهتمام , امير مساح