effects of chemical seed priming on germination and antioxidant enzymes activity of two cucumber (cucumis sativus l.) cultivars

Seed priming is one of the most important measures in propagation of plants by seed, which leads to increase of percentage and rate of germination. this study was conducted as a factorial arrangement in a completely randomised design on two farm cucumber cultivars (‘impress’ and ‘emperor’). priming treatments were silicic acid (sa) and ascorbic acid (asa) at three levels of 50, 100 and 150 mg l-1, pyridoxine at three levels of 0.02%, 0.04% and 0.06% and compound treatment (sa 75 mg l-1 + asa 75 mg l-1 + pyridoxine 0.03%). there was a positive and significant correlation between the catalase (cat) enzyme activity in the radicle and plumule and polyphenol oxidase (ppo) in the radicle and germination rate and percentage. in the ‘impress’ cultivar, the highest cat activity in the radical and plumule was observed after using of 150 mg l-1 asa. the highest activity of polyphenol oxidase (ppo) in the radical was detected after using of 0.04% pyridoxine. in the ‘emperor’ cultivar, the highest cat enzyme activity was detected in the radical and plumule, respectively by using of 75 mg l-1 asa, 75 mg l-1 sa, and 0.03% pyridoxine. asa (50 mg l-1) induced the highest activity of ppo enzyme in the radicle. finally, to increase the antioxidant enzyme activity in cucumbers against unfavourable environmental conditions, our results confirmed the effectiveness of 150 mg l-1 asa and 0.04% pyridoxine for the ‘impress’ cultivar and the compound treatment and 50 mg l-1 asa for the ‘emparator’ cultivar.