Effect seed priming ion seedling vigour index in seed aged milk thistle (Silybum marianum)

In order to investigate the changes in activity of antioxidant enzymes seedlings milk thistle during aging and the role pretreatment of this enzyme, factorial experiment in a completely randomized design carried was in Ardabil University Mohaghegh in 2013. The treatments consisted of pretreatment with potassium nitrate at concentrations of 0, 15 , 30 , 45 and 60 mg L and agine to time 0 , 48 , 96 and 144 hours. Results showed were in during aging antioxidant activity enzymes decreased and pretreatment enhances the enzymatic activity. Among the different concentrations of potassium nitrate, the use of 30 mg L most traits showed the highest value. Results of regression equations to predict the length and weight of power indices showed, between the activity of antioxidant enzymes, glutathione peroxidase and peroxidase activity, the highest proportion in excess of the projected length vigour index and peroxidase and glutathione reductase activity also the greatest share of in predicting weight vigour index showed. The results of path analysis showed peroxidase activity has a direct effect and superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase has more direct impact on the length vigour index and superoxide dismutase, ascorbate peroxidase, glutathione reductase had a direct impact on the weight vigour index. In general, the roles of antioxidant enzymes (particularly peroxidase and glutathione peroxidase and reductase) of potassium nitrate in seed vigor can be said to improve the enzymes reduce the effects of aging and increase the seed vigour.