COLD STRESS RESISTANCE AND THE ANTIOXIDANT ENZYME SYSTEM IN PISUM SATIVUM

Pea (Pisum sativum) is one of the major commercial forage all over the world, but its yield is restricted by cold stress due to cold sensitivity. In this study, the response of 31 pea genotypes with different cold resistance was tested under cold stress. Pea plants were cultivated from seeds in a temperature-controlled greenhouse (25/15°C) for 10 days prior to experiments. Cold-resistant and cold-sensitive lines and cultivars were selected using values of different thermal analysis. In addition, alterations in the activity of antioxidant enzymes (ascorbate peroxidase, catalase and superoxide dismutase), free proline content and their relation to LT50 with cold resistance were investigated, and three breeding lines were selected at cold acclimation and non-acclimationconditions. Proline content gradually increased at cold acclimation compared to those leaves at non-acclimated. Cold acclimation improved the activities of APX, SOD and CAT. The highest correlation between enzyme activities and cold resistance was observed in the case of SOD, APX and CAT of 19 breeding lines’ leaves. Our results indicated LT50 as closely related to proline content and antioxidant enzyme activities at cold acclimation.