Cold stress effect on some physiological characteristics and antioxidant systems in some grass pea (Lathyrus sativus) ecotypes

In order to study the effect of cold stress on some physiological characteristics of nine ecotypes of grass pea, a factorial split plot experiment based on completely randomized design with two factors and four replications was carried out in growth chamber. The first factor was cold treatment at two levels (25 and -3˚C) and the second factor was ecotype at nine levels collected from local areas named Bam, Sirjan, Torbat Heydariyeh, Baft 1 (Kiskan area), Baft 2 (Bidgerdoyeh area), Shiraz, Kuhbanan, Rabar and Bardsir. Traits measured in this experiment included content of soluble sugars, proline, starch, chlorophyll a, b and total chlorophyll, as well as the activity of antioxidant enzymes. The results showed that in all ecotypes with decreasing temperature from 25 to -3 degrees the content of soluble sugars, proline, ion leakage and the activity of catalase and peroxidase enzymes increased whereas the content of starch and chlorophyll a, b and total decreased. Significant variation was observed between ecotypes in terms of cold stress tolerance. In Baft 2 and Bardsir ecotypes, proline content was higher than other ecotypes. Also, the highest soluble sugar content was related to Baft 2 ecotype and the highest catalase activity was related to Bardsir ecotype. In addition, these ecotypes had higher survival score. Based on the results of survival score, Baft2 and Bardsir ecotypes showed the highest resistance to cold stress and Bam, Shiraz and Sirjan ecotypes showed the lowest resistance.