Mahrokh Sharghi
Seyed Mehdi Razavi - Associate Professor Department of Biology, University of Mohaghegh Ardabili
Saeid Latifi-Navid - Assistant Professor Department of Biology, University of Mohaghegh Ardabili

It has been well documented that environmental stress such as low temperature can prevent light and dark reactions of photosynthesis in plant, this process cause formation of reactive oxygen species (ROS). ROS that may cause different damage in plant cell organelles. In this study we assay antioxidant enzymes activity changes, protein content and chlorophyll fluorescence under low temperature to find resistant and sensitive cultivars. Four cultivars of Beta vulgaris (JAM, BR1, IC, 7233) seedlings were grown in growth chamber conditions with 16h light and 25/16°C day/night temperature and 70% humidity. After six-week we put them under low temperature (2°) for two-day. Then we assay antioxidant enzymes activity changes, protein content and chlorophyll fluorescence. Our results showed that the catalase activity increased significantly only in Jam cultivar and in other cultivars it had not significant changes. Peroxidase and polyphenol oxidase activity had no significant changes in all cultivars. APX activity significantly increased in 7233 and BR1 cultivars. Total protein content increased in all cultivars and Fv/Fm ratio decreased in all cultivars. Chlorophyll content also increased in JAM and IC cultivars.

cold stress, sugar beet, antioxidant enzyme, catalase, ascorbate peroxidase