CHANGES IN PHOTOSYNTHETIC PIGMENTS, ANTHOCYANIN CONTENT AND ANTIOXIDANT ENZYME ACTIVITIES OF MAIZE (Zea mays L.) SEEDLINGS UNDER HIGH TEMPERATURE STRESS CONDITIONS

Abstract

This study was performed in order to determine the effects of gradually increasing temperatures on maize, which belongs to the C4 plant group. 20 day old seedlings were exposed to increasing heat stress (25/20, 30/25, 35/30, 40/35, 45/40°C at 16/8 photoperiods) for 5 days. The first temperature treatment (25/20°C) was used as control. Stress injury was measured in terms of malondialdehyde (MDA), hydrogen peroxide (H2O2), chlorophyll (a and b), carotenoid and anthocyanin contents and maximum quantum efficiency of photosystem II (Fv/Fm). MDA and H2O2 levels were found to significantly increase at high temperatures (35, 40, 45°C). Chlorophyll content was observed to be highest at 35°C and a decrease was determined at 40 and 45°C. Fv/Fm was found to decrease at 40 and 45°C. Carotenoid and anthocyanin contents dramatically increased under high temperature stress. In addition, significant increases were determined in the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) under high temperature (45°C), while peroxidase (POX) and glutathione S-transferase (GST) activities showed no change. Treatments above 35°C triggered high temperature stress in maize seedlings. The results of this study showed that temperatures above 35°C lead to stress effects on photosynthesis and induced enzymatic and non-enzymatic antioxidant activity in maize seedlings.

Keywords

• mısır
• antioksidan enzimlar
• antosiyanin
• sıcaklık stresi
• maize
• antioxidant enzymes
• heat stress
• anthocyanin