Abstract: Selenium (Se) is an essential element for antioxidation reactions in human and animals. Inorder to study its biological role in higher plants, two cultivars (‘Zhongjiao 7’and ‘Naishijiao’) of pepper(Capsicum frutescens L. ) were cultivated in pot filling peat and vermiculite with Se concentration of 0, 0.3,
0.6, 0.9 and 1.2 mg·kg^{- 1}. When the flower buds appeared, the plants were transferred into climatic room and exposed to high temperature stress by three steps ( 25℃ 2 h→35℃ 2 h→40℃ 2 h). Then the leaves were harvested for measurement of chlorophyll and malondialdehyde (MDA) contents and activities of four antioxidant enzymes. The results showed that selenium improved the content of total chlorophyll and increased the activities of glutathione peroxidase ( GPX) and peroxidase ( POD) about 11.5 times and 63.6% , respectively, whereas decreased the activities of superoxide dismutase ( SOD) and catalase (CAT). In addition, selenium also decreased the MDA content of leaves by 36%. The general trends of the tested parameters in two cultivars of peppers no distinct difference is showed. It is suggested that selenium play an important regulative role on the activities of antioxidant enzymes under high temperature stress, thus decrease the content of MDA and improve the tolerance to high temperature stress of pepper plants.

Key words: Selenium (Se), Pepper, High temperature stress, Reactive oxygen species, Antioxidant enzymes