Effects of Low Temperature and Potassium Chloride on Physiological and Biochemical Indices of Rice (Oryza sativa L.) at the Seedling Stage

Ambient temperature directly affects growth and development of rice (Oryza sativa L.), especially at the seedling stage. This study aimed to determine the effects of temperature and potassium Chloride (KCl) on certain physiological and biochemical indicators at the seedling stage of two improved rice cultivars (CR۲۰۳ and DT۱۰). Under the influence of low temperature (۱۰°C), degradation of carbohydrates in seeds was inhibited and the total organic acid content and α-amylase activity decreased, resulting in higher starch content and lower reducing sugar content in both rice cultivars, compared to treatment at the optimal temperature (۲۸°C). For seeds treated with KCl, the α-amylase activity and total organic acid content of the two rice cultivars increased; therefore, the reducing sugar content increased while the starch content decreased. The peroxidase and catalase activities of CR۲۰۳ decreased under a low-temperature treatment, while those of DT۱۰ increased under the same conditions. Meanwhile, treating seeds with KCl increased the peroxidase and catalase activities of both rice cultivars; however, the peroxidase activity of DT۱۰ increased slightly. The results also suggest that low temperature inhibits the physiological activities of CR۲۰۳ and DT۱۰ at the seedling stage, while treatment of seeds with KCl increases the physiological activities of both rice cultivars. These results suggest that treating seeds with KCl contributed to improve the tolerance to low temperature stress of the CR۲۰۳ and DT۱۰ rice cultivars at the seedling stage. In general, treatment of rice seeds with KCl could be recommended to increase cold tolerance at the seedling stage.

Keywords:

Catalase , cv. CR۲۰۳ , cv. DT۱۰ , Seed treatment.