Leaf Condition of Rice ( Oryza sativa L.) in Response to Cold Stress during Ripening Stage

Cold stress can decrease yield and quality of rice. Although many studies have investigated the impact of cold stress on rice, researches on physiological changes of rice plants under low temperature during ripening stage are insufficient. Thus, the objective of this study was to analyze changes of leaf condition in rice plant during ripening stage in response to low temperature. Results showed that photosynthesis activity of flag leaf was decreased continuously after heading and that it was reduced more in cold condition. Chlorophyll content in flag leaf was also reduced in control and cold conditions after heading. In control condition, chlorophyll content showed a significant correlation with nitrogen content in leaf. However, chlorophyll content under cold condition showed a high correlation with Malondialdehyde content. These results strongly suggest that the leaf lipid peroxidation by cold stress can induce the decrease of leaf chlorophyll content and photosynthesis activity during ripening stage in rice.