초록
The electron transport activities of choloroplasts isolated from hte detached rise (Oryza sativa L. cv. Chucheong) leave stored under low temperature(4$^{\circ}C$) with light illumination were investigated to understand the role of light in the low temperature inhibition of photosynthesis in the chilling-sensitive plants. Chlorophyll content of the detached leaves upon incubation at 28$^{\circ}C$ and 4$^{\circ}C$ in the dark was also measured. The rice seedlings were grown with Hoagland medium in the growth chamber of 28$^{\circ}C$ temperature and 400 ft.c fluorescent light with the photoperiod of 16 h. Although chlorophyll content of the detached leaves stored in the dark declined by 61.7% after 28$^{\circ}C$ treatement, there occurred only 5.2% decrease of chlorophyll with 4$^{\circ}C$ treatment. Low temperature treatment(4$^{\circ}C$) for 6 days brought about decreases in total photosystem(PS II＋PS I) activities by 35.2% and 73.6% in te presence and absence of light, respectively, while after 28$^{\circ}C$ treatment of the detached leaves for 6 days in the dark there was only 27.6% decrease in PS II＋PS I activity. PS II activities were also decreased by 35.6% and 72.2% in the light and dark, respectively. PS I activities were decreased slightly, however, by 7.6% and 16.2% in the light and dark, respectively. Investigations into DPClongrightarrowDCPIP and NH2OHlongrightarrowDCPIP activities revealed that low temperature inhibition of PS II activities was not due to the inactivation of the water oxidation capacity at low temperature. It was concluded that light protects the electron transport activities of isolated rice chloroplasts from the inhibitory effect of low temperature in the detached leaves.