COMPARISON OF THE ALLOCATION OF ABSORBED LIGHT ENERGY IN LEAVES BETWEEN TWO DIFFERENT ECOTYPES OF PHYSIC NUT (JATROPHA CURCAS L.) UNDER HIGH TEMPERATURE

The changes in utilization and allocation of absorbed light energy in two ecotypes of Jatropha curcas originally growing in Hainan Province and Guizhou Province were examined under high temperature. Exposure to high temperature caused a decrease in maximum quantum efficiency of photosystem Ⅱ photochemistry (Fv/Fm) and an increase in primary fluorescence (Fo) of both two ecotypes of J. curcas, suggesting that photosystem Ⅱ function was inhibited partially by high temperature stress. In comparison with Guizhou ecotype, Hainan ecotype showed more increasing heat dissipation fraction of excess excitation energy and maintained higher light energy conversion efficiency under moderate high temperature (30-40℃). At 45℃, the mechanism of heat dissipation was being destroyed; Hainan ecotype still allocated 7% absorbed light to photochemical reaction, while that in Guizhou ecotype was completely loss (0%). The present result suggested that J. curcas from Hainan Province has greater tolerance responding to short term high temperature exposure than that from Guizhou Province.