低温光抑制后PSII活性的快速恢复不利于PSI活性的恢复

In order to investigated the effects of different light intensities (0, 15, 200 μmol m-2 s-1) with or without DCMU on recovery process of cucumber (Cucumis sativus L.) leaves after treatment with low temperature (6℃) combined with moderate light intensity (200 μmol m-2 s-1) for 6 h, chlorophyll a fluorescence transient and light absorbance at 820 nm as well as analyzing chlorophyll quenching were analyzed,. Both the Fv/Fm and the ΔI/Io decreased after chilling treatment under 200 μmol m-2 s-1 light. After the leaves were transferred to 25℃, Fv/Fm recovered immediately under both 200 and 15 μmol m-2 s-1 light. ΔI/Io recovered immediately under 15 μmol m-2 s-1 light, but the recovering rate of ΔI/Io was slower than that of Fv/Fm. The recovery of ΔI/Io was severely restrained by 200 μmol m-2 s-1 light, while a pretreatment with DCMU effectively alleviated this restraining. The results indicate that recrease of electron transport from PSII to PSI protected PSI from further photoinhibition, quicken up the recovery of PSI. Under a given light, faster recovery of PSII compare to PSI was badly for the recovery of PSI or even to the whole photosystem