Journal of Photosciences

Different Susceptibilities to Low Temperature Photoinhibition in the Photosynthetic Apparatus Among three Cultivars of Cucumber (Cucumis sativus L.)

Volume 8(2001), 105-112 page

ÀúÀÚ: Kwang-Hoon OH, Woo Sung Lee and Choon-Hwan Lee

   8-3-105.pdf (134.0K)

Keywords: chilling  chlorophyll fluorescence  cucumber cultivars  photoinhibition  photosynthesis


Susceptibility to low temperature photoinhibition in photosynthetic apparatus was compared among three cucumber cultivars, Gahachungjang (GH), Banbaekjijeo (BB) and Gaeryangsymji (GR).
By chilling in the light for 6 h, a sustained decrease in the potential quantum yield (Fv/Fm) and the oxidizable P700 contents was observed, and the decrease was less in GH than in BB and GR.
Although the difference was small, some FPSII remained in GH after light-chilling for 6 h indicating that a few electrons can flow around photosystem II (PSII).
As a consequence, the primary electron acceptor of PSII, QA, was reduced slowly and was not fully reduced after lightchilling for 6 h in GH.
Although the amplitude was small, the development of NPQ was also faster in GH, indicating a higher capacity for non-photochemical energy dissipation.
The relative fraction of a fast relaxing component of NPQ (qf) was higher in GH.
After light-chilling for 5 h, the values of qf in BB and GR became much smaller than that in GH, indicating BB and GR suffered more significant uncoupling of ATPase and/or irreversible damages in PSII.
When fluorescence induction transients were recorded after chilling, significant differences in quenching coefficients (qQ and qN) were observed among the three cultivars.