Abstract:

The aim was to investigate the effect of the high temperature on the light utilization efficiency of photosystemⅡ of cucumber fruit. The effects of high temperature stress on the chlorophyll fluorescence parameters of cucumber fruit were measured by MINI-IMAGING-PAM. The results showed that the initial fluorescence (Fo) and quantum yield of unregulated energy dissipation Y(NO) of cucumber fruit were raised with the temperature. In contrary, the maximal fluorescence (Fm), maximal photochemical (Fv/Fm), effective quantum yield Y(Ⅱ) and quantum yield of regulated energy dissipation Y (NPQ) of PSⅡ were reduced. The photosynthetic apparatus were protected by the increased quantum yield of regulated energy dissipation and keeping the higher efficiency of reaction centers when the temperature was under 46℃. With the temperature rising again, the excessive light was dissipated by the regulated energy dissipation apparatus of fruit, and destroyed the photosynthetic apparatus.