Studies On Light Absorption And Utilization Characteristics Of Photosystemâ…±on Surface Of Cucumber Fruit

According to the problem of yield flabby in greenhouse cucumber, the effects on photosystemⅡ(PSⅡ)light absorption and utilization of monochromatic plastic film bags, different light transmittance bags, LED lamp, temperature, pollination and water logging on the surface of cucumber fruit were studied on the different process of growth. The fresh weight of fruit and the content of chlorophyll of the surface of fruit were determined, and chlorophyll fluorescence kinetics parameters of cucumber fruit surface were measured by chlorophyll fluorescence spectrometer (MINI-IMAGING- PAM).1. Compared with blades, the initial fluorescence(F_o), maximal fluorescence(F_m), maximal photochemical (F_v/F_m), and Absorption (Abs.) were reduced at 8.81%,17.50%,2.83% and 9.97% accordingly on the surface of cucumber fruit.But quantum yield of regulated energy dissipation (Y(NPQ)) and quantum yield of uonregulated energy dissipation (Y(NO)) were higher than the blades at 46.92% and 29.12% respectively.The stick type cucumber fruit was lower than short-thick type at Abs.,but higher at light use efficiency of PSⅡ.2.The white laminating and aluminium foil had different light transmission .The fresh weigh of fruit under white laminating bags was higher than the control,while the content of chlorophyll of surface of cucumber fruit was not significant difference.Undr aluminium foil bags,the fruit weight was heavier than the control,but the content of chlorophyll was obviously reduced.The F_m and F_v/F_m of PSⅡwere droped with the reduction of the rate of light transmission obviously,and be inferior to the control significantly.The Y(NPQ) and Y(NO) raised with the light transimittance,and effective quantum yield(Y(Ⅱ)) was opposited.3.The red LED lamp was used to handle the cucumber fruit at light intensity. Abs.was increased with light intensity. When light intensity at 0,the F_v/F_m was highest,reduced with light intensity rising until the intensity rised to 1000μmol·m^-2·s^-1,and stability at 2000μmol·m^-2·s^-1.Y(Ⅱ) was highest at 500μmol·m^-2·s^-1,and stability at 2000μmol·m^-2·s^-1. 4.Three monochromatic plastic film bags with different spectra(the maximum absorption peaks in blue area was shorted BPF, or in green was shorted GBF, or red area was shorted RPF) were applied to bag the cucumber fruit, At the sixth days after bagging, the fruit weight under BPF and GPF was higher than RPF and control. F_o, F_m, F_v/F_m, Y(Ⅱ) and Y(NPQ) of PSⅡof cucumber fruit treated with BPF and GPF were higher than other treatments. In contrary, chlorophyll contents and average absorption in the range of effective radiation(400-700nm) A400-700 was significantly higher under BPF and GPF than RPF and control. The efficiency of light energy utilization(UⅡ) of fruit was highest under control, the blue and red were center, and the green was lowest.5.After high temperature treatmented,the F_v/F_m of PSⅡof cucumber fruit was droped rapidly when the temperature rised to 49℃and droped to 0.1 at 58℃. Y(Ⅱ) was susceptibler than F_v/F_m and droped when the temperature rised to 43℃.When the temperature between 43℃to 46℃,the energy was dissipated by Y(NPQ).After46℃,the Y(NPQ )reduced to zero,and Y(NO) was raised to 1.6.The F_o and F_m was undifferentiated between the pollination fruit and not,but F_v/F_m and Y(Ⅱ) was higher on the not pollination fruit ,the Y(NPQ) was higher on the pollination fruit. The cucumber fruit was short of oxygen under water logging treatment. F_o with the processing time extend, showed the trend of first decreases increases, F_m was decrease gradually with the trend fast fistly and slow after.After 24 h of submergence F_v/F_m was reduced to 0.316.The energy was dissipated by Y(NPQ) at earlier stage and Y(NO) was elevated at last stage.7.The F_v/F_m of PSⅡof cucumber fruit was stability in between 0.7 0.8 in the earlier stage of stroing at low temperature.But F_o and F_m was reducing with the time after treatment.After 144 h,the F_v/F_m was fast setback and reduced to 0.3 at 312h.The Y(Ⅱ) was droped on ladder type,and Y(NPQ) was varies within a small range, between 0.1 to 0.2,but higher than the control.Y(NO)was lower than the control.