Effects of Light Quality on the Photosystem Activity of Tomato Fruit Surface

The effect of light quality on the photochemical activity of tomato fruit surface was studied by a MINI-IMAGING-PAM system.The results showed that as the intensity of light quality rises(200-2 500 μmol/(m2 · s)),the maximal photochemical efficiency(Fv/Fm),the effective PS II quantum yield(Y(II)),the apparent electron transport rate(ETR)and the open PSII reaction centers(Fv′/Fm′)of tomato fruit surface which was under red light and blue light treatments all decreased in the shape of S,while the relative deviation(β/α-1)from full balance between two photosystems rised gradually,indicating that excitation energy high intensity has broken the balance of excitation energy distribution between PSII and PSI,thus leading to the poorer cooperation of two photosystems.Chlorophyll fluorescence of tomato fruit surface which was under green light treatments was proved to be feasible,showing that green light may reduce the chlorophyll to absorb excessive of light energy and decrease photoinhibition.Fv/Fm、Y(Ⅱ)、ETR and Fv′/Fm′ of tomato fruit surface which was under blue light was smaller than red light and blue light,these gaps will widen with an increase in intensity,which indicated blue light was sensitive to photoinhibition.In case of lower light intensity(200-1 000 μmol/(m2 · s)),Fv/Fm、Y(Ⅱ)and Fv′/Fm′ of tomato fruit surface which was under red light was higher than green light,while over 1 000 μmol/(m2 · s) leading to reverse results,which showed that the capacity of adapting to high light intensity of tomato fruit surface which was under green light was strong.