Effect of Light Quality on Photosynthetic Characteristics of Ginger Leaves

【Objective】Effect of light quality on the characteristics of light energy utilization and photosynthesis in leaves was studied in order to provide theoretic references for shading ginger at seedling stage.【Method】The diurnal changes of chlorophyll fluorescence, photosynthetic characteristics and photorespiration in leaves of ginger cv. Laiwu grown in tunnel where light intensity was the same but light quality was different by covering with different colored plastic film and colorless nylon net at seedling stage. 【Result】Though the diurnal variation of chlorophyll fluorescence in leaves of different treatments was similar, the maximal photochemical efficiency (Fv/Fm), the efficiency of excitation energy capture by open PSII reaction centers (Fv’/Fm’), quantum yield of PSII (ΦPSⅡ), photochemical quenching coefficient (qP) and photochemical reflectance index (PRI) of leaves treated with green film was the highest, followed by blue, white or red film in turn. In contrast, green, blue, white or red film induced the relative deviation (β/α-1) from full balance between two photosystems and nonphotochemical quenching (NPQ) increased in turn. The daily changing pattern of net photosynthetic rate (Pn) in leaves of different treatments was two-peak-type, the values with green film treatment was the highest, followed by white, red or blue film in order from high to low, while that of photorespiration (Pr) and Pr/Pn was reverse. Red film induced the highest apparent quantum yield (AQY) and the lowest compensation point (LCP). In parallel, green film induced the highest carboxylation efficiency (CE) and maximum regeneration rate of RuBP as well as the maximum photosynthetic rate (Pmax)【.Conclusion】Increasing the ratio of green light in light quality could reduce the photoinhibition, make the correspondence of transferring electron between PSI and PSII well, decrease heat dissipation of excitation energy, enhance the light energy utilization efficiency. Therefore the capacity of adapting to high light intensity in ginger leaves covered with green film isstrong, and Pn is high.