| Abstract: | The effect of light qualities, for example white light (WL), blue light (BL), red light (RL) and green light (GL), respectively, provided by the LEDs on the growth, pigment content, light absorption and chlorophyll fluorescence parameters of Isochrysis galbana strain IOAC724S was measured. The growth rate of algae exposed to GL was not significantly different from that of WL, but was significantly higher than that of blue light (BL) or red light (RL). These four light colours were all efficiently absorbed by algal cells, with an absorption rate up to 92%–93%. The light absorbed by pigments contributes only part of the light absorbed by cells, ranging from 8.3% (at RL) to 59.7% (at BL). Among the monochromatic light, the highest light absorption was obtained in cells cultivated at BL, but the photochemical reaction was lowered. No positive effect of monochromatic RL was found. Cells cultivated at BL and RL were, respectively, restricted by down‐regulated photosynthetic efficiency and sufficient light absorption; meanwhile, GL showed a dramatic increase in photosynthetic efficiency, associated with a light absorption close to that for cells exposed to WL (both at 30.6%), suggesting that GL promotes the photosynthesis of I. galbana by balancing the light absorption and utilization. |
