LONG-TERM ACCLIMATIZATION OF SCENEDESMUS-BICELLULARIS TO HIGH-FREQUENCY INTERMITTENT LIGHTING (100 HZ) .1. GROWTH, PHOTOSYNTHESIS AND PHOTOSYSTEM-II ACTIVITY

Responses of the green microalga, Scenedesmus bicellularis to high-frequency intermittent lighting (IL, 100 Hz) were assessed after a 4 week acclimatization. Effects of IL on growth, photosynthesis and photosystem II (PSII) activity were studied at limiting and saturating irradiances, and compared to those of continuous light (CL) of the same instantaneous and daily irradiances. Even after a 4 week acclimatization period, the photosynthetic capacity (P-max), the photosynthetic efficiency (alpha) and the photosynthetic activity at growth irradiance, either expressed on a per cell or a chlorophyll a basis, showed little difference, neither did the index of light adaptation (I-k) or PSII activity. In contrast, growth was lower under IL at saturating irradiance. Results are discussed considering the non-linearity of the relationship between growth or photosynthesis and irradiance.