Effect of Blue‐green Light on Photosynthetic Pigments and Chloroplast Structure in the Marine Diatom Stephanopyxis Turris1

Blue‐green light increased the chlorophyll concentration and chloroplast number of cells of Stephanopyxis turris (Grev.) Ralfs, compared to white light controls. Light fields for growth were 400 μW·cm−2 (12:12 LD cycles). Chlorophyll increased up to 100%/cell, but no change in the ratio of chlorophylls to major carotenoids occurred. The effect was, therefore, not that of complementary chromatic adaptation. At the same time, blue‐green light enhanced the photosynthetic fixation of CO2. At the ultrastructure level, an increase in, and rearrangement of, the thylakoid system occurred.