Effect of solar near ultraviolet radiation on growth of Chlorella cells

Cells of Chlorella regularis (Artari) Oltmanns (S-50) were grown under solar radiation in Tokyo, using a newly constructed outdoor culture system. The maximum specific growth rate (log₂ unit h⁻¹) was about 0.3, which was a little lower than the highest value reported using artificial light in the laboratory. The near ultraviolet light, consisting mostly of UV-A, inhibited the growth from 10 to 40% in summer mornings; the inhibition was not significant in the afternoon. The percentage inhibition was correlated with the total dose of the ultraviolet radiation. (author)