EFFECT OF BLUE-GREEN LIGHT ON GROWTH-RATE AND CHEMICAL-COMPOSITION OF3 DIATOMS

The diatoms Chaetoceros sp., Skeletonema costatum and Thalassiosira ps eudonana were grown with different irradiances of white and of blue-gr een light, and with a mixture of blue-green plus 6.5 mu mol m(-2) s(-1 ) of white light. Exponential growth rates were higher in mixed blue f or the first two, while T. pseudonana grew faster in white light but, in all cases, mean cell division rates did not differ with increasing irradiances. Harvesting in stationary, rather than in late exponential growth phase, resulted in higher protein contents for Chaetoceros sp. and S. costatum, but for T. pseudonana the highest value was in the e xponential phase. The highest protein content was in blue-green light for the three species and it increased with irradiance. As to other fr actions, the three strains showed different responses, related to ligh t quality and quantity, as well as to culture ages.