The study of fluorescence characteristics and biochemical composition of a marine diatom Thalassiosira pseudonana 3H in light and dark cycles—Ⅱ . The effects of light

The effects of light on the fluorescence characteristics and biochemical composition of a marine diatom Tha-lassiosira pseudonana in light and dark cycles were investigated with semi-continuous culture.The results indicate that,with the increase of growing light intensity,DCMU enhanced fluorescence yield(Fd/Chl),enhanced fluorescence ratio(Fd/F),cellular carbohydrate content.carbohydrate/chlorophyll a and carbohydrate/protein ratio increased,but the fluorescence yield and cellular chlorophyll a content decreased;The protein content declined with the increase of light intensity in the range of 10-100μmol/(m2·s)and increased at higher than 100μmol/(m2·s).Sampling time during the day had great effect on the relationships between growing light intensity and cellular chlorophyll a,carbohydrate content,carbohydrate/chlorophyll a and carbohydrate/protein ratio.