The Effects of Light Intensity on the Growth Rates of Green Algae.

Abstract

tion of pyridine nucleotides by spinach grana and coupled carbon dioxide fixation. Nature 167: 768-769. 1951. 29. VISHNIAC, W. and OCHOA, S. Fixation of carbon di-oxide coupled to the photochemical reduction of pyridine nucleotides bv chloroplast preparations. Jour. Biol. Chem. 195: 75-93. 1952. 30. ZBINOVSKY. V. and BURRIS. R. H. Metabolism of infiltrated organic acids by tobacco leaves. Plant Physiol. 27: 240-249. 1952. 31. ZUCKER, M. and NASON, A. A pyridine nucleotide-hydroxylamine reductase from Neurospora. Jour. Biol. Chem. 213: 463-478. 1955. 32. ZUCKER, M. and NASON, A. Enzymatic reduction of hydroxylamine to ammonia by reduced pyridine nucleotides. Federation Proc. 13: 328. 1954. Aimong the environmental factors affectingf the growth rates of unicellular algae, light is frequently at an improper level. In many laboratory cultures used for physiological research the light intensity is too low to permit logarithmic growth. In nature the intensity is well above saturation and may be high enough to inhibit growth during much of the day. The intensities for saturation and inhibition depend on the suitability of other factors of the environment, e.g., temperature, CO2 level, and nutrient supply. In attempting to predict the performance of an alga under a given set of conditions it is necessary to know its potential under optimum conditions. Such infor-mation is basic to the evaluation of physiological studies and to the design and operation of culture ap-paratus. This paper describes the growth responses of five green algae to different light intensities under comp,arable environmental conditions. 1'IATERIAL AND METHODS