Influence de la lumière et de la température sur les taux de croissance et de photosynthèse de Scenedesmus crassus Chodat, isolée de la retenue eutrophe El Kansera (Maroc)

Abstract

For Scenedesmus crassus isolated from the eutrophic impoundment « El Kansera » (Morocco), the specific growth and photosynthesis rates were measured, over a range of light intensities [10-800 µE.m-2.m-1] and temperatures from 10 to 35°C, under 15/9 light: dark cycle. Optimum conditions of irradiance (Iopt) and temperature (Topt) were 312 µE.m-2.s-1 and 28°C, for the maximum specific growth (µmax = 1, 72 j-1). Both photosynthetic rate (Pmax) and light saturation charactereristics Ik(p) increased with temperature. The high values of Pmax (4, 40 mgC. mgChla-1.h-1) and Ik(p) (240 µE.m-2.s-1) were obtained at 35°C. Little photoinhibition (less than 5 %) of Pmax was observed at irradiance exceeding 300 µE.m-2.s-1, while the growth rate decreased markedly at irradiance above saturation. Pmax appears correlated with Ik(p) and µmax. © Gauthier-Villars, 1995.