Effects of temperature and light intensity on cell concentration and growth rate of Dunaliella salina Teodoresco

Cell concentrations and growth rate of Dunaliella salina Teodoresco in light intensities of 50 and 150 μmol. photons.m-2.s-1 and temperatures 25 ± 0.5 and 31 ± 0.5 oC (mean ± SD) were studied. The algae was isolated from the Urumieh Lake and cultured in various treatments (n = 12). Algae cells were counted regularly using Thoma counting chamber in 3 replicates on daily basis. The curve of changes in population was plotted. The highest cell concentration (mean ± SD) of 4.8 ± 0.6 × 10 6 cell.ml-1 was observed in light intensity of 150 μmol. photons.m-2.s-1 and temperature 25 ±0.5 oC. The minimum cell concentration (2.8 ± 0.3 × 10 6 cell.ml-1) was observed in light intensity of 50 μmol. photons.m-2.s-1 and temperature 31 ± 0.5 oC. The maximum growth rate (0.38 d-1) was recorded in light intensity of 150 μmol.photon.m-2.s-1 and temperature 25 ± 0.5 oC and the minimum (0.16 d-1) in 50 μmol.photon.m-2.s-1 at temperature 31 ± 0.5 oC Increase in temperature from 25 to 31 oC was found to be correlated with decrease in cell concentration and growth rate in D. salina., but increase in light intensities from 50 to 150 μmol. photons.m-2.s-1 resulted in increase of these factors.