Effects of green light spectrum supplementation on growth of green microalgae Scenedesmus quadricauda.

Microalgae has a significant role with high-value product, lighting condition is a potential source to manage and increase algae growth. LED light has shown promising results in the growth rate of microalgae and the activity of secondary metabolites. S. quadricauda was grown under monochromatic LED light wavelengths, i.e., white, red, blue, green and also dichromatic red/ blue LED in ratios of 1/3, 3/1 at the total light intensity of 50 μmol photons m-2 s -1 , to measure the dry weight, optical density, and chlorophyll concentration. The results indicated that the red and blue light combination was the optimum light wavelength for high optical density and chlorophyll concentration in S. quadricauda. The order of growth rate R3/B1> R1/B3> Blue> Red> White> Green. Green light yielded the best chlorophyll production in S. quadricauda, red light was the lowest chlorophyll results. Furthermore, the green light was supplemented gradually into the combination of red: blue (1: 3) at the light intensity of 2, 4, 6, 8, and 10 µmol m-2 s -1 as an expense of red and blue light. Treatment with 6 µmol/ m-2 s -1 green light supplemented with red/blue combinations was the highest growth rate result and the lowest is with 2 µmol/ m-2 s -1 . No statistical differences between any of the treatments. Supplementation of green light showed that there is no negative or positive effect on the growth of S. quadricauda species. Seems that supplementation of green light is compensated for red and blue light expenses although green light alone has a suppressive effect on the growth of cultures of S. quadricauda. KEYWORDS: Scenedesmus qaudricuada, LED, Red Light, Blue Light, Dichromatic Combination, Green Light