Effects of illumination on the chlorophyll fluorescence parameters and astaxanthin content of Haematococcus pluvialis

In this paper, the effects of different illumination on the chlorophyll fluorescence parameters and astaxanthin content of Haematococcus pluvialis were examined. The main parameters determined in the present study including the maximal photochemical efficiency of PSII (Fv/Fm), the potential activity of PSII (Fv/Fo), the actual photochemical efficiency of PSII in the light (PSⅡ), theelectron transport rate (ETR), the photochemical quenching (qP), the non-photochemical quenching (NPQ), cell density, relative chlorophyll content and astaxanthin content. One-way analysis of variance showed that illumination had significant effects on the fluorescence parameters, relative chlorophyll content, cell density and astaxanthin content of H.pluvialis during the entire experimental period (P0.05). Multiple comparisons show that the optimal growth illumination of H.pluvialis under the experimental conditions was 50 molm-2s-1. The astaxanthin content (gcell-1) at 300 molm-2s-1 were significantly higher than that in other treatments. But the astaxanthin content (gmL-1) at 50 molm-2s-1 was highest in all treatments. The analysis of correlations showed that there were significant positive correlations between relative chlorophyll content and cell density during the entire experimental period. Moreover, some fluorescence parameters (Fv/Fm, Fv/Fo, PSⅡ, ETR, qP, NPQ), relative chlorophyll content and cell density all showed significant correlations with illumination, the pattern and strength of the correlations varied with culture days.