EFFECTS OF CD2+ STRESS ON THE GROWTH AND PHOTOCHEMICAL ACTIVITY OF PORPHYRIDIUM PURPUREUM
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Abstract
This study investigated the effects of Cd2+ on the biomass, chlorophyll a content, phycoerythrin content and ATP content, the maximum quantum yield of PSII (Fv/Fm), the effective photochemical yield of PSII (YII), the relative electron transfer rate (ETR) and non-photochemical fluorescence of quenching (NPQ) of the Porphyridium purpureum. The results showed that the growth rate of P. purpureum decreased significantly by the stress of Cd2+ in a dosage-dependent pattern. The content of chlorophyll a, phycoerythrin and ATP decreased significantly by Cd2+ stress with a dose-dependent way. The chlorophyll fluorescence parameters (Fv/Fm, YII and ETR) under Cd2+ stress were significantly lower than those of the control groups and decreased rapidly with increased Cd2+ concentration. NPQ value increased significantly at low Cd2+ (<200 μmol/L) and decreased significantly at high Cd2+ (>500 μmol/L). Therefore, the gorwth and phtochemical activities ofPorphyridium purpureum would be significantly affected by the concentration of the Cd2+ above 5 μmol/L and the accumulation of Cd2+ would have an impact on the ecological balance of the Porphyridium purpureum in aquatic environment.
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