The Influence Of Environmental Stress On The Growth And Photosynthesis Of Chlorella Pyrenoidosa

Based on the photosynthesis theory,chlorophyll fluorescence anaysis is making use of the chlorophyll in the plants as the natural indicator to research about the photosynthesis and the influence of environment on it.It is a signifcant tool to do photosynthesis research with the advantages such as rapid, sensitive and no damage to the cells and nearly all photosynthesis process can be illustrated by this reliable and rapid research method.This paper,making use of this technology,research about the influence of 3 kinds of environmental stress(Hg,Cu and heat)on the photosynthesis of Chlorella pyrenoidosa,with a combination of traditional indicators such as biomass and photosynthesis pigments in order to understand the response of Chlorella pyrenoidosa to different environmental stress thus provide scientific support to the exploration of new indicators in biomonitoring.The results show that,1.The Hg stress can influence the growth of Chlorella pyrenoidosa,meanwhile reduce the Fv/Fm,ΦPSII,rETR and qP significantly,increase the value of qN and NPQ indicating that the algae can protect the PSII system from further harm through the increase of heat dissipation.2.The effect of Cu on the growth of Chlorella pyrenoidosa is much serious than the photosynthesis,which is illustrated that the quantum yield is not sensitive to the increase of copper expect 2mg/L.Meanwhile,the non-photochemical quenching increase significantly under the stress of Cu,which maintain the relative stability of PSII system.3.Heat stress reduces the Fv/Fm,ΦPSII and rETR to a great degree when over the critical temperature.The qN and NPQ remain stable during the heat stress process but increase by 4 times after it which proves that the alage active the defense mechanism to restore the activity of photosynthesis after the damage.4.Rapid light curve is affected by the heat stress,with the parameters including Pm,αand I_k reduced,indicating that the photosynthesis capability is damaged.5.Under the stress of Cu,the demand for N and P is decline and the absorption for N is much more than P. 6.Under the stress,the absorption amount of Cu is increased while the absorption rate remains decreased,which domenstrated that Cu is prevented to enter into cells through the protection mechanism.