Effects Of Cd,Pb And Their Compound Pollution Stress On The Growth And Physiological Characteristics Of Rumex Japonicus Houtt

Pb and Cd are common in our life,so the pollution of Pb and Cd should not be ignored.In order to study the effect of Pb and Cd pollution on the physiological characters,growth and development of Rumex japonicus Houtt.,and the adaptive mechanism of plants under the Pb and Cd pollution stress,we select the native species named R.japonicusas in the mining area as the material by using pot culture methods under the stress of heavy metals of Pb and Cd.We measured the enrichment and bioaccumulation characteristics of heavy metals by field investigation,absorption properties of different organs to heavy metal and mineral elements,in order to reveal the toxic mechanism under the heavy metals on the R.japonicusand and assess their resistance to heavy metals of Pb and Cd pollution stress,to explore and evaluate the potential and realistic feasibility of R.japonicus in phytoremediation.The results showed as bellows.1.The characteristics of growth adaptability of Rumex japonicus under the Cd and Pb pollution stress.Except for the highest concentration of Pb 1000 mg/kg,with the concentration of Cd,Pb and their compound treatment increasing and stress time prolonging,the plant height,fresh weight and root length all significantly reduced and the inhibition effects of Cd,Pb compound stress were stronger than single Cd,Pb stress.Under Cd,Pb and their compound treatment,the content of Pb and Cd in different parts of R.japonicus increased differently,with the concentration of Cd,Pb and their compound stress increasing.The heavy metal content of the shoot is higher than the root's under the high concentration stress.The most of the heavy metal were deposited in the root R.japonicus different parts to absorb Pb.2.The characteristics of photosynthetic adaptability of Rumex japonicus under Cd and Pb stress.with the concentration of Cd,Pb and their compound treatment increasing and stress time prolonging,the content of chlorophyll a,chlorophyll b,total chlorophyll in R.japonicus all firstly decreased,and then increased.However,they all decreased compared with the control group.Except for the highest concentration of Pb 1000 mg/kg under the stress time of 42 days,with the concentration of Cd,Pb and their compound treatment increasing,the photosynthetic fluorescence origin fluorescence(Fo)and the non-photochemical quenching(NPQLss)all increase,the maximum fluorescence(Fm),variable fluorescence(Fv),potential activity(Fv/Fo)and other photosynthetic fluorescence all dropped.Showed that the concentration of Cd,Pb and their compound treatment destroyed the PSII reaction centers.In a short time of 21 days,Pb single stress had the least effect on PSII.with the concentration of Cd,low concentration Pb(<800 mg/kg)and their compound treatment increasing and stress time prolonging,the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr)all dropped,but the trend of the intercellular CO2 concentration(Ci)was opposite,showed that under the Cd,low concentration Pb and their compound treatment,the decline of photosynthetic capacity was mainly caused by non stomatal factors,when under the higher concentration 800 mg/kg,Stomatal conductance plays an important role.3.The characteristics of physiological adaptation of Rumex japonicus under Cd and Pb stress.the MDA and soluble sugar content of R.japonicus were increased with Cd single and combined stress concentration and time increasing,there were negative linear relationships between the MDA,soluble sugar content and Pb single stress,that there is a strong self repair ability in R.japonicus under Pb single stress.After 42 days of culture,Pb and Cd compound stress concentration were(5+100)mg/kg,10+200mg/kg,the ability of plants to scavenge reactive oxygen species and the ability to repair oxygen damage was enhanced after induction,MDA content were lower than the control group.With the increase of stress concentration,Self-control ability of R.japonicus was lowered.After 42 d of culture,When Pb and Cd compound stress concentration(>(10+200)mg/kg),soluble sugar content was lower than 21d's.with the concentration of Cd,Pb and their compound treatment increasing and stress time prolonging,the soluble protein and root activity of R.japonicus all decreased,and low concentration of heavy metal stress on soluble protein of R.japonicus was promoted.