Studies On The Physiologic And Biochemical Response To Pb Stress And Pb Contaminated Environment Phytoremediation Of Althaea Rosea And Malva Crispa

In this paper,Althaea rosea and Malva crispa were studied by poting hydroponic methodologies.Two plant species were treated by lead stress,including their growth index,osmotic adjustment system,antioxidant enzyme systems and physiological characteristics.Furthermore,the change of absorbing Pb and other metal ions were measured and analyzed.The experimental results were obtained and analyzed in the following sections:?1?Under the different experiment conditions on lead tailings stress,this study examines the matrix of leading tailings influences the seedling growth of A.and M.The results suggest the plant height,root length and dry mass of the two types of plant seedlings were significantly lower than the control groups.In the pure lead tailing,the growth of.ground and underground increased substantially,which explains the patience of A.enhanced under this circumstance.With the increasing of contents' Pb lead tailing,two plant seedlings increased in both ground and underground parts.Within high content of metal stress treatment,the patience and migration rate of two plants maintained at high levels,and the patience indexes were vastly below one.Therefore,it is feasible in plant fixation and especially important to lead tailing.It directly proves that both types of plants could potentially be used as reclamation plants of Pb lead tailings.?2?A pot experiment was conducted to investigate the influence of Cu content in tailings on physiological index of seedlings on A.and M..The results show the contents of Chl.a,Chl.b and Cxc in the.and M.appeared first increased followed by a decline.The photosynthesis contents reached the highest value under 50%garden soil+50%lead tailings treatment of M.The Chl.a,Chl.b,Cxc have increased 25.6%,28.4%and 64.1%respectively from the control group to a significant level?P<0.05?.However,with increasing of the lead contents,the chlorophyll content of two plant seedlings were gradually declining.The experiment results imply the low content of lead could promote the generation of chlorophyll synthesis of two kinds of plants,but while the content of Pb was increased constantly,the lead stress had inhibited the generation of chlorophyll synthesis and the growth of A.and M.The changing patterns of SOD between A.and M.were comparable.The POD activity of A.would decline with the increasing of concentrations of Pb.On the contrary,the case of M.was different,the underground parts of M.increased 67.1%compared with the control group during the 50%garden soil+50%lead tailings treatment.It proved that the resistant ability of lead tailing stress by M.is higher than Althaea rosea.As a result,the lower of the MDA content M.possesses,the more integrity of cell M.owns.Therefore,the resistant ability of lead tailing stress by M.is higher than Althaea rosea,which concludes that tolerance of lead by M.is higher than of Althaea rosea.?3?Hydroponic method suggested that lead could influence the growth and physiological characteristics of A.and M..In this study,the low concentrations of lead stress could promote photosynthesis and increase chlorophyll content.However,the high concentrations of lead stress inhibited the growth and interrupted the growing of Chl.a,Chl.b in the A.and M.and carotenoids generation;On the other hand,with increasing concentration of lead stress and stress period,the amount of cells increased electrolyte leakage,Rooster chrysanthemum and the relative conductivity of the leaf cells A.had been rising;with higher concentrations of Pb,the SOD activity presented with progressive trend.The SOD activity of its underground part was higher and the upward trend is more significant.The results showed that for tailings M.repair effect is stronger.?4?A.and M.growth potential appeared first increased followed by a declining trend.This trend suggests the plants growth can be promoted under the low levels of Pb treatment.The growth of A.showed downward trend,and growth of M.was relatively slow.Pb stress impacted significantly on Althaea rosea.On the contrary,the M.possesses higher tolerance;The results suggest both plant roots portion absorb more Pb than shoots do.The higher the stress concentrated,the larger the plant of Pb absorbed.Lead stress could promote A.and M.Ca²⁺?Na⁺ ion uptake,these two Malvaceace for Ca²⁺?Na⁺ ions migrated at higher rates of shoots control;A.also had a lot of enrichment Cu²⁺?K⁺ions and showed a significant upward trend.M.,by constrast,the Na⁺ underground absorption was lower than the control 16.3%under 30mg/L Pb concentration,followed by a decline in absorption rate.The higher concentrations of Pb²⁺ could inhibit the Cu²⁺ absorption or decrease the uptake;Pb stress could promote A.migration Cu²⁺,K⁺and Na⁺ions and M.migration Pb²⁺,Ca²⁺,K⁺ and Na⁺.