Studies Of Rhynchosia Volubilis And Puerperal Lobata On The Tolerance And Phytoremediation Of Pb Talings

Two species of Leguminosae,Rhynchosia volubilis and Pueraria lobata were selected as the material for the research of the effects of different concentrations of lead(Pb)tailings on the seedling growth,physiological indicators and heavy metals accumulation and translocation by pot culture.Meantime,the effects of different concentrations of organic acids on the seedling growth,physiological responses and ions accumulation were studied further.The results are as follows:(1)The effect of different portions of Pb tailings on the physiological and biochemical response of the seedlings of two species.The results showed that the photosynthetic pigment contents of Rh.volubilis were lower than that of the control,chlorophyll a and chlorophyll b of P.lobata were lower than the control,while the carotenoids were only slightly lower than the control under 1/2 Pb treatment.The relative conductivity of Rh.volubilis in the upper part of the ground was 28.27% higher than that in the control at 1/2 Pb,and there was no significant difference between the other treatments and the control.The relative conductivity of Rh.volubilis in the aboveground parts of Rh.volubilis increases with the increase of Pb content,which indicated that the damage to the aboveground part of Rh.volubilis increases with the increase of Pb content.There was no significant difference in the relative conductance between Pb treatments in the underground part of Rh.volubilis and P.lobata.The activity of POD in the aboveground part of P.lobata was higher than that in the upper part of Rh.volubilis,and there was no significant difference between the treatments and the control.The results of POD activities in underground of Rh.volubilis and P.lobata showed a trend of first rise and then fall.With the increase of the content of Pb tailings,the content of AsA in the upper part of Rh.volubilis was lower than that of the control,and the lowest was found at 3/4 Pb treatment and 28.55% lower than the control.The upper part of P.lobata was reduced by 10.92% compared with the control when treated with all Pb tailings.The contents of AsA in the underground part of Rh.volubilis and P.lobata were not significantly different from each other.The results showed that the two species had some resistance under different portions of Pb tailings and P.lobata was better than Rh.volubilis.(2)The effect of different portions of Pb tailings on the growth and the accumulations of Pb and other metals of two plant seedlingsThe results showed that the plant height,root length and dry weight of Rh.volubilis and P.lobata decreased with the increase of Pb tailings,and the tolerance index of Rh.volubilis and P.lobata decreased with the increase of Pb tailings.The uptake of Pb ions in the upper and lower parts of Rh.volubilis and P.lobata showed a significant upward trend.The accumulations of Cu and Cd in the two plants were higher than that in the shoots.High contents of Pb tailings inhibited the accumulation on the Rh.volubilis,but less impact on P.lobata.The results showed that Pb tailing stress had an inhibitory effect on the growth of Rh.volubilis and P.lobata,but with the increase of Pb tailings,the accumulations of Pb,Cu and Cd in Rh.volubilis and P.lobata were promoted.(3)The effects of different organic acids on physiological indexes of two species under Pb tailings stress.It was found that the content of photosynthetic pigments of Rh.volubilis and P.lobata were lower than that of the control under the treatment of organic acids,which indicated that the addition of organic acids inhibited the synthesis of photosynthetic pigments in plants,and the inhibition to the plant chlorophyll b and chlorophyll a were stronger in high concentration of organic acids than the low concentration of organic acids.The activity of SOD in the Rh.volubilis was higher than that in the control.The activity of SOD in the Rh.volubilis base was 0.1 mmol/kg CA and 1 mmol/kg EDTA,which was 41.85% and 33.18% higher than that of the controls.The SOD activity in aboveground and underground of P.lobata was higher than the control,and with the EDTA treatment concentration increased,SOD activity was increased too.The activity of POD in P.lobata was higher than that in Rh.volubilis.The content of MDA in the underground part of the two plants was higher than that of the control.After adding the organic acid,the toxicity of Rh.volubilis and P.lobata was taken placed,and the contents of the ground were the lowest at 1 mol / kg EDTA.There was no significant difference in the content of AsA between Rh.volubilis and P.lobata under different organic acids.High concentration of CA increased GSH content in Rh.volubilis,while high concentration of EDTA inhibited GSH content in Rh.volubilis.The content of GSH in the upper part of P.lobata was significantly and was 41.54% higher than control at 0.1 mmol / kg EDTA.The results indicated that the addition of organic acids inhibited the biomass of two plants.Rh.volubilis and P.lobata had different responses to Pb tailings under different concentrations of organic acids.(4)The effects of different organic acids on the growth and the accumulation of Pb and other metals of two spcies in Pb tailings.The addition of two different concentrations of organic acids to Pb tailings had little effect on the plant heights and dry weights of Rh.volubilis and P.lobata,but there was no significant difference with the control,but the root lengths and the dry weights of Rh.volubilis and P.lobata were greater effected,and in the high concentration of EDTA significant inhibition of dry weights and root lengths of the two plants had observed.Rh.volubilis and P.lobata can grow normally in Pb tailings,and P.lobata is more resistant than Rh.volubilis after adding organic acid.EDTA promoted the accumulation of Pb,Cu and Cd in Rh.volubilis and P.lobata higher than that of CA,and the higher the EDTA concentration,the greater the promoting effect.The metal translocation of Pb and Zn are improved in different degrees,and EDTA treatment is higher than CA treatment.The results showed that the addition of EDTA could inhibit the biomass of plant,but it could promote the accumulation of metals in Rh.volubilis and P.lobata.Overall,EDTA has a certain effect on the promotion of Pb accumulations of Rh.volubilis and P.lobata,and Rh.volubilis and P.lobata could be used in the remediation of Pb contaminated environment and the remediation ability of P.lobata was better than Rhynchosia volubilis.