Study On Physiological Effects Of Pistacia Chinensis Bunge With Heavy Metals And Stimulated Acid Rain Treatment

P.chinensis Bunge,a kind of deciduous arbors,is native to China,Anacardiaceae Pistacia.It is a light demander with developed main roots and a strong sprout capability.Its capabilities of drought and wind resistant are pretty good.This plant could be grown on weak acid soil and even on alkaline soil.It resists many noxious gases such as sulfur dioxide,hydrogen chloride,bituminous coal and so on.And it has a life span of hundreds years.Generally,it is very suitable for cultivation as an ornamental species.It has been paid much attention to that the heavy metals and acid rain pollution,which is really a major global environmental problem.Scientists all over the world has been studing on it these years. But their experimental materials are limited primarily to crops.P.chinensis Bunge is at once oil crop, ornamental tree and water conservation tree,There is on doubt that it has a broad marketing space and developing prospect.In this experiment,P chinensis Bunge was used as experimental material to research the effect of stress of Hg²⁺,Cd²⁺and Acid Rain on physiological Characteristic of it.The results provid theory basis for the further studies ofpistacia chinensis.As increasing the concentration of Hg²⁺ and/or Cd²⁺ in soil,especially when the mass concentration of Hg²⁺ was greater than 0.10mg/kg,the total content of chlorophyll in leavies decreased 6.9%.But we see a slight increasing while the mass concentration of Cd²⁺ and Hg²⁺ was below 0.05mg/kg.This is because reactive oxygen species were yielded by heavy metal stress, which accelerated the biosynthetic of chlorophyll.Compared with the content of soluble sugaron the tenth day,the content of it was decreased by 9.2%when the mass concentration of Hg²⁺ was 0.15mg/kg.While when the mass concentration of Cd²⁺ was 0.15mg/kg there was a significant difference between the contents of soluble sugar on the fifth day and the tenth day to contrast,when the mass concentration of Cd²⁺ was 0.10mg/kg,the contents of soluble sugar on the fifth day showed a decreasing obvious tendency and a significant difference to contrast also.Both Hg²⁺ and Cd²⁺ could influence the accumulation of soluble sugar in the leavies of the plant.The content of it increased with the increase of concentration of heavy metal ions but decreased with the time coursing.This suggests that,Under heavy metal stress,P chinensis Bunge regulate its cells osmotic pressure to maintain the expansion pressure of cells by the accumulation of osmotic adjustment substances,so that it resist the hurt from adversity.The content of MDA in leavise increased with the increasing of heavy metals's concentration. when the mass concentration of Hg²⁺ was 0.20 mg/kg the content of MDA was 1.15mol/g,which was the maximum.It was such a significant difference to contrast that the content of MDA was 105.4%more than contrast,when the mass concentration of Cd²⁺ was 0.10 mg/kg the content of MDA was 1.05mol/g,which was the maximum in this case.Difference was significant also. Compared with it on the day ten,the content of MAD on the day fifteenth decreased obviously.The fall was 20.2%.According to our research,Hg²⁺ with light concentration had little effect on activity of SOD.But when its concentration was above 0.10mg/kg,the activity of SOD growth rose at the beginning then dropped later.The maximum appeared after ten days.The activity of POD under the stress of Hg²⁺ and Cd² was higher than contraposition's.There has been an appreciable increase of it when the concentration of heavy metals was above 0.10mg/kg.The content of proline increased with the increasing of concentration of the heavy metals.It reached 0.130ug.g-1 on the fifteenth day when the mass concentration of Hg²⁺ was 0.20 mg/kg, which was the highest one and was 7.6 times more than contraposition's.The content of proline reached 0.106ug.g-1 on the tweentith day if the mass concentration of Cd²⁺ was 0.20 mg/kg,which was the maximum and was 5.2 times more than contrast.Over time,leavies of the plant were severely hurted under acid rain stress.Content of chlorophyll in leavies and net photosynthetic rate growth rose at the beginning then dropped later with the increasing pH and time,Content of chlorophyll was 43.04%lower than contrast at pH2.5.In this case stomatal conductance and transpiration rate decrease obviously and reached the minimum on the day nine.The lowest stomatal conductance and transpiration rate appeared on the nineth day at pH3.5.It was a significant difference.Content of MDA and membrane permeability of leavies increased obviously.There was a positive correlation between the two degrees(r=0.9764).But the change of MAD's content was much bigger than that of membrane permeabilityThe activity of SOD decreased with a increasing pH.It decreased immediately by 34.17%and 57.25%,which have significant difference compared with control's(P＜0.05)。This finding illustrate that acid rain would have higher impact on the activity of SOD of P.chinensis Bunge's leavies only when its pH is lower than 3.5.According to our researchs above,P.chinensis Bunge has a capability of Hg²⁺,Cd²⁺ resistance, which means that P.chinensis Bunge could gowth normally in Chong Qing.Otherwise,acid rain couldn't hurt this plant except the pH is higher than 3.5.