Ecophysiological response of Nerium indicum. Mill to irrigating treatment of landfill leachate into landfill final cover
渗滤液覆盖层灌溉处理对夹竹桃的生理生态效应

Vegetation planted on the final cover of landfill site is essential for the safety,stabilization and ecological remediation of closed landfill.Meanwhile,the volume and pollutants of biorefractory landfill leachate could be effectively reduced by plant-soil ecosystem on final cover when irrigated with leachate.For this kind of process,the vegetation should be able to tolerate the stress from leachate irrigation.The impacts of leachate irrigation on physiological and biochemical characteristics of vegetation have been reported in the literature,but coordinated stresses of natural circumstance and leahcate irrigation on vegetation are less known.In the present paper,the influence of leachate irrigation on vegetable growth and physiological response were studied throughout one year,with dogbane oleander(Nerium indicum.Mill) as vegetable materials for final cover.The results showed that dogbane oleander could survive when irrigated with leachate at a hydraulic loading of 10 mm/d,grow faster than the control group(i.e.,irrigated with water).The growth trend of dogbane oleander evolved seasonally.The dynamic changes of physiological parameters such as malondialdehyde(MDA),proline(Pro) of leachate irrigation group and control group were likewise and regulated by the air temperature,while the parameters such as superoxide dismutase(SOD),peroxidase(POD),ascorbic acid(AsA) and glutathione (GSH) fluctuated almost seasonally.For example,the activity of SOD and POD was enhanced obviously during the period of June to August and period of October to April.At the same time,AsA and GSH accumulated greatly.Although the seasonal evolution of the physiochemical parameters of leachate irrigation group was more sensitive and fluctuant than that of control group,no obvious discrepancy could be observed between the temporal trends of two groups.It was noted that MDA positively relating to stress were higher than that of control group during the period of June to August,while the activities of SOD and POD positively relating to the stress-resistant ability were lower.The experimental results showed that ecophysiological responses of dogbane oleander were mainly regulated by seasonal change of climate,but not influenced by leachate irrigation.Therefore,the leachate irrigation would not impose observable stress on the growth of dogbane oleander.However,atrocious circumstance might aggregate the coordinated stresses of environmental factor and leachate irrigation.