| Acid rain is a worldwide pollution problem facing mankind one of the major environmental problems. For the ecological impact of acid rain on plant damage and, under simulated acid rain damage to the mechanism of resistance of plant physiological mechanism has important theoretical and practical significance, can be chosen for the garden department and strong anti-pollution, high purification ability Trees provide a scientific basis.In this article, Nerium indicum Mill was studied with the method with simulated acid rain treatment plants studied by means of simulated acid rain on physiological characteristics of Nerium indicum, Nerium indicum explore the role of stress in the mechanism of acid rain, as the folder Bamboo Peach in the popularization and application of acid rain control area and lay a theoretical foundation, the same time, it can acid rain pollution in the selection of plants to provide theoretical basis and practical experience of gardening on the acid rain control area and reasonable allocation of the choice of tree species and to improve Nerium indicum resistance acid rain cultivation technology has important practical significance. The results are as follows:(1) The first injury is the mesophyll between veins, followed by tip and leaf margin, the study found that with the increase of processing cycle, the cumulative dose of simulated acid rain increased, new symptoms began to appear, but the original symptoms much deeper level. Only pH2.0 and pH3.0 treatment group treatment group appeared injured spot, characterized by symptoms:white spots, yellow irregular necrotic spots, necrotic spots on the yellow and black burn spots; significant time disease appears relatively late, pH2.0 treatment group in the third cycle symptoms, pH3.0 treated symptoms in the fifth cycle; Nerium indicum in six cycles of simulated acid rain showed only minimal damage after the symptoms of slight injuries. From the apparent point of view, Nerium indicum on the simulated acid rain showed strong resistance.(2)In dealing with the initial victims of leaf area index were 0%, pH2.0 and pH3.0 treatment group treated injuries occur late in dealing with symptoms, affected leaf area index are below 5%, Nerium indicum visible damage threshold pH2.0 the following, the specific values should be determined after detailed pH gradient. Nerium indicum to simulated acid rain sensitivity levels for the most resistant class V.(3)Nerium indicum's growth is not made with the lower pH value of the linear change, pH3.0 the growth of the largest treatment group, pH2.0 treatment group the smallest growth. Nerium indicum growth rate of the largest in the control group, with the decrease of pH, acid rain began to lower pH, the smaller the treatment group, growth rate, the deeper the degree of reduction. Simulated acid rain inhibited the growth of Nerium indicum, the stronger the acidity the greater the inhibition. However, the treatment group and control group no significant difference between (p>0.05), showed that simulated acid rain on growth despite inhibition of Nerium indicum, Nerium indicum on acid rain, but there is strong resistance.(4)In simulated acid rain stress, shoot growth in all treatment groups than control group volume, treatment group, with the lower pH value of the volume increase shoot growth. Shoot growth rate of the control group is the largest, followed by the growth rate of treated pH2.0, pH4.0 and pH3.0 treatment group treated with the shoot growth rate was almost reduced to half the growth rate of the control group, acid rain on Nerium indicum inhibited the growth of new shoots. However, pH2.0 treatment group, inhibition greatly reduced, it is possible the higher acidity of simulated acid rain can promote the growth of new shoots of Nerium indicum, which is on the amount of shoot growth results. Each treatment group and control group no significant difference between (p>0.05), showed that simulated acid rain on growth of Nerium indicum shoots although inhibition of acid rain, but Nerium indicum showed strong resistance to stress.(5)Nerium indicum simulated acid rain effect on photosynthesis. And Nerium indicum photosynthesis, chlorophyll content, chlorophyll a/b, Pn, Gs, Ci, Ts as the decrease of pH, acid rain decreased photosynthetic capacity caused by Nerium indicum down, so Nerium indicum growth was inhibited.(6)The greater the acidity of simulated acid rain, the longer the treatment period, the greater the impact on the MP, but Nerium indicum Mill stress in each treatment group and control group can be recovered to similar levels; with simulated acid rain pH value decreases, increase in processing cycle, MDA will continue to accumulate, but the balance in the protection of the system under, MDA will continue to decrease and will not cause serious damage to plants. High concentrations of acid rain lipid peroxidation that in low concentrations of simulated acid rain.(7)CAT, POD and SOD is protective in vivo enzyme responsible for the removal of biological free radicals on the important function of the three synergies can be maintained at a lower level of free radicals in order to avoid membrane damage. With the increase in the number of simulated acid rain, more and more serious injuries, but the oleander's own protective enzyme system response to injury mechanisms can be very good, timely rid of a lot of H2O2, to ensure normal growth of Nerium indicum Mill.
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