| In this dissertation, six different indoor plants including Sansevieria trifasciata var. laurentii,Aloe vera var. chinensis, Chlorophytum comosum var. mediopictum, Scindapsus aureum,Adiantum capillus-veneris and Asplenium antiquum had been tested in the experiment. Weanalyzed the accumulation of superoxide radicals（·O2-）, contents of chlorophyll （Chl）,malondialdehyde （MDA） and proline （Pro）, activities of superoxide dismutase （SOD）,peroxidase （POD）, catalase （CAT） and the variation of leaf microstructure in plants throughindoor artificial fumigation box, under the single and compound stress of benzene andformaldehyde. Studying the different responses to the pollution of benzene and formaldehydeamong the plants, the dissertation revealed that the response mechanism to the pollution ofbenzene and formaldehyde in indoor plants, as well as the toxicity mechanism of benzene andformaldehyde in the plants. By doing this, I hope that the results will provide a more scientificreference for enriching the theoretical research on plant responses to environmental stress. Themajor results were as follows:1. Toxicity mechanism in plants under the stress of benzene or formaldehydeTreated with0.1,1,3,5mg/m3formaldehyde or0.11,0.55,1.1,3.3mg/m3benzene for48hours, the contents of Chl in six plants decreased as the concentration of benzene andformaldehyde increased, the·O2-was accumulating, the MDA and Pro content were increasing,therefore, the activities of SOD, POD and CAT in different species showed three differentpatterns such as increasing continuously, decreasing continuously and firstly increasing and thendecreasing.When the concentration of benzene and formaldehyde reached the maximum （benzene3.3mg/m3and formaldehyde5mg/m3）, the major physiological indexes of six plants had greatdifferences compared with the contrast. Adiantum capillus-veneris was the plant with the largestdecline in Chl content, reduced more than30%. The plants with the smallest decline wereScindapsus aureum and Sansevieria trifasciata var. laurentii, decreased about20%. Adiantumcapillus-veneris and Asplenium antiquum were the plants with the largest increase in super oxideanion content, increasing over95%. The plant with the smallest increase was Scindapsus aureum,increasing less than72%. Except of the activities of SOD in Adiantum capillus-veneris andAsplenium antiquum first increased and then decreased, they increased continuously as theconcentration of benzene and formaldehyde increasing. It indicated the present concentration offormaldehyde or benzene had the greatest toxic effects on Adiantum capillus-veneris andAsplenium antiquum. This dissertation measured the anti ability to benzene and formaldehyde of six plantsthrough the principle component analysis. The anti ability to formaldehyde from the strongest toweakest was Chlorophytum comosum var. mediopictum, Sansevieria trifasciata var. laurentii,Scindapsus aureum, Aloe vera var. chinensis, Asplenium antiquum and Adiantum capillus-veneris.The anti ability to benzene from the strongest to weakest was Chlorophytum comosum var.mediopictum, Sansevieria trifasciata var. laurentii, Aloe vera var. chinensis, Scindapsus aureum,Adiantum capillus-veneris and Asplenium antiquum.2. Effects on microstructure of spider plant under the stress of benzene or formaldehydeBenzene and formaldehyde had some different effects on the pore structure and thethickness of leaf cross-section of Chlorophytum comosum var. mediopictum. Under the stress ofbenzene, the stomatal length-diameter of Chlorophytum comosum var. mediopictum had notsignificant difference by contrast, and the stomatal short-diameter reduced26.46%in14days bycontrast. Under the stress of formaldehyde, the length-diameter and short-diameter had notobvious differences by contrast, but the shape had changed from dumbbell shape to rectangle.Most stomas gradually entered the closed state as the stress time increasing.The leaf cross-section thickness and stomatal density of Chlorophytum comosum var.mediopictum decreased under the stress of benzene and formaldehyde. Under the treatment ofbenzene and formaldehyde, the thickness decreased23.6%and35.53%14days later, as well as,the stomatal density was21.95%lower than that of control.3. Toxicity mechanism in plants under the compound stress of benzene and formaldehydeThe toxicity mechanism in plants under the compound stress of benzene and formaldehydewas related to the compound pattern. The changes of photosynthetic system and antioxidantsystem under the compound stress were not the simple addictive effects as that under the singlestress, while they were a complex interaction. When the concentration of formaldehyde was lessthan1mg/m3, the physiological indexes of plants would be relieved, and such effects woulddecrease while the concentration of benzene and formaldehyde increases. When theconcentration of formaldehyde was more than1mg/m3, the physiological indexes of plants wouldbe synergistic inhibited under the compound stress of benzene and formaldehyde.Through the principle component analysis, the ordered resistance to the compound stress ofbenzene and formaldehyde from the strongest to weakest was Chlorophytum comosum var.mediopictum, Sansevieria trifasciata var. laurentii and Adiantum capillus-veneris, when underthe compound stress of formaldehyde in high concentration （Treatment3:3mg/m3, Treatment4:5mg/m3） and benzene.4. Response mechanism to the stress of benzene and formaldehyde in indoor plantsThe production and elimination of reactive oxygen types in plants were in dynamic balanceunder the normal growth conditions. The membrane could not be destroyed and kept the normalstructure when it was under the stress of benzene and formaldehyde in low concentration, and theaccumulation of free radical was in the scope that the antioxidant enzyme was normal. As theconcentration increasing, the reactive oxygen types of the six plants would be over accumulated. Once they were out of the elimination ability of antioxidant enzyme （SOD, POD and CAT）, theirsynthesis would be limited and the activities would decrease, and lipid peroxidation of cellswould lead to the content of MDA increase, then the cell structure and physiological functionwould be destroyed, the photosynthesis would be limited and the content of Chl would decrease,or even the plant would die if the situation was serious.5. Purification effect of indoor plants under the compound stress of benzene and formaldehydeWhen treated with0.1,1,3mg/m3formaldehyde and benzene （single or compoundtreatment） for24hours, the fumigation box and soil absorbed benzene and formaldehydeincreasingly as the time prolonging. In the same condition, the adsorption capacity of fumigationbox was weaker than that of soil, and the adsorption capacity to benzene was weaker than toformaldehyde.The purifying effects of plants were highly related to the stress concentration, and the higherconcentration, the worse purifying effects. Under stress of benzene or formaldehyde,37.61%benzene and41.64%formaldehyde were removed by Adiantum capillus-veneris. The averageremoval rates of benzene and formaldehyde byScindapsus aureum and Sansevieria trifasciatavar. laurentii were more than49%. Under compound stress of benzene and formaldehyde,41.06%formaldehyde and41.28%benzene were removed by Adiantum capillus-veneris, in themeantime, average more than45%formaldehyde and benzene were removed by Scindapsusaureum and Sansevieria trifasciata var. laurentii. |
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