Mechanism Of Growth And Physiological Response Of Three Arbor Species To Oil Contamination

The loess plateau in northern Shaanxi belongs to arid and semiarid aera,where water andsoil loss is severe.The process of oil mining, smelting and transportation have caused oilpollution in large areas, making the environment deteriorating even further. Oil pollution cancause the soil block, change the composition and structure of soil organic matter andmicroflora, and influence the plant growth as well. At the same time, the harmful material inpetroleum accumulate in plants, causing harm to animals and human through food chain.Therefore, screening the trees species which have the high anti-pollution ability has extremelysignificance for oil polluting soil restoration and environmental pollution controlling.Three kinds of main tree species, Robinia pseudoacacia, Platycladus orientalis andPinus tabulaeformis were used as the objects of this research. The oil contaminated soil wasartificially mixed, the pot experiment was carried out. The growth response and physiologicalmechanism of the three species responding to oil-contaminated soil were discussed. Theresults of the study provide scientific theoretical basis for selecting tree species which havestrong ability to resist pollution and petroleum contaminated soil phytoremediation.Researchhas made the following main conclusions:1. The influence of oil pollution on the growth characteristics was different for three treespecies. Robinia pseudoacacia seedings react obviously to oil pollution. The plant height,ground diameter, dry matter on the ground, quality, level of lateral root length, and root drymatter quality basicly are negatively related with the increase of oil concentration. As the oilconcentration increase, the growth parameters are decrease.While Platycladus orientalisseedings react inconspicuously to oil pollution. The plant height, ground diameter, main rootlength, and root dry matter quality under each concentration treatment indicate no significantdifference compared with the controll. The ground dry matter is significantly lower than thecontrol under the pollution concentration in15to20g/kg. It indicates that high oil pollutionhas certain influence on Platycladus orientalis. In relatively high concentrations (15to20g/kg)treatments, the main root length, lateral root length, root dry matter quality and otherindicators of Pinus tabulaeformis seedlings are significantly lower than control, especially itsground dry mass under different pollution concentration reduce distinctly.This shows thatdifferent oil pollution concentration have the big impaction on the species. 2. The response of antioxidant protection systems for different species to oil pollution isclosely related to oil pollution intensity and time, and own characteristics. This shows thechanging characteristics of particularity, diversity, dynamic and complexity.3. Antioxidant enzymes in antioxidant protection systems, or antioxidants, or the bothsynergy in in three species, played a certain role during different periods. Although the H2O2content of Robinia pseudoacacia and Platycladus orientalis under different pollutionconcentration increase or significantly increase, compared with controll,which shows reactiveoxygen accumulates in their bodies, MDA content doesn’t increase significantly in a longtime compared with control, indicating that under the effect of antioxidant protection systemit does not cause substantial damage to membrane structure. The damage of antioxidantprotection system for Robinia pseudoacacia and Platycladus orientalis within theconcentration of20g/kg treatment is not abvious, the two did not suffer in essence. Underlong term oil pollution, H2O2and MDA content of Pinus tabulaeformis under eachconcentration level increase significantly than control, the increase of the both basically arepositively correlated with the treated concentration, declaring under various concentration ofoil pollution, Pinus tabulaeformis seedlings have been oxidative damaged. As the higher theconcentration is, the greater the poison of Pinus tabulaeformis seedlings suffer.4. The osmotic regulation substances cumulation of different species are influenced byoil pollution intensity and stress time.The ability for osmotic regulation substances to play therole in regulation system of each species depends on the size of the substances’ accumulation.As a consequence, oil pollution under three kinds of trees osmotic regulation ability is in adynamic change.Soluble sugar in three kinds of tree species have common osmotic regulationeffect, while praline and soluble protein can participate in different period of osmoticregulation under different oil pollution intensity...