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The Response to Lead(Pb) Stress and Pb-accumulating Characteristics of Hydrangea Paniculata

Author: KongXiang
Tutor: ZhaoJiuZhou
School: Jiangxi University of Finance
Course: Ornamental Plants and Horticulture
Keywords: Hydrangea paniculata Pb Tolerance physiological index Organic acid Lead enrichment
CLC: S682.19
Type: Master's thesis
Year: 2009
Downloads: 24
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Abstract

Lead stress and plant resistance were studied in this paper with the genus of Hydrangea paniculata, using soilless culture, soil culture, as well as Pb-contaminated soil potted plants, the mechanism of plant stress-tolerance, Pb uptake and plant accumulation capacity were studied ,and the mineral nutrition, metabolism, the effects of ethylene diamine tetra acetic acid (EDTA), citric acid (CA) were tested. The results are as follows:1. Studies of lead stress resistance of Hydrangea paniculata under soilless cultureThe physiological index were studied on the Pb concentration and its stress period of H. paniculata under soilless culture, the results showed as follow:The results showed that the chlorophyll content in the plants were higher than contrast(CK) with the treatment of low concentration (≤50mg / L) Pb stress, and with time lasting it showed irregular changes. The chlorophyll content were decreased while Pb concentrations was above 100(mg/L) which were increased in the beginning of testing and then decreased when the time lasting under the same concentration of Pb treatment. There were no change on the chlorophyll content of H. paniculata after 20 days, and the plants were death after 17 day with the treatment of Pb200(mg/L).MDA content increased To be accompanied by the Pb concentration increasing. During 30 day treatment of Pb stress, MDA content were increased in the beginning of testing and then decreased respectively.The activities of POD were increased significant respectively by the increasing of Pb concentration.The changes of physiology index had the same trend as biomass of plants (including plant height ,roots length and roots number and fresh weight) ,in which the growing index were higher then that of contrast under the stress of Pb 50(mg/L), and the Pb concentration of 50mg/L promoted the plants growth.2. Effects of lead-contaminated soil on plant resistance and Its lead accumulation of Hydrangea paniculataThe effects of lead-contaminated soil mixed with garden soil in a certain proportion on were studied , plant growth and physiological index were tested, the results showed that cone Hydrangea has a strong lead-enrichment function in the soil culture using a proportion of lead-contaminated soil .With the proportion of lead polluted soil increased , the Pb concentration increased either in plants . Pb concentration of plants underground parts was about 3799.5mg/kg, which was about 2.82 times of CK, and the plant aerial parts was about 1545.673 mg/kg that was 1.15 times of CK.The moderate damage of pants happened in the proportion of lead-contaminated soil to reach 75%,and all the growth index showed a significant decline in under this condition.Chlorophyll content decreased under the proportion of lead-contaminated soil to reach 50%,and It were showed increasing trend of MDA content and POD activity along with the increase in the proportion of lead-contaminated soil, and in its maximum (100%) is somewhat reduced, while the cell membrane permeability is always higher, reaching 56.29%, is the contrast 6.55 times, indicating low levels of lead can promote the growth and physiological activity of H. paniculata, and when the lead reached a certain amount of time would result in toxic effects on the plants.3. Effects of lead-tailing soil on plant resistance and Its lead accumulation of Hydrangea paniculataUsing lead-tailing soil and garden soil mixed with a certain proportion as growing media cultivated H.paniculata seedlings. The resistance habit changes in physiological index, as well as the amount of lead concentration in roots, stems and leaves were tested. The results showed that the low proportion of lead-tailing soil had much limiting effects, so that promote the growth rate, increased in the contents of Chlorophyll and soluble sugar. It shorted plant height, less leaf and roots number and yellow leaf color happened as the proportion of lead-tailing soil reached 75% in growing media ,The Pb contents in roots ,stems and leaves as well as electrical conductivity ,MDA,CAT increased significance respectively, along with the increase in the proportion of lead-contaminated soil. The activity of SOD and POD increased in the beginning and then decreased.4. Effects of EDTA and CA on antioxidant enzyme activities and lead- absorbing characteristics of Hydrangea paniculata on lead tailings soilEffects of EDTA and CA applied in Pb tailings soil on seedling biomass and antioxidant enzyme activities and lead accumulation characteristics of H.paniculata were studied in this part. The results showed that the Pb concentration in all part of plant treated by EDTA were higher than CK, in which treated with EDTA (2mmol/kg) had higher Pb contents than that of Pb (0.5mmol/kg).The EDTA had much promotive effects in Pb-accumulation in plant than CA, and which enhanced the activities of SOD and POD, decreased the contents of MDA.It was one of innovative characters that the results showed obviously in the characteristics of .Pb resistance and capability of Pb accumulation of H.paniculata , and it had reached the standard of phytoremediation because of Pb concentration of 1345.7(mg/kg) in leaves and 3799.385(mg/kg) in roots of H.paniculta.

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