臺灣博碩士論文加值系統

工業非法排放未經處理的廢水或事業廢棄物，導致附近農地在引水灌溉時遭受重金屬汙染。在臺灣，農地汙染場址以重金屬鎘 (Cd) 、銅 (Cu) 、鉻 (Cr) 、鎳 (Ni) 、鋅 (Zn) 、鉛 (Pb) 之汙染為最。大部分的植物暴露於重金屬汙染會產生含氧的自由基，造成氧化壓力 (oxidative stress)。然而植物發展出一套抗氧化防禦系統來抵抗重金屬逆境，其中包含許多抗氧化酵素如超氧化物歧化酶 (superoxide dismutases, SOD) 、過氧化氫酶 (catalase, CAT) 、抗壞血酸過氧化酶 (ascorbate peroxidases, APX) 以及穀胱甘肽還原酶 (glutathione reductase,GR) 等，協助清除植物體內過多的活性氧 (Reactive oxygen species)。

本研究選擇相思樹 (Acacia confusa) 、水黃皮 (Pongamia pinnata) 、三年桐 (Aleurites fordii) 、狼尾草 (Pennisetum purpureum) 四種能源植物，探討抗氧化酵素協助植物抵抗氧化逆境時的活性變化，以及植物吸收並累積重金屬於葉部的含量，對四種植物進行比較。結果顯示四種植物的SOD活性在不同濃度處理下沒有顯著差異，表示各樹種在重金屬逆境下細胞中的活性氧分子皆升高，SOD活性的表現也隨之增加。整體而言CAT活性在樹種間有差異，不同濃度間也有差異，每個樹種展現不同的反應能力與 SOD 協力清除植體內有害的O2-和 H2O2 。GR在對照組與其他濃度處理皆有差異，GR活性的提高幫助完成ascorbate–glutathione cycle的最後去毒階段。

酵素SOD、CAT、APX以及GR的協同作用，大多可幫助植物清除體內過多的活性氧，抵抗氧化逆境，避免細胞損傷。然而，因不同植物的特性，因此一植物只對一、兩種重金屬有較好的吸收能力。總括來看，僅水黃皮能夠對Cu有吸收效果；Cr的部分只有相思樹能夠吸收；Ni可由三年桐和狼尾草吸收，以三年桐的吸收量較高；而雖然四種植物都有發現Pb含量，但狼尾草吸收鉛的平均值高於其他樹種，而水黃皮和三年桐無顯著差異，重金屬Pb屬狼尾草有較佳的吸收能力。

Illegal discharge of untreated industrial waste water or industrial waste, leads to farmland nearby suffered heavy metal contamination during irrigation. In Taiwan, agricultural land sites contaminated with the pollution of cadmium (Cd) , copper (Cu) , chromium (Cr) , nickel (Ni) , zinc (Zn) , lead (Pb) the most. Most of the plants expose to heavy metal pollution will produce oxygen free radicals, resulting in oxidative stress . However, plants develop a series of antioxidant defense system to resist the heavy metal stress, which contains many antioxidant enzymes such as superoxide dismutase (SOD) , catalase (CAT) , ascorbate peroxidase (APX) and glutathione reductase (GR) , to assist plants removing excessive reactive oxygen species .

In this study, four energy plants including Taiwan Acacia (Acacia confusa) , Poonga Oil Tree (Pongamia pinnata) , Tung Oil Tree (Aleurites fordii) , and Napier Grass (Pennisetum purpureum) were treated with heavy metals, discuss the reaction of antioxidant defense system, as well as the antioxidant enzyme activity of plants against oxidative stress. Heavy metal accumulation of four plants were investigated and compared. The results indicate that SOD activity has no significant difference in four plants under different concentrations, which represent the rise of reactive oxygen species, and increase the performance of the SOD activity . The CAT activity has significant difference between four plants, as well as different concentrations, which indicate each species show a different ability to cope with SOD to clear potential harmful O2- and H2O2. GR has significant difference between the control and other concentration, high GR activity maintain the depletion stage of glutathione, completing the final stage of ascorbate-glutathione cycle.

With the cooperation of SOD, CAT, APX and GR in plant, most plants can help get rid of the excess reactive oxygen species against oxidative stress, preventing plant cell from damage. However, due to the characteristics of different plants, a plant only has a better ability to absorb and accumulate one or two heavy metals. In conclusion, only Pongamia pinnata has the better absorption effect of Cu. Cr can be absorbed only by Acacia confusa. Ni can be accumulated by Aleurtes fordii and Pennisetum alopecuroides, but the average value is higher in Aleurites fordii. Although Pb can be found in four plants, the average value of Pennisetum alopecuroides is higher than the other plants. There is no significant differences between Pongamia pinnata and Aleurites fordii, and Pennisetum alopecuroides have a better Pb absorption capacity.

摘 要 i
Abstract ii
目錄 iv
圖目錄 vi
表目錄 vii
英文縮寫 (按字母順序) viii
一、前言 1
二、前人研究 4
(一) 能源植物之相關研究 4
1. 相思樹 (Acacia confusa) 4
2. 水黃皮 (Pongamia pinnata) 4
3. 三年桐 (Aleurites fordii) 5
4. 狼尾草 (Pennisetum purpureum) 5
(二) 重金屬之種類與特性 5
(三) 植物體對重金屬的防禦機制 6
1. 非酵素型抗氧化劑 6
2. 抗氧化酵素 7
(四) 重金屬影響植物生理反應之相關研究 8
(五) 植物吸收重金屬的能力 13
(六) 重金屬濃度與暴露時間對植物體相關酵素的影響 16
三、材料與方法 18
(一) 試驗材料 18
(二) 栽植地點與方式 18
(三) 試驗設計及試驗處理 18
(二) 試驗項目及方法 19
1. 重金屬含量分析 19
2. 植物萃取液製備 20
3. 蛋白質含量測定 20
4. 酵素活性分析 21
5. 統計與分析 22
四、結果與討論 23
(一) 重金屬 23
1. 重金屬含量 23
2. pH值 29
(二) 抗氧化防禦系統 30
1. 超氧化歧化酶 (SOD) 31
2. 過氧化氫酶 (CAT) 36
3. 抗壞血酸過氧化酶 (APX) 40
4. 穀胱苷肽還原酶 (GR) 44
五、結論 49
六、參考文獻 51

古森本 (2008) 生質能源之開發與潛力。農業生技產業季刊 13:46-53 。
成游貴 (2006) 狼尾草育種與多元化利用。科學發展 407:54-29。
成游貴 (1998) 狼尾草台畜草二號備受肯定。狼尾草台畜草二號之栽培管理與青貯 1-9。屏東：台灣省畜產試驗所恆春分所。
成游貴 (2003) 狼尾草多元化利用育種。中華農學會報 4(2)：203-213。
許福星、成游貴、李美珠 (1994) 牧草栽培及管理。芻料作物生產及利用 6-7。台南：臺灣省畜產試驗所。
何強、井文涌、王翊亭 (2004) 環境學導論。北京:清華大學出版社。161頁。
高景輝 (2005) 植物生理分析技術。五男圖書出版有限公司。87-88頁。
劉業經、呂福原、歐辰雄 (1994) 台灣樹木誌。國立中興大學農學院出版委員會。p.197-198、p.234-235、p.403。
陳嘉介 (2011) 以相思樹與藍桉生產纖維酒精之效率與能源分析。國立台灣大學林環境暨資源學研究所碩士論文。
徐聖、羅漢強、王亞男、柯淳涵 (2010) 水黃皮種子油做為生質能源之潛力回顧。中華林學季刊43(3):489-504。
張嫤雪、林幸君、徐世勳 (2012) 農業經濟叢刊18(1):111-136。
Ann, C., Karen, S., Jos, R., Kelly, O., Els, K., Tony, R., Nele, H., Nathalie, V., Suzy V.S., Frank, V.B., Yves, G., Jan, C., Jaco, V., 2011. The cellular redox state as a modulator in cadmium and copper responses in Arabidopsis thaliana seedlings. J. Plant Physiol. 168, 309–316.
Assuncao, A.G.L., Schat, H., Aarts, M.G.M., 2003. Thlaspi caerulescens, an attractive model species to study heavy metal hyperaccumulation in plants. New Phytol. 159, 351-360.
Bell, F. G., Bullock, S. E. T., Halbich, T. F. J., Lindsay, P., 2001. Environmental impacts associated with an abandoned mine in the Witbank Coalfield, South Africa. International Journal of Coal Geology 45, 195–216.
Bielawski, W., Joy, K. W., 1986. Reduced and oxidized glutathione and glutathione reductase activity in tissues of (Pisum sativum) . Planta 169, 267.
Bricker, T. J., Pichtel, J., Brown, H. J., Simmons, M., 2001. Phytoextraction of Pb and Cd from superficial soil: effects of amendments and croppings. Journal of Environmental Science and Health, Part A Toxic/Hazardous Substances and Environmental Engineering 36, 1597–1610.
Beaucham, C., Fridovic, I., 1971. Superoxide dismutase - improved assays and an assay applicable to acrylamide gels. Analytical Biochemistry 44: 276-280.
Bert, M., Macnair, R., De Laguerie, P., Saumitou-Laprade, P., Petit, D. 2000. Zinc tolerance and accumulation in metallicolous and nonmetallicolous populations of Arabidopsis halleri (Brassicaceae) , New Phytol. 146, 225–233.
Boldt, R. and J.G. Scandalios. 1995. Circadian regulation of the Cat3 catalase gene in maize (Zeamays L.): Entrainment of the circadian rhythm of Cat3 by different light treatments. Plant J. 7, 989-999.
Bricker, T.J., Pichtel, J., Brown, H.J., Simmons, M., 2001. Phytoextraction of Pb and Cd from superficial soil: effects of amendments and croppings. J. Environ. Sci. and Health, Part A Toxic/Hazardous Substances and Environ. Engineering 36, 1597–1610.
Brooks, R.R. (Ed.) , Plants that Hyperaccumulate Heavy Metals, 1998. CAB International, Wallingford, UK, p. 380.
Clemens, S., 2006. Toxic metal accumulation, responses to exposure and mechanisms of tolerance in plants. Biochemie 88, 1707.
Candan, N., Tarhan, L., 2003. The correlation between antioxidant enzyme activities and lipid peroxidation levels in Mentha pulegium organs grown in Ca, Mg, Cu, Zn and Mn tress conditions. Plant. Sci. 165,769–776.
Cordova, R.E.V., Valgas, C., Souza-Sierra, M.M., 2003. Biomass growth, micronucleus induction, and antioxidant stress enzyme responses in Vicia faba exposed to cadmium in solution. Environ Toxicol. Chem. 22, 645–649.
Cunningham, S.D., Berti, W.R., Huang, J.W., 1995. Phytoremediation of contaminated soils, Trends Biotechnol. 13, 393–397.
Chaney, R.L., 1983. Plant uptake of inorganic waste constitutes, Parr, J.F., Marsh, P.B., Kla, J.M. (Eds.) . Land Treatment of Hazardous Wastes, Noyes Data Corp., Park Ridge, 50–76.
Chaney, R.L., Malikz, M., Li, Y.M., Brown, S.L., Brewer, E.P., Angle J.S., Bake, A.J.M., 1997. Phytoremediation of soil metals. Curr. Opin. Biotechnol. 8(3), 279-284.
Dong, J., Wu, F. B., Zhang, G. P., 2006. Influence of cadmium on antioxidant capacity and four microelement concentrations in tomato seedlings (Lycopersicon esculentum) . Chemosphere 64, 1659–1666.
Duffus, H. J., 2001. Heavy Metals - A Meaningless Term. Chemistry International
Dazy, M., Masfaraud, J.F., Ferard, J.F., 2009. Induction of oxidative stress biomarkers associated with heavy metal stress in Fontinalis antipyretica Hedw. Chemosphere 75, 297-302.
Dinakar, N., Nagajyothi, P.C., Suresh, S., Udaykiran, Y., Damodharam, T., 2008. Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L.seedling. J. Environ. Sci. 20, 199–206.
Ekmeci, Y., Tanyolac, D., Ayhan, B., 2009. A crop tolerating oxidative stress induced by excess lead: maize. Acta Physiol. Plant 31, 319.
Freeman, J. L., Persans, M. W., Nieman, K., Albrecht, C., Peer,W., Pickering, I. J.,
Salt, D. E., 2004. Increased glutathione biosynthesis plays a role in nickel tolerance in Thlaspi nickel hyperaccumulators. Plant Cell 16, 2176–2191.
Foster, J.G., Hess, J.L., 1980. Responses of superoxide-dismutase and glutathione reductase activities in cotton leaf tissue exposed to an atmosphere enriched in oxygen. Plant Physiol 66: 482-487
Foyer, C. H., Noctor, G., 2005. Redox homeostasis and antioxidant signaling: a metabolic interface between stress perception and physiological responses. Plant Cell 17, 1866–1875.
Fidalgo, F., Freitas, R., Ferreira, R., Pessoa, A.M., Teixeira, J., 2011. Solanum nigrum L. antioxidant defense system isozymes are regulated transcriptionally and post-translationally in Cdinduced stress. Environ. Exp. Bot. 72, 312–319
Gallego, S. M., Benavides, M. P., Tomaro, M. L., 1996. Effect of heavy metal ion excess on sunflower leaves: evidence for involvement of oxidative stress. Plant Science 121, 151–159.
Gossett DR, Millhollon EP, Lucas MC., 1994. Antioxidant response to NaCl stress in salt tolerant and salt-sensitive cultivars of cotton. Crop Sci 34:706–14.
Grill, E., Winnacker, E. L., Zenk, M. H., 1985. Phytochelatins: the principal heavy-metal complexing peptides of plants. Science 230, 674–676.
Gallego, S.M., Benavides, M.P., Tomaro, M.L., 1996. Effect of heavy metal ion excess on sunflower leaves: evidence for involvement of oxidative stress. Plant Sci. 121, 151–159.
Gangwar, S., Singh, V.P., Srivastava, P.K., Maurya, J.N., 2011. Modification of chromium (VI) phytotoxicity by exogenous gibberellic acid application in Pisum sativum (L.) seedlings. Acta. Physiol. Plant 33, 1385–1397.
Ghnaya, A.B., Charles, G., Hourmant, A., Hamida, J.B., Branchard, M., 2009. Physiological behavior of four rapeseed cultivar (Brassica napus L.) submitted to metal stress. C. R. Biol. 332, 363–370.
Hopkins G. and Norman P., 2008. Introduction to Plant Physiology. 3rd ed. Wiley publishing. p111-121.
Hirata, K., Tsuji, N., Miyamoto, K., 2005. Biosynthetic regulation of phytochelatins, heavy metal-binding peptides. Journal of Bioscience and Bioengineering 100, 593–599.
Huang, H., Gupta, D.K., Tian, S., Yang, X., Li, T., 2012. Lead tolerance and physiological adaptation mechanism in roots of accumulating and non-accumulating ecotypes of Sedum alfredii. Environ. Sci. Pollut. Res. 19, 1640–1651.
Hu, J.Z., Shi, G.X., Xu, Q.S., Wang, X., Yuan, Q.H., Du, K.H., 2007. Effects of Pb2+on the active oxygen-scavenging enzyme activities and ultrastructure in Potamogeton crispus leaves. Russ. J. Plant Physiol. 54, 414–419.
Iqbal, N., Masood, A., Nazar, R., Syeed, S., Khan, N.A., 2010. Photosynthesis, growth and antioxidant metabolism in mustard (Brassica juncea L.) cultivars differing in Cd tolerance. Agri. Sci. China 9, 519–527.
Kanoun B., M., Vicente, J.A.F., Nabais, C., Prasad, M.N.V., Freitas, H., 2009. Ecophysiological tolerance of duckweeds exposed tocopper. Aquat. Toxicol . 91, 1–9.
Kato, M., Shimizu, S., 1987. Chlorophyll metabolism in higher-plants. VII. Chlorophyll degradation in senescing tobacco-leaves - phenolic-dependent peroxidative degradation. Can J Bot 65: 729-735
Khan, N.A., Singh, S., Nazar, R., 2007. Activities of antioxidative enzymes, sulphur assimilation, photosynthetic activity and growth of wheat (Triticum aestivum) cultivars differing in yield potential under cadmium stress. J. Agro. Crop. Sci. 193, 435–444.
Kumar, A., Prasad, M.N.V., Sytar, O., 2012. Lead toxicity, defensestrategies and associated indicative biomarkers in Talinum triangulare grown hydroponically. Chemosphere. 89, 1056–1165.
Lamhamdi, M., Bakrim, A., Aarab, A., Lafont, R., Sayah, F., 2011. Lead phytotoxicity on wheat (Triticum aestivum L.) seed germination and seedlings growth. C. R. Biol. 334, 118–126.
Liu, D., Li, T.Q., Yang, X.E., Islam, E., Jin, X.F., Mahmood, Q., 2008. Effect of Pb on leaf antioxidant enzyme activities and ultrastructure of the two ecotypes of Sedum alfredii Hance. Russ. J. Plant Physiol. 55, 68–76.
Malecka, A., Piechalak, A., Mensinger, A., Hanć, A., Barałkiewicz, D., Tomaszewska, B., 2012. Antioxidative defense system in Pisum sativum roots exposed to heavy metals (Pb, Cu, Cd, Zn) . Pol. J. Environ. Stud. 21, 1721–1730.
Malecka, A., Piechalak, A., Morkunas, I., Tomaszewska, B., 2008. Accumulation of lead in root cells of (Pisum sativum) . Acta Physiol. Plant. 30, 629.
Malecka, A., Piechalak, A., Tomaszewska, B., 2009. ROS production and antioxidative defense system in pea root cells treated with lead ions. Part 1. The whole roots level. Acta Physiol. Plant. 31, 1053.
Millar, A. H., Mittova, V., Kiddle, G., Heazlewood, J. L., Bartoli, C. G., Theodoulou, F. L., Foyer, C. H., 2003. Control of ascorbate synthesis by respiration and its implications for stress responses. Plant Physiology 133, 443–447.
Mithofer, A., Schulze, B., Boland, W., 2004. Biotic and heavy metal stress response in plants: evidence for common signals. FEBS Letters 566, 1–5.
Maksymiec, W., Krupa, Z., 2006. The effects of short-term exposition to Cd, excess Cu ions and jasmonate on oxidative stress appearing in Arabidopsis thaliana. Environ. Exp. Bot. 57, 187–194.
Maleva, M.G., Nekrasova, G.F., Malec, P., Prasad, M.N.V., Strzałka, K., 2009. Ecophysiological tolerance of Elodea canadensis to nickel exposure. Chemosphere 77, 393–398.
McGrath, S.P., Lombi, E., Gray, C.W., Caille, N., Dunham, S.J., Zhao, F.J., 2006. Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri. Environ. Pollut. 141, 115-125.
Mishra, S., Srivastava, S., Tripathi, R.D., Trivedi, P.K., 2008. Thiol metabolism and antioxidant systems complement each other during arsenate detoxification in Ceratophyllum demersum L.Aquat. Toxicol. 86, 205–215.
Mishra, S., Tripathi, R.D., Srivastava, S., Dwivedi, S., Trivedi, P.K., Dhankher, O.P., Khare, A., 2009. Thiol metabolism play significant role during Cd detoxification by Ceratophyllum demersum L.Biores. Tech. 100, 2155–2161.
Mittler, R., 2002. Oxidative stress, antioxidants and stress tolerance. Trends Plant Sci 7, 405–410.
Mobin, M., Khan, N.A., 2007. Photosynthetic activity, pigment composition and antioxidative response of two mustard (Brassica juncea) cultivars differing in photosynthetic capacity subjected to cadmium stress. J. Plant. Physiol. 164, 601–610.
Nakano, Y., Asada, K., 1981. Hydrogen peroxide is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Physiol 22: 867-880
Nicoletta, R., Flavia, N.I., 2011. Heavy metal hyperaccumulating plant: How and why do they do it? And what makes them so interesting? Plant Sci. 180, 169-181.
Noctor, G., Arisi, A.C.M., Jouanin, L., Kunert, K.J., Rennenberg, H., Foyer, C.H., 1998. Glutathione: biosynthesis, metabolism and relationship to stress tolerance explored in transgenic plants. J. Exp. Bot. 49, 623–647.
Nottaris, D., Crespi, P., Greppin, H., 1997. Penel C. Effect of UV-C on two cell lines from sugarbeet. Arch. Sci. 50, 223–32.
Panda, P., Nath, S., Chanu, T.T., Sharma, G.D., Panda, S.K., 2011. Cadmium stress-induced oxidative stress and role of nitric oxide in rice (Oryza sativa L.) . Acta. Physiol. Plant 33, 1737–1747.
Piotrowska, A., Bajguz, A., Godlewska-Zyłkiewicz, B., Czerpak, R., Kaminska, M., 2009. Jasmonic acid as modulator of lead toxicity in aquatic plant Wolffia arrhiza (Lemnaceae) . Environ. Exp. Bot. 66, 507–513.
Prasad, K.V.S.K., Saradhi P.P., Sharmila, P., 1999. Concerted action of antioxidant enzymes and curtailed growth under zinc toxicity in Brassica juncea. Environ. Exp. Bot. 42, 1-10.
Qureshi, M. I., Qadir, S., Zolla, L., 2007. Proteomics-base dissection of stress-responsive pathways in plants. J. Plant Physiol. 164, 1239.
Rausch, T., Gromes, R., Liedschulte, V., Muller, I., Bogs, J., Galovic, V., Wachter, A., 2007. Novel insight into the regulation of GSH biosynthesis in higher plants. Plant Biology (Stuttgart) 9, 565–572.
Rascio, N., Navari-Izzo, F., 2011. Heavy metal hyperaccumulating plants: how and why do they do it? And what makes them so interesting? Plant Sci. : an international journal of experimental plant biology 180, 169-181.
Reddy, A.M., Kumar, S.G., Jyonthsnakumari, G., Thimmanaik, S., Sudhakar, C., 2005. Lead induced changes in antioxidant metabolism of horse gram (Macrotyloma uniflorum (Lam.) Verdc.) and Bengal gram (Cicer arietinum L.) . Chemosphere 60, 97–104.
Reeves, R.D., 2006. Hyperaccumulation of trace elements by plants, in: J.L. Morel, G.
Echevarria, N. Goncharova (Eds.) , Phytoremediation of Metal-Contaminated
Soils, NATO Science Series: IV: Earth and Environ. Sci., Springer,
NY, 1–25.
Salt, D. E., Rauser, W. E., 1995. MgATP-dependent transport of phytochelatins across the tonoplast of oat roots. Plant Physiology 107, 1293–1301.
Scandalios, J.G., 1993. Oxygen stress and superoxide dismutases. Plant Physiol 101, 7–12.
Schutzendubel, A., Schwanz, P., Teichmann, T., Gross, K., Langenfeld-Heyser, R., Godbold, D.I., Polle, A., 2001. Cadmium-induced changes in antioxidative systems, H2O2 content and differentiation in pine (Pinus sylvestris) roots. Plant Physiology 127, 887-892.
Schutzendubel, A., Polle, A., 2002. Plant responses to abiotic stresses: heavy metal-induced oxidative stress and protection by mycorrhization. Journal of Experimental Botany. 53, 1351–1365.
Schwartz, C., Gerard, E., Perronnet, K., Morel, J. L., 2001. Measurement of in situ phytoextraction of zinc by spontaneous metallophytes growing on a former smelter site. Science of the Total Environment 279, 215–221.
Siddiqui, S., Meghvansi, M. K., Wani, M. A., Jabee, F., 2009. Evaluating cadmium toxicity in the root meristem of (Pisum sativum L.) . Acta Physiol. Plant 31, 531.
Sun, R. I., Zhou, Q. X., Jin, C. X., 2006. Cadmium accumulation in relation to organic acids in leaves of Solanum nigrum L. as a newly found cadmium hyperaccumulator. Plant and Soil 285, 125-134.
Teisseire, H., Guy V., 2000. Copper-induced change in antioxidant enzymes activities in fronds of duckweed (Lemna minor) . Plant Science 153, 65–72.
Tang, K., Zhan, J., Yang, H., Huang, W., 2010. Changes of resveratrol and antioxidant enzymes during UV-induced plant defense response in peanut seedlings. Journal of Plant Physiology 167, 95-102.
Verbruggen, N., Hermans, C., Schat, H., 2009. Molecular mechanisms of metal hyperaccumulation in plants. New Phytol. 181, 759-776.
Verma, S., Dubey, R.S., 2003. Lead toxicity induces lipid peroxidation and alters the activities of antioxidant enzymes in growing rice plants. Plant Sci. 164, 645–655.
Wang, D., Poss, J.A., Donovan, T.J., Shannon, M.C., Lesch., S.M., 2002. Biophysical properties and biomass production of elephant grass under saline conditions. J. Arid Environ. 52: 447–456.
Wang, Z., Zhang, Y., Huang, Z., Huang, L., 2008. Antioxidative response of metal-accumulator and non-accumulator plants under cadmium stress. Plant Soil 310, 137.
Wojtaszek, P., 1997. Oxidative burst: an early plant response to pathogen infection. Biochemical Journal 322, 681–692.
Xu, X., Liu, C., Zhao, X., Li, R., Deng, W., 2014. Involvement of an Antioxidant Defense System in the Adaptive Response to Cadmium in Maize Seedlings (Zea mays L.). Bull Environ Contam Toxicol 93(5):618–624.
Yadav, S. K., 2010. Heavy metals toxicity in plants: an overview on the role of glutathione and phytochelatins in heavy metal stress tolerance of plants. South African Journal of Botany 76, 167–179.
Yadav, S.K., 2010. Heavy metals toxicity in plants: An overview on the role of glutathione and phytochelatins in heavy metal stress tolerance of plants. Bot. 76, 167-179.
Yanai, J., Zhao, F.J., McGrath, S.P., Kosaki, T., 2006. Effect of soil characteristics on Cd uptake by the hyperaccumulator Thlaspi caerulescens. Environ. Pollut. 139, 167-175.
Yusuf, M., Fariduddin, Q., Varshney, P., Ahmad, A., 2012. Salicylic acid minimizes nickel and/or salinity-induced toxicity in Indian mustard (Brassica juncea) through an improved antioxidant system. Environ. Sci. Pollut. 19, 8–18.
Zenk, M. H., 1996. Heavy metal detoxification in higher plants–a review. Gene 179, 21–30.
Zhang, H., Xia, Y., Wang, G., Shen, Z., 2008. Excess copper induces accumulation of hydrogen peroxide and increases lipid peroxidation and total thiol activity of copper-zinc superoxide dismutase in roots of Elsholtzia haichowensis. Planta 227, 465–475.
Zhou, Z.S., G.K., Elbaz, A.A., Yang, Z.M., 2009. Salicylic acid alleviates mercury toxicity by preventing oxidative stress in roots of Medicago sativa. Environ. Exp. Bot. 65, 27–34.