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柽柳和银水牛果对镉胁迫的生理响应与耐受积累特征
崔 振, 李昌晓, 李晓雪,等
西南大学 生命科学学院
摘要:
【目的】研究镉胁迫对柽柳和银水牛果生长、叶片叶绿素含量、抗氧化酶活性的影响及2种植物对镉的耐受积累特征,为西部镉污染地区土壤修复提供理论依据。【方法】以柽柳和银水牛果两年生幼树为研究对象,通过向镉本底值为0.31 mg/kg的土壤添加外源镉(CdCl2·2.5H2O)的方式设置了CK(0 mg/kg)、T1(2 mg/kg)、T2(5 mg/kg)、T3(10 mg/kg)4个处理(镉添加量以纯镉计)。在试验进行至90 d 时,测定不同镉胁迫处理2种幼树功能叶叶绿素含量、株高、生物量、生理生化指标和镉含量。【结果】镉胁迫抑制了植物生长发育过程中叶绿素的合成,随镉添加量的增加,柽柳和银水牛果的叶绿素a、叶绿素b、总叶绿素含量均表现显著降低趋势,柽柳叶绿素a/b值显著降低,银水牛果叶绿素a/b值显著升高。柽柳和银水牛果的株高、生物量、耐性指数(Ti)均随土壤镉添加量的增加而下降。T1、T2、T3处理柽柳的Ti分别为67.14,51.21,35.21,均大于银水牛果的Ti(分别为58.25,45.48,27.08)。镉胁迫显著增加了柽柳和银水牛果叶片的MDA含量,同时启动了2种植物体内积极的抗氧化酶系统,SOD、POD、CAT、APX活性均在T2处理达到最大值。柽柳根部和茎部镉含量在T3处理达到最大值,分别为5.03和4.76 mg/kg,而叶镉含量在T2处理达到最大值(9.64 mg/kg);银水牛果根部、茎部、叶部镉含量在T3处理达到最大值,分别为2.58,1.44,0.50 mg/kg;银水牛果的转移系数为0.75~0.81,柽柳的转移系数为0.85~3.57。【结论】柽柳和银水牛果在土壤镉含量为5.31 mg/kg时具有较高的生长适应性和耐性,柽柳根部向地上部分转移镉的能力及地上部分积累镉的能力都远大于银水牛果,适用于镉污染区域的植物修复。
关键词:  镉胁迫  柽柳  银水牛果  生理响应  镉积累特征
DOI:
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基金项目:国家国际科技合作专项(2015DFA90900);重庆市林业重点科技攻关项目(渝林科研2016-8;2015-6);中央财政林业科技推广示范项目(渝林科推[2014-10]);重庆市研究生科研创新项目(CYB16066)。
Physiological responses and tolerance accumulation characteristics of Tamarix ramosissima and Shepherdia argentea under cadmium stress
CUI Zhen, LI Changxiao, LI Xiaoxue,et al
Abstract:
【Objective】This study investigated the response of Tamarix ramosissima and Shepherdia argentea seedlings to cadmium (Cd) to provide theoretical basis for repairing Cd pollution in western China.【Method】By adding exogenous Cd into soil with background value of 0.31 mg/kg,different Cd concentration treatments including CK (0 mg/kg),T1 (2 mg/kg),T2 (5 mg/kg),and T3 (10 mg/kg) were set up.The photosynthetic pigment contents,growth,biomass,physiological and biochemical indexes,and Cd concentrations in various parts of T.ramosissima and S.argentea seedlings were measured after 90 days.【Result】The contents of chlorophyll a,chlorophyll b and total chlorophyll in T.ramosissima and S.argentea decreased with the increase of Cd concentration,while chlorophyll a/b ratio of T.ramosissima decreased significantly,and chlorophyll a/b ratio of S.argentea increased significantly.The plant heights,biomass and tolerance indexes (Ti) of T.ramosissima and S.argentea decreased with increasing Cd content.The Ti values of T.ramosissima and S.argentea were 67.14,51.21,35.21 and 58.25,45.48,27.08 in three treatment groups,respectively.The synthesis of photosynthetic pigments during plant growth was inhibited by Cd stress.Malonaldehyde (MDA) contents of T.ramosissima and S.argentea significantly increased along with the increasing concentration of Cd and antioxidant enzyme activities of leaf of T.ramosissima and S.argentea presented same trends.Superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and ascorbate peroxidase (APX) activities raised first and then decreased with peak at T2.Cd contents in root and stem of T.ramosissima reached the peaks of 5.03 and 4.76 mg/kg at T3,and the highest Cd content in leaf was 9.64 mg/kg at T2.Cd contents in root,stem,and leaf of S.argentea reached the peaks of 2.58,1.44,and 0.50 mg/kg at T3.The translocation factor (TF) were 0.85~3.57 for T.ramosissima and 0.75~0.81 for S.argentea.【Conclusion】T.ramosissima and S.argentea seedlings had high growth adaptation and tolerance under 5.31 mg/kg Cd stress,and the capacities of translocation and Cd accumulation in aboveground parts of T.ramosissima seedlings were higher than that of S.argentea seedlings.Thus,T.ramosissima had higher considerable potential for application to Cd contaminated areas in western China.
Key words:  Cd stress  Tamarix ramosissima  Shepherdia argentea  physiological response  Cd accumulative characteristic