Cd和表面活性剂复合污染对小麦叶片若干生理状性的影响

研究了溶液培养条件下Ｃｄ－直链十二烷基苯磺到钠（ＬＡＳ）、Ｃｄ－二六烷基三甲基溴化铵（ＣＴＡＢ）和Ｃｄ－聚氧乙烯山梨醇月桂酸酯（Ｔｗｅｅｎ－８０）３种复合污染对小麦生理状态的影响。结果表明,表面活性剂促进Ｃｄ在小麦叶中的积累,其效应顺序为ＣＴＡＢ〉ＬＡＳ〉Ｔｗｅｅｎ８０．Ｃｄ和表面活性剂复合污染条件下,小麦叶中Ｃｄ的大量积累导致的细胞膜脂过氧化水平大大高于单纯Ｃｄ污染下的水平。细胞中ＳＨ基含量降低     

镉、铅及其复合污染对大麦幼苗部分生理指标的影响

以Cd、Pb为胁迫因子,以大麦为试验材料,采用室内培养法,研究了重金属Cd﹑Pb及复合污染不同时间（3、5d）对大麦幼苗叶片部分生理指标的影响。结果表明,随着 Cd﹑Pb及Cd+Pb处理浓度的增加,大麦幼苗叶片中可溶性糖的含量表现为先升后降。在Cd﹑Pb单一处理条件下,不同浓度Cd﹑Pb均可造成叶细胞膜透性增大,叶片的相对电导率和脯氨酸含量上升。不同浓度的Cd+Pb复合处理对叶细胞膜的损伤均大于单一处理,低浓度Cd+Pb（5+50 mg·L^-1）复合处理组的可溶性糖含量比单一处理高。在不同处理时间（3、5d）内,所有Cd+Pb复合处理组叶中脯氨酸含量均高于单一处理组,Cd﹑Pb复合处理对脯氨酸的积累有促进作用。单一处理中Cd对大麦幼苗的毒性比Pb大,而复合处理（Cd+Pb）对大麦幼苗的损伤和毒害作用比单一处理更为严重,其交互作用机理值得进一步研究。     

Cd-Cu复合胁迫对黄菖蒲叶片及根系中Cd和Cu的积累及其迁移率的影响

采用水培法研究了Cd-Cu复合胁迫(5 mg·L-1Cd-10 mg·L-1Cu;5 mg-L-1Cd-20 mg·L-1Cu;25 mg·L-1 Cd-10 mg·L-1Cu;25 mg·L-1Cd-20 mg·L-1Cu)条件下黄菖蒲(Iris pseudacorus L.)叶片和根系对Cd和Cu的积累作用及黄菖蒲体内Cd和Cu迁移率的变化规律.结果表明,在50 d的胁迫期内,黄菖蒲叶片和根系中的Cd和Cu含量分别随培养液中Cd和Cu浓度的提高而增加,并随胁迫处理时间的延长基本呈增加的趋势,在胁迫末期明显提高.在不同浓度Cd-Cu复合胁迫条件下,黄菖蒲根系中的Cd和Cu积累量明显高于叶片.在Cd浓度不变的条件下,黄菖蒲叶片和根系中的Cd含量随培养液中Cu浓度的提高而增加;在Cu浓度不变的条件下,黄菖蒲叶片中Cu含量随培养液中Cd浓度的提高而降低.在不同胁迫时间,黄菖蒲植株对Cd的迁移率不同,但培养液中Cd的浓度较高,黄菖蒲植株对Cd的迁移率也较高;黄菖蒲植株对Cu的迁移率随胁迫时间的延长基本上呈上升趋势.研究结果显示,在Cd-Cu复合胁迫条件下,Cu对黄菖蒲体内Cd的吸收具有一定的协同吸收作用,而Cd对Cu的吸收则有一定的拈抗作用.     

重金属对土壤中小麦种子发芽与根伸长抑制的生态毒性

测定了4种土壤（红壤、草甸棕壤、暗棕壤和栗钙土）条件下,Cu,Zn,Pb和Cd单一污染对小麦种子发芽与根伸长抑制主及其复合污染效应（暗棕壤条件下）。结果表明,同一浓度下,重金属对小麦根伸长抑制率均明显大于对种子发芽抑制率,植物根对金属污染的生态毒性比种子发芽敏感,土壤有机质和土壤N含量与Cu,Zn,Pb和Cd污染对小麦根伸长抑制率显著负相关（R^2OR=0.91,R^2K-N=0.92),土壤PH和阳离子交换量与Cu,Zn,Pb和Cd污染对小麦根伸长抑制率的相关性不显著（R^2PH=0.62,R^2CEC=0.60),在单一污染对小麦根伸长为刺激作用浓度（较低浓度）或为抑制作用浓度下（较高浓度）,复合污染均表现为协同作用。^     

不同镉水平下小麦对镉及矿质养分吸收和积累的品种间差异

土壤Cd污染不仅影响作物的生长发育和产量形成,也对食物安全产生了潜在威胁,本试验以苗期生长特性有明显差异的2个小麦品种为供试材料,设置0、0．03、0．1、0．3和1．0mg.kg^-1Cd等5种处理水平,研究不同Cd水平下两品种的生长和Cd及矿质养分吸收,结果表明,低浓度Cd（0.03mg.kg^-1)对两品种的生长和干物质积累有明显的促进作用,而高浓度Cd（＞0.3mg.kg^-1)则显著抑制生长,且受抑制程度与品种有关,甘谷534的耐性相对较强;地上部和根系的Cd含量,Cd处理水平与品种之间存在着显著的互作,低Cd水平下（＜0.1mg.kg^-1),甘谷534的Cd含量较高,而高Cd水平下,则以鄂81513的Cd含量较高;Cd处理显著影响矿质养分的吸收,鄂81513在0.1mg.kg^-1Cd水平下5种大量元素含量明显低于对照,而甘谷534变化相对较小,这与两品种生长和分蘖对Cd处理的反应表现一致。     

Cd2+与CTAB复合污染对枫香幼苗生长与生理生化特征的影响

采用盆栽试验方法,研究了表面活性剂十六烷基三甲基溴化铵(CTAB)与重金属Cd²⁺单一及复合污染对枫香幼苗生长和生理生化指标的影响。结果表明,在单一CTAB污染条件下,较低浓度的CTAB(0.1-0.5 g/kg) 能促进枫香幼苗的生长,较高浓度的CTAB(0.5-2g/kg) 对枫香幼苗有毒害作用。在单一浓度Cd²⁺处理条件下,土壤中Cd²⁺浓度为100mg/kg时,枫香幼苗的生长受到严重的抑制。在同一浓度Cd²⁺污染土壤中,随着浇灌水中CTAB浓度的增加,枫香幼苗的株高、干重、叶片叶绿素含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性都呈先升后降的趋势。与生长盛期比较,枫香幼苗生长末期的叶绿素含量大幅下降;由于幼苗长期处于复合污染条件下,生长末期叶片SOD、POD活性均低于生长盛期的酶活性;且随着时间推移,枫香幼苗叶片中丙二醛(MDA)积累量有所升高。     

直链烷基苯磺酸盐(LAS)的生物降解性

阴离子表面活性剂直链烷基苯磺酸盐（LAS）在工业生产和人们生活中得到了广泛应用,但大量产生的含有LAS的污水在环境中造成的污染也日益严重,因而引起了人们的高度重视,本从LAS的好氧和厌氧生物降解以及LAS降解菌等诸多方面阐述了LAS生物降解性的研究进展。     

镉富集植物油菜与玉米间作对玉米吸收积累镉的影响

采用室内盆栽试验,在不同镉(Cd)添加水平下(0、2、5和10 mg·kg~(-1),分别记为Cd0、Cd2、Cd5和Cd10),研究玉米/油菜间作对营养生长期玉米生长和吸收积累Cd的影响。结果表明:间作促进了玉米生长,除Cd2处理外,间作玉米(Cd0、Cd5、Cd10)生物量比单作高19%~50%(P0.05);随着土壤中Cd浓度的增加,玉米各器官Cd含量也呈逐步增加的趋势,低、中浓度Cd污染条件下(Cd0、Cd2、Cd5),玉米/油菜间作可以阻控玉米地下部Cd向地上部转移,尤其是向叶转移,其中Cd2处理中间作玉米根系Cd含量与单作无显著差异,而间作玉米叶的Cd含量比单作低40%(P0.05);Cd5处理间作玉米根系Cd含量较单作显著增加25%(P0.05),而间作玉米叶的Cd含量较单作无显著增加;同处理间作玉米茎的Cd含量与单作间无显著差异;当土壤Cd污染浓度过高时,阻控作用会转变成促进效应,Cd10处理中间作玉米根系Cd含量与单作间无显著差异,而间作玉米叶、茎Cd含量比单作高17%、33%(P0.05);此外,土壤低、中浓度Cd污染条件下,间作对玉米单株Cd积累量的影响不明显,而高浓度Cd污染条件下(Cd10),间作显著提高玉米单株Cd积累量(61%)(P0.05)。因此,在低、中浓度Cd污染条件下,玉米/油菜间作对玉米吸收积累Cd有较明显的阻控效应,同时也是实现玉米安全、优质栽培的理想模式。     

镉胁迫下春小麦中镉的分布、富集及转移规律

采用盆栽试验,研究了镉胁迫下重金属镉(Cd)在春小麦中的分布、富集及转移规律。结果表明:Cd胁迫下,小麦根、茎、叶和籽粒中Cd积累量随外源Cd的增加而增加,小麦不同部位Cd积累量为根叶茎籽粒;籽粒中Cd含量与土壤中Cd显著相关;小麦不同部位对Cd的富集能力差异显著,且随外源Cd处理浓度的增加,各部位富集系数逐渐降低,低Cd浓度时各部位更易富集Cd;小麦植株地上部的转移系数亦呈递减趋势为茎、叶籽粒;在春小麦全生育期,土壤中Cd含量无明显变化,根对外源Cd的富集吸收于生育期70d左右达峰值,小麦植株中的Cd也在80d左右达到峰值后逐步减少,表明植株中的Cd,随籽粒的成熟逐步转移至籽粒。     

表面活性剂对长柔毛委陵菜(Potentilla griffithii var. velutina)修复重金属污染的促进作用

研究了十二烷基苯磺酸钠(SDBS)、十六烷基三甲基溴化铵(CTAB)、聚乙二醇辛基苯基醚(TritonX-100)等不同离子类型的表面活性剂对水稻土中重金属的解吸效果,并采用盆栽实验研究了上述3种表面活性剂对Zn超富集植物长柔毛委陵菜(Potentilla griffithii var. velutina)的生物量、吸收和富集重金属的影响.结果表明:CTAB对水稻土中Zn、Pb、Cd和Cu的解吸效果好于SDBS和TritonX-100,而且3种表面活性剂对各重金属的解吸率大小都为Cd>Zn>Cu>Pb.3种表面活性剂促进长柔毛委陵菜叶、柄和根的生物量增加了0.2～2.5倍,并且长柔毛委陵菜各部位的生物量大小为叶>柄>根.3种表面活性剂都增加了长柔毛委陵菜各部位对Zn、Cd吸收及其叶和柄对Pb、Cu的吸收,同时显著促进Zn、Pb、Cd和Cu从植物根部向地上部转运,从而增加了Zn、Pb、Cd和Cu在长柔毛委陵菜地上部的提取量和分布以及长柔毛委陵菜对Zn、Pb、Cd和Cu的富集能力;因此3种表面活性剂都提高了长柔毛委陵菜修复重金属污染土壤的效率.     

Dry Matter and Leaf Structure in Young Wheat Plants as Affected by Cadmium, Lead, and Nickel

The effects of 1 mM cadmium, lead and nickel on dry mass, Cd, Pb, and Ni contents, and changes in leaf structure in young wheat plants were studied. In leaves, Cd content was highest, followed by Pb and Ni, in roots Cd content was also highest, but followed by Ni and Pb. Roots accumulated considerably larger amounts of the three heavy metals than leaves. Largest reductions of leaf and root mass were obtained with Cd. Pb and Ni effects were almost equal. Ni excess had a strong negative effect on mesophyll thickness, while Cd mostly reduced the number and size of vascular bundles and vessel diameter. High Pb reduced the diameter of vessels causing their different deformations. This revised version was published online in July 2006 with corrections to the Cover Date.     

Remobilization of cadmium in maturing shoots of near isogenic lines of durum wheat that differ in grain cadmium accumulation.

Cadmium accumulation in grain of durum wheat (Triticum turgidum L. var. durum) represents a concern to consumers. In an effort to understand the regulation of Cd accumulation in maturing grain, the remobilization of 109Cd applied to stem and flag leaves was examined in two near-isogenic lines that differ in grain Cd accumulation. Absorbed 109Cd was primarily retained in the labelling flap (50-54% and 65-80% for stem and flag leaves, respectively). Cadmium exported from the stem flap initially (3 d) accumulated in the stem in a declining gradient towards the head. Subsequent remobilization of Cd deposited in the stem was associated with Cd accumulation in the grain. Cadmium exported from the flag leaf flap was primarily directed to the grain. Little (<1%) Cd accumulated in the glumes or rachis, and transport of Cd to shoot tissues below the flag leaf node was low (<1%). On average, 9% and 17% of absorbed 109Cd accumulated in the grain 14 d after labelling the stem and flag leaf, respectively. Irrespective of labelling position, the low Cd-accumulating isoline averaged 1.5-2-fold lower Cd accumulation per grain and Cd concentration in the grain than the high Cd-accumulating isoline. Cadmium accumulation in the grain was inversely correlated with Cd retention in the stem (stem labelled) and labelling flap (flag leaf labelled) for both isolines. Cadmium translocation to the grain was not inhibited by Zn when both were applied simultaneously (50 pM 109Cd; 0.5 microM 65Zn) to the flag leaf. These results show that elevated remobilization of Cd from the leaves and stem to the maturing grain may be partially responsible for the high accumulation of Cd in durum wheat grain.     

Leaf-applied sodium chloride promotes cadmium accumulation in durum wheat grain

Cadmium (Cd) accumulation in durum wheat grain is a growing concern. Among the factors affecting Cd accumulation in plants, soil chloride (Cl) concentration plays a critical role. The effect of leaf NaCl application on grain Cd was studied in greenhouse-grown durum wheat (Triticum turgidum L. durum, cv. Balcali-2000) by immersing (10 s) intact flag leaves into Cd and/or NaCl-containing solutions for 14 times during heading and dough stages. Immersing flag leaves in solutions containing increasing amount of Cd resulted in substantial increases in grain Cd concentration. Adding NaCl alone or in combination with the Cd-containing immersion solution promoted accumulation of Cd in the grains, by up to 41%. In contrast, Zn concentrations of grains were not affected or even decreased by the NaCl treatments. This is likely due to the effect of Cl complexing Cd and reducing positive charge on the metal ion, an effect that is much smaller for Zn. Charge reduction or removal (CdCl₂⁰ species) would increase the diffusivity/lipophilicity of Cd and enhance its capability to penetrate the leaf epidermis and across membranes. Of even more significance to human health was the ability of Cl alone to penetrate leaf tissue and mobilize and enhance shoot Cd transfer to grains, yet reducing or not affecting Zn transfer.     

Soil solution dynamics and plant uptake of cadmium and zinc by durum wheat following phosphate fertilization

A growth chamber study was conducted to evaluate the effect of application of phosphate fertilizer on soil solution dynamics of cadmium (Cd) and Cd accumulation in durum wheat (Triticum turgidum L. var. durum). Treatments consisted of three phosphate fertilizer sources containing 3.4, 75.2, and 232 mg Cd kg^?1 applied at three rates (20, 40 and 80 mg P kg^?1) plus a no fertilization control. An unplanted treatment at 40 mg P kg^?1 was included to separate the effects on soil solution Cd dynamics of the crop from that of the fertilizer. Soil solution samples were obtained using soil moisture samplers every 10 days after germination. The experimental results indicated that plant biomass significantly increased with P application rates and decreased with increased Cd concentration in the phosphate fertilizers. Total cadmium concentration in soil solution was not consistently affected by phosphate fertilization rate and fertilizer sources, and therefore Cd concentration in the fertilizer. Application of phosphate fertilizer, however, increased the concentration and accumulation of Cd and shoot Cd/Zn ratio, and decreased shoot Zn concentration in durum wheat. Phosphate sources had a marginally significant effect (P?=?0.05) on shoot Cd concentration and did not affect Cd accumulation in durum wheat. Concentration of Cd in soil solution was unrelated to Cd concentration in durum wheat. These results suggest that the immediate increase in Cd concentration and Cd accumulation in durum wheat with phosphate application is due more to competition between Zn and Cd for absorption into plants, enhanced root to shoot translocation and enhanced root development, than to a direct addition effect from Cd contained in phosphate fertilizer. In the short term, application of phosphate fertilizers can increase Cd concentration in the crops, regardless of the Cd concentration of the fertilizer. An optimal P fertilization, possibly in combination with Zn application, may offer an important strategy for decreasing Cd concentration and accumulation in crops.     

镉对小麦幼苗脂质过氧化和保护酶活性的影响

小麦幼苗经镉胁迫后,随着镉浓度的增高,叶征和根系中的膜脂过氧化产物丙二醛（ＭＤＡ）的含量和过氧物酶（ＰＯＤ）活性明显升高,超氧物歧化酶（ＳＯＤ）活性也有所提高。叶片中ＭＤＡ积累量和ＳＯＤ活性都高于根,而ＰＯＤ活性则是根高于叶片。随幼苗生长时间延长,叶片和根中的ＭＤＡ积累量增加,而ＳＯＤ活性却降低。     

Uptake and retranslocation of leaf-applied cadmium (109Cd) in diploid, tetraploid and hexaploid wheats

Uptake and retranslocation of leaf-applied radiolabeled cadmium (109Cd) was studied in three diploid (Triticum monococcum, AA), four tetraploid (Triticum turgidum, BBAA) and two hexaploid (Triticum aestivum, BBAADD) wheat genotypes grown for 9 d under controlled environmental conditions in nutrient solution. Among the tetraploid wheats, two genotypes were primitive (ssp. dicoccum) and two genotypes modern wheats (ssp. durum). Radiolabelled Cd was applied by immersing the tips (3 cm) of mature leaf into a 109Cd radiolabelled solution. There was a substantial variation in the uptake and export of 109Cd among and within wheat species. On average, diploid wheats (AA) absorbed and translocated more 109Cd than other wheats. The largest variation in 109Cd uptake was found within tetraploid wheats (BBAA). Primitive tetraploid wheats (ssp. dicoccum) had a greater uptake capacity for 109Cd than modern tetraploid wheats (ssp. durum). In all wheats studied, the amount of the 109Cd exported from the treated leaf into the roots and the remainder of the shoots was poorly related to the total absorption. For example, bread wheat cultivars were more or less similar in total absorption, but differed greatly in the amount of 109Cd retranslocated. The diploid wheat genotype 'FAL-43' absorbed the lowest amount of 109Cd, but retranslocated the greatest amount of 109Cd in roots and remainder of shoots. The results indicate the existence of substantial genotypic variation in the uptake and retranslocation of leaf-applied 109Cd. This variation is discussed in terms of potential genotypic differences in binding of Cd to cell walls and the composition of phloem sap ligands possibly affecting Cd transport into sink organs.     

Synergistic effects of cadmium and NaCl on the growth,photosynthesis and ion content in wheat plants

The addition of NaCl to cadmium had significant synergistic effect on the wheat root and shoot fresh mass, relative growth rate and net assimilation rate, while showed no significant effects on the dry mass production, leaf area, leaf area ratio, leaf mass ratio and specific leaf area. Additive depression of the rate of photosynthesis and the stomatal conductance was recorded, while no significant effect on the transpiration rate was observed. The Cd stress disturbed the mineral nutrition of the wheat plants either directly or indirectly, NaCl markedly reduce the uptake and internal concentration of K and Ca in the shoot. The combination of cadmium and NaCl showed no additive effects on the content of ions in the root as well as in the shoot of wheat plants.     

Cadmium tolerant and sensitive wheat lines: their differences in pollutant accumulation,cell damage,and autophagy

Cadmium (Cd) is a major abiotic stressor that affects plant growth and reduces the productivity of field crops. Here, we examined the ultrastructural, physiological, and molecular changes in three wheat cultivars [Sumai 3, Jingdong 8 (JD 8), and Nannong 9918 (9918)] in response to different concentrations of Cd (0, 10, 50, and 100 μM) in 1/4 Hoagland nutrient solution. The results showed that JD 8 contained the lowest shoot Cd content and the highest root Cd content among the three cultivars at higher Cd concentrations and so JD 8 was proposed to be a relatively Cd-tolerant cultivar. Next, the stress responses of JD 8 and 9918 were compared. Cadmium reduced root growth and size and number of the leaves, inhibited root hair development, and promoted leaf cell death. The result of trypan blue staining showed that the dead leaf cells induced by Cd stress gradually emerged in the xylem, supporting the hypothesis that cell death could restrict Cd transport. The Cd-induced deterioration of the leaf ultrastructure led to the complete disorganization of the chloroplasts, which had lower amounts of transitory starch and an increased number of osmiophilic granules compared to those in the untreated controls. Autophagy-related genes and autophagy in the leaves were induced by Cd stress. At the same concentration and Cd treatment time, the Cd-tolerant genotype JD 8 exhibited less toxic symptoms compared to the Cd-sensitive genotype 9918. The results of this study provide insights into the ultrastructural and physiological damages induced by Cd stress, which may help in selecting Cd-tolerant wheat cultivars.     

Interaction of NaCl and Cd stress on compartmentation pattern of cations,antioxidant enzymes and proteins in leaves of two wheat genotypes differing in salt tolerance

Physiological mechanisms of salinity–Cd interactions were investigated in inter- and intracellular leaf compartments of salt-tolerant wheat × Lophopyrum elongatum (Host) A. Löve (syn. Agropyron elongatum) amphiploid and its salt-sensitive wheat parent (Triticum aestivum L. cv Chinese Spring). In comparison with the intracellular fluid, only very low Na⁺ concentrations (up to about 4 mM) were found in the intercellular leaf compartment of wheat after a 75 mM supply of NaCl. NaCl salinity led to a higher Cd concentration in leaves of the salt-sensitive genotype. Cd in the intercellular leaf compartment was not detectable. Higher K⁺ concentrations in the intercellular leaf compartment of the salt-sensitive genotype suggest a higher plasma membrane permeability caused by NaCl + Cd stress. Ascorbate peroxidase (APX) activity was increased in leaves of the salt-sensitive genotype under the combined NaCl and Cd stress. The highest non-specific peroxidase activities were detected under the combined stresses. It is suggested that NaCl and Cd stress in combination enhance the production of oxygen radicals and H₂O₂, especially in leaves of the salt-sensitive genotype. As a consequence, disturbed membrane function may cause elevated Cd concentrations in the intracellular leaf compartment under salinity. Cd did not change protein concentration and pattern in leaves. The protein content in inter-and intracellular leaf compartments of both genotypes was increased under salinity. A different protein pattern was obtained in inter- and intracellular leaf compartments. Thus, several physiological interactions between NaCl stress and Cd were found in the two wheat genotypes.     

重金属对水稻和小麦DNA甲基化水平的影响

和对照相比,0．025（或0.05)-0.1mmol/L的Cu^2 （或0．05）－1．0mmol/L的Cd^2 或Hg^2 导致水稻（或小麦）叶DNA中的5－甲基胞嘧啶百分含量大幅度上升;当Cu^2 浓度＞0.1mmol/L时,小麦和水稻叶DNA中5－甲基胞嘧啶的百分含量随Cu^2 浓度的增高略有下降,但仍高于对照。0.1-1.0mmol/L的Cu^2 ,Cd^2 和Hg^2 也导致小麦穗DNA为5－甲基胞嘧啶的百分含量随Cu^2 ,Cd^ 和Cd^2 能使小麦和水稻根系DNA中5－甲基胞嘧啶的百分含量显著高于对照,而0.1-1.0mmol/L的Hg^2 以及1．0mmol/L的Cu^2 和Cd^2 则造成小麦和水稻根系DNA中5－甲基胞嘧啶的百分含量显著低于对照。