不同作物与玉米间作对玉米吸收积累镉的影响

采用盆栽技术,研究了7种间作作物对玉米吸收积累镉(Cd)的影响.结果表明,多数间作作物对玉米生物量没有明显影响,只有扁豆对玉米生长有较明显的抑制作用,使玉米生物量降至对照的67.8 %.间作豆科作物大幅提高玉米的Cd积累总量,其中鹰嘴豆的作用最为明显,使玉米对Cd的累积量增加1倍以上.7种间作植物对Cd也有不同水平的吸收,其中,油菜与籽粒苋可在地上部大量积累Cd（油菜地上部Cd浓度达53.9 mg·kg^-1,籽粒苋达51.0 mg·kg^-1),且籽粒苋根的Cd含量高达91.8 mg·kg^-1 (土壤Cd为3 mg·kg^-1).间作植物与玉米对Cd的吸收具有不同的交互作用特征,豆科作物在自身较少吸收Cd的条件下,显著提高了玉米对Cd的积累;籽粒苋在自身大量累积Cd的同时,一定程度上抑制了与其间作的玉米的Cd累积量;油菜地上部分吸收较多的Cd,但降低了玉米地上部分Cd含量.研究表明,如果将玉米作为大生物量的Cd污染修复植物来应用,可将其与豆科植物间作,以提高Cd清除效率;籽粒苋与油菜具有大量积累Cd的能力,可作为Cd污染土壤的修复植物.     

盐胁迫下构树幼苗各器官中K+、Ca2+、Na+和Cl-含量分布及吸收特征

将当年生构树幼苗置于含有不同浓度（04、1、2、3、4 g·kg^-1）NaCl的土壤中,研究其生物量积累、叶片细胞质膜透性和K⁺、Ca²⁺、Na⁺、Cl^-等离子的吸收、分布及运输,并观察盐害症状.结果表明：构树幼苗的叶片质膜透性随着NaCl浓度的增加和胁迫时间的延长而升高,根冠比随NaCl浓度的升高而增加,大于3 g·kg^-1的土壤盐胁迫对构树叶片的质膜透性及植株的生物量积累影响显著.构树幼苗各器官中Na⁺和Cl^-含量随土壤NaCl浓度升高而显著增加,K⁺和Ca²⁺则随之降低,叶片各离子含量均明显高于根和茎.说明盐胁迫影响根系对K⁺和Ca²⁺的吸收,并抑制了它们向地上部分的选择性运输,使叶和茎的K⁺和Ca²⁺含量下降.构树通过吸收积累Na⁺和Cl^-抵御土壤盐分带来的渗透胁迫,但过量的Na⁺和Cl^-积累会造成单盐毒害.作为抗盐性较高的非盐生植物,构树地上部分的拒盐作用不显著.     

印度芥菜-苜蓿间作对镉胁迫的生态响应

采用温室盆栽试验,研究了重金属镉（Cd）胁迫对印度芥菜和苜蓿间作下的土壤-植物系统的影响,同时对苜蓿的Cd饲用安全进行了评估.结果表明：在土壤Cd含量为0.37～20.37 mg·kg^-1范围内,与单作印度芥菜和苜蓿相比,间作使印度芥菜生物量降低了0.4%～11.8%,而使苜蓿生物量提高了55.3%~70.0%.土壤有效Cd主要受土壤全量Cd和种植植物种类的影响,种植方式对其影响不大.在土壤Cd含量为5.37 mg·kg^-1时,间作印度芥菜地上部Cd含量较单作提高了14.5%,而间作苜蓿地上部Cd含量较单作降低了57.1%;此时,单作和间作苜蓿地上部Cd含量分别为0.21和0.09 mg·kg^-1,均未超过饲料卫生限定标准(0.5 mg·kg^-1).在土壤Cd含量为10.37～20.37 mg·kg^-1范围内,虽然单作和间作苜蓿Cd含量均超过饲料卫生限定标准,但间作种植方式仍然使苜蓿地上部Cd含量较单作降低了2.8%～48.3%,印度芥菜地上部Cd含量也较单作降低了1.1%～48.6%.不论单作还是间作印度芥菜的Cd转运系数都远高于苜蓿.     

钙对土壤镉有效性的影响及其机理

采用盆栽试验,研究了赤红壤上两种镉污染水平下,施用4种钙量（0、40、100、200 mg·kg^-1）对小油菜生物量、镉吸收量及土壤溶液中钙、镉浓度的影响.结果表明：在低镉或者高镉污染水平下,与对照相比,小油菜干质量均以高钙用量处理的增幅最大,两季平均增加了5.5%（低镉）和17.3%（高镉）;增加钙的施用量,使土壤溶液中钙浓度明显增加,小油菜体内钙浓度也明显增加;当钙施用量为100 mg·kg^-1时,土壤溶液中镉浓度较对照分别增加74.5%（低镉）和31.0%（高镉）,而小油菜体内镉浓度较对照分别降低4.5％（低镉）和13.1％（高镉）.两种镉污染水平下,土壤溶液中钙/镉（质量比）值与小油菜体内镉浓度均呈显著正相关.土壤溶液中钙/镉比值影响土壤镉的有效性,进而影响小油菜对镉的吸收.     

蒸腾作用及根系特征对不同品种油菜吸收镉的影响

采用营养液培养试验研究了12个油菜品种地上部的镉含量、蒸腾速率和根系形态特征(根长、根表面积、根体积),并对不同品种油菜地上部镉含量与蒸腾速率和根系形态特征进行了相关分析。结果表明:不同品种油菜对镉的吸收累积有显著差异,油菜地上部镉含量以鲜质量计为1.8～4.4mg·kg-1,相差1.5倍,同时不同品种油菜的蒸腾速率与根系形态均存在显著性差异;蒸腾速率和根表面积、根体积均与不同油菜品种地上部镉浓度、吸镉总量呈显著正相关(P0.01),根长只与油菜吸镉总量呈显著正相关,表明高的蒸腾强度和发达的根系均能促进油菜地上部镉的累积量。     

镉在黄瓜和油菜中的运输与分布规律

采用水培方法,研究了黄瓜和油菜中镉的分配特点及根细胞壁对镉的亲和力,了解不同蔬菜根细胞壁对镉的吸收和运输的影响.结果表明:随着营养液中镉浓度的增加,黄瓜和油菜根中水和氯化钙提取镉的比例增加,而根中镉的比例降低;营养液中镉浓度在10 μmol·L-1时,根中水和氯化钙提取镉的比例占根中镉总量的10%以上;而营养液中镉浓度在1 μmol·L-1时,油菜根中水和氯化钙提取镉的比例仅占根中镉总量的2%;黄瓜根中氯化钙提取镉的比例高于油菜;在相同镉浓度处理下,油菜根和地上部镉的浓度明显高于黄瓜,并且油菜地上部与根部镉的比例高于黄瓜;植物根中镉的浓度是地上部的8～66倍,根细胞壁对镉有一定的固定作用,限制了镉从根向地上部的转移.     

不同品种小白菜对镉的吸收积累差异

通过盆栽试验,研究了60个小白菜品种在不同程度镉污染土壤中吸收和积累镉能力的差异.结果表明：在土壤镉浓度为0.6 mg·kg^-1时,小白菜镉含量超过国家标准的为8.33％;而在土壤镉浓度为1.2 mg·kg^-1时其超标率达66.67%,表明小白菜容易受到镉污染.2种镉浓度下白菜地上部分镉含量均低于国家食用标准,且其生物量不受影响的小白菜品种为：长梗白菜、上海青、矮箕苏州青、青优四号、矮脚葵翩黑叶白菜、皱叶黑油冬儿、高华青梗白菜、早生华京、金冠清江白、夏王青梗菜、利丰青梗白菜和杭州油冬儿.这12个品种可作为在镉轻度污染土壤中种植的安全系数较高的小白菜品种.     

上海市小羽藓属植物重金属含量及其与环境的关系

应用原子吸收法对上海市13个样点的小羽藓植物体及相应土壤样品中的Cu、Pb、Cd、Zn、Cr 5种重金属元素含量进行了测定.通过对植物体内含量的聚类分析,将13个样点按重金属污染程度的轻重分为3个组：1)污染严重点,包括桂林公园、复兴公园、光启公园3个样点,均位于市区交通繁忙地带,其小羽藓体内重金属含量分别为：Cu 35.25～50.36 mg·kg^-1、Pb 55.50～65.00 mg·kg^-1、Cd 1.68～2.30 mg·kg^-1、Zn 829.63～1140.13 mg·kg^-1、Cr 7.41～16.41 mg·kg^-1;2)污染点,包括长风公园、古钟园、中山公园、和平公园、上海师范大学徐汇校区5个样点,均位于市区近郊,小羽藓体内重金属含量分别为：Cu 18.51～62.50 mg·kg^-1、Pb 14.38～34.25 mg·kg^-1、Cd 0.81～1.40 mg·kg^-1、Zn 354.25～671.75 mg·kg^-1、Cr 3.62～25.08 mg·kg^-1;3)相对清洁点,包括佘山、大观园、罗泾、植物园、崇明东平国家森林公园5个样点,位于上海市远郊,小羽藓体内重金属含量分别为：Cu 11.13～16.41 mg·kg^-1、Pb 4.63～27.25 mg·kg^-1、Cd 0.93～1.28 mg·kg^-1、Zn 489.25～1 086.75 mg·kg^-1、Cr 1.53～7.62 mg·kg^-1.结果表明,小羽藓属苔藓植物可作为监测上海地区环境重金属污染的良好指示植物.苔藓植物体内重金属含量水平与土壤重金属含量存在一定的相关性,而且也受其他因素的影响.     

外源四环素对土壤酶活性和油菜品质的影响

通过向土壤中添加四环素溶液研究种植油菜条件下,不同浓度（0、0.30、0.60、0.90 mg·kg^-1）的外源四环素对土壤酶活性和油菜品质的影响.结果表明：各处理土壤的脲酶与0.90 mg·kg^-1浓度处理的土壤转化酶活性在整个培养期均受到抑制,0.30、0.60 mg·kg^-1浓度处理的土壤转化酶活性则表现为激活-抑制-激活趋势,各处理土壤蛋白酶活性表现为抑制-激活趋势,且土壤酶活性受到外源四环素的影响程度及持续时间与处理浓度呈正相关（r=0.950**）.各处理土壤过氧化氢酶活性在前期被激活,后期差异不明显.四环素对土壤脲酶、过氧化氢酶、转化酶和蛋白酶活性的作用时间分别为：7周、6～8周、7周和6～7周.收获时0.30、0.60、0.90 mg·kg^-1处理的油菜叶片中可溶性糖含量与对照相比分别下降91.99%、87.92%和90.12%,而可溶性蛋白质含量分别上升26.47%、28.13%和23.22%.     

镉处理对油菜生长和抗氧化酶系统的影响

通过盆栽实验研究了Cd处理对油菜生长和抗氧化酶系统的影响.结果表明,油菜整株鲜重、叶鲜重随Cd胁迫呈显著降低趋势.逐步回归表明,叶鲜重下降导致油菜整株鲜重下降.油菜叶细胞膜渗透性和MDA随Cd胁迫增大而增加.Cd处理浓度为20 mg·kg^-1时,叶细胞膜渗透性和MDA分别增加29.68％和15.19％,叶细胞膜渗透性和 MDA呈显著正相关,相关系数为0.823^*.Cd处理浓度为5 mg·kg^-1时,叶绿素a、b和a+b含量达到峰值,分别比对照高23.97%、33.63%和26.45%;Cd胁迫对类胡萝卜素含量无显著影响.几种色素对Cd敏感顺序为：叶绿素b>叶绿素a>叶绿素a+b>类胡萝卜素;3种抗氧化酶对Cd敏感顺序为：POD>CAT>SOD.各生理指标IC50表明,油菜只适宜种植在Cd含量小于5 mg·kg^-1的土壤中.     

长柔毛委陵菜对锌的吸收动力学特性

采用水培方法研究了不同Zn处理水平和处理时间下长柔毛委陵菜对锌的吸收动力学特性. 结果表明,在10 mg·L^-1 Zn处理下,植株地上部和根系的Zn含量均在第8天达到最高值,分别为2.49×10³ mg·kg^-1和2.21×10³ mg·kg^-1;在100 mg·L^-1 Zn处理下,植株地上部的Zn含量在第16天达最高值1.23×10³ mg·kg^-1,而根系Zn含量不存在饱和现象. 在0～160 mg·L^-1 Zn处理下,植株叶片和叶柄Zn含量随Zn处理水平的提高显著增加,Zn浓度大于160 mg·L^-1后, 植株叶片和叶柄Zn含量不再随介质中Zn浓度的提高而增加（甚至减少）, 根系含Zn含量与介质中的Zn浓度和培养时间呈正相关,且根系Zn吸收动力学曲线具有二型性,即开始为快速的线性吸收,随后是较缓慢的饱和吸收,两者分界点约在1～2 h,这可能分别与根细胞壁吸附Zn和Zn跨根细胞膜运输有关.     

Hyperaccumulation of cadmium by roots, bulbs and shoots of garlic (Allium sativum L.)

The effects of cadmium chloride concentration on root, bulb and shoot growth of garlic (Allium sativum L.), and the uptake and accumulation of Cd2+ by garlic roots, bulbs and shoots were investigated. The range of cadmium chloride (CdCl2 x 2.5H2O) concentrations was 10(-6) - 10(-2) M. Cadmium stimulated root length at lower concentrations (10(-6) - 10(-5) M) significantly (P < 0.005) during the entire treatment period. The seedlings exposed to 10(-3) - 10(-2) M Cd exhibited substantial growth reduction (P < 0.005), but did not develop chlorosis. Garlic has considerable ability to remove Cd from solutions and accumulate it. The Cd content in roots of garlic increased with increasing solution concentration of Cd2+. The roots in plants exposed to 10(-2) M Cd accumulated a large amount of Cd. approximately 1,826 times the control. The Cd contents in roots of plants treated with 10(-3), 10(-4), 10(-5) and 10(-6) M Cd were approximately 114, 59, 24 and 4 times the control, respectively. However, the plants transported only a small amount of Cd to their bulbs and shoots and concentrations in these tissues were low.     

The role of root damage in the chelate-enhanced accumulation of lead by Indian mustard plants

In the present study, increasing ethylenediaminetetraacetic acid (EDTA) concentration from 0 to 0.5 mmol L(-1) resulted in progressive increases in root elongation and in shoot and root dry matter (DM) of Indian mustard seedlings (Brassica juncea. L.) exposed at 0.5 mmol L(-1) of lead (Pb). The highest concentration of Pb in the shoots of Indian mustard reached 1140 mg kg(-1) dry weight (DW) in the treatment with 0.5 mmol L(-1) of Pb + 0.25 mmol L(-1) of EDTA. A significantly positive correlation was found between the concentrations of Pb and EDTA in the shoots of mustard. Roots were pretreated with an MC (methanol:trichloromethane) solution, 0.1 mol L(-1) of HCl, and 65 degrees C hot water. The plants were then exposed to 0.5 mmol L(-1) of Pb + 3 mmol L(-1) of EDTA in solution for 2 d. The pretreatments with MC, HCl, and hot water all increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Therefore, some physiological damage to roots would be useful to enhance the uptake of metal by plants and to minimize the application of doses of chelates in the practical operation of chelate-assisted phytoremediation.     

土施L-蛋氨酸、L-苯基丙氨酸、L-色氨酸对玉米生长和养分吸收的影响

通过盆栽试验,研究了3种植物生长调节剂前体物质对玉米生长发育和养分吸收的影响,并确定了其适宜用量.结果表明,土施L蛋氨酸(L-MET)、L-苯基丙氨酸(L-PHE)和L-色氨酸(L-TRP)能不同程度地增加玉米株高、地上部和地下部干重,提高玉米根系活力、体内硝酸还原酶和过氧化氢酶的活性,促进玉米对氮、磷、钾、锌养分的吸收.在所有供试浓度中,以土施L-MET0.0185～0.185mg·kg^-1、L-PHE0.2mg·kg^-1和L-TRP0.03～0.3mg·kg^-1效果最佳,而且L-PHE和L-TRP对玉米生长的促进作用和提高养分的吸收能力均优于L-MET.     

Cadmium hyperaccumulation protects Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis)

Metal hyperaccumulation has been proposed as a plant defensive strategy. Here, we investigated whether cadmium (Cd) hyperaccumulation protected Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis). Two ecotypes differing in Cd accumulation, Ganges (high) and Prayon (low), were grown in compost amended with 0-1000 mg Cd kg(-1) in two experiments under glasshouse conditions. F2 and F3 plants from the Prayon x Ganges crosses were grown with 5 mg Cd kg(-1). Plants were naturally colonized by thrips and the leaf feeding damage index (LFDI) was assessed. The LFDI decreased significantly with increasing Cd in both ecotypes, and correlated with shoot Cd concentration in a log-linear fashion. Prayon was more attractive to thrips than Ganges, but the ecotypic difference in the LFDI was largely accounted for by the shoot Cd concentration. In the F2 and F3 plants, the LFDI correlated significantly and negatively with shoot Cd, but not with shoot zinc (Zn) or sulphur (S) concentrations. We conclude that Cd hyperaccumulation deters thrips from feeding on T. caerulescens leaves, which may offer an adaptive benefit to the plant.     

Heavy-metal ion uptake by plants from nutrient solutions with metal ion,plant species and growth period variations

Summary Rape, cucumber, wheat, oats and tomato were grown for one to two weeks in nutrient solutions with heavy metals added. Of the metal ions tested (Cr³⁺, Cu²⁺, Co²⁺, CrO₄ ^2-, Ni²⁺, Cd²⁺, Pb²⁺, Mn²⁺, Zn²⁺ and Ag⁺), manganese, nickel and lead exhibited the greatest mobility in cucumber plants, which resulted in the highest shoot/root concentration ratio. Silver was not translocated to the shoots of cucumber plants in measurable amounts.When the plants were grown with 1.0, 10 and 100 M cadmium or nickel in the solution, the shoot and root concentration increased 5–10 times if the metal ion concentration of the solution was increased 10 times.The plants showed great differences in cadmium and nickel uptake. In the shoot, the cadmium concentration increased in the order: oats = wheat < cucumber = rape < tomato, and in the root in the order: oats = wheat < cucumber = rape < tomato. The great uptake of cadmium and nickel by tomato is notable and agrees with other reports.The nickel, and especially the cadmium, concentration in roots and shoots increases with the age of the plant.The results are discussed and related to other investigations. The need for research on the uptake mechanisms of non-essential heavy metals is emphasized. re]19750415     

Effect of iron plaque outside roots on nutrient uptake by rice (Oryza sativa L.). Zinc uptake by Fe-deficient rice

This solution culture study examined the effect of the deposition of iron plaque on zinc uptake by Fe-deficient rice plants. Different amounts of iron plaque were induced by adding Fe(OH)₃ at 0, 10, 20, 30, and 50 mg Fe/L in the nutrient solution. After 24 h of growth, the amount of iron plaque was correlated positively with the Fe(OH)₃ addition to the nutrient solution. Increasing iron plaque up to 12.1 g/kg root dry weight increased zinc concentration in shoots by 42% compared to that at 0.16 g/kg root dry weight. Increasing the amount of iron plaque further decreased zinc concentration. When the amounts of iron plaque reached 24.9 g/kg root dry weight, zinc concentration in shoots was lower than that in shoots without iron plaque, implying that the plaque became a barrier for zinc uptake. While rice plants were pre-cultured in –Fe and +Fe nutrient solution in order to produce the Fe-deficient and Fe-sufficient plants and then Fe(OH)₃ was added at 20, 30, and 50 mg Fe/L in nutrient solution, zinc concentrations in shoots of Fe-deficient plants were 54, 48, and 43 mg/kg, respectively, in contrast to 32, 35, and 40 mg/kg zinc in shoots of Fe-sufficient rice plants. Furthermore, Fe(OH)₃ addition at 20 mg Fe/L and increasing zinc concentration from 0.065 to 0.65 mg Zn/L in nutrient solution increased zinc uptake more in Fe-deficient plants than in Fe-sufficient plant. The results suggested that root exudates of Fe-deficient plants, especially phytosiderophores, could enhance zinc uptake by rice plants with iron plaque up to a particular amount of Fe.     

Effect of iron plaque outside roots on nutrient uptake by rice (Oryza sativa L.): Phosphorus uptake

Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots have been shown to affect the uptake of some nutrients. In the present experiment, different amount of this iron plaque were induced on the roots of rice (Oryza sativa L. cv. TZ88-145) by supplying different Fe(OH)₃ concentrations in nutrient solutions, and the effect of the iron plaque on phosphorus uptake was investigated. Results showed that 1) iron plaque adsorbed phosphorus from the growth medium, and that the amount of phosphorus adsorbed by the plaque was correlated with the amount of plaque; 2) the phosphorus concentration in the shoot increased by up to 72% after 72 h at concentration of Fe(OH)₃ in the nutrient solution from 0 to 30 mg Fe/L, corresponding with amounts of iron plaque from 0.2 to 24.5 mg g^-1 (root d. wt); 3) the phosphorus concentration in the shoots of rice with iron plaque was higher than that without iron plaque though the concentration in the shoot decreased when Fe(OH)₃ was added at 50 mg Fe/L producing 28.3 mg g^-1 (root d. wt) of plaque; and 4) the phosphorus concentrations in Fe-deficient and Fe-sufficient rice plants with iron plaque were the same, although phytosiderophores were released from the Fe-deficient roots. The phytosiderophores evidently did not mobilise phosphorus adsorbed on plaque. The results suggest that iron plaque on rice plant roots might be considered a phosphorus reservoir. This revised version was published online in June 2006 with corrections to the Cover Date.     

The use of chloro-complexation to enhance cadmium uptake by Zea mays and Brassica juncea: testing a "free ion activity model" and implications for phytoremediation

Maize and Indian mustard plants were studied to: 1) investigate the effect of Cl- complexation on Cd uptake from soil historically amended with sewage sludge (Cd 58 mg kg(-1)) and, 2) model the uptake of Cd by these plants with a Free Ion Activity Model (FIAM). Plants were treated with NaCl (50 to 300 mM in the soil pore water) along with controls using Na2SO4. Cadmium enhanced solubility in soil by Cl- generally reflected increases in Cd uptake by both plants. The free ion Cd2+ activity in soil solution, as modeled by WHAM-VI, remained almost unchanged despite the wide range of NaCl concentrations. Therefore, Na+ exchange for Cd2+ could not fully explain the differences in Cd content between the Cl- treatments because of the high buffering Cd2+ capacity in soiL Activities of Cd-chloro complexes showed the best correlations with the Cd concentrations in the plants compared to the activity of Cd2+. The FIAM showed a reasonable good fit for the plants when assuming competition by Cd2+ and CdCl+ for root sorption sites. Indirect evidence suggests that CaSO4 precipitation may have limited the formation of CdSO4 complexes and reduced Cd soil solubility. The implications of these results for phytoremediation are discussed.