茄子苗对镉积累和耐性的品种间差异

通过盆栽实验方法研究了13种茄子幼苗对镉(Cd)积累与耐性的品种间差异。结果表明,这些茄子幼苗根及地上部Cd含量均随土壤中外加Cd的量的增加而提高。品种间存在着显著差异(P<0.05),其中Cd含量最高品种根部和地上部的Cd含量分别为Cd含量最低品种的2.1、2.4倍(2mg·kg-1Cd处理组)和1.5、1.6倍(4mg·kg-1Cd处理组)。不同品种幼苗对Cd的富集系数均大于1,表现出较强的富集能力。但转运系数均小于1,Cd从根部向地上部转移能力较弱,大多数品种间差异不大。当Cd添加量为2mg·kg-1时,只有绿龙长茄地上部生物量显著下降(P<0.05)。当Cd添加量提高到4mg·kg-1时,6个品种地上部生物量显著下降(P<0.05),这些品种对Cd的耐性较弱。综合评价,辽茄三号对Cd积累的含量最低,富集系数和转移系数也较低,对Cd具有较强的耐性,具有Cd低积累特征。     

Genotype variations in accumulation of cadmium and lead in celery (Apium graveolens L.) and screening for low Cd and Pb accumulative cultivars

To help reduce risks of heavy metal pollution, two pot experiments were conducted to investigate the variations, transfer potential, and stability of Cadmium (Cd) and Lead (Pb) accumulations in celery (Apium graveolens L.) and to screen for low Cd and Pb accumulative cultivars. The maximum differences in shoot Cd concentration were 4.7-fold under low-Cd exposure and 3.3-fold under high-Cd exposure. These genotype variations in Cd accumulation are sufficiently large to help reduce Cd contamination risk in soil by using the Low-Cd-Accumulative genotypes. Cd accumulation of the Low-Cd-Accumulative genotypes is significantly positive correlated with Pb accumulation. Evidence obtained proves that Cd and Pb accumulations in celery are stable and genotype-dependent at the cultivar level. The presence of high-Pb contamination in soil promoted Cd accumulation in shoots of celery. Celery is considered a species with high risks in Cd pollution and low risks in Pb pollution. Among the tested cultivars, cv. Shuanggangkangbing (SGKB) had the lowest shoot Cd and Pb accumulating abilities, and thus is the most important material for breeding of pollution-safe cultivars (PSCs) to minimize Cd and Pb accumulations in celery.     

Variations between rice cultivars in root secretion of organic acids and the relationship with plant cadmium uptake

To attempt to understand certain mechanisms causing the variations between rice cultivars with regard to Cd uptake and accumulation, pot soil experiments were conducted with two rice cultivars at different levels of Cd, i.e., 0 (the control), 10, 50 mg Cd kg⁻¹ soil. The two rice cultivars differ significantly with regard to Cd uptake and accumulation. Root secretions of low-molecular-weight organic acids (LMWOA) for each treatment were measured with ion chromatography. The results showed that LMWOA concentrations in the soil planted with Shan you 63 (a high soil Cd accumulator) were all higher than those in the soil planted with Wu yun jing 7 (low soil Cd accumulator) at different soil Cd levels, although the magnitudes of the differences varied for individual LMWOA and depend on soil Cd concentrations. For all six LMWOA, there were significant differences at P < 0.05 or < 0.01 levels for soils treated with 10 and 50 mg kg⁻¹ Cd. The magnitude of the differences was greater under soil Cd treatments, especially at relatively low levels (for example, 10 mg Cd kg⁻¹ soil), than in the control. Acetic acid and formic acid constituted more than 96% of the total concentration of the six LMWOA, while citric acid constituted only about 0.1%. The rice cultivar with higher concentrations of LMWOA in soil accumulated more Cd in the plants. The results indicate that LMWOA secretion by rice root, especially in Cd-contaminated soils, is likely to be one of the mechanisms determining the plant Cd uptake properties of rice cultivars.     

2种常规水稻Cd、Zn吸收与器官分配的生育期变化：品种、土壤和Cd处理的影响

Cd在土壤-作物-膳食食物链中的迁移是人类对环境Cd暴露及其健康风险的主要途径,而水稻是子粒Cd积累最强的大宗作物之一.采用全生育期淹水盆栽试验研究了2种常规水稻(高Cd吸收品种“苏香粳1号”和低Cd吸收品种“99-22”)在添加Cd(2mg·kg-1)和不添加Cd处理下对2种土壤(红沙泥田,乌栅土)中Cd、Zn的吸收及其生育期变化.结果表明:1)常规水稻对Cd、Zn的吸收积累受土壤、品种和外源Cd的影响.Cd处理、土壤、品种间的正交互作用(高Cd吸收品种植于高Cd处理且Cd有效性高的红壤中)使常规稻植株Cd/Zn比成数十倍提高,从而使子粒Cd/Zn比产生强烈升高;2)水稻对Cd、Zn的吸收强度因不同生育期而异,Cd吸收的主要时期是分蘖期和成熟期,而Zn吸收的主要时期则是分蘖期、抽穗期和灌浆期.在整个生育期中,水稻Cd吸收伴随着对Zn的排斥现象,这在高Cd吸收下尤为强烈;3)水稻各器官对Cd、Zn的吸收分配无论是同品种的生育期间抑或同生育期时的不同品种间均有显著差异.Cd积累量为根系>穗粒>茎叶,而Zn却表现为茎叶>根系、穗粒.观察到水稻吸收的Cd在生育后期向穗粒的强烈运移.相对于低Cd吸收品种来说,Cd向穗粒转运较强,而Zn的转运较弱是高Cd吸收品种子粒Cd积累强而Cd/Zn比高的植株因素.     

Water management affects arsenic and cadmium accumulation in different rice cultivars

Paddy rice (Oryza sativa L.) is a staple food and one of the major sources of dietary arsenic (As) and cadmium (Cd) in Asia. A field experiment was conducted to investigate the effects of four water management regimes (aerobic, intermittent irrigation, conventional irrigation and flooding) on As and Cd accumulation in seven major rice cultivars grown in Zhejiang province, east China. With increasing irrigation from aerobic to flooded conditions, the soil HCl-extractable As concentrations increased significantly and the HCl-extractable Cd concentrations decreased significantly. These trends were consistent with the As and Cd concentrations in the straw, husk and brown rice. Water management both before and after the full tillering stage affected As and Cd accumulation in the grains. The intermittent and conventional treatments produced higher grain yields than the aerobic and flooded treatments. Cd concentrations in brown rice varied 13.1–40.8 times and As varied 1.75–8.80 times among the four water management regimes. Cd and As accumulation in brown rice varied among the rice cultivars, with Guodao 6 (GD6) was a low Cd but high-As-accumulating cultivar while Indonesia (IR) and Yongyou 9 (YY9) were low As but high-Cd-accumulating cultivars. Brown rice Cd and As concentrations in the 7 cultivars were significantly negatively correlated. The results indicate that As and Cd accumulated in rice grains with opposite trends that were influenced by both water management and rice cultivar. Production of ‘safe’ rice with respect to As and Cd might be possible by balancing water management and rice cultivar according to the severity of soil pollution.     

Comparisons in subcellular and biochemical behaviors of cadmium between Iow-Cd and high-Cd accumulation cultivars of pakchoi （Brassica chinensis L.）

Subcellular distributions and chemical forms of cadmium （Cd） in the leaves, stems and roots were investigated in low-Cd accumulation cultivars and high-Cd accumulation cultivars ofpakchoi （Brassica chinensis L.）. Root cell wall played a key role in limiting soil Cd from entering the protoplast, especially in the low-Cd cultivars. The high-Cd cultivars had significantly higher leaf and stem Cd concentrations than the low-Cd cultivars in cell wall fraction, chloroplast/trophoplast fraction, organelle fraction and soluble fraction. In low-Cd cultivars, which were more sensitive and thus had greater physiological needs of Cd detoxification than high-Cd cultivars, leaf vacuole sequestrated higher proportions of Cd. Cd in the form of pectate/protein complexes （extracted by 1 tool. L~ NaC1） played a decisive role in Cd translocation from root to shoot, which might be one of the mechanisms that led to the differences in shoot Cd accumulation between the two types of cultivars. Furthermore, the formation of Cd- phosphate complexes （extracted by 2% HAc） was also involved in Cd detoxification within the roots of pakchoi under high Cd stress, suggesting that the mechanisms of Cd detoxification might be different between low- and high-Cd cultivars.     

镉和温度预暴露对小麦吸收镉的影响

土壤中重金属Cd污染是一个累积过程,污染历史会影响植物对土壤中Cd的吸收.近年来,随着全球气候的变暖,温度对Cd的生物有效性的影响日益引起关注.通过模拟土壤溶液,研究了Cd的浓度、温度和预暴露时间对小麦吸收Cd的影响.小麦在浓度为0.01和0.1μmol·L-1的Cd中经过不同时间的预暴露后进行6h的短期吸收实验.结果发现,经1d预暴露后,小麦根部吸收Cd的量有增加趋势,这说明Cd对小麦产生了刺激作用,小麦地上部分的含Cd量也有所增加但不显著.经5d预暴露后,小麦对Cd产生了抗性,这使得小麦根部降低了对Cd的吸收量;并且当Cd为0.1μmol·L-1时,根部Cd吸收量的降低最为明显;由于Cd从根部向地上部迁移是一个复杂的生理过程,预暴露对地上部分Cd含量的影响没有根具有规律性;经过37℃高温胁迫4h后,小麦根部及地上部分的Cd含量减少高达40%;预暴露和高温共同作用后,其减少量更多,这说明预暴露和高温共同作用能够减少小麦对Cd的吸收量.     

砷胁迫下水磷耦合对不同磷效率水稻根表铁膜及其各部位砷含量的影响

为探索缓解水稻砷毒害的农艺措施,以耐低磷水稻99011和低磷敏感水稻99012为材料,通过土培试验,研究水分、磷用量及其交互作用对不同砷浓度酸性土壤中水稻根表铁膜以及植物体内砷分配的影响。结果表明,节水灌溉(干湿交替)明显减少水稻根表铁膜量,降低铁膜、根系、秸秆、颖壳和精米中的砷含量。与30mg·kg-1P2O5相比,180mg·kg-1P2O5能明显减少两个品种水稻的根表铁膜量以及根系和秸秆中的砷含量;对耐低磷品种铁膜砷含量影响不大,但显著降低磷敏感品种铁膜砷含量;在50mg·kg-1砷处理中增加磷用量对水稻颖壳砷含量影响不大,在100mg·kg-1砷处理时能显著降低颖壳砷含量;增加磷用量可明显增加耐低磷品种的精米砷含量,降低磷敏感品种的精米砷含量。水、磷交互效应主要受水分效应的影响。加砷处理后,相同处理下耐低磷品种的根表铁膜量和铁膜中的砷含量显著高于磷敏感品种,而根系、秸秆、颖壳和精米中的砷含量则相反。研究表明,可以通过节水灌溉,并根据砷污染程度和植物磷营养特性确定适当的磷肥用量,从而减少砷在水稻体内的累积,提高食品安全。     

不同锰处理对镉胁迫下2种油菜重金属累积和根系形态的影响

采用水培试验,研究Cd胁迫(10μmol·L~(-1))条件下,不同浓度Mn(0,0.1,1,10,100μmol·L~(-1))处理对2种镉累积能力不同的油菜生物量、Cd和Mn含量以及根系形态参数的影响。结果表明,与正常营养处理Mn1相比,缺Mn和Mn过量处理显著降低2种油菜的地上部和镉低积累油菜"华骏"的根部生物量,而对普通油菜"寒绿"的根部生物量没有显著影响。与Mn1处理相比,缺Mn处理下2种油菜的Cd累积总量和"华骏"地上部Cd含量显著降低;Mn过量处理下2种油菜根部和地上部Cd含量均呈升高趋势,2种油菜的Cd累积总量无显著变化或显著降低。随Mn处理浓度升高,2种油菜地上部和根部Mn含量显著升高,缺Mn处理下2种油菜根部的Mn含量低于Mn缺乏的临界值。与Mn1处理相比,缺Mn处理下"华骏"的根长、表面积、体积、平均直径和根尖数显著降低;Mn过量处理下"寒绿"的根长以及"华骏"的根系表面积、体积显著降低;缺Mn处理下2种油菜细根表面积所占的比例增加,粗根表面积比例降低;Mn过量时,"寒绿"的粗根表面积比例增加,细根比例降低,而"华骏"则相反。总的来看,缺Mn处理影响油菜根系和地上部生长,减少地上部Cd含量和植株Cd累积总量;Mn过量处理下油菜生长也受到抑制,但是油菜地上部和根部Cd含量有所升高;2种油菜的根系形态学参数在不同Mn处理下变化规律不同,表现出不同的响应策略。     

玉米（Zea mays）对镉积累与转运的品种差异研究

通过田间实验,研究了25个玉米（Zea mays）品种在Cd质量分数为50 mg·kg-1胁迫条件下,Cd对不同玉米品种生长的影响,以及不同玉米品种对Cd积累和转运的品种差异,以期筛选出Cd低积累玉米品种。结果表明：25个玉米品种的生物量和产量对Cd胁迫的响应,以及不同品种根、茎叶和籽粒对Cd的吸收、累积及转运能力存在显著差异（P＜0.05）。有20个品种生物量和19个品种产量下降;有2个品种籽粒的Cd质量分数超过了国家规定的食品卫生标准（≤0.1 mg·kg-1）,占供试品种的8.0%,所有品种茎叶的Cd质量分数均超过了国家规定的饲料卫生标准（≤0.5 mg·kg-1）,超标率为100%;25个玉米品种的富集系数范围为0.063~0.899、茎叶转运系数范围为0.038~0.554、籽粒转运系数范围为0.000~0.111,均小于1,其中有8个品种富集系数〉0.5,1个品种茎叶转运系数〉0.5,而所有品种的籽粒转运系数均〈0.5,说明玉米对土壤Cd仍有一定的吸收能力,但地下部向地上部转运能力以及由茎叶向籽粒的转运能力较弱;根据玉米生物量、产量、籽粒Cd含量以及对Cd的富集系数和转运系数等指标进行评价,认为云瑞8号、会单4号、路单7号3个品种可作为Cd低累积玉米品种,可在云南Cd重度污染土壤上推广种植。     

Influence of iron plaque on chromium accumulation and translocation in three rice (Oryza sativa L.) cultivars grown in solution culture

Hydroponic experiments were conducted to investigate the role of iron plaque on root surface in chromium accumulation and translocation in three rice cultivars (90-68-2, CDR22 and Jin 23A). Rice seedlings were grown under 1.0 mg L^?1 trivalent chromium (Cr(III)) stress with and without phosphorus (P) treatments. P addition significantly increased the shoot and root biomass in all three rice cultivars. In the absence of P, the amounts of iron plaque (DCB-extractable Fe) on the root surface increased resulting in the increase of Cr accumulation in iron plaque. Compared to that with P treatment, Cr concentrations in iron plaque without P treatment were enhanced by 2–3 folds in the three rice cultivars. There was a significantly positive correlation between DCB-extractable Cr and DCB-extractable Fe on the root surface of the three rice cultivars. There were no significant effects on Cr concentration in roots and shoots between P treatments, but significant differences among cultivars were observed. Cultivar Jin 23A had the lowest Cr concentration both in roots and shoots regardless of P treatment. The results suggest that iron plaque could be a trap for immobilising Cr from environment but may not affect Cr uptake and translocation. Screening and breeding the cultivars with low Cr accumulation is considered as the most effective approach in Cr contaminated areas.     

Effects of cadmium on nutrient uptake and translocation by Indian Mustard

Plants that hyperaccumulate metals are ideal subjects for studying the mechanisms of metal and mineral nutrient uptake in the plant kingdom. Indian Mustard (Brassica juncea) has been shown to accumulate moderate levels of Cd, Pb, Cr, Ni, Zn, and Cu. In this experiment, 10 levels of Cd concentration treatments were imposed by adding 10-190 mg Cd kg(-1) to the soils as cadmium nitrate [Cd(NO3)2]. The effect of Cd on phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and the micronutrients iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in B. juncea was studied. Plant growth was affected negatively by Cd, root biomass decreased significantly at 170 mg Cd kg(-1) dry weight soils treatment. Cadmium accumulation both in shoots and roots increased with increasing soil Cd treatments. The highest concentration of Cd was up to 300 mg kg(-1) d.w. in the roots and 160 mg kg(-1) d.w. in the shoots. The nutrients mainly affected by Cd were P, K, Ca, Fe, and Zn in the roots, and P, K, Ca, and Cu in the shoots. K and P concentrations in roots increased significantly when Cd was added at 170 mg kg(-1), and this was almost the same level at which root growth was inhibited. Zn concentrations in roots decreased significantly when added Cd concentration was increased from 50 to 110 mg kg(-1), then remained constant with Cd treatments from 110 to 190 mg kg(-1). However, Zn concentrations in the shoots seemed less affected by Cd. It is possible that Zn uptake was affected by the Cd but not the translocation of Zn within the plant. Ca and Mg accumulation in roots and shoots showed similar trends. This result indicates that Ca and Mg uptake is a non-specific process.     

典型菜地土壤汞在小白菜和胡萝卜可食部位的富集规律

对广东省蔬菜种植面积较大的10个城市典型菜地土壤和蔬菜（小白菜和胡萝卜）对应采样,分析217个蔬菜可食部位中重金属汞（Hg）质量分数及对应土壤中Hg全量和有效态质量分数,研究大田条件下小白菜和胡萝卜可食部位富集Hg的规律。结果表明,广东省菜地土壤存在一定的Hg污染,约20％的土壤超过国家土壤环境质量标准（GBl5618－1995）中二级标准值,但小白菜和胡萝卜中Hg质量分数较低,均值分别为0．0012和0．0013mg·kg-1,仅2个小白菜样品Hg质量分数超过国家食品卫生标准《食品中污染物限量》（GB2762-2005）中的限值0．01mg·kg-1。TGA提取的土壤有效态Hg质量分数与土壤Hg全量显著正相关,TGA提取Hg量仅占土壤总Hg质量分数的3％-4％。小白菜和胡萝卜对Hg的富集系数分别为0．90％和0．94％,表明土壤中绝大部分的Hg不易转化迁移、为蔬菜吸收。小白菜和胡萝卜可食部位Hg质量分数与土壤中Hg全量和有效态质量分数均存在显著的线性关系,其中蔬菜与土壤Hg有效态质量分数的关系优于其与土壤Hg全量的关系。依据国家食品卫生标准,通过拟合回归方程计算出的保障小白菜和胡萝b质量安全的菜地土壤Hg有效态质量分数临界值分别为O．038和0．063mg·kg-1。计算出的土壤Hg全量临界值远大于我国现行土壤环境质量标准的二级标准值,表明该标准值对于保障广东省小白菜和胡萝b质量安全来说可能过于严格。     

根表铁锰膜对不同生育期水稻吸收和转运As的影响

采用土壤盆栽试验法,研究不同生育期水稻根表铁锰膜形成及其对As吸收和转运的影响。结果表明,两个水稻品种YD6和NK57均在分蘖期形成的铁锰膜量最多,成熟期形成的铁锰膜量最少。水稻根系和茎叶吸收积累As随着水稻不同品种和不同生育期变化较大,As的吸收和积累与铁锰膜形成存在相关性。与分蘖期相比,YD6和NK57成熟期根系As含量分别减少81.6%和62.1%。孕穗期YD6和NK57茎叶As含量分别比分蘖期减少86.4%和65.5%,比成熟期减少87.8%和67.1%。分蘖期水稻根系和茎叶As含量与DCB-Fe或DCB-Mn浓度均呈显著的负相关关系,而孕穗期水稻根系和茎叶As含量与DCB-Fe浓度呈显著的正相关关系,说明不同生育期铁锰膜对水稻植株吸收和转运As的影响不同。两个水稻品种不同生育期,As均主要富集和分配在根表铁锰膜中,铁锰膜中As的分配比率达62.9%～84.9%。NK57从根表铁锰膜、根系和茎叶向籽粒转运As的能力比YD6强,籽粒中As含量是YD6的2.1倍。结果表明可以通过选育As低积累和低转运的水稻品种,来降低污染地区As对人体健康的威胁。     

根表铁膜对水稻铅吸收转运的影响

通过温室土壤盆栽试验研究不同生育期水稻根表铁膜形成对水稻吸收和转运Pb的影响。结果表明,两种水稻根表铁膜形成量(以DCB-Fe含量计)及铁膜中吸附的Pb量均随着生育期的延长而减少。水稻根表铁膜Fe含量与铁膜吸附的Pb量呈显著的正相关关系(r=0.798,p0.01)。水稻根系和茎叶吸收积累Pb随着不同品种和不同生育期而变化。品种NK57籽粒Pb含量显著高于品种YD6,前者为后者的1.9倍。从富集系数和分配比率来看,Pb主要富集在水稻的铁膜和根系中,而积累在茎叶和籽粒中的比率较少。Pb从水稻根表铁膜、根系和茎叶向籽粒中的转运系数在两个水稻品种间差异均不显著。水稻分蘖期和孕穗期根表铁膜量与根系Pb含量均呈显著的正相关关系(p0.05),但是成熟期水稻根表铁膜量与根系、茎叶和籽粒中Pb含量相关性均不显著,说明根表铁膜形成对水稻分蘖期和孕穗期吸收积累Pb有一定影响,但对水稻成熟期根系、茎叶和籽粒吸收积累Pb影响不大。     

镉在土壤-植物系统中的迁移转化及其影响因素

重金属镉(Cd)被列为环境污染物中最危险的五种物质之一。因其极易通过食物链在人体内积累并危害人体健康的特性，环境Cd污染尤其是土壤系统的Cd污染已成为国内外环境污染研究的热点，Cd在土壤一植物系统中迁移转化规律备受关注。本文概述了国内外土壤Cd污染研究现状；在已有研究的基础上，总结并阐述了影响Cd在土壤一植物系统中迁移转化的几个重要因素：土壤基本理化性质(pH值、有机质等)、Zn元素、P元素、陪伴阴离子Cl^-和SO4^2-，其中包括尚未被普遍认识的P元素和陪伴阴离子Cl^-和SO4^2-；并详细论述了各因子对Cd在土壤一植物系统中迁移转化的影响及其可能机理。     

Interaction of selenium and cadmium in wheat at different salinities

Abstract

Interaction of Se up to 8?mg?kg^?1 soil and Cd at 5 and 15?mg?kg^?1 soil in wheat at different salinities was evaluated. Se concentrations in wheat shoots were progressively increased in parallel to Se in soil but decreased by addition of Cd. With increasing salinity, Cd concentrations increased and Se decreased. At low salinity, low addition of Se to the soil reduced Cd accumulation. At moderate and high salinities, only high Se amendment led to decline in Cd uptake, at the expense of reduction in biomass yield. Se at 0.5?mg?kg^?1 soil alleviated the negative effect of Cd on shoot yield.     

Phytoaccumulation prospects of cadmium and zinc by mycorrhizal plant species growing in industrially polluted soils

The natural vegetation growing along a wastewater channel was subjected to analyze the uptake of Cadmium (Cd) and Zinc (Zn) and their subsequent accumulation in aboveground and underground plant parts. Species which were mycorrhizal and growing in soils receiving industrially contaminated wastewater were collected along with their rhizospheric soil samples. The nearby uncontaminated control (reference) area was also subjected to sampling on similar pattern for comparison. Both Cd and Zn concentrations were significantly higher in soils of the study area as compared to the reference site. Five plant species i.e. Desmostachya bipinnata, Dichanthium annulatum, Malvastrum coromandelianum, Saccharum bengalense, and Trifolium alexandrinum were analyzed for metal uptake. The maximum phytoaccumulation of Cd was observed in Desmostachya bipinnata (20.41 μg g⁻¹) and Dichanthium annulatum (15.22 μg g⁻¹) for shoot and root tissues, respectively. However, Malvastrum coromandelianum revealed maximum Zn accumulation for both the shoot and the root tissues (134 and 140 μg g⁻¹, respectively). The examination of cleared and stained roots of the plants from both the areas studied revealed that all of them were colonized to a lesser or a greater degree by arbuscular mycorrhizal (AM) fungi. The Cd hyperaccumulating grasses i.e. Desmostachya bipinnata and Dichanthium annulatum, from study area had smaller root:shoot (R/S) ratio as compared to those growing on reference area indicating a negative pressure of soil metal contamination. The lower R/S ratio in the mycorrhizal roots observed was probably due to increased AM infection and its mediatory role in soil plant transfer of heavy metals. Furthermore, comparatively lower soil pH values in the study areas may have played a key role in making the overall phytoavailability of both the metals. Consequently variations in Cd and Zn tissue concentration among species were observed that also indicate the phytoaccumulation potential of the native species.     

High cadmium pollution risk on vegetable amaranth and a selection for pollution-safe cultivars to lower the risk

A pot experiment was carried out by growing 29 different genotypes (Amaranthus spp.) of vegetable amaranth under low- (0.12 mg·kg^-1) and middle- (0.40 mg·kg^-1) cadmium (Cd) exposure. The result showed that amaranth was vulnerable to cadmium (Cd) contamination in soil. Variations of Cd concentrations in both roots and edible parts among genotypes were significant (P<0.001) in both treatments. Cd concentrations in edible parts of the tested genotypes grown under low- and middle-Cd levels were significantly correlated (p<0.01), implying that Cd-accumulating property of amaranth is genotype-dependent. Differences in Cd chemical forms between cv. Nanxingdayemashixian (cv. Nan), a selected typical pollution-safe cultivar (Cd-PSC), and cv. Pennongjianyexian (cv. Pen), a selected typical non-Cd-PSC, under different Cd exposure conditions were compared. It was found that the alternation of Cd in F_NaCl (Cd form extracted by 1 mol·L^-1 NaCl) may be a key factor in regulating Cd accumulation of different amaranth genotypes and that the protein-binding Cd is considered to be associated with Cd translocation. The results indicated that amaranth is capable of enduring high level of Cd pollution when grown as vegetable crop, and accordingly, consuming vegetable amaranth would bring high health risk. Therefore, adopting Cd-PSC strategy would help reducing the risk of Cd pollution in amaranth. In this study, cv. Nan was identified as a Cd-PSC and recommended to be applied production practice.     

砷污染土壤中不同基因型水稻根表铁膜的形成及其对砷吸收和转运影响

采用土壤盆栽试验法,研究6个不同基因型水稻品种根表铁膜形成及其对As吸收、转运的影响。结果表明,水稻形成根表铁膜在不同基因型品种之间差异显著（p<0.001）,其中品种94D-22形成铁膜量（以Fe含量计）是品种圭630的1.5~1.8倍,添加As处理对水稻根表铁膜形成影响不显著。低As含量的对照土壤中,水稻根表铁膜量与根系As含量存在着显著的正相关关系（r=0.657,n=24,p<0.01）,与As转移系数呈显著的负相关关系(r=-0.612,n=24,p<0.01）。土壤添加As后,水稻根表铁膜量与茎叶As含量存在显著的正相关关系（r=0.653-0.673,n=24,p<0.01）,与As转运之间无显著相关性。比较生长于As污染土壤的不同水稻品种,科优1360茎叶积累As较少,且其根系转运As能力也较差,而品种94D-22正好相反。研究结果表明,在As含量较低的土壤中,水稻根表铁膜的存在可成为根系As的障碍层,阻止As向地上部转运;但在As含量较高的土壤,根表铁膜的存在却促进了水稻茎叶对As的积累,其对As的转运没有显著影响。人们可通过作物品种筛选来防治土壤As污染危害、降低As对人体健康的威胁。