Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the di erence in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was found in a range of 0.004–0.057 mg/kg, while the Zn content in a range of 10.25–30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with “Zn hungry” through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.     

镉胁迫对不同杂交水稻品种Cd、Zn吸收与积累的影响

土壤-作物-食品是人类摄取Cd的重要途径.水稻是Cd积累能力最强的粮食作物,且水稻对Cd的吸收常伴随Zn缺乏,这对人类健康具有潜在的暴露风险.因此,本文选择2种杂交水稻(普通杂交稻材料"J196"和超级稻品种"中浙优1号")为供试水稻,以红壤性水稻土为供试土壤,采用添加Cd(2.5 mg·kg^-1)和不添加Cd(0 mg·kg^-1)处理进行盆栽试验,研究了水稻在成熟期对土壤中Cd的吸收分配及籽粒中Cd、Zn的积累特点.结果表明,添加Cd处理的水稻籽粒Cd积累量为未加Cd处理的6~10倍.在供试土壤Cd污染条件下,超级稻表现出对Cd具有较强的吸收能力,其籽粒中的Cd积累量也可高达1.83 mg·kg^-1,就地消费人群的籽粒Cd暴露风险水平为人体安全临界摄入剂量水平的数倍,Zn存在相对缺乏的食物安全风险.中浙优1号具有较强的籽粒Cd分配能力和较弱的籽粒Zn转运能力,而加Cd处理下,其对Cd、Zn的根部、茎叶滞留能力更强,这也正是高籽粒含量品种籽粒Cd积累强而Cd/Zn比高的原因.因此,在高产水稻育种中必须考虑水稻对Cd、Zn吸收的品种差异与籽粒Cd暴露、Zn缺乏的风险.为降低镉暴露风险,推广高产杂交水稻时应考虑Cd的吸收特性,同时在土壤-品种间进行合理布局,并进行膳食结构优化以增加人体对Zn的摄入.     

Variations between rice cultivars in iron and manganese plaque on roots and the relation with plant cadmium uptake

To understand certain mechanisms causing variations between rice cultivars with regard to cadmium uptake and tolerance, pot soil experiments were conducted with two rice cultivars of di erent genotypes under di erent soil Cd levels. The relationships between plant Cd uptake and iron/manganese (Fe/Mn) plaque formation on roots were investigated. The results showed that rice cultivars di ered markedly in Cd uptake and tolerance. Under soil Cd treatments, Cd concentrations and accumulations in the cultivar Shanyou 63 (the genotype indica) were significantly higher than those in the cultivar Wuyunjing 7 (the genotype japonica) (P < 0.01, or P < 0.05), and Shanyou 63 was more sensitive to Cd toxicity than Wuyunjing 7. The di erences between the rice cultivars were the largest at relatively low soil Cd level (i.e., 10 mg/kg). Fe concentrations in dithionite-citrate-bicarbonate root extracts of Shanyou 63 were generally lower than that of Wuyunjing 7, and the di erence was the most significant under the treatment of 10 mg Cd/kg soil. The results indicated that the formation of iron plaque on rice roots could act as a barrier to soil Cd toxicity, and may be a “bu er” or a “reservoir” which could reduce Cd uptake into rice roots. And the plaque may contribute, to some extent, to the genotypic di erences of rice cultivars in Cd uptake and tolerance.     

不同浓度锌处理下水稻幼苗对镉的累积效应

为探究锌（Zn）对水稻镉（Cd）累积的影响及其根表铁膜所发挥的作用,选取Cd高累积型水稻品种中9优547（简称"Z547"）和Cd低累积型水稻品种金优402（简称"J402"）,采用温室水培试验,研究0、2、5、10、15和20 μmol/L等6个Zn浓度下水稻幼苗对Cd的累积效应,以及不同浓度Zn处理对根表铁膜生成量的影响.结果表明:①随着c（Zn）的增加,Z547和J402水稻幼苗生物量均呈先增后减的趋势,分别在c（Zn）为2和10 μmol/L时达到最大值.②Z547和J402水稻幼苗中w（Cd）均呈先降后增的趋势,分别在c（Zn）为5和2 μmol/L时达到最小值;当水稻幼苗中w（Cd）达到最小值时,Z547根和地上部中w（Cd）分别为31.65和11.47 mg/kg,J402根和地上部中w（Cd）分别为22.58和14.36 mg/kg.③不同浓度Zn处理下水稻幼苗各部位中w（Cd）均与根表铁膜中w（Mn）、w（Fe）、w（Fe+Mn）呈显著正相关,高铁膜处理水稻幼苗中w（Cd）显著高于低铁膜处理,表明根表铁膜生成量的增加会促进Cd在水稻幼苗中的累积.研究显示,当c（Zn）较低时,c（Zn）的增加会抑制水稻幼苗对Cd的累积;当c（Zn）较高时,c（Zn）的增加会促进水稻幼苗对Cd的累积,而Zn可通过控制根表铁膜的生成来影响水稻幼苗对Cd的累积.      

叶面喷施2,3-二巯基丁二酸对水稻幼苗镉吸收转运及抗氧化系统的影响

稻米Cd超标问题已成为社会各界广泛关注的热点问题之一,探索降低Cd向地上部转运并缓解水稻Cd胁迫的新方法,对保障食品安全具有重要意义.本研究拟通过在水稻幼苗叶面喷施2,3-二巯基丁二酸(DMSA)评估利用该重金属螯合剂降低Cd向水稻地上部转运并缓解Cd胁迫的可行性.以我国南方水稻主栽品种之一中早35幼苗为研究材料,采用水培法研究了叶面喷施不同浓度DMSA对Cd在水稻幼苗体内吸收转运的影响,同时考察了对水稻幼苗丙二醛(MDA)、谷胱甘肽(GSH)含量以及对抗氧化酶过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性的影响.结果表明,叶面喷施DMSA 0.2、 0.4和1.0 mmol·L~(-1) 4次后,水稻幼苗地上部Cd含量随着DMSA喷施浓度增加呈显著降低趋势, 3种处理浓度与对照相比分别降低22.1%、 39.7%和43.5%,但是对水稻幼苗根部Cd含量无显著影响;对地上部及根中K、Ca、Mg、Fe、Zn和Mn这6种矿质元素含量无显著影响;喷施4次DMSA后显著降低了幼苗地上部MDA和GSH含量,同时使CAT和SOD活性显著增加,有效缓解了Cd对水稻幼苗造成的胁迫效应.DMSA能抑制Cd从水稻根部向地上部转运,同时不影响对人体必需矿质营养元素的吸收和转运,具备成为水稻降Cd叶面调理剂的潜力.     

根分泌物对根际重金属动态的影响

介绍了采用上，下分根试验，使水稻根系下部生长在不同浓度铁营养液中，研究不同供铁处理对不同品种水稻吸收生金属和微量元素及其在体内转移和运输的影响。结果表明缺铁处理时常优８７－８８品种的植株地下部铁含量仅为正常供铁处理的５８％，而Ｃｄ，Ｚｎ的含量却比正常供的植株高１．４倍；缺铁时远诱一号和科长８９－１１３两个品种植株地上部含铁量也比正常供铁时低，但差异不如常优８７－８８明显，Ｃｄ，Ｚｎ含量比正常供铁时     

Identification of rice cultivars with low brown rice mixed cadmium and lead contents and their interactions with the micronutrients iron, zinc, nickel and manganese

Paddy fields in mining areas are usually co-contaminated by a cocktail of mixed toxic heavy metals (e.g., Cd and Pb in Pb/Zn mines). However, previous studies on rice cultivars screened for effective metal exclusion have mostly focused on individual metals, and have been conducted under pot-trial or hydroponic solution conditions. This study identified rice cultivars with both low Cd and Pb accumulation under Cd-and Pb-contaminated field conditions, and the interactions of the toxic elements Cd and Pb with the micronutrient elements Fe, Zn, Mn and Ni were also studied. Among 32 rice cultivars tested, there were significant differences in Cd (0.06-0.59 mg/kg) and Pb (0.25-3.15 mg/kg) levels in their brown rice, and similar results were also found for the micronutrient elements. Significant decreases in concentrations of Fe and Mn were detected with increasing Cd concentrations and a significant elevation in Fe, Mn and Ni with increasing Pb concentrations. A similar result was also shown by Cd and Ni. Three cultivars were identified with a combination of low brown rice Cd and Pb, high micronutrient and grain yield (Wufengyou 2168, Tianyou 196 and Guinongzhan). Present results suggest that it is possible to breed rice cultivars with low mixed toxic element (Cd, Pb) and high micronutrient contents along with high grain yields, thus ensuring food safety and quality.     

Does copper reduce cadmium uptake by different rice genotypes？

A hydroponics experiment was conducted to investigate the effect of copper （Cu） on cadmium （Cd）, calcium （Ca）, iron （Fe）, and zinc （Zn） uptake by several rice genotypes. The experiment was carried out as a 2×2×4 factorial with four rice genotypes and two levels of Cu and Cd in nutrient solution. Plants were grown in a growth chamber with controlled environment. The results showed a significant difference between the biomass of different rice genotypes （P 〈 0.001）. The Cd and Cu concentration in the solution had no significant effect on the biomass. The addition of Cu significantly decreased Cd uptake by shoots and roots of rice （P 〈 0.001）. The Cd concentration did not significantly influence Ca uptake by plants, whereas the Cu concentration did （P = 0.034）. There was a significant influence of Cd on Fe uptake by shoots and roots （P 〈 0.001, P = 0.003, respectively）. Zn uptake decreased significantly as the addition of Cd and Cu increased in shoots. We concluded that Cu had significant influence on Cd uptake. The possible mechanisms were discussed.     

Assessment of potential soybean cadmium excluder cultivars at different concentrations of Cd in soils

The selection of cadmium-excluding cultivars has been used to minimize the transfer of cadmium into the human food chain. In this experiment, five Chinese soybean plants were grown in three soils with different concentrations of Cd (0.15, 0.75 and 1.12 mg/kg). Variations in uptake, enrichment, and translocation of Cd among these soybean cultivars were studied. The results indicated that the concentration of Cd in seeds that grew at 1.12 mg/kg Cd in soils exceeded the permitted maximum levels in soybeans. Therefore, our results indicated that even some soybean cultivars grown on soils with permitted levels of Cd might accumulate higher concentrations of Cd in seeds that are hazardous to human health. The seeds of these five cultivars were further assessed for interactions between Cd and other mineral nutrient elements such as Ca, Cu, Fe, Mg, Mn and Zn. High Cd concentration in soil was found to inhibit the uptake of Mn. Furthermore, Fe and Zn accumulations were found to be enhanced in the seeds of all of the five soybean cultivars in response to high Cd concentration. Cultivar Tiefeng 31 was found to fit the criteria for a Cd-excluding cultivar under different concentrations of Cd in soils.     

Combined toxicity of copper and cadmium to six rice genotypes （Oryza sativa L.）

Accumulation of copper (Cu) and cadmium (Cd) in six rice cultivars (94D-22, 94D-54, 94D-64, Gui630, YY-1 and KY1360) was evaluated through exposure to heavy metal contamination (100 mg/kg Cu, 1.0 mg/kg Cd, and 100 mg/kg Cu + 1.0 mg/kg Cd) in a greenhouse. The dry weight of shoot and root, concentrations of Cu and Cd in plant tissues and the Cu, Cd, P, Fe concentrations in the root surface iron plaques were analyzed eight weeks later after treatment. The results indicated that the plant biomass was mainly determined by rice genotypes, not Cu and Cd content in soil. Separated treatment with Cu/Cd increased each metal level in shoot, root and iron plaques. Soil Cu enhanced Cd accumulation in tissues. In contrast, Cu concentrations in shoot and root was unaffected by soil Cd. Compared to single metal contamination, combined treatment increased Cd content by 110.6%, 77.0% and 45.2% in shoot, and by 112.7%, 51.2% and 18.4% in root for Gui630, YY-1 and KY1360, respectively. The content level of Cu or Cd in root surface iron plaques was not affected by their soil content. Cu promoted Fe accumulation in iron plaques, while Cd has no effect on P and Fe accumulation in it. The translocation of Cu and Cd from iron plaques to root and shoot was also discussed. These results might be beneficial in selecting cultivars with low heavy metal accumulation and designing strategies for soil bioremediation.     

钒镉复合污染对水稻吸收积累镉、钒和磷的影响

采用溶液培养法研究钒与镉复合污染对水稻生长及其吸收积累镉的影响,以便弄清在钒与镉复合污染条件下水稻的生长情况.试验结果表明,钒镉复合污染可影响水稻的生长发育.在培养液镉浓度(1 0mg·L-1)不变的情况下,随着溶液中钒浓度的增加,水稻根长、根系和茎叶的干重不断减少.当溶液中钒浓度达到1 6mg·L-1和3 2mg·L-1时,水稻茎叶和根系干重减少分别达到显著水平(p<0 05).钒镉复合污染也影响水稻植株对磷、钒和镉的吸收与积累.当培养液中镉浓度不变时,随着溶液中钒浓度的增加,水稻根系和茎叶中的磷浓度不断降低,而钒含量却不断提高,根系比茎叶积累更多的钒.此外,钒可抑制水稻植株对镉的吸收与积累.     

不同铁营养状况下根系特征及蒸腾对黄瓜幼苗吸收镉的影响

采用营养液培养方法,研究了不同铁营养状况下的根系形态变化及蒸腾作用对不同品种黄瓜幼苗吸收镉的影响.结果表明,不加铁处理对地上部生物量的影响大于对根系的影响,并且不同品种间生物量差异显著.不加铁处理和低水平铁处理时,黄瓜根长变长、根表面积变大.与不加铁处理相比,加铁处理显著抑制了黄瓜根系对镉的吸收,中农5号(缺铁敏感黄瓜品种)和津春4号(缺铁不敏感黄瓜品种)每克根对镉的吸收量分别降低了25.5%~45.5%和28.8%~55.0%;但却增加了镉向地上部的转运,镉在叶中的分配系数分别增加了2.2~3.6倍(中农5号)和2.6~3.7倍(津春4号).缺铁敏感的中农5号吸镉总量与根长、根表面积都呈显著正相关性,而缺铁不敏感的津春4号吸镉总量与根长、根表面积之间的关系不显著.不管是中农5号还是津春4号,其蒸腾速率与每克根吸收镉的量均呈显著的正相关关系.不同铁营养状况影响了黄瓜幼苗的根系形态和蒸腾速率,从而影响了根系对镉的吸收,高铁水平显著抑制了黄瓜根系对镉的吸收.     

紫云英还田配施石灰对水稻镉吸收转运的影响

采用田间小区试验,研究了紫云英(CMV)与石灰(L)单施及两者配施(CMVL)对土壤Cd有效性、水稻根表胶膜及Cd吸收转运的影响.结果表明:L与CMVL处理土壤pH值分别显著提高2.11～2.43和1.68～2.48个单位、二乙烯三胺五乙酸提取态(DTPA-Cd)含量分别显著降低18.88％～40.53％和20.74％...     

叶施L-半胱氨酸对水稻镉和矿质元素含量的影响

为评估将L-半胱氨酸（L-Cys）作为水稻降Cd叶面调理剂的可行性,通过湖南的田间试验,采用小区试验法研究了L-Cys对水稻籽粒中Cd和矿质元素含量的影响,并通过检测水稻各营养器官的Cd分布和Cd赋存形态的变化,探究了L-Cys调控水稻籽粒Cd积累的作用机制.结果表明,在开花期叶面喷施一次L-Cys即可使水稻籽粒Cd含量显著降低,同时提高其Mg和K的含量,对Ca、Mn和Zn的含量无显著影响.L-Cys的降Cd效果随喷施浓度增加而增强,当浓度为10 mmol·L^-1时,籽粒中Cd含量降至我国食品安全标准0.2 mg·kg^-1以内,降幅达59.2%,同时显著降低了水稻营养器官穗轴、第一节、穗颈、旗叶、第二节间、第二节、第二叶、基部茎叶和根中的Cd含量,降幅分别为58.3%、56.0%、62.7%、67.0%、59.3%、61.5%、60.2%、54.9%和50.3%.水稻不同部位间的Cd转移因子显示,第一节是水稻营养体拦截有害元素Cd的关键器官.叶面喷施L-Cys提高了Cd从旗叶到第一节和第二节间到第一节的转移因子,增幅最高达105.4%和45.8%,并抑制了Cd从第一节继续向上到穗颈的转运,降幅最高达27.5%.在水稻第一节中,L-Cys处理同时降低了无机态、水溶态和残渣态Cd的含量,并提高了其中残渣态Cd的比例至94.4%.由此可见,叶面喷施L-Cys能够降低水稻各营养器官Cd积累量,并促进水稻中Cd向第一节的转运及其对Cd的固定作用,进而提高关键器官第一节对Cd的拦截能力,最终显著抑制Cd向籽粒中的转运积累,同时,叶面喷施L-Cys不降低水稻籽粒中矿质营养元素的含量,具有较好的应用前景.     

城市室内灰尘重金属水平、影响因素及健康风险:以贵阳市为例

本研究以贵阳市为研究区域,选择73户家庭和6间办公室采集室内灰尘样品,用ICP-OES测定灰尘中常量元素Ca、Fe和重金属元素Cd、Cr、Cu、Ni、Pb和Zn含量,探究室内灰尘重金属水平及影响因素,并综合室内和室外灰尘暴露量,评估儿童所受灰尘重金属健康风险.结果表明:1家庭室内灰尘中Ca、Fe的平均含量(g·kg-1)为107、31.9;Cd、Cr、Cu、Ni、Pb和Zn的平均含量(mg·kg-1)分别为1.77、107、231、81.9、199、721;2办公室灰尘中Cu和Zn含量显著高于家庭灰尘,其他元素与其在家庭灰尘中的含量差别不大;3不同楼层家庭灰尘中Ca、Fe含量差别不大,Cd、Cu和Pb含量差异明显,1楼室内灰尘重金属含量相对较高,同时高层住宅室内Pb含量大于低层住宅;4家庭住户室外环境和室内装修及使用情况等导致家庭室内灰尘重金属水平差异分布;5灰尘重金属对儿童的暴露没有表现出明显的健康风险.     

太湖流域主要粮食作物中19种元素的背景值及其特征

本研究用等离子体发射光谱法、石墨炉原子吸收法、原子荧光法和冷原子吸收法等对太湖地区糙米和小麦中Cu、Zn、Pb、Cd、Ni、Mn、Co、Al、Fe、V、Cr、Mo、P、Ca、Mg、K、Na、Hg、As等19种元素进行测定,经统计学检验分别得出其背景值,发现Hg、As、Pb、Cd和Cr 5种有毒元素的含量均低于卫生标准,对人畜无害。分析了糙米、小麦中元素含量的特征,包括不同作物、不同地区、不同土类之间的元素含量差异,土壤pH值和有机质对元素含量的影响和土壤有效态元素与粮食中相应元素的相关性等。     

佛山市冬季PM2.5中重金属元素的污染特征

为了解珠江三角洲典型工业城市佛山冬季大气细颗粒物中重金属元素的污染特征,在佛山的城区(禅城)和城市清洁点(三水)同步采集24h PM2.5样品,分析了16种元素Fe、Ti、Zn、V、Mn、Cu、As、Rb、Sr、Cd、Cs、Ba、Hg、Tl、Pb和Bi的浓度.禅城的重金属处于较高的污染水平,三水重金属元素浓度普遍低于禅城,但Fe、Ti、Sr、Cd的浓度高于禅城.与国家大气颗粒物中重金属浓度标准相比,禅城的As、Cd超标严重,Pb略超标,三水的As、Cd超标严重.Zn、Cu、As、Pb的富集因子均高于10,表明其主要与人类活动导致的污染有关.重金属元素的浓度在灰霾期都有增高的趋势,但各重金属浓度日变化趋势和幅度在禅城较为一致,在三水则不太一致.气团后向轨迹分析表明,研究期间重金属元素的浓度分布受靠近或者始于福建的广东东北方向气团、广福沿岸气团、海洋方向气团和来自江西的气团影响,其中第1类气团主要使得重金属元素浓度提高,后面3类气团均使得重金属浓度下降.     

水分管理对硫铁镉在水稻根区变化规律及其在水稻中积累的影响

选取了酸性矿山废水污灌区重金属污染水稻土,通过盆栽试验研究了不同水分管理条件(60%最大田间持水量,80%最大田间持水量,最大田间持水量,前期淹水+抽穗扬花期烤田,全生育期淹水)下水稻根际土壤及其不同器官(稻根、茎叶和籽粒)中硫、Fe和Cd的含量变化.结果表明,随着土壤水分含量的增加,在分蘖期根际土壤中Cd的含量略有升高,在成熟期对水稻根际土壤中Fe和Cd含量的影响不大;水稻不同器官对铁的吸收逐渐增加,对Cd的吸收则逐渐减少,两者呈明显的负相关关系;但抽穗扬花期烤田对水稻各器官对Fe的吸收影响不大,却明显增加了各器官中Cd的含量.除旱作处理外,不同水分管理方式下,土壤中全硫和有效硫含量随着土壤水分含量增加逐渐减少,抽穗扬花期烤田能明显增加根际土壤中总硫和有效硫含量,水稻对Cd的吸收与根际硫含量增加存在协同关系.上述结果证实,水稻对Cd的吸收不仅与Fe吸收有关,土壤中硫的充分供给能显著增加Cd在水稻中的积累.     

Influence of soil type and genotype on Cd bioavailability and uptake by rice and implications for food safety

Cadmium (Cd) entering the human body via the food chain is of increasing concern. This study investigates the effects of soil type and genotype on variations in the Cd concentrations of different organs of nine rice plants grown on two types of soils with two Cd levels. Cd concentrations in nine rice cultivars varied significantly with genotype and soil type (P < 0.01). The Cd concentration was higher in red paddy soil (RP) than in yellow clayey paddy soil (YP). The average Cd concentrations of different organs in three rice types were indica > hybrid > japonica for the Cd treatments and controls. The polished grain concentration in YP and RP soils had a range of 0.055-0.23 mg/kg and 0.13-0.36 mg/kg in the Cd treatment, respectively. Two rice cultivars in YP soil and five rice cultivars in RP soil exceeded the concentration limits in the Chinese Food Hygiene Standard (0.2 mg/kg). The Cd concentrations in roots, stems, and leaves were all significantly and positively correlated to that in polished grain in a single test. The Cd concentrations in polished grain were positively and significantly (P < 0.01) correlated with the calculated transfer factors of stem to grain and leaf to grain Cd transfer. The results indicated that the variations of Cd concentration in grain were related to Cd uptake and the remobilization of Cd from stem and leaf to grain. Also, the cultivars with a strong tendency for Cd-accumulation should be avoided in paddy soil with low soil pH and low organic matter content to reduce the risks to human health from high Cd levels in rice.     

土施和喷施锌肥对镉低积累油菜吸收镉的影响

采用盆栽试验,研究了土施和喷施不同用量Zn SO4对镉(Cd)低积累油菜生长、Cd吸收及微量元素含量的影响,并通过分析Cd在油菜体内的累积分配规律及土壤Cd有效性变化来揭示其作用机理.结果表明,土施锌(Zn)肥可以显著提高Cd低积累油菜的地上部生物量,最大可使其比对照处理增加71.4%;而喷施Zn肥对Cd低积累油菜地上部生物量没有显著影响.土施和喷施Zn肥都可显著降低Cd低积累油菜的地上部Cd含量,最大降幅为41.4%;在Zn肥用量相差8~10倍的情况下,二者降低油菜地上部Cd含量的效果无显著差异.土施Zn肥可使Cd低积累油菜地上部Cu和Fe含量显著升高,而喷施Zn肥对其没有显著影响,土施和喷施Zn肥都使Cd低积累油菜地上部Mn含量显著降低.土施Zn肥可显著提高土壤有效态Zn含量,但对土壤有效Cd含量没有显著影响;土施和喷施Zn肥可以显著降低油菜根部Cd净吸收量和Cd转运系数,油菜地上部Cd含量与根部Cd净吸收量呈显著的正相关关系(p0.01),而与Cd转运系数无显著的相关性,这表明施用Zn肥降低油菜地上部Cd含量主要是由于抑制根部Cd吸收引起的.总之,喷施Zn肥是调控Cd低积累油菜安全生产的较好措施.