Exchangeable Cs/K ratio in soil is an index to estimate accumulation of radioactive and stable Cs in rice plant

Pot and field experiments were conducted to clarify the effect of soil exchangeable potassium (K) and cesium-137 (¹³⁷Cs) on ¹³⁷Cs accumulation and to establish soil index in rice (Oryza sativa L.). Four paddy soils in Fukushima Prefecture, Japan, showing different transfer factors for radioactive Cs derived from the accident of Fukushima Daiichi Nuclear Power Station in the field were compared in terms of ¹³⁷Cs accumulation in rice in a pot experiment. ¹³⁷Cs accumulation in shoots and brown rice widely varied among soils with the transfer factor ranging from 0.018 to 0.068 for shoots and 0.004 to 0.065 for brown rice. ¹³⁷Cs concentration in brown rice and shoots tended to decrease with higher levels of soil exchangeable K, and they were more closely related to the exchangeable Cs/K ratio. Similar relationships between the Cs/K ratio and Cs accumulation in plants were obtained for the stable isotope cesium-133 (¹³³Cs). The distributions of ¹³⁷Cs and ¹³³Cs in grains were also similar and variable among soils. The transfer factors obtained in pot experiments mostly agreed with field observations. The results imply that the exchangeable ¹³⁷Cs/K can be a potential soil index to estimate ¹³⁷Cs accumulation in rice.     

外源铅胁迫对不同土壤上水稻生长及铅形态的影响

采用温室水稻盆栽试验研究2种土壤上水稻铅的生物有效性及土壤铅形态的变化。结果表明:铅对2种土壤水稻干物重和籽粒重量的影响表现为,随铅处理浓度升高,水稻干物重和籽粒重量明显下降。黄红壤上种植的水稻干物重和籽粒重量高于青紫泥。不同铅处理下水稻各器官铅含量表现为根>茎>叶>壳>籽粒。2种土壤上NH4OAc提取的有效态铅含量与外源铅的量呈显著正相关。随外源土壤铅含量增加土壤pH显著下降。随土壤铅含量增加土壤铅的生物有效性增强,水稻对铅的吸收明显增加,水稻可食部的铅含量升高。采用连续提取法分析了土壤铅的形态,结果表明,青紫泥铁锰氧化态和有机态的铅含量高于黄红壤,水溶态、交换态和碳酸盐态含量低于黄红壤。铅在黄红壤上的移动性较青紫泥高。     

水稻对~(134)Cs的吸收和~(134)Cs在水稻-土壤中的分配

试验表明,水稻对~(134)Cs的吸收,孕穗期吸收速率最快;土壤理化性质不同,吸附~(134)Cs的能力有差异;不同生育期灌溉~(134)Cs溶液,水稻对其吸收量不同,离成熟期近,吸收得多;灌溉次数多和灌溉水中~(134)Cs活度高,水稻吸收的~(134)Cs也多。糙米经精白加工后,可使~(134)Cs的污染减少22.6—45.6％;~(134)CS在水稻各部位比活度大小的顺序为糠>根>稻草>谷壳>精白米;活度以稻草中最高,占水稻植株总活度的51.4％,糙米、根和谷壳分别占28.4％。11.8％和8.4％:~(134)Cs在土壤中移动很少,有95.1％集中在0—2.5cm的表土层内;~(134)Cs在水稻-土壤中的分配为6.1％:93.9％;K~+抑制水稻对~(134)Cs的吸收,K~+浓度与水稻中~(134)Cs比活度之间呈指数回归形式。     

两个水稻品种富硒特性比较研究

以前期田间试验筛选出的富硒能力较强的水稻品种捷丰优629和谷丰优8312为材料,采集硒含量不同的稻田土壤,通过盆栽试验进一步研究了两个水稻品种对土壤硒的吸收、分配及其糙米和精米中无机硒与有机硒含量的组成特点。结果表明:两个水稻品种植株的硒累积量、糙米和精米的硒含量与有机硒含量都是高硒土壤极显著高于低硒土壤,表明高硒土壤有利于稻米硒的累积与有机硒的合成,因此生产优质富硒大米最好选择硒含量较高的稻田土壤。无论在高硒土壤还是低硒土壤上,捷丰优629植株中硒累积量和籽粒中硒累积量与谷丰优8312的差异都不显著,但捷丰优629的糙米和精米中硒含量以及有机硒含量都极显著高于谷丰优8312,表明捷丰优629吸收的硒易分配到可食用部位(糙米和精米),而且其无机硒向有机硒的转化能力较强,因此综合比较来看捷丰优629富硒特性优于谷丰优8312。     

外源锌对水稻植株镉的累积差异分析

通过水稻威优46盆栽种植试验,研究了外源Zn施用(0,40,80,160 mg/kg 4个水平)对Cd中度(0.72mg/kg)和重度(5.26mg/kg)污染土壤中Cd生物有效性及水稻Cd累积的差异。结果表明:施Zn对各检测指标存在影响,但土壤Cd总量仍是土壤Cd活性和水稻Cd累积差异变动的主控因素。在Cd中度污染土壤中,施Zn降低了土壤交换态Cd含量1.9%~17.0%,但水稻根表铁膜、根和糙米中Cd含量随Zn施用浓度的增大而增大,糙米Cd含量从0.09mg/kg上升到0.17mg/kg,相关分析显示糙米Cd含量与土壤交换态Zn含量显著正线性相关。在Cd重度污染土壤中,施Zn增大了土壤交换态Cd含量2.1%~4.8%,但降低了水稻各部位中Cd含量,当施Zn浓度超过80mg/kg时,糙米Cd含量可从对照组的0.45mg/kg降低到0.12mg/kg,符合国家食品污染物限量标准(GB 2762-2017)的要求,相关分析显示糙米Cd含量与土壤交换态Zn含量显著负线性相关。对2种Cd污染程度的土壤,施Zn均可增大Cd在水稻地下部的累积率,从而降低水稻地上部Cd的累积率。在Cd重度污染土壤中,可通过施Zn降低糙米Cd含量,施Zn量80mg/kg是试验中最佳施用量;但在Cd中度污染土壤中,施Zn有增大糙米Cd含量的风险。     

Cesium uptake of field-grown Amaranthus species in Fukushima focusing on Cs concentration in xylem exudate and root distribution

ABSTRACT

Radiocesium (RCs) discharged by the Fukushima Daiichi Nuclear Power Plant (Tokyo Electric Power Co., Inc.) accident has extensively contaminated agricultural land in Fukushima Prefecture and its neighboring areas. Many studies have demonstrated that Cs (RCs and ¹³³Cs) uptake of plants is affected by the exchangeable K (Ex-K) concentration in soil. However, the precise plant–soil interaction in relation to Cs uptake is still unclear. The aim of this study was to investigate Cs uptake of plant in field by focusing on xylem exudate and roots because nutrients in xylem exudate reflect medium (soil) conditions and affect nutrient accumulation in shoots. Two varieties of amaranth, K4 (Amaranthus caudatus L.) and Mexico type (A. hypochondriacus L.), which have different Cs uptake abilities, were grown in four fields and in pots (750 to 3440 Bq kg^?1 of RCs) in Fukushima Prefecture. Cs concentrations in xylem exudate, shoot, and soil; Ex-K concentration in soil; and root distribution in soil were determined. RCs concentration in xylem exudate varied from 0.04 to 164 Bq kg^?1 and ¹³³Cs concentration in xylem exudate ranged from 0.01 to 33.7 μg kg^?1. The Cs concentrations were decreased by the high Ex-K concentration and the large amount of 2:1 type clay minerals in soil. The average of the ratios of Cs concentration in shoot to Cs concentration in xylem exudate for all samples was 127 ± 112 (mean ± standard deviation), although no clear correlation was found between them. The correlations betwee\n RCs and ¹³³Cs concentrations in xylem exudate and shoot were strong in pot and in the field with low Ex-K concentration. Eighty-five percent of the total root length was distributed in the topsoil (0–20 cm soil layer). The positions where roots take up Cs were estimated from the differences in the vertical distribution of RCs and ¹³³Cs concentrations in soil. The estimated Cs uptake ratios of topsoil to total soil layer ranged from 7% to 91% and varied with the concentration and the vertical distribution of Ex-K in soil.     

Effect of Bioaccumulation of Cs and Sr Natural Isotopes on Foliar Structure and Plant Spectral Reflectance of Indian Mustard (Brassica Juncea)

The objectives of this study are: (1) Evaluate the capacity of Indian mustard (Brassica juncea) for uptake and accumulation of Cs and Sr natural isotopes. (2) Identify foliar structural and other physiological changes (biomass, relative water content etc.) resulted from the accumulation of these two elements. (3) Monitor the Cs and Sr uptake and bioaccumulation process by spectral reflectance. Potted Indian mustard plants were exposed to different concentrations of Cs (50 and 600 ppm) and Sr (50 and 300 ppm) natural isotopes in solution form for 23 days. Bioaccumulation of Cs and Sr were found in the order of leaves > stems > roots for both Cs- and Sr-treated plants. The highest leaf and root Sr accumulations are observed to be 2,708, and 1,194 mg kg^?1, respectively; and the highest leaf and root Cs accumulations are 12,251, and 6,794 mg kg^?1, respectively. High translocation efficiency for both elements is documented by shoot/root concentration ratios greater than one. Biomass decreases were observed for plants treated with higher concentration of Cs or Sr. Cs accumulation affected the pigment concentration and internal structure of the leaf and the spectral characteristics of plants. Within the applied concentration range, Sr accumulation resulted in no significant changes in relative water content (RWC), leaf structural and spectral characteristics of mustard plants. Cs shoot concentration showed significant negative correlation with relative water content (RWC; r = ?0.88*) and normalized difference vegetative index (NDVI) value (r = ?0.68*) of plant shoots. The canopy spectral reflectance and NDVI analysis clearly revealed (p < 0.05) the stress caused by Cs accumulation.     

施肥措施对水稻吸收~(137)Cs的影响

研究了施用石灰,褐煤和钾肥等对减少＾１３７Ｃｓ在水稻植株中积累的影响。结果表明,施用相当于土壤阳离子代换量１／２０的钾盐,使水稻对＾１３７Ｃｓ的积累比对照组减少３２％以上,随时间变化,这种效应更加显著。     

Influence of potassium on uptake and distribution op cesium in bush beans

Bush beans, Phaseolus vulgaris L. cv. Improved Tendergreen, were grown for 18 days in 3700 ml. nutrient solutions in a factorial experiment involving 3 levels of K (10^‐2, 10^‐3, 10^‐4N) and 3 levels of Cs (10^‐4, 5 x 10^‐5, 10^‐5N). Mild K deficiency was observed for the low K level but no yield differences were due to Cs. Increasing K markedly decreased the Cs concentrations in all plant parts. The relative uptake of K vs Cs was not influenced by Cs but was by K. The concentration ratio (C.R.) for K in trifoliate leaves varied from 99 (high K) to 7315 (low K). The C.R, for Cs in trifoliate leaves varied from 8,67 (high K) to,0.96 (low K). Potassium was translocated to trifoliate leaves from 89 to 843 times that of Cs. The “Y”; values for Cs in plant parts was consistently near 1 meaning that Cs uptake was directly proportional to its concentration in the nutrient solution. The “Y”; values for K in plant parts were around 0.5 for 10^‐3/10^‐4N K but only about 0,2 for 10^‐2/10^‐3N K. Roots accumulated about 6 times more Cs than did leaves while K was quite uniformly distributed among plant parts. The uptake relationship for K and Cs then was vastly different indicating that K would not likely be a good carrier of radiocesium in food chains.     

大田生产条件下不同品种水稻植株中镉的分布特点

通过4个水稻品种在大田生产条件下的试验,研究分析了水稻植株Cd积累和分布的特点。结果表明,水稻的根系是吸收Cd的主要器官,也是Cd的主要储存场所,无论在水稻分蘖期还是成熟期都很明显;在水稻成熟期,籽粒（糙米）中Cd的含量显著地低于其他器官,水稻植株器官中Cd的分布情况大致为：根〉鞘＞叶＞茎＞糙米,但随着品种的不同而有所变化;根据4个水稻品种在成熟期的植株Cd积累量的分析,9311是植株高累积Cd的水稻品种,Jia－48和Jia－51的糙米中Cd的积累很低;水稻品种间对于Cd的吸收和累积能力有显著的差异,但水稻类型间（粳稻与籼稻间）Cd含量没有显著差异,因此不能按照水稻类型来选育糙米中低Cd积累品种,应针对品种选育出糙米中低Cd积累的高产优质水稻品种。     

Genotypic variation in grain cadmium concentration of lowland rice

Cadmium (Cd) contamination of paddy rice soils is commonly observed in the Yangtse River Delta, China. Large Cd uptake by rice plants and its translocation into the grains can entail human‐health risks. Genotypic variations in Cd uptake and a differential Cd partitioning into grains will be the basis for developing a rice screening or breeding tool for low grain Cd. A field experiment, conducted at the experimental farm of Jiaxing, Zhejiang province from 2002 to 2004, compared 38 rice genotypes of different types (indica vs. japonica) collected from the Yangtse River Delta. The results showed large differences in Cd concentrations in straw, brown rice, and grain chaff among the rice genotypes grown on Cd‐contaminated soil. Concentrations in brown rice ranged from 0.06 to 0.99 mg Cd kg^–1. The total Cd uptake in brown rice varied between 0.96 and 28.58 μg plant ^{– 1}. In general, indica‐type cultivars accumulated significantly more Cd than the japonica‐type cultivars. The Cd concentration in straw was highly correlated with that in brown rice. While significant differences in the Cd‐partitioning ratio (% share of total Cd uptake found in brown rice) among rice genotypes were observed, these were not correlated with Cd concentration of brown rice. This indicates that the Cd accumulation in rice grains appears to be governed mainly by the Cd uptake by the plant and probably not by differential Cd partitioning. The large genotypic variation suggests the possibility to lower the Cd content of rice by genotype selection. The development of such breeding tools should focus on low Cd uptake rather than Cd partitioning between straw and grain.     

Growth,sodium, and potassium uptake and translocation in salt stressed tomato

Salinity tolerance in some plant species has been related to characteristics of potassium (K) and sodium (Na) uptake and transport. Tomato (Lycopersicon esculentum Mill., cv. Rossel) plants were grown in nutrient solution to determine effects of two K levels [0.2 (low) and 2 mmol (high)] combined with 0, 100, and 200 mmol NaCl on growth, and on Na and K uptake and translocation. Net uptake rates of Na and K were determined by disappearance in the growth medium and by plant accumulation. At the low level of K in solution, salinity decreased shoot and root dry weight and leaf area. Addition of 2 mmol K ameliorated of the added NaCl effects and improved growth parameters. Salinity reduced net K uptake rates and to a lesser extent K translocation from root to shoot, which resulted in higher K shoot concentration and a lower K root concentration. The inhibitory effect of salinity on K translocation was greater with low K level in nutrient solution. Net uptake of K was dependent on K level in the growth medium. Addition of K resulted in decreases of shoot Na uptake. The translocation of Na from roots to shoots was reduced by K level in nutrient solution. These results indicate that K supply and K accumulation and regulation in plant tissue contribute to salt tolerance and growth enhancement.     

Vertical distribution and bioavailability of 137Cs in organic and mineral soils

The vertical distribution and bioavailability of ¹³⁷Cs in Histosols and mineral soils with different physicochemical properties from the southeast of Bavaria (Germany) more than ten years after the Chernobyl accident were the focus of this study. The vertical distribution of ¹³⁷Cs was low in the investigated soils. About 85–98 % of the total ¹³⁷Cs was located in the upper 10 cm of the mineral soils. Slightly higher ¹³⁷Cs percentages were observed in deeper soil layers of the peat soils. Although the organic matter is assumed to enhance ¹³⁷Cs mobility in soils, ¹³⁷Cs was also located in the upper 10 cm of the peat soils (73–85 %). The highest ¹³⁷Cs‐activities were found in the humus layers of forest soils, where 45–93 % of the total ¹³⁷Cs soil inventories were observed. To determine the bioavailability of radiocesium, the soil‐to‐plant transfer of ¹³⁷Cs and additionally added ¹³⁴Cs was investigated under controlled conditions. The results revealed that the ^134+137Cs soil‐to‐plant transfer factors as well as the percentages of NH₄‐exchangeable ^134+137Cs were much higher for the peat soils and humus layers than for the mineral soils. Nevertheless, the migration of ¹³⁷Cs from the humus layers to the underlying soils was low. Considering the high bioavailability and low migration of radiocesium in the humus layers, it is suggested that radiocesium is involved in a shortcut element cycle in the system humus layer‐plant uptake‐litter. Furthermore, the organic matter has to be taken into account for radiocesium immobilization.     

Effect of cadmium toxicity on micronutrient concentration,uptake and partitioning in seven rice cultivars

Heavy metal uptake, translocation and partitioning differ greatly among plant cultivars and plant parts. A pot experiment was conducted to determine the effect of cadmium (Cd) levels (0, 45 and 90 mg kg^?1 soil) on dry matter yield, and concentration, uptake and translocation of Cd, Fe, Zn, Mn and Cu in seven rice cultivars. Application of 45 mg Cd kg^?1 soil decreased root and shoot dry weight. On average, shoot and root Cd concentrations and uptake increased in all cultivars, but micronutrients uptake decreased following the application of 45 mg Cd kg^?1. No significant differences were observed between 45 and 90 mg kg^?1 Cd levels. On average, Cd treatments resulted in a decrease in Zn, Fe and Mn concentrations in shoots and Zn, Cu and Mn concentrations in roots. Differences were observed in Cd and micronutrient concentrations and uptake among rice cultivars. Translocation factor, defined as the shoot/root concentration ratio indicated that Cu and Fe contents in roots were higher than in shoots. The Mn concentration was much higher in shoots. Zinc concentrations were almost similar in the two organs of rice at 0 and 45 mg Cd kg^?1. A higher Cd level, however, led to a decrease in the Zn concentration in shoots.     

富钾烤烟品种成熟期钾素代谢特征研究

【目的】 研究富钾烤烟品种成熟期钾素代谢特征,有助于了解烟草高效吸收钾的机理,为富钾烤烟基因型的筛选提供参考依据。 【方法】 选用富钾烤烟品种ND202和常规品种K326、NC89进行盆栽试验, 分析了不同烤烟品种生长过程中非根际和根际土壤速效钾含量的变化,成熟期根系生理特性差异,成熟期不同部位钾积累量、钾离子通道和转运体基因表达差异。 【结果】 富钾品种ND202成熟期叶片中的钾积累量极显著地高于K326和NC89,茎和根中的钾积累量品种间差异不显著,ND202全株钾积累量最高,达到10.18 g/株,分别比NC89和K326高109.90%和90.28%,差异达极显著水平。成熟期ND202的平均根鲜重和根体积显著高于K326,根系活力显著高于NC89。ND202根际土壤速效钾含量分别在团棵期极显著低于NC89,在旺长期极显著低于K326,在成熟期极显著低于2个品种,非根际土壤速效钾在成熟期极显著高于NC89和K326。成熟期内流型钾离子通道基因NKT1和NtKC1在不同品种不同部位的相对表达量不同,ND202上部叶中的NKT1表达量显著高于K326和NC89,根、上部叶和中部叶中NtKC1的相对表达量极显著高于NC89和K326,ND202的钾离子通道基因NtTPK1在根、中部叶中极显著高于NC89和K326,有利于钾离子的吸收;ND202下部叶中外流型钾离子通道基因NTORK1的相对表达量极显著低于NC89和K326,钾素外排较少有利于钾含量的提高;钾转运体基因NtHAK1和NtKT12在不同品种不同部位的相对表达量不同,ND202在根、上部叶和中部叶中NtHAK1的相对表达量,在根和上部叶中NtKT12的相对表达量均极显著地高于K326和NC89,有利于钾素运转和积累。 【结论】 富钾品种ND202具有成熟期根系较发达,根系吸收能力较强,钾离子通道和转运体基因相对表达量较高,叶片中钾积累量较大的特征。      

不同母质土壤-水稻系统Cd吸收累积特征及差异

通过选取土壤有效态镉(Cd)含量相近、母质不同的水稻土河沙泥(河流冲积物发育)和紫泥田(紫色砂页岩母质发育),添加不同浓度的外源Cd(0,0.5,1,2,5mg/kg)模拟Cd污染稻田土壤进行盆栽试验,研究不同母质稻田土壤Cd胁迫条件下水稻不同生育期对Cd吸收累积的差异,并推算出土壤Cd环境安全临界值。结果表明,水稻生育期2种土壤有效态Cd含量均在分蘖期最高,河沙泥有效态Cd含量平均为0.47mg/kg,紫泥田平均为0.36mg/kg,同一外源Cd水平下,河沙泥土壤有效态Cd含量高于紫泥田。对河沙泥而言,随着外源Cd浓度的增加,水稻总生物量呈现先增加后下降的趋势,当外源Cd浓度为1mg/kg时达到最大生物量,为47.11g/pot;而紫泥田水稻生物量呈现逐渐增加的趋势,但各处理间差异不显著(P0.05)。2种土壤中水稻糙米、谷壳、茎叶、根Cd含量均随外源Cd浓度的增加而增加,整体分布特征为根茎叶谷壳糙米,且河沙泥高于紫泥田;河沙泥水稻平均Cd累积量为51.71μg/pot,紫泥田平均Cd累积量为42.56μg/pot,2种土壤成熟期水稻Cd累积量对比分蘖期分别增加1.45,1.07倍。回归分析表明,河沙泥和紫泥田稻米Cd超标的土壤Cd安全临界值分别为2.03,3.14mg/kg。水稻对Cd的吸收累积特征及土壤Cd安全临界值因土壤母质不同而存在显著差异。     

Bedeutung der Kalium-Verarmung in der Rhizosphäre und der Tonminerale für die Freisetzung von nichtaustauschbarem Kalium und dessen Bestimmung mit HCl

Significance of K-depletion in the rhizosphere and clay minerals for the release of nonexchangeable potassium and its determination with HCl Experiments were carried out with four different soils (basaltic soil, C-horizon of a keuper, sea alluvium, and a podsolic brown earth from loess) to investigate whether the fractions of exchangeable K and HCl-soluble nonexchangeable K are decreased in root vicinity by the K uptake of ryegrass (Lolium perenne). After a growth period of 70 days with five cuts distinct K depletion profiles were obtained showing that in the direct vicinity of the root the decrease in exchangeable K was the most pronounced. The K depletion in this fraction extended to 2 cm distance from the root zone. Also the concentration of HCl-soluble nonexchangeable K of the interlayers was decreased in root vicinity. It is assumed that the decrease in K concentration in soil solution is a prerequisite for the net release of interlayer K. The decrease in exchangeable K plus HCl soluble nonexchangeable K was equal to the amount of K taken up by the grass from the basaltic- and the alluvial soil. In the case of the podsolic brown earth and the keuper soil, however, much more K was taken up by the grass than was found in the decrease of exchangeable K plus HCl soluble nonexchangeable K. It is assumed that in these two soils the fraction of the HCl soluble K was more altered by the expansion of interlayers during the growth of rye-grass. The net release of interlayer K was neither related to the concentration of exchangeable K, HCl-soluble non-exchangeable K, the K fixation power nor the clay concentration. It is supposed that the net release of interlayer K also depends on clay mineral characteristics.     

复合污染土壤中水稻根际元素特性及效应研究

【目的】以广东大宝山重金属复合污染农田为生长介质,通过研究水稻不同部位生长量、 金属含量、 对金属的富集系数,及其与根际、 非根际土金属含量、 形态变化的相关关系,探讨根际效应可能对水稻体内金属积累转运以及生物量的影响。【方法】选取了广东大宝山稻田重金属复合污染(As、 Pb、 Fe、 Cu、 Zn)土壤及当地常见的20个水稻品种进行根际袋试验,即将根际袋内的土视为根际土,根际袋外的土视为非根际土,将供试水稻品种种植于根际袋土壤中60天后收获,测定水稻各部位的生长量、 不同金属的含量,根际土和非根际土中各金属有效态的含量。【结果】Fe、 Cu、 Pb、 Zn、 As在根部的富集系数均大于其在茎叶的富集系数,各金属在茎叶和根部的富集能力排序分别为Zn Cu As ≈ Pb ≈ Fe和Fe Zn As Cu Pb。根际土和非根际土中各种金属有效态含量均为Fe Cu Pb Zn As。研究还发现,有效态Fe、 Cu和Zn浓度对整株干重的影响显著,作用强弱顺序为Cu Zn Fe,对水稻生长影响作用显著的三种有效态金属Fe、 Cu和Zn均为植物生长所必需的元素。供试土壤中有效态Cu浓度对水稻的生长所起的作用最强。根际土有效态Fe浓度对根系Fe的积累作用效果显著,有效态As浓度显著抑制了根系Fe的积累,且有效态As浓度的作用强于有效态Fe。【结论】根际土中有效态Fe对株高、 根干重、 茎叶干重和整株干重均起着抑制作用,有效态Cu对水稻生长起到了促进作用。根际土有效态As和非根际土有效态Zn对根部Fe的积累起到了抑制作用,根际土有效态Fe和非根际土有效态Cu则起到了促进作用。非根际土有效态Fe和有效态Zn对水稻根长的增加均起到了促进作用。     

两种不同土壤对水稻镉吸收及其动态积累特征的影响

  目的  探究水稻在不同土壤上的镉吸收转运动态特征。  方法  选择我国轻中度镉超标水稻土红砂泥（普通铁聚水耕人为土）和油泥土（普通铁渗水耕人为土）,采用盆栽试验种植水稻,分别在水稻幼苗期、分蘖中期、孕穗中期和成熟期分析不同器官镉累积的动态特征。  结果  水稻种植前油泥土CaCl₂提取态镉浓度（0.02 mg kg?1）比红砂泥（0.15 mg kg?1）低86.7%,导致苗期至分蘖中期油泥土水稻植株体内镉的平均累积速率（0.09 μg plant?1 d?1）比红砂泥（0.32 μg plant?1 d?1）低71.9% ,但分蘖中期至孕穗中期油泥土水稻植株体内镉平均累积速率（0.038 μg plant?1 d?1）比红砂泥(0.073 μg plant?1 d?1)低47.9%,表明分蘖中期之前是土壤类型影响水稻植株体内镉积累的关键期。到了成熟期,由于红砂泥上水稻植株体内镉向糙米的分配比率（11.0%）低于油泥土（16.6%）,加之两种土壤上成熟期水稻植株体内镉累积量均下降,且红砂泥上水稻植株体内镉累积量下降率（28.9%）高于油泥土（18.2%）。油泥土水稻糙米镉累积量比红砂泥低44.4%。  结论  土壤差异除了通过影响土壤有效态镉浓度而影响水稻对镉的吸收外,也通过影响水稻植株体内镉的转运过程,进一步影响糙米镉含量。     

硅酸盐调控抑制水稻对富硒水稻土中Cd吸收

研究目的:通过水稻盆栽试验,探讨了海泡石(SP)、硅钙复合矿物(CS)和水溶性叶面硅肥(YS)3种硅酸盐不同复配处理对富Se水稻土中Cd的迁移和转运和Se的生物有效性的调控效果,以及对糙米中矿质元素吸收的影响。结果表明,海泡石(SP)、海泡石-硅钙复合矿物(SPC)和海泡石-硅钙复合矿物-水溶硅肥(SCY)处理水稻根际土pH值增加0.15～0.31个单位,使土壤Cd由可交换态向碳酸盐结合态和有机结合态转变,而土壤Se由残渣态向生物可利用态转变。与对照(CK)相比,SP、SPC和SCY处理水稻根际土CaCl2-Cd含量降低了19.5%～34.0%,而土壤有效态Se的含量增加了17.8%～36.8%。且SPC和SCY处理糙米中的Cd含量显著降低,比食品安全国家标准(0.2mg/kg)降低了25.0%～90.0%。各处理在降低糙米中Cd的同时,对糙米中Se含量和各矿质元素(Cu、Fe、Zn、Mg和Mn)无显著影响。该研究可为进一步利用SP有效修复富Se水稻土中Cd污染和提高土壤Se的生物有效性提供了有益途径。