Influence of the ionic strength of nutrient solutions and tropical acid soil solutions on aluminum activity

Aluminum (Al) activity was determined in nutrient solutions and in acid soil solutions. Aluminum concentrations in the solutions ranged from 7.4 μM to 370.3 μM giving values of ionic strength of nutrient solutions higher than the values of acid soil solutions. The increase of ionic strength values was due to the increase of Al concentrations. The values of Al activities of 20 uM in the acid soil solutions were noticed when Al concentrations were lower than 70 μM. On the other hand, these values of Al activities in nutrient solutions were noticed only when the Al concentrations were higher than 70 μM. This study demonstrates why it is important to use higher Al concentrations in nutrient solutions to obtain Al toxic effects.     

Aluminum inhibits growth and stability of cortical microtubules in wheat (Triticum aestivum) roots

Aluminum (Al) occurs abundantly in soil and solubilized aluminum ions in acid soil inhibit plant growth, in particular, root growth. Although several toxic effects of Al on plant growth have been reported, the mechanism of Al toxicity remains to be clarified.     

Differential responses of sericea lespedeza to aluminum stress

Toxic levels of aluminum can cause severe yield reductions in many crop species, but sericea lespedeza [Lespedeza cuneata (Dum.‐Cours.) G. Don] has demonstrated considerable tolerance. Aluminum tolerances of six sericea lespedeza cultivars (Am 312, Appalow, AU Lotan, Interstate, Interstate 76, Serala) representing a broad genetic base were evaluated in a Monmouth soil [26.2% Al saturation (pH 4.8) vs. 2.8% Al saturation (pH 5.7)] and in nutrient solutions (0 vs 111 μM Al; pH 4.5). The soil and nutrient culture studies were harvested 30 and 27 d after seeding, respectively.

Aluminum stress did not reduce root and shoot growth significantly, nor were the pooled Al stress x cultivar interactions significant. Cultivars differed significantly in mean shoot and root vigor in nutrient solutions but not in soil. R‐esponses in soil were only weakly correlated with responses in nutrient solutions. Am 312 and Appalow had the lowest relative weight values (dry weight stressed/dry weight unstressed) in both media and Interstate and Interstate 76 the highest. Interstate 76 exhibited a significant positive response (5% level) to Al when evaluated in nutrient solutions.     

Interaction of aluminum and iron oxides and clay minerals and their effect on soil physical properties: A review

Abstract

Amorphous and crystalline aluminum and iron oxide minerals play a major role in stabilizing soil structure as measured by aggregate stability and clay dispersion. Aluminum and iron oxide interactions with clays are pH dependent. At low pH, where the oxides carry sufficient positive charge, they precipitate on clay surfaces. These coatings, once formed, are stable at higher pHs. Precipitation of oxides at high pH occurs as phases separate from the clays. Aluminum and iron oxides stabilize clay minerals by decreasing critical coagulation concentration, clay dispersion, water uptake, and clay swelling and by increasing microaggregation. The presence of aluminum and iron oxide minerals in soils has a favorable effect on soil physical properties, increasing aggregate stability, permeability, friability, porosity, and hydraulic conductivity, and reducing swelling, clay dispersion, bulk density, and modulus of rupture.     

Acid soil tolerances of two wheat cultivars related to soil Ph,KCl‐extractable aluminum and degree of aluminum saturation

Aluminum toxicity, associated with soil acidity, is a major growth‐limiting factor for plants in many parts of the world. More precise criteria are needed for the identification of potential Al toxicity in acid soils. The objective of the current study was to relate the acid soil tolerances of two wheat cultivars to three characteristics of an acid Tatum subsoil (clayey, mixed, thermic, typic Hapludult): pH in a 1:1 soil to water suspension; KCl‐extractable Al; and degree of Al saturation. Aluminum‐tolerant ‘BH 1146’ (Brazil) and Al‐sensitive ‘Sonora 63’ (Mexico) wheat cultivars were grown in greenhouse pots of soil treated with CaCO₃ to establish final soil pH levels of 4.1, 4.6, 4.7, 4.9, 5.2 and 7.3. Soil Al, Ca and Mg were extracted with 1 N KCl, and Al saturation was calculated as KCl‐Al/KCl Al + Ca + Mg%.

Within the soil pH range of 4.1 to 4.9, BH 1146 tops and roots produced significantly more dry matter than did those of Sonora 63; however, at pH 5.2 and 7.3, the top and root yields of the two cultivars were not significantly different. Significant cultivar differences in yield occurred over a range of 36 to 82% saturation of the Tatum soil. Graphs of relative top or root yields against soil pH, KCl‐extractable Al and Al saturation indicated that the two cultivars could be separated for tolerance to Tatum soil under the following conditions: pH less than 5.2 (1:1 soil‐water); KCl‐Al levels greater than 2 c mole kg^‐1 and Al saturations greater than 20%. Results demonstrated that any soil test used to predict Al toxicity in acid soils must take into account the Al tolerances of the plant cultivars involved.     

矿区复垦土壤养分变化趋势研究

系统研究了孝义露天铝矿不同复垦年限的土壤养分变化 ,结果表明 :随着复垦年限的增加 ,复垦土壤有机质、全氮、有效磷均呈逐年增加趋势 ,土壤容重逐年下降 ,土壤全磷、全钾、速效钾、土壤 pH、交换量和Cu、Zn、B、Mn、Fe等微量元素的有效态含量变化不明显。研究证明通过种植牧草和大量施用有机肥和化肥 ,可加速复垦土壤的熟化、土壤理化性状逐年改善 ,土壤生产力逐年提高。     

Quantification of Aluminum-Induced Changes in Wheat Root Architecture by X-ray Microcomputed Tomography

Root architectural traits are of fundamental importance for plant performance, especially under unfavorable soil conditions. This study examined the effect of aluminum (Al) toxicity in different growing media (nutrient solutions and soil) on root architecture of two wheat (Triticum aestivum L.) cultivars with different Al tolerances. Seedlings were grown in acidic and limed soil and in two contrasting nutrient solutions. Root systems of soil-grown plants were scanned using x-ray microcomputed tomography (µCT) while that of nutrient solution–grown plants were assesses using WinRhizo, 3 and 5 days after planting (DAP), respectively. Aluminum caused significant reduction of all examined root traits (number of seminal roots, root length, length of the longest seminal root, root surface area, and root volume). Growth in acidic soil caused significant reduction in root length, length of the longest seminal root, and root surface area at 5 DAP. Soil-grown plants produced a larger root system compared to plants grown in nutrient solutions. Aluminum toxicity–induced differences of root traits were also found between different nutrient solutions. Beside the well-known reduction of root length, Al toxicity had a profound effect on other root architectural traits. X-ray µCT has revealed root architectural changes under specific conditions of acidic, Al-toxic soil. Differences obtained in Al-induced effects on root architecture between different nutrient solutions as well as between different growing systems emphasize the need for further study of root architecture, especially under specific conditions of Al toxicity in acidic soils.     

Tolerances of wheat germplasm to acid subsoil

Aluminum toxicity is a major growth limiting factor for plants in many acid soils of the world. Correcting the problem by conventional liming is not always economically feasible, particularly in subsoils. Aluminum tolerant plants provide an alternative and long‐term supplemental solution to the problem. The genetic approach requires the identification of Al tolerance sources that can be transferred to cultivars already having desirable traits. Thirty‐five cultivars and experimental lines of wheat (Triticum aestivum L. em. Thell) were screened for Al tolerance on acid Tatum soil (clayey, mixed thermic, typic Hapludult) receiving either 0 or 3500 mg CaCO₃/kg (pH 4.1 vs. pH 7.1). Entries showed a wide range of tolerance to the acid soil. On unlimed soil at pH 4.3, absolute shoot dry weights differed by 5‐fold, absolute root dry weights by 6.5‐fold, relative shoot weights (wt. at pH 4.3/wt. at pH 7.1 %) by 4.7‐fold and relative root dry weights by 7‐fold. Superior acid soil (Al) tolerance of ‘BH‐1146’ from Brazil and extreme sensitivities of cultivars ‘Redcoat’ (Indiana, USA) and ‘Sonora 63’ (Mexico) were confirmed. Seven experimental (CNT) lines from Brazil showed a range of acid soil tolerance but were generally more tolerant than germplasm from Mexico and the USA. One line, ‘CNT‐1’, was equal to BH‐1146 in tolerance and may be useful in transferring Al tolerance to existing or new cultivars. Five durum cultivars (Triticum, durum, Desf.) were extremely sensitive to the acid Tatum subsoil at pH 4.3 compared with pH 7.1.     

Differential responses of red clover germplasms to aluminum stress

Toxic levels of aluminum can cause severe yield reduction in red clover (Trifolium pratense L.), especially in the presence of drought stress. Aluminum tolerances of 17 red clover cultivars and germplasms representing a broad genetic base were evaluated in a Monmouth soil [26.2% Al saturation (pH 4.8) vs. 2.8% Al saturation (pH 5.7)] and in nutrient solutions (0 vs 111 μM Al; pH 4.5). The soil and nutrient culture studies were harvested 29 and 27 d after seeding, respectively.

Aluminum stress reduced shoot and root growth significantly in soil but not in nutrient culture. Entries differed significantly in shoot vigor in both media and in root vigor in nutrient culture; responses to the two media were positively correlated. Relative weights (dry weight stressed/dry weight unstressed) in soil and nutrient culture were not correlated.

In soil, Al stress significantly reduced shoot growth of all entries except ‘Tristan’, whereas root growth was not affected significantly in ‘Atlas’, ‘Lakeland’, ‘Persist’, ‘Reddy’, ‘Redman’, or Tristan. Reddy, ‘Redland II’, Redman, and Tristan had the highest relative shoot and root weights whereas ‘Kenstar’ had the lowest. In nutrient culture, only the shoot growth of Atlas, Lakeland, Redman and ‘YKYC’ and the root growth of Redman were significantly reduced under Al stress. Atlas, ‘Kenland’, and Redman had among the lowest relative shoot and root weights and Kenstar among the highest. Some entries exhibited a positive growth response to Al.     

铝对植物的毒害和植物抗铝毒机理及其影响因素

本文综述了土壤中铝的存在形式、铝对植物产生的毒害、植物抗铝毒的内、外部机理以及铝毒效应的影响因子 .从植物抗铝毒遗传特性的差异出发 ,探讨利用抗铝毒作物基因型 ,提高酸性土壤上的作物生产力 .最后就植物抗铝毒研究提出一些看法     

Tolerance of durum wheat lines to an acid,aluminum‐toxic subsoil

Durum wheat, Triticum durum Desf., is reportedly more sensitive to aluminum (Al) toxicity in acid soils than hexaploid wheat, Triticum aestivum L. em. Thell. Aluminum‐tolerant genotypes would permit more widespread use of this species where it is desired, but not grown, because of acid soil constraints. Durum wheat germplasm has not been adequately screened for acid soil (Al) tolerance. Fifteen lines of durum wheat were grown for 28 days in greenhouse pots of acid, Al‐toxic Tatum subsoil at pH 4.5, and non‐toxic soil at pH 6.0. Aluminum‐tolerant Atlas 66 and sensitive Scout 66 hexaploid wheats were also included as standards. Based on relative shoot and root dry weight (wt. at pH 4.5/wt. at pH 6.0 X 100), durum entries differed significantly in tolerance to the acid soil. Relative shoot dry weight alone was an acceptable indicator of acid soil tolerance. Relative dry weights ranged from 55.1 to 15.5% for shoots and from 107 to 15.8% for roots. Durum lines PI 195726 (Ethiopia) and PI 193922 (Brazil) were significantly more tolerant than all other entries, even the Al‐tolerant, hexaploid Atlas 66 standard. Hence, these two lines have potential for direct use on acid soils or as breeding materials for use in developing greater Al tolerance in durum wheat. Unexpectedly, the range of acid soil tolerance available in durum wheat appears comparable to that in the hexaploid species. Hence, additional screening of durum wheat germplasm for acid soil (Al) tolerance appears warranted. Durum lines showing least tolerance to the acid soil included PI 322716 (Mexico), PI 264991 (Greece), PI 478306 (Washington State, USA), and PI 345040 (Yugoslavia). The Al‐sensitive Scout 66 standard was as sensitive as the most sensitive durum lines. Concentrations of Al and phosphorus were significantly higher in shoots of acid soil sensitive than in those of tolerant lines, and these values exceeded those reported to cause Al and phosphorus (P) toxicities in wheat and barley.     

磷化铝对土壤微生物数量和酶活性的影响

为明确磷化铝对土壤微生物数量和酶活性的影响,采用室内培养的方法,研究了经0.1、1mg.g-1和10mg.g-13个浓度磷化铝熏蒸处理后,供试土壤中微生物数量和土壤酶活性的变化。结果表明,磷化铝处理土壤后,各个浓度的磷化铝对土壤细菌、真菌和放线菌数量具有抑制作用,浓度越高,抑制作用越强,但一段时间后低浓度（0.1mg.g-1）处理对土壤微生物数量的影响恢复至对照水平。磷化铝对土壤脲酶表现为抑制作用,并随浓度升高而增强;低浓度处理对土壤中的蔗糖酶活性抑制作用不明显,而高浓度（10mg.g-1）处理表现为强烈的抑制作用;各浓度处理初期对土壤过氧化氢酶表现为抑制或激活作用,但到第30d,恢复至对照水平。这说明,施入常规剂量的磷化铝对土壤微生物数量和土壤酶活性会产生一定的影响,在经过一定时间后均可恢复至对照水平。     

铝胁迫对决明属水土保持牧草幼苗根系的影响

耐铝能力对红、黄壤山区水土保持牧草的生长具有重要影响。AFT2 2 17(C .nictitans)、CPI3 472 1(C .rotundi folia)和CPI8613 4(C .rotundifolia)三个决明品系水土保持牧草耐铝能力均较强 ,但对Al3+ 敏感性有差异 ,按反应强弱排序为 :CPI8613 4>AFT2 2 17>CPI3 472 1;经 6个Al浓度梯度处理 ,从主根长、侧根数、根细胞质膜透性等指标分析 ,三个决明品系中CPI3 472 1的幼苗耐铝能力相对较强 ,AFT2 2 17、CPI8613 4耐铝能力稍弱 ,铝毒临界值前者为 60mg/L ,后两者为 40mg/L。同时试验表明决明品系水土保持牧草的根系需要适量铝的刺激 ,才能生长得更好     

Relationships between Soil Parameters and the Growth of Wheat Plants on an Acid Soil in Rwanda

Three wheat categories with different biomass production were studied on tropical Inceptisols in Rwanda. Growth parameters such as number of tillers per square meter, average plant height, and shoot and root biomass were determined, and elemental concentrations of roots and leaves measured. In order to identify reasons for inhibited wheat growth soil parameters such as pH, exchangeable cations, C_org and N_tot were determined. As aluminum toxicity was suspected on the acid soils, aluminum fractionation was carried out in water extracts of the soil samples using 8-hydroxyquinoline. Growth parameters correlated well with exchangeable aluminum and with soil pH. These findings, along with root morphology, indicated aluminum toxicity at the low productivity plots. Aluminum fractionation results strengthened this hypothesis, but did not give much additional information. The reasons for this are discussed. Simultaneously, the elemental concentrations of the leaves suggested Ca, Mg and P deficiencies.     

秸秆和硫酸铝改良剂对苏打盐碱土吸附腐殖酸性能的影响

为了揭示硫酸铝改良剂对苏打盐碱土在秸秆还田条件下固碳性能的影响,研究了添加秸秆和硫酸铝并于恒温条件下培养300天后的盐碱土对腐殖酸的吸附性能。结果表明:在腐殖酸吸附动力学中,秸秆和硫酸铝不同添加量条件下,盐碱土对腐殖酸的吸附均在120min时达到平衡,准二级动力学方程拟合效果最好,R2值最高(0.936)。Langmuir方程和Freundlich方程均可较好地拟合盐碱土对腐殖酸的等温吸附。添加相同比例的玉米秸秆条件下,Langmuir方程拟合获得的最大吸附量分别表现为69.335,42.830,40.498,42.593mg/g。而添加同等比例的硫酸铝改良剂条件下,最大吸附量分别表现为21.358,32.647,69.335,49.232,62.375,42.830mg/g。     

有机物料对酸性红壤铝毒的缓解效应

利用盆栽试验研究了施用不等量稻草对酸性红壤旱耕地铝毒的缓解效应。结果表明,添加不等量的秸秆碳(C)后,土壤pH值显著提高,土壤交换性铝和吸附态羟基铝的含量则明显降低,土壤有机络合态铝的含量也呈增加趋势。添加铝盐并不影响秸秆碳对降低土壤交换性铝和吸附态羟基铝含量的作用。在本研究中,土壤pH值与土壤交换性铝和土壤吸附态羟基铝均呈显著负相关,方程分别为y=-2193.9x+11545,R2=0.9798**,y=-655.34x+9748,R2=0.7837**。土壤交换性铝和吸附态羟基铝与玉米主根长,地上部磷、钾含量均呈显著负相关,是抑制玉米吸收养分的主要限制因素,土壤吸附态羟基铝是次于交换性铝的又一活性较大的铝化合物。     

Composition of surface water in the Central Forest State Natural Biospheric Reserve

The chemical composition of surface water in the Central Forest State Natural Biospheric Reserve is characterized by well-pronounced seasonal dynamics related to the intensity of biological turnover. Three groups of chemical elements with different types of seasonal dynamics are specified. The impact of soils on the chemical composition of surface water is most pronounced in the summer, when concentrations of dissolved organic carbon and microelements are the highest and correlate with one another. The groundwater is the main source of calcium, sodium, and magnesium for the local Mezha River. Aluminum and water-soluble organic substances are supplied with soil solutions from organic horizons (10–50 cm). Iron and manganese are discharged into the river both with surface soil waters and with the groundwater flow. The migration of aluminum in the Mezha River basin is mainly controlled by the pH conditions, whereas the migration of iron depends on the concentration of dissolved organic carbon.     

The total concentration and fractional composition of the aluminum compounds in soil solutions from peaty-podzolic-gleyic soils developed on binary deposits

The total concentration and fractional composition of aluminum compounds were determined in soil solutions obtained using vacuum lysimeters from the main genetic horizons of peaty-podzolic-gleyic soils developed on binary deposits. The total concentration of aluminum in the brooks draining the area with a predominance of these soils was also estimated. The total aluminum concentration in the soil solutions reached the maximum values (0.079–0.092 mmol/l) in the Eih horizon and generally decreased down the profile. The aluminum in the soil solutions occurred in the form of monomeric inorganic and organic compounds and complexes with high-molecular-weight organic acids. The proportion of inorganic monomeric aluminum compounds in the solutions from the peaty-podzolic-gleyic soils increased compared to that in the podzolic soils; no aluminosilicate compounds were found. Aluminum arrived to the brooks draining the areas with the predominant peaty-podzolic-gleyic soils mainly from the above-moraine horizons, including the Eih, E, and Ecn. It was supposed that the removal of aluminum from these soils exceeded that from the podzolic soils.     

Effect of additions of brown coal and peat on soil solution composition and root growth in acid soil from wheatbelt of western Australia

Abstract

Additions of several categories of organic materials including fresh plant materials, compost, manure, coal derived products, and peat have been shown to ameliorate soil acidity. The main effect is increased soil pH and the corresponding decrease in soil solution and exchangeable aluminum (Al). The organic matter addition is expected to decrease the solubility of soil aluminum so that lower activities are maintained at a given pH value, but this effect has not been tested. Aluminum solubility was investigated after addition of brown coal and peat to an acid soil. Root length was used as a bioassay for the acid ameliorating properties of the organic materials. Addition to soil of brown coal and peat resulted in changes in Al activity in the soil solution. The negative log of Al activity (pAl) was directly proportional to the soil solution pH. A single pAl‐pH line could describe the control, calcium chloride and organically treated soil samples. This line was parallel to that of gibbsite. The intercept was greater suggesting undersaturation with respect to that mineral. The coal and peat applied at the rate of 1 and 2% had little effect on the solubility of soil Al. Any decrease in Al activity was solely dependent on increased soil pH. Relative root length was inversely related to Al activity. This relationship was improved by including base cations in the index of Al phytotoxicity. This index could provide the basis for evaluating the value of brown coal and peat in ameliorating soil acidity.     

不同水稻品种磷利用效率与耐铝性的关系研究

铝毒和磷缺乏是酸性土壤上作物生产的主要限制因子。本研究中我们探究了5个粳稻和5个籼稻品种的磷利用效率和耐铝性之间的相互关系。结果表明,粳稻品种的耐铝性显著高于籼稻品种。对于耐铝性强的水稻品种,施加磷肥后地上部生物量显著增加,而铝敏感的品种对磷肥响应较小,这可能是由于其耐铝性差而酸性土壤中的铝毒导致根系结构和功能受损,从而影响养分的吸收和利用。不同水稻品种的耐铝性和磷吸收效率呈正比而与磷利用效率呈反比,且粳稻的地上部磷浓度及磷吸收效率高于籼稻,但磷利用效率则低于籼稻。这些结果对于酸性土壤中筛选耐铝和磷高效利用的水稻品种具有重要意义。