APPLICATION OF INCREASING LEVELS OF ZINC TO SOIL REDUCED ACCUMULATION OF CADMIUM IN LUPIN GRAIN

Yellow lupin (Lupinus luteus L.) and narrow-leafed lupin (L. angustifolius L.) are grown as grain legumes in rotation with spring wheat (Triticum aestivum L.) on acidic sandy soils of south-western Australia. Yellow lupin can accumulate significantly larger cadmium (Cd) concentrations in grain than narrow-leafed lupin. A glasshouse experiment was undertaken to test whether adding increasing zinc (Zn) levels to soil increased Zn uptake by yellow lupin reducing accumulation of Cd in yellow lupin grain. Two cultivars of yellow lupin (cv. ‘Motiv’ and ‘Teo’) and 1 cultivar of narrow-leafed lupin (cv. ‘Gungurru’) were used. The soil was Zn deficient for grain production of both yellow and narrow-leafed lupin, but had low levels of native soil Cd (total Cd <0.05 mg kg^?1) so 1.6 mg Cd pot^?1, as a solution of cadmium chloride (CdCl₂·H₂O), was added and mixed through the soil. Eight Zn levels (0–3.2 mg Zn pot^?1), as solutions of zinc sulfate (ZnSO₄·7H₂O), were added and evenly mixed through the soil. Yellow lupin accumulated 0.16 mg Cd kg^?1 in grain when no Zn was applied, which decreased as increasing Zn levels were applied to soil, with ～0.06 mg Cd kg^?1 in grain when the largest level of Zn (3.2 mg Zn pot^?1) was applied. Low Cd concentrations (<0.016 mg Cd kg^?1) were measured in narrow-leafed lupin grain regardless of the Zn treatment. When no Zn was applied, yellow lupin produced ～2.3 times more grain than narrow-leafed lupin, indicating yellow lupin was better at acquiring and using indigenous Zn from soil for grain production. Yellow lupin required about half as much applied Zn as narrow-leafed lupin to produce 90% of the maximum grain yield, ～0.8 mg pot^?1 Zn compared with ～1.5 mg Zn pot^?1. Zn concentration in whole shoots of young plants (eight leaf growth stage) related to 90% of the maximum grain yield (critical prognostic concentration) was (mg Zn kg^?1) 25 for both yellow lupin cultivars and 19 for the narrow-leafed lupin cultivar. Critical Zn concentration in grain related to 90% of maximum grain yield was (mg Zn kg^?1) 24 for both yellow lupin cultivars compared with 20 for the narrow-leafed lupin cultivar.     

Growth,P uptake in grain legumes and changes in rhizosphere soil P pools

In soils with low P availability, several legumes have been shown to mobilise less labile P pools and a greater capacity to take up P than cereals. But there is little information about the size of various soil P pools in the rhizosphere of legumes in soil fertilised with P although P fertiliser is often added to legumes to improve N₂ fixation. The aim of this study was to compare the growth, P uptake and the changes in rhizosphere soil P pools in five grain legumes in a soil with added P. Nodulated chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), white lupin (Lupinus albus L.), yellow lupin (Lupinus luteus L.) and narrow-leafed lupin (Lupinus angustifolius L.) were grown in a loamy sand soil low in available P to which 80 mg P kg⁻¹ was added and harvested at flowering and maturity. At maturity, growth and P uptake decreased in the following order: faba bean > chickpea > narrow-leafed lupin > yellow lupin > white lupin. Compared to the unplanted soil, the depletion of labile P pools (resin P and NaHCO₃-P inorganic) was greatest in the rhizosphere of faba bean (54% and 39%). Of the less labile P pools, NaOH-P inorganic was depleted in the rhizosphere of faba bean while NaOH-P organic and residual P were most strongly depleted in the rhizosphere of white lupin. The results suggest that even in the presence of labile P, less labile P pools may be depleted in the rhizosphere of some legumes.     

CADMIUM CONCENTRATION IN YELLOW LUPIN GRAIN IS DECREASED BY ZINC APPLICATIONS TO SOIL BUT IS INCREASED BY PHOSPHORUS APPLICATIONS TO SOIL

Yellow lupin (Lupinus luteus L.), which is grown as a grain legume in rotation with spring wheat (Triticum aestivum L.) on acidic, sandy soils of south-western Australia, accumulates cadmium (Cd) in grain. Application of fertilizer is required to combat zinc (Zn) and phosphorus (P) deficiency for yellow lupin production on these soils, which may affect Cd concentration in grain. In the same field experiment conducted at two sites on acidified sand over clay duplex soils, five Zn levels (0, 0.8, 1.6, 3.2, 6.4 kg Zn ha^-1), as Zn oxide, and three P levels (0, 10, and 20 kg P ha^-1), as triple superphosphate, were applied. At both sites, applying increasing Zn levels decreased Cd concentration in grain, whereas applying increasing P levels increased Cd concentration in grain. The ZnxP interaction was not significant for either grain yield or Cd concentration in grain. At the 8–10 leaf stage, Zn and P concentration was measured in whole shoots (WS), and Zn concentration was also measured in the youngest mature growth (YMG). The concentrations of the elements that were related to 90% of the maximum grain yield (critical prognostic plant test Zn and P) was i) for WS, 29 mg kg^-1for Zn and 3.5 g kg^-1for P; and ii) for YMG, was 23 mg kg^-1for Zn.     

Use of White Lupin Plant for Phytostabilization of Cd and As Polluted Acid Soil

Cadmium and arsenic are two of the most important and toxic pollutants ubiquitous in the environment. The occurrence of numerous polluted areas as the affected by the accident of Aznalcóllar pyrite mine has promoted the employment of the phytoremediation as a feasible technology able to control and reduce the risk of this contamination at low cost. White lupin plant is proposed as a candidate for phytoremediation. This work aims to study if it is possible to use white lupin in phytoremediation of soils affected by acid pyrite sludge, with simultaneous As and Cd pollution. Pot and field experiments with sludge-affected soil were carried out. The pot trial showed that the NTA treatment increased Cd and As concentrations in lixiviates, exceeding the maximum permissible levels, so that its use in field experiments was avoided. In the field experiment, phytoextraction of Cd and As by lupin plants was very low, suggesting that it was not recommended for phytoextraction. However, lupin culture in the field produced several benefits as: increase of acid soil pH probably by citrate excretion, decrease in soluble As and Cd fractions in soil, high concentration of As and Cd in roots with accumulation of heavy metals in root nodules. All these results support the use of Lupinus albus for phytostabilization and revegetation of the spill polluted soils.     

COMPARING FERTILIZER PHOSPHORUS REQUIREMENTS OF CANOLA,LUPIN, AND WHEAT

Increases in yield due to applications of phosphorus (P) (0, 5, 10, 15, 20, and 40 kg P/ha) applied as single (ordinary) superphosphate were measured for canola (Brassica napus), lupin (Lupinus angustifolius) and wheat (Triticum aestivum) in a field experiment on a deep sandy soil near Esperance, south-western Australia (WA). There are no data comparing the P requirements of these species grown at the same time, which was done by determining the amount of P required to produce 90% of the maximum yield for each species. The amount of P required was about 50% less for canola than wheat and about 10% more for lupin than wheat (60% more than canola). For each amount of P applied, the concentration of P in shoots and grain was greater for canola, followed by lupin and then wheat, suggesting that canola and lupin roots were better at accessing soil P than wheat. The critical concentration of P (diagnostic) required for 90% maximum yield of dried shoots measured in September was about 2.3 g/kg P for wheat, 2.8 g/kg P for lupin, and 3 g/kg P for canola. Similar critical values were obtained when P concentration in the shoots was related to grain yield (prognostic).     

Cadmium uptake by Lupinus albus (L.): Cadmium excretion,a possible mechanism of cadmium tolerance

Cadmium (Cd) uptake by white lupin (Lupinus albus) was studied at low Cd concentrations (0.05nM to 5 μM) in hydroponic solution. Ten 12‐day old seedlings were pretreated in 0.5 mM CaCl₂ solution in presence and absence of metabolic inhibitors (DCCD, DNP or NaN3). Cadmium solutions were labelled with carrier free ¹⁰⁹CdCl2. Cadmium uptake was measured after a 2 h desorption in unlabelled CdCl2 solution. In the absence of any metabolic inhibitor and at 5 [μM Cd, roots absorbed 235.23 μg Cd/g root dry weight. Over the range of lnM to 5 μM Cd, exchangeable Cd represented approximately 5% of the absorbed fraction, and about 25 % of the total absorbed Cd was adsorbed to the root. Cadmium was passively absorbed to about 30% as observed in the presence of the inhibitor (DCCD). Ative absorption which represented 70% of Cd uptake involved H⁺‐ATPase carriers. Cadmium absorption was reduced to 30 and 20% in presence of lanthanum (La³⁺) and zinc (Zn²⁺), respectively which suggested that calcium (Ca), Cd, and Zn use the same carriers. Cadmium uptake in presence of DNP or NaN3 was approximately 4‐ fold that in control. Data showed presomption for an excretion of Cd out of root cells which could be the expression of a detoxification process limiting cell contamination.     

Root Morphology,Proton Release,and Carboxylate Exudation in Lupin in Response to Phosphorus Deficiency

Narrow-leafed lupin (Lupinus angustifolius L.) is widely planted in infertile acidic soils where phosphorus (P) deficiency is one of the major limiting factors for plant growth. A hydroponic experiment was conducted to examine the morphological and physiological responses of roots of narrow-leafed lupin in response to altered P supply at 0, 1, 10, 25 or 75 μ M P as monopotassium phosphate (KH₂PO₄). Low P (P₀ and P₁) significantly decreased the plant biomass, but the supply of 10 μ M P was sufficient to produce similar plant biomass as the maximal P supply (P₇₅), indicating an efficient P acquisition by narrow-leafed lupin. Phosphorus deficiency did not enhance rates of carboxylate exudation and proton release by plant roots, indicating that carboxylate exudation and proton release are not the mechanisms for efficient P acquisition. In contrast, low P supply evidently modified the root morphology by increasing the primary root elongation, and developing a large number of cluster-like first-order lateral roots with dense root hairs, thus allowing efficient P acquisition by narrow-leafed lupin under low P supply.     

Nitrogen Use Efficiency of Rice Under Cadmium Contamination:Influence of Rice Cultivar Versus Soil Type

There is a need for rice cultivars with high yields and nitrogen (N) use efficiency (NUE), but with low cadmium (Cd) accumulation in Cd-contaminated paddy soils. To determine the relative effects of rice genotype, soil type, and Cd addition on rice grain yield and NUE, a pot experiment consisting of nine rice cultivars was conducted in two types of paddy soils, red soil (RS) and yellow soil (YS), without or with Cd spiked at 0.6 mg kg^-1. The N supply was from both soil organic N pools and N fertilizers; thus, NUE was defined as the grain yield per unit of total crop-available N in the soil. Cd addition decreased grain yield and NUE in most rice cultivars, which was mainly related to reduced N uptake efficiency (NpUE, defined as the percentage of N taken up by the crop per unit of soil available N). However, Cd addition enhanced N assimilation efficiency (NtUE, defined as the grain yield per unit of N taken up by the crop) by 21.9% on average in all rice cultivars. The NpUE was mainly affected by soil type, whereas NtUE was affected by rice cultivar. Hybrid cultivars had higher NUEs than the japonica and indica cultivars because of their greater biomass and higher tolerance to Cd contamination. Reduction of NUE after Cd addition was stronger in RS than in YS, which was related to the lower absorption capacity for Cd in RS. Canonical correspondence analysis-based variation partitioning showed that cultivar type had the largest effect (34.4%) on NUE, followed by Cd addition (15.2%) and soil type (10.0%).     

土壤pH值与镉含量对水稻产量和不同器官镉累积的影响

为探明水稻产量与镉积累分配对土壤pH值和镉含量的响应,以3个籽粒Cd含量差异明显的晚稻品种(天优华占,TY;星2号,X2;湘晚籼13号,XW)为试验材料,分别于不同pH值稻田研究土壤镉(Cd)含量对水稻产量和不同器官Cd累积的影响,并比较了品种间差异。结果表明,水稻产量因土壤pH值下降而下降,且品种间降幅差异明显,以X2最大(21.72%33.81%),XW最小(3.05%17.71%);添加0.5 mg·kg^-1Cd时水稻减产不显著,但添加1.0 mg·kg^-1Cd时各品种均显著减产,且其降幅与品种和土壤pH值有关,X2和XW在酸化条件下降幅较大,而TY在正常pH条件下降幅较大。植株(整株)Cd含量存在品种间差异,各品种植株Cd含量均随着土壤Cd浓度的提高与土壤pH值的下降而显著提高,且植株Cd含量峰值因土壤酸化而提前。水稻器官间Cd含量依次表现根>茎>穗>叶,各器官Cd含量均随着土壤Cd浓度提高而显著增大,但增大倍数存在器官间差异;品种间器官Cd含量差异明显,营养器官表现为X2>TY>XW,而稻穗表现为TY>X2>XW。水稻各器官及全株Cd累积量均随着土壤Cd浓度提高和土壤pH值降低而显著增大,成熟期累积量表现为茎>穗>根>叶;品种间Cd累积量差异明显,营养器官和整株Cd累积量表现为X2>XW>TY,而穗Cd累积量表现为TY>X2>XW。Cd分配比例一般以茎为最高,叶最低,土壤酸化使茎、叶所占比例增大,根、穗所占比例降低;品种间Cd分配比例存在一定差异,穗Cd所占比例表现为TY>X2>XW。可见,水稻产量与器官间Cd累积分配规律受到土壤Cd含量和pH值的影响显著,同时也具有明显的品种间差异。本研究为不同水稻品种在不同pH值与Cd含量稻田上的应用提供了理论依据。     

Cadmium Uptake by Cowpea and Mungbean as Affected by Cd and P Application

A green house experiment was conducted to determine the interactive effects of cadmium (0, 2.5, 5, 10, and 20 mg Cd kg-1 soil) and phosphorus (0, 20 and 40 mg P kg-1 soil) on dry matter yield of cowpea and mungbean, and tissue concentration and uptake of cadmium (Cd) and Phosphorus (P). Application of Cd to soil decreased the dry matter yield of both the crops significantly at each level of applied P. Phosphorus application, on the other hand, increased the dry matter yield of both crops significantly at each level of Cd additions to the soil. Cadmium concentration in plant tissue and uptake of Cd by plants increased markedly with the increasing rates of Cd in the soil. The magnitude of increase in tissue Cd concentration, however, was higher in the absence than in the presence of added P. Consequently, the concentration of Cd in plants decreased with increasing levels of P application to the soil. This decrease in tissue Cd concentration with increasing P supply in the soil was mainly attributed to increased dry matter yield of crops. The concentration of P in cowpea and mungbean tissue increased while the uptake of P by these crops decreased markedly with increasing levels of Cd in the soil, irrespective of the rates of P applied.     

植物汁液化学组成及其与菜心抗性和Cd累积的关系

Sap mixtures of the xylem, phloem, and vacuoles from low and high Cd accumulator varieties of Brassica parachinensis L. H. Bailey were analyzed under Cd stress to understand the biochemical mechanisms of Cd accumulation in plants. Low Cd accumulator （‘Teqing-60＇） and high Cd accumulator （‘Chixin-2＇） plants were grown in Cd-treated soil in pots in a greenhouse. Percentage of cell wall-bound Cd was estimated, pH level and the concentrations of amino acids, organic acids, anions, and cations in both stem and root saps were determined for the calculation of Cd speciations using the computer program GEOCHEM. The results showed that ‘Teqing-60＇ had a significantly higher （P ≤ 0.05） percentage of Cd bound to cell walls in roots and a significantly higher （P ≤ 0.05） pH in the root sap. ‘Teqing-60＇ also contained a higher concentration of total amino acids in both roots and stems compared with the high Cd accumulator variety ‘Chixin- 2＇. However, between the two accumulators, for stems and for roots, there were no significant differences in non-amino organic acids. GEOCHEM calculations showed that Cd in the root sap of ‘Teqing-60＇ mainly combined with amino acids, especially alanine. Compared with ‘Chixin-2＇, in the root sap of ‘Teqing-60＇, much lower levels of Cd as free ions or bound to simple ligands were found, indicating that less ‘Teqing-60＇ is transferred to stems and leaves. Cadmium activity in the shoot sap of ‘Teqing-60＇ was much lower than that in ‘Chixin-2＇; therefore, ‘Teqing-60＇ exhibited higher Cd resistance. However, direct determination of the Cd complexes from xylem and phloem sap is needed to verify these results.     

水稻土镉污染与水稻镉含量相关性研究

采用盆栽试验的方法,考察了水稻土中重金属镉（Cd）的浓度对水稻生长及Cd富集的影响以及Cd在水稻植株的分布情况,并进一步研究了糙米（可食部位）对Cd的富集量与土壤中Cd总量的关系。结果表明,在各个浓度Cd胁迫下,根、茎叶、稻壳、糙米相比,2个品种水稻都是根累积的Cd含量要高于茎叶和稻壳、糙米,即根〉茎叶〉稻壳〉糙米;在水稻的茎叶细胞中,Cd主要分布在细胞壁,细胞可溶性成分,细胞器Cd的分布量较少,即细胞壁〉可溶性部分〉细胞器及膜部分;随Cd浓度增加,茎叶中的Cd积累量极显著增加,各细胞组分中的Cd含量均显著增加;根据国标GB 2762—2005对大米中Cd的限量标准（≤0.2 mg.kg^-1）,水稻土土壤总Cd临界值分别为2.0 mg.kg^-（1博优225）、3.1 mg.kg^-（1矮糯）。因此,在污染土壤上宜选种食用部位重金属积累低的水稻品种,以减少人类吸收重金属的风险。     

Comparative phosphorus requirement of four lupin species

The yield response of yellow lupin (Lupinus luteus), sand plain lupin (L. cosentinii), narrow‐leafed lupin (L. angustifolius), and white lupin (L. albus) to applications of phosphorus (P), as single superphosphate (0 to 80 kg P ha^‐1), was measured in the year of application in a field experiment on a sandy soil. Comparative P requirement was determined from yields when no P was applied, the amount of P required to produce the same percentage of the maximum (relative) yield, such as 90% of the maximum yield, and the P content measured in dried tops. For all these criteria, P requirement generally increased in the order L. cosentinii < L. albus < L. angustifolius < L. luteus. Proteoid roots, found only on L. cosentinii and L. albus plants, were probably responsible for these species using indigenous soil P and applied fertilizer P more effectively than L. luteus and L. angustifolius.     

Estimating N rhizodeposition of grain legumes using a N in situ stem labelling method

Grain legumes in crop rotations cause significant increases in yield for succeeding non-legumes, which cannot be explained simply by the small effect that legumes have on the soil nitrogen balance, as found in the analysis of N in crop residues. Besides known positive non-N-effects, other effects, mainly rhizodeposition and its contribution to the N balance and nitrogen dynamics after harvesting the grain, are poorly understood. In this study, N rhizodeposition, defined as root-derived N in the soil after removal of visible roots, was measured in faba bean (Vicia faba L.), pea (Pisum sativum L.) and white lupin (Lupinus albus L.). In a pot experiment the legumes were pulse labelled in situ with ¹⁵N urea using a cotton wick method. About 84% of the applied ¹⁵N was recovered for the three legume species at maturity. The ¹⁵N was comparatively uniformly distributed among plant parts. The N rhizodeposition constituted 13% of total plant N for faba bean and pea and 16% for white lupin at maturity, about 80% of below ground plant N, respectively. Some 7% (lupin)-31% (pea) of the total N rhizodeposits were recovered as micro-roots by wet sieving (200 μm) the soil after all visible roots had been removed. Only 14-18% of the rhizodeposition N was found in the microbial biomass and a very small amount of 3-7% was found in the mineral N fraction. In pea, 48% and in lupin 72% of N rhizodeposits could not be recovered in the mentioned pools and a major part of the unrecovered N was probably immobilised in microbial residues. The results of this study clearly indicate that N rhizodeposition from grain legumes represent a significant pool for N balance and N dynamics in crop rotations.     

Aluminium-Toleranz von Ackerbohne (Vicia faba), Lupine (Lupinus luteus), Gerste (Hordeum vulgare) und Roggen (Secale cereale). I. Sproß- und Wurzelwachstum in Abhängigkeit vom Aluminium-Angebot

AI tolerance of horse bean, yellow lupin, barley and rye. I. Shoot and root growth as affected by Al supply In solution culture considerable differences existed in Al tolerance between the plant species horse bean (Vicia faba ?Herz Freya”?), yellow lupin (Lupinus luteus ?Schwako”?), barley (Hordeum vulgare ?Roland”?) and rye (Secale cereale ?Kustro”?): compared to barley (0.05 μg Al l^?1 = 1.85 μM Al) an 80 fold higher concentration of Al was necessary for lupin and rye for comparable growth depression and for horse bean a 5 times higher Al concentration. Injury by Al after 7 days of Al treatment was most effectively and sensitively characterized by an inhibition of elongation of seminal and especially of lateral roots. Numbers of laterals were also reduced. Dry matter production of roots and shoots was less affected by Al. In lupin, low Al supply even slightly increased the dry weight. The high Al tolerance of rye and yellow lupin in solution culture during the seedling stage is in good agreement with their adaptation to acid mineral soils.     

5个蓖麻品种对土壤中镉富集的差异

为了评价能源作物蓖麻对污染农田中重金属镉(Cd)的富集修复能力,本研究以5个蓖麻品种为试验材料,通过大田试验对比了不同蓖麻品种在Cd污染农田中的生长情况、对Cd的富集和转运能力以及对Cd污染土壤的修复能力。结果表明,5个蓖麻品种在Cd污染农田中生长良好,其中滇蓖2号的株高、茎粗及单株产量显著高于其他品种,分别为440.78 cm、5.04 cm以及338.85 g。5个蓖麻品种根、茎、叶及果实的Cd含量、Cd积累量和富集系数均存在显著差异,其中经作蓖麻1号根、茎和果实的Cd含量最高,分别为1.40、1.14和0.33 mg·kg^-1。污染修复能力方面,滇蓖2号Cd的积累量达3.38 mg/株,提取率为5.34%,显著高于其他品种。经作蓖麻1号尽管富集能力最强,但由于其生物量最小,其Cd积累量及年提取效率均最低。综上可知,蓖麻对土壤中重金属Cd的富集能力较强,可用于修复云南个旧地区的Cd污染土壤,且种植滇蓖2号可以获得较好的修复效果。本研究结果为云南Cd污染土壤治理提供了理论基础和参考依据。     

Evaluation of Extraction Methods for Plant-Available Soil Cadmium to Wheat by Several Extraction Methods in Cadmium-Polluted Paddy Field

To develop a new method for the extraction of plant-available cadmium (Cd), the correlation between the Cd content of polluted soil extracted with several extractants and the Cd content of wheat plants (variety “A” Triticum aestivum L.) was examined. Among the HCI concentrations of soil extractants tested, the content of 0.025 mol L^?1 HCI (HCl_0.025)-extractable Cd of soil showed a significant correlation with the Cd content of wheat grain and Cd uptake by shoot. The correlation between the soil Cd content extracted with 1 mol L^?1 NH₄Cl and the Cd content of wheat grain was nearly the same as that in the case of HCI_0.025. In contrast, other reagents such as MgCl₂, diethylenetriaminepentaacetate (DTPA) and tetra-sodium pyrophosphate (Na₄P₂O₇) could not give a good correlation between the extractable Cd content of soil and the Cd content of wheat grain. Therefore, it was considered that HCl_0.025-extractable Cd is a suitable indicator of the content of plant-available Cd of soil to wheat. This extraction method can be applied to weakly acid Grey Lowland soil. Using the equation for the relation between the content of HCl_0.025-extractable Cd of soil and the Cd content of grain of the wheat variety “A”, the Cd content of grain of other 11 wheat varieties was evaluated. The wheat variety “A” showed the lowest absorption of Cd. The Cd content of variety “B” grain was located on the regression line of that of variety “A”, suggesting that both varieties exhibited the lowest ability to absorb Cd among the varieties tested. Grain yields of both “A” and “B” varieties were reasonably high. On the other hand, other varieties showed a substantially high ability to absorb soil Cd compared with the varieties “A” and “B”. The new method proposed for the determination of the content of plantavailable Cd proved to be suitable for the evaluation of plant-available Cd of soil and also for the screening of wheat varieties with a high or low Cd accumulation capacity in grain.     

Lupin Flours as Additives: Dough Mixing,Breadmaking, Emulsifying,and Foaming

The nutritional quality of various food products could be improved by supplementation with grain legumes to increase protein content and to improve the balance of essential amino acids. The lupin grain is a good candidate for this role, given its yield potential in a range of climatic environments and soil types. To establish the practicality of extending the use of lupins as food additives, the functional properties of various species and cultivars of lupin were studied for their effect as additives to baked products and their ability to provide foaming and emulsifying properties. Of the two lupin species that are commonly cultivated commercially, Lupinus albus showed the greater potential as a bread additive; loaf height and structure were maintained when lupin flour was substituted for wheat flour at levels up to 5%. This level of substitution offered the advantage of reducing mixing time. The detrimental effects at higher substitution levels appeared to be associated with the nonprotein components of the lupin flour. L. albus showed better functionality than L. angustifolius in emulsifying attributes, although L. angustifolius showed greater potential as a foaming agent. Defatting the lupin flour may be necessary to show these properties to best advantage. Certain cultivars (within each species) showed preferable performance, indicating the potential for plant breeding to provide germplasm better suited to uses as food additives.     

Effect of soil cadmium concentration on three Chilean durum wheat cultivars in four environments

Durum wheat (Triticum turgidum L. var durum) is a species that accumulates cadmium (Cd). Durum wheat cultivars differ in their absorption ability of Cd; therefore, identifying and selecting genetic material with low Cd accumulation reduces human exposure to this toxic element. In the present study, Cd concentration was evaluated in three Chilean durum wheat cultivars (Llareta-INIA, Corcolén-INIA, and Lleuque-INIA) grown in four Chilean locations with varying concentrations of Cd in soils. The objective of this study was to evaluate the response of these durum wheat cultivars to different doses of cadmium in terms of grain yield; Cd concentration in different plant tissues (grain, straw, roots); soil Cd concentration was also evaluated. Results show that grain yield was not affected by soil Cd; differences in Cd concentration in plant tissues were generally associated with location, cultivar, and soil Cd concentration. Grain Cd concentration in all three cultivars was classified in the low accumulation category for this metal; ‘Lleuque-INIA’ noted as having a very low accumulation.     

Effect of water management on cadmium and arsenic accumulation by rice (Oryza sativa L.) with different metal accumulation capacities

Purpose

Water management affects the bioavailability of cadmium (Cd) and arsenic (As) in the soil and hence their accumulation in rice grains and grain yields. However, Cd and As show opposite responses to soil water content, but information, particularly on irrigation, is missing on a field scale. The purpose of the present study was therefore to find a water management regime that can lower accumulation of both Cd and As in grain without yield loss.

Materials and methods

Two rice (Oryza sativa L.) cultivars, A16 and A159, with different grain Cd accumulation capacities were employed in field plot experiments with four water management regimes comprising aerobic, intermittent, conventional practice and flooded. The dynamics of Cd and As bioavailability in the soil and Cd and As concentrations in roots, straw and grains were determined at the early tillering, full tillering, panicle initiation, filling and maturity stages of crop growth.

Results and discussion

The lower water content regimes (aerobic and intermittent) mostly led to higher soil HCl-extractable Cd than the higher soil water content regimes (conventional and flooded). HCl-extractable As in contrast was favoured by the higher soil water content treatments. Conventional and flooded irrigation accordingly gave higher plant As concentrations but lower Cd compared to aerobic and intermittent irrigation. Cd concentrations in roots and straw of both varieties increased with growth stage, especially in aerobic and intermittent regimes, while As concentrations in plants showed little change or a slight decrease. As the water irrigation volume increased from aerobic to flooded, brown rice Cd decreased from 1.15 to 0.02 mg?kg^?1 in cultivar A16 and from 1.60 to 0.05 mg?kg^?1 in cultivar A159, whereas brown rice As increased. Aerobic and flooded treatments produced approximately 10–20 % lower grain yields than intermittent and conventional treatments. Cultivars with low Cd accumulation capacity show higher brown rice grain As than those with high Cd uptake capacity.

Conclusions

Of the four water management regimes, the conventional irrigation method (flooding maintained until full tillering followed by intermittent irrigation) ensured high yield with low Cd and As in the brown rice and so remains the recommended irrigation regime.