The influence of the ectomycorrhizal fungus Rhizopogon subareolatus on growth and nutrient element localisation in two varieties of Douglas fir (Pseudotsuga menziesii var. menziesii and var. glauca) in response to manganese stress

Acidification of forest ecosystems leads to increased plant availability of the micronutrient manganese (Mn), which is toxic when taken up in excess. To investigate whether ectomycorrhizas protect against excessive Mn by improving plant growth and nutrition or by retention of excess Mn in the hyphal mantle, seedlings of two populations of Douglas fir (Pseudotsuga menziesii), two varieties, one being menziesii (DFM) and the other being glauca (DFG), were inoculated with the ectomycorrhizal fungus Rhizopogon subareolatus in sand cultures. Five months after inoculation, half of the inoculated and non-inoculated seedlings were exposed to excess Mn in the nutrient solution for further 5 months. At the end of this period, plant productivity, nutrient concentrations, Mn uptake and subcellular compartmentalisation were evaluated. Non-inoculated, non-stressed DFM plants produced about 2.5 times more biomass than similarly treated DFG. Excess Mn in the nutrient solution led to high accumulation of Mn in needles and roots but only to marginal loss in biomass. Colonisation with R. subareolatus slightly suppressed DFM growth but strongly reduced that of DFG (-50%) despite positive effects of mycorrhizas on plant phosphorus nutrition. Growth reductions of inoculated Douglas fir seedlings were unexpected since the degree of mycorrhization was not high, i.e. ca. 30% in DFM and 8% in DFG. Accumulation of high Mn was not prevented in inoculated seedlings. The hyphal mantle of mycorrhizal root tips accumulated divalent cations such as Ca, but not Mn, thus not providing a barrier against excessive Mn uptake into the plants associated with R. subareolatus.     

Heavy metals in white lupin: uptake, root-to-shoot transfer and redistribution within the plant

The translocation of manganese (Mn), nickel (Ni), cobalt (Co), zinc (Zn) and cadmium (Cd) in white lupin (Lupinus albus cv. Amiga) was compared considering root-to-shoot transport, and redistribution in the root system and in the shoot, as well as the content at different stages of cluster roots and in other roots. To investigate the redistribution of these heavy metals, lupin plants were labelled via the root for 24 h with radionuclides and subsequently grown hydroponically for several weeks. 54Mn, 63Ni and 65Zn were transported via the xylem to the shoot. 63Ni and 65Zn were redistributed afterwards via the phloem from older to younger leaves, while 54Mn remained in the oldest leaves. A strong retention in the root was observed for 57Co and 109Cd. Cluster roots contained higher concentrations of all heavy metals than noncluster roots. Concentrations were generally higher at the beginning of cluster root development (juvenile and immature stages). Mature cluster roots also contained high levels of 54Mn and 57Co, but only reduced concentrations of 63Ni, 65Zn and 109Cd.     

Lignin and cellulose concentrations in roots of Douglas fir and European beech of different diameter classes and soil depths

Comparing two tree species, we tested the effects of root diameter (up to 30 mm) and soil depth (down to 1.2 m) on the concentrations of lignin, cellulose and nitrogen (N) in roots of approximately 50-year-old Douglas fir and European beech growing in a temperate forest in South-western Germany. Fine roots (diameter 0.5–2 mm) exhibited significantly higher lignin concentrations, but lower cellulose concentrations than medium or coarse roots (diameter >5 mm). The cellulose and lignin concentrations of the roots as well as their lignin:cellulose ratios did not differ significantly among soil depths. In the Douglas fir, there was a tendency of decreasing N concentrations and increasing lignin:N ratios with increasing soil depth. This trend was absent or less pronounced in the beech. Beech roots displayed significantly higher cellulose and N concentrations and lower lignin:cellulose and lignin:N ratios than roots of the Douglas fir. Generally, the lignin concentrations of the roots did not differ between the tree species. Cellulose and lignin concentrations exhibited a significantly negative correlation. As several studies have demonstrated that plant litter decomposition is governed by the lignin:cellulose and lignin:N ratios more than by the lignin concentration of the detritus, the fraction of individual tree species in the stand composition might affect the decomposability of roots in beech–Douglas fir forests, and might also have an influence on soil carbon sequestration.     

Differential response of salt-marsh species to variation of iron and manganese

Salt-marsh plants of the lower, middle and upper marsh were compared in their response to iron and manganese. The species studied showed differential sensitivity to high concentrations of Fe (1 000 μM) and Mn (10 000 μM) in hydroculture experiments, species of the lower marsh being more resistant than species of the upper marsh. Fe and Mn concentrations in the root were higher than in the shoot, which was also found in plants inundated with seawater. High Fe and Mn concentrations in the root are probably the result of the oxidizing power of plant roots with a subsequent low translocation of Fe (II) and Mn (II) to the shoot. At high (toxic) Fe and Mn levels in the nutrient solution, Fe and Mn concentrations were much higher in the shoots of sensitive species than in resistant species. The P content of roots and shoots was not influenced by increased Fe and Mn concentrations. Fe and Mn resistance in Spartina anglica and Juncus gerardii, may be in part due to a high root porosity. Other species, however, that are similarly resistant to Fe and Mn lack a well-developed aerenchym. Root porosity, radial oxygen loss and Fe (II) and Mn (II) exclusion by oxidation to Fe (III) (hydr)oxides deposited on the roots form part of the resistance mechanism of hygrohalophytes to Fe and Mn; the differences in this respect between the species may also be due to other metabolic aspects.     

Influence of temperature on the expression of manganese toxicity by two soybean varieties

Summary Two soybean varieties (Glycine max) were grown in nutrient solution to investigate their response to manganese toxicity at two different temperature regimes. Dry matter yields of both varieties were markedly reduced by lower temperature (21°C day/18°C night). At these temperatures leaf crinkle symptoms of Mn toxicity were very severe on Bragg and moderate on Lee at high levels of Mn in solution (15 ppm). However increasing the temperature to 33°C day/28°C night completely eliminated symptoms on both varieties. High levels (15 ppm) of Mn in nutrient solution decreased yields of both varieties at low temperature with Bragg showing the greater reduction. At high temperature neither variety showed yield reductions at 15 ppm Mn. Higher concentrations of Mn in shoots and roots were obtained at higher temperature, indicating that increased tolerance was not associated with lower plant Mn levels. Lee consistantly contained higher levels of Mn in the shoots than Bragg in the 15 ppm Mn solution at both temperatures although appearing to be more tolerant at low temperatures. The implications of these results for environmental effects on the expression of Mn toxicity in the field are discussed. re]19751202     

Hydraulic control of stomatal conductance in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] and alder [Alnus rubra (Bong)] seedlings

Experiments were conducted on 1-year-old Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] and 2- to 3-month-old alder [Alnus rubra (Bong)] seedlings growing in drying soils to determine the relative influence of root and leaf water status on stomatal conductance (g_c). The water status of shoots was manipulated independently of that of the roots using a pressure chamber that enclosed the root system. Pressurizing the chamber increases the turgor of cells in the shoot but not in the roots. Seedling shoots were enclosed in a whole-plant cuvette and transpiration and net photosynthesis rates measured continuously. In both species, stomatal closure in response to soil drying was progressively reversed with increasing pressurization. Responses occurred within minutes of pressurization and measurements almost immediately returned to pre-pressurization levels when the pressure was released. Even in wet soils there was a significant increase in g_c with pressurization. In Douglas fir, the stomatal response to pressurization was the same for seedlings grown in dry soils for up to 120 d as for those subjected to drought stress over 40 to 60 d. The stomatal conductance of both Douglas fir and alder seedlings was less sensitive to root chamber pressure at higher vapour pressure deficits (D), and stomatal closure in response to increasing D from 1.04 to 2.06 kPa was only partially reversed by pressurization. Our results are in contrast to those of other studies on herbaceous species, even though we followed the same experimental approach. They suggest that it is not always appropriate to invoke a ‘feedforward’ model of short-term stomatal response to soil drying, whereby chemical messengers from the roots bring about stomatal closure.     

垂直方向磷素竞争对杉木根系生长及生物量分配的影响

针对自然环境中有效磷养分主要分布于土壤表层而容易导致植物根系激烈竞争的问题,选择同一杉木(Cunninghamia lanceolata)无性系幼苗为研究对象,采用水平方向空间狭小而垂直方向空间大的室内盆栽模拟装置,以单株种植为对照,构建双株种植的竞争处理,通过设置3个供磷水平:不供磷处理(0 mg/kg KH_2PO_4)、低磷处理(6 mg/kg KH_2PO_4)和正常供磷处理(12 mg/kg KH_2PO_4),采用破坏性试验方式收获,分别在试验的前期(50 d)、中期(100 d)和后期(150 d)测定不同处理条件下杉木幼苗根系生物量与根系形态的变化,研究邻株杉木根系在垂直方向上对有限磷素资源的竞争策略。结果表明:竞争处理和供磷水平对杉木幼苗根系长度、平均直径等形态指标的影响存在交互作用(P0.05),对杉木幼苗生物量分配、比根长等指标的影响均不存在明显的交互作用(P0.05)。竞争处理中杉木根系形态增量均明显高于非竞争处理的单株幼苗,且随着胁迫时间的增加,根系形态增量均呈现显著的上升趋势,其中在胁迫中期和后期的增量明显高于前期,且邻株竞争处理明显提高了杉木的比根长,提升了根系觅磷的能力;随着供磷水平的提高,根表面积和根体积增量大体上呈现先上升后下降的趋势。与非竞争处理相比,竞争条件下杉木地上部生物积累量差异不明显,而根系生物量、根冠比均低于非竞争处理的单株幼苗。     

Glyphosate-induced impairment of plant growth and micronutrient status in glyphosate-resistant soybean (Glycine max L.)

This investigation demonstrated potential detrimental side effects of glyphosate on plant growth and micronutrient (Mn, Zn) status of a glyphosate-resistant (GR) soybean variety (Glycine max cv. Valiosa), which were found to be highly dependent on the selected growth conditions. In hydroponic experiments with sufficient Mn supply [0.5 μM], the GR cv. Valiosa produced similar plant biomass, root length and number of lateral roots in the control treatment without glyphosate as compared to its non-GR parental line cv. Conquista. However, this was associated with 50% lower Mn shoot concentrations in cv. Conquista, suggesting a higher Mn demand of the transgenic cv. Valiosa under the selected growth conditions. Glyphosate application significantly inhibited root biomass production, root elongation, and lateral root formation of the GR line, associated with a 50% reduction of Mn shoot concentrations. Interestingly, no comparable effects were detectable at low Mn supply [0.1 μM]. This may indicate Mn-dependent differences in the intracellular transformation of glyphosate to the toxic metabolite aminomethylphosphonic acid (AMPA) in the two isolines. In soil culture experiments conducted on a calcareous loess sub-soil of a Luvisol (pH 7.6) and a highly weathered Arenosol (pH 4.5), shoot biomass production and Zn leaf concentrations of the GR-variety were affected by glyphosate applications on the Arenosol but not on the calcareous Loess sub-soil. Analysis of micronutrient levels in high and low molecular weight (LMW) fractions (80% ethanol extracts) of young leaves revealed no indications for internal immobilization of micronutrients (Mn, Zn, Fe) by excessive complexation with glyphosate in the LMW phase.     

Identification of Barley Varieties Tolerant to Cadmium Toxicity

Two successive hydroponic experiments were carried out to identify barley varieties tolerant to Cd toxicity via examining Soil–Plant Analyses Development (SPAD) value, plant height, leaves and tillers per plant, root number and volume, and biomass accumulation. The results showed that SPAD values (chlorophyll meter readings), plant height, leaf number, root number and volume, and biomass accumulation of shoot/root were significantly reduced in the plants grown in 20 μM Cd nutrient solution compared with control, and the uptake and translocation of Zn, Mn, and Cu was also strictly hindered. Furthermore, there was a highly significant difference in the reduction in these growth parameters among varieties, and varieties “Weisuobuzhi” and “Jipi 1” showed the least reduction both in the two experiments, suggesting their high tolerance to Cd toxicity, while “Dong 17” and “Suyinmai 2” with the greatest reduction and the toxicity symptoms appeared rapidly and severely, denoting as Cd-sensitive varieties. Significant variety difference in Cd concentration was also found, with Weisuobuzhi containing the highest and Jipi 1 the lowest Cd concentration in shoots.     

Phosphorus and micronutrient metal uptake by some tree species as affected by phosphate and lime applied to an acid sandy soil

Summary The effects of added P and lime on Douglas fir and Scots pine seedlings, and poplar and willow cuttings growing in a podzolic soil (pH 3.8, 90 ppm total P) were studied in pot experiments. Conifer dry weights responded best to P applied in the absence of lime, whereas liming to pH 4.3 promoted the P response of the broadleaved species. Normal rates of P, and of lime (broad-leaved species), by promoting growth, also raised total contents of P and metals (Zn, Mn, Cu, Fe) in the various plant parts (stems, foliage, roots), but generally lowered the metal concentrations. The results strongly suggest that P interfered with the root to shoot translocation of Cu, Fe and Al (Al only estimated in Scots pine), but not with that of Zn and Mn. It is postulated that internal plant tolerance (promoted by P) plays a more important part in neutralizing toxic metal concentrations (Zn, and possibly also Fe) in the soil than do exclusion mechanisms. High applications of P without Cu may depress growth, as demonstrated for willow. Water-soluble soil P data may be misinterpreted if other limiting soil factors (pH, Cu status) have not been eliminated.     

Arbuscular mycorrhizal contribution to heavy metal uptake by maize (Zea mays L.) in pot culture with contaminated soil

In two pot-culture experiments with maize in a silty loam (P2 soil) contaminated by atmospheric deposition from a metal smelter, root colonization with indigenous or introduced arbuscular mycorrhizal (AM) fungi and their influence on plant metal uptake (Cd, Zn, Cu, Pb, Mn) were investigated. Soil was -irradiated for the nonmycorrhizal control. In experiment 1, nonirradiated soil provided the mycorrhizal treatment, whereas in experiment 2 the irradiated soil was inoculated with spores of a fungal culture from P2 soil or a laboratory reference culture, Glomus mosseae. Light intensity was considerably higher in experiment 2 and resulted in a fourfold higher shoot and tenfold higher root biomass. Under the conditions of experiment 1, biomass was significantly higher and Cd, Cu, Zn and Mn concentrations significantly lower in the mycorrhizal plants than in the nonmycorrhizal plants, suggesting a protection against metal toxicity. In contrast, in experiment 2, biomass did not differ between treatments and only Cu root concentration was decreased with G. mosseae-inoculated plants, whereas Cu shoot concentration was significantly increased with the indigenous P2 fungal culture. The latter achieved a significantly higher root colonization than G. mosseae (31.7 and 19.1%, respectively) suggesting its higher metal tolerance. Zn shoot concentration was higher in both mycorrhizal treatments and Pb concentrations, particularly in the roots, also tended to increase with mycorrhizal colonization. Cd concentrations were not altered between treatments. Cu and Zn, but not Pb and Cd root-shoot translocation increased with mycorrhizal colonization. The results show that the influence of AM on plant metal uptake depends on plant growth conditions, on the fungal partner and on the metal, and cannot be generalized. It is suggested that metal-tolerant mycorrhizal inoculants might be considered for soil reclamation, since under adverse conditions AM may be more important for plant metal resistance. Under the optimized conditions of normal agricultural practice, however, AM colonization even may increase plant metal absorption from polluted soils.     

Multiple-host fungi are the most frequent and abundant ectomycorrhizal types in a mixed stand of Douglas fir (Pseudotsuga menziesii) and bishop pine (Pinus muricata)

The ectomycorrhizal fungal associations of Douglas fir ( Pseudotsuga menziesii D. Don) and bishop pine ( Pinus muricata D. Don) were investigated in a mixed forest stand. We identified fungi directly from field-collected ectomycorrhizal (ECM) root tips using PCR-based methods. Sixteen species of fungi were found, of which twelve associated with both hosts. Rhizopogon parksii Smith was specific to Douglas fir. Three other species colonized only one of the hosts, but were too infrequent to draw conclusions about specificity. Seventy-four percent of the biomass of ECM root tips sampled in the stand were colonized by members of the Thelephoraceae and Russulaceae. All 12 species of fungi that associated with both tree species did so within a 10×40 cm soil volume, suggesting that individual fungal genotypes linked the putatively competing tree hosts.     

Effect of P and Mn on growth response and uptake of Fe,Mn and P by sorghum

Summary The effects of P and Mn on growth response and uptake of Fe, Mn and P by grain sorghum were investigated using nutrient culture. High P and Mn concentrations in solution (greater than 40 and 1 mg/l for P and Mn, respectively) markedly reduced plant height and shoot and root dry weight of 4-week-old sorghum plants. High Mn concentrations in solution increased the concentrations of Mn and P in shoot tissue and uptake of Mn, but depressed the uptake of P. High levels of P enhanced Mn uptake by sorghum and accentuated Mn toxicity at low Mn levels. The tissue Fe and total uptake of Fe were both reduced markedly by the high levels of P and Mn concentrations in solution. The increases of P, Mn and Fe concentrations in root tissue with a concomitant decrease of Fe in shoots suggested that the translocation of Fe from roots to shoots was hindered under high P and Mn conditions. Since coating occurred on root surfaces and intensified with increasing Mn concentrations in the substrate, part of the reduction of Fe in shoots could be attributed to the formation of high valent manganese oxides on the root surfaces which may retain Fe and reduce its absorption by sorghum.Contribution from the Department of Agronomy and Range Sci., University of California, Davis, CA.     

Tolerance to ion toxicities enhances wheat (Triticum aestivum L.) grain yield in waterlogged acidic soils

Aims

The high concentrations of Mn, Fe and Al in acid soils during waterlogging impair root and shoot growth more severely in intolerant than tolerant wheat genotypes. This study aims to establish whether this difference in vegetative growth and survival during waterlogging (1) is verifiable across a range of tolerant/intolerant genotypes and acid soils, and (2) results in improved recovery after cessation of waterlogging and enhanced grain yield.

Methods

Wheat genotypes contrasting in their tolerance to ion toxicities were grown in four acid soils until 63DAS and maturity, with a 42-day waterlogging treatment imposed at 21 DAS.

Results

The shoot Al, Mn and Fe concentrations increased by up to 5-, 3- and 9-fold respectively due to waterlogging in various soils. Compared to the intolerant lines, Al-, Mn- and Fe-tolerant genotypes maintained a relatively lower increase in shoot concentrations of Al (79 vs. 117%), Mn (90 vs. 101%) and Fe (171 vs. 252%) and demonstrated better waterlogging tolerance at the vegetative stage expressed in relative root (38% vs. 25%) and shoot (62% vs. 52%) growth. After cessation of waterlogging and the continued growth to maturity, tolerant genotypes maintained a relatively lower plant concentration of Al, Mn and Fe, but produced a higher above-ground biomass (74% vs. 56%) and most importantly demonstrated improved waterlogging tolerance (a relative grain yield of 78% vs. 54%) compared to intolerant genotypes. Maturity following waterlogging stress was delayed less in tolerant than intolerant genotypes (114 vs. 124%, respectively), which would reduce the potential yield loss where post-anthesis coincides with drought.

Conclusions

The results confirm the validity of a novel approach of enhancing waterlogging tolerance of wheat genotypes grown in acid soil via increased tolerance to ion toxicities.     

Arsenic tolerance, uptake and translocation by seedlings of three rice cultivars

By simulating the anaerobic conditions with agar nutrient solutions, effect of arsenic (As) on the growth and As uptake by hybrid, conventional and glutinous rice cultivars were studied. It showed insignificant effect of As on the root dry weights of three rice cultivars when treated by As of different concentrations. The shoot dry weights of hybrid and glutinous decreased with As concentrations increasing, while low concentrations of As (0.5 mg L^?1) could enhance the growth of conventional rice. Generally, As concentrations in roots and shoots increased as As concentrations of treatment solutions increasing. The root system had strong ability to uptake and accumulate As. The root As concentrations ranged from 156 to 504 mg kg^?1, representing 63.40%–81.90% of the total As concentrations in rice, which were much higher than shoot As concentrations. The fact that the glutinous rice had higher biomass, higher tolerance, and lower As concentrations in its roots and shoots than the other two rice cultivars proved that the glutinous rice was more applicable to As-polluted soils.     

Rapidly detecting the effects of warm storage stress on Douglas fir seedlings

Abstract

The physiological response of 3-year-old Douglas fir (Pseudotsuga menziesii[Mirb.] Franco) transplanted seedlings lifted to warm (15°C) (i.e. simulated ambient) storage in November, January and March in Ireland was investigated, with an aim of developing rapid methods for detecting stress. Chlorophyll fluorescence (CF), root electrolyte leakage (REL), shoot and root water content (WC), dry weight (DW), root growth potential (RGP) and survival were assessed. CF declined as the duration of warm storage increased and this was greatest for the November-lifted stock. CF measurements were closely related to survival in the greenhouse. Shoot tip and taproot DW declined during warm storage for stock lifted in November and March. Warm storage had no effect on shoot DW and caused a small decline in root DW for stock lifted in January. Changes in WC during storage were greater in the roots than in shoots, and values were significantly lower in treated plants following 21-day storage than in the controls (no storage). In conclusion, the results suggested that CF could be used to detect the effect of ambient storage stress (simulated by warm storage) on Douglas fir seedling vitality, and was more a more reliable indicator of plant quality than the other parameters.     

Aluminium alleviates manganese toxicity to rice by decreasing root symplastic Mn uptake and reducing availability to shoots of Mn stored in roots

Background and Aims Manganese (Mn) and aluminium (Al) phytotoxicities occur mainly in acid soils. In some plant species, Al alleviates Mn toxicity, but the mechanisms underlying this effect are obscure.Methods Rice (Oryza sativa) seedlings (11 d old) were grown in nutrient solution containing different concentrations of Mn²⁺ and Al³⁺ in short-term (24 h) and long-term (3 weeks) treatments. Measurements were taken of root symplastic sap, root Mn plaques, cell membrane electrical surface potential and Mn activity, root morphology and plant growth.Key Results In the 3-week treatment, addition of Al resulted in increased root and shoot dry weight for plants under toxic levels of Mn. This was associated with decreased Mn concentration in the shoots and increased Mn concentration in the roots. In the 24-h treatment, addition of Al resulted in decreased Mn accumulation in the root symplasts and in the shoots. This was attributed to higher cell membrane surface electrical potential and lower Mn²⁺ activity at the cell membrane surface. The increased Mn accumulation in roots from the 3-week treatment was attributed to the formation of Mn plaques, which were probably related to the Al-induced increase in root aerenchyma.Conclusions The results show that Al alleviated Mn toxicity in rice, and this could be attributed to decreased shoot Mn accumulation resulting from an Al-induced decrease in root symplastic Mn uptake. The decrease in root symplastic Mn uptake resulted from an Al-induced change in cell membrane potential. In addition, Al increased Mn plaques in the roots and changed the binding properties of the cell wall, resulting in accumulation of non-available Mn in roots.     

The significance of the magnesium to manganese ratio in plant tissues for growth and alleviation of manganese toxicity in tomato (Lycopersicon esculentum) and wheat (Triticum aestivum) plants

Results are reported for tomato (Lycopersicon esculentum L. var. Ailsa craig) and wheat (Triticum aestivum L. cv. Mara) which demonstrate that increasing concentrations of Mg in the plant raises plant tolerance to Mn toxicity.Water culture experiments with tomato show that under conditions of high Mn supply (200 µM, Mn), not only does increasing Mg application (0.75 mM to 15 mM) depress Mn uptake, but the higher Mg concentrations in the shoot counteract the onset of Mn toxicity when the concentrations of Mn in the shoot are also high. The ratio of Mg: Mn in the tissues is a better indicator of the appearance of toxicity symptoms than Mn concentration alone. Toxicity symptoms were observed when the Mg:Mn ratio in the shoot tissue was from 1.13 to a value between 3.53 and 6.54. The corresponding Mg: Mn ratio in the older leaves was from 0.82 to between 2.27 and 3.51.For wheat grown in soil, analyses of leaves revealed that growth could be expressed by the following relationship: Y=A+B exp(-kX), where Y=growth, X=Mg:Mn ratio, A, B and k=constants. Growth was significantly reduced when the Mg:Mn ratio fell below 20:1. From a measurement of this ratio it is therefore possible to predict the appearance of Mn toxicity and its influence on growth.     

不同镉水平下大麦幼苗生长和镉及养分吸收的品种间差异

利用水培试验研究了不同Cd水平下大麦幼苗的Cd和几种矿质元素吸收、积累、生长和生物学产量的品种间差异 .结果表明 ,1μmol·L-1Cd处理显著降低麦苗株高、绿叶数、叶绿素计读数、地上部和根系干重 ,显著抑制植株对Zn、Mn、Cu的吸收和累积 ;品种之间存在着显著差异 ,无芒六棱受抑制最为严重 ,米麦 114和浙农 1号表现出相对较强的抗性 .麦苗Cd含量和累积量品种之间也有显著差异 ,浙农 1号的Cd含量最高 ,米麦 114最低 .相关分析表明 ,麦苗生物学产量与地上部Cd含量、累积量及根系Cd含量呈显著负相关 ,其中与地上部Cd含量的相关性最强 ,与根系Cd累积量无显著相关 .