Root growth response of rainfed lowland rice to aerobic conditions in northeastern Thailand

Background and aims

Rice plants alternately experience anaerobic and aerobic conditions during their life cycle in rainfed lowlands. Each condition affects root growth differently. Our objective was to clarify the specific rice root response to aerobic conditions in rainfed lowlands.

Methods

At the Ubon Ratchathani Rice Research Center in northeastern Thailand, we obtained root samples from 17 ‘Surin1’ (Thai variety) BC₃-derived lines and 7 CT9993-5-10-1-M × IR62266-42-6-2 doubled-haploid lines from flooded and non-flooded paddy fields at the reproductive stage in 2010 and 2011.

Results

In the non-flooded trial, rice was grown aerobically by draining the perched water; soil moisture at a depth of 20 cm fluctuated between ?10 and ?30 kPa. Deep rooting was likely promoted under aerobic conditions, but slightly drier soils under longer dry spells seemed to restrict root penetration, as the topsoil rapidly hardened during dry spells of only a few days. Fine-root development in the topsoil was inhibited under aerobic conditions.

Conclusions

Even without drought stress, rice roots respond significantly to the disappearance of standing water in rainfed lowlands via deep rooting and root branching. We identified one promising ‘Surin1’ BC₃-derived line showing an adaptive response of deep rooting under aerobic conditions, which can be used as a breeding material for rainfed lowland rice in Thailand.     

Comparison of As sequestration in iron plaque and uptake by different genotypes of rice plants grown in As-contaminated paddy soils

Background and aims

Limited information is available on comparing the iron plaque formation capabilities and their effect on arsenic (As) uptake by different rice plant genotypes grown in As-contaminated soils. This study investigates the effect of iron plaque on As uptake in different rice genotypes grown in As-contaminated soils from the Guandu Plain of northern Taiwan.

Methods

Twenty-eight rice genotypes including 14 japonica and 14 indica genotypes were used in this study. Rice seedlings were grown in As-contaminated soils for 38 days. The iron plaque formed on the rice roots were extracted using dithionite–citrate–bicarbonate. The concentrations of As, Fe, and P in soil solutions, iron plaque, and plants were measured. The speciation of As in the root’s iron plaque was determined by As K-edge X-ray absorption near-edge structure spectroscopy (XANES).

Results

The amounts of iron plaque formation on roots were significantly different among 28 tested rice genotypes, and 75.7–92.8 % of As uptake from soils could be sequestered in iron plaque. However, there were no significant negative correlations between the amounts of Fe or As in the iron plaque and the content of As accumulated in rice plants of tested genotypes. XANES data showed that arsenate was the predominant As species in iron plaque, and there were difference in the distribution of As species among different rice genotypes.

Conclusions

The iron plaque can sequester most of As uptake from soils no matter what rice genotypes used in this study. However, the iron plaque alone did not control the extent of As accumulation in rice plants from As-contaminated soils among 28 tested rice genotypes. Low As uptake genotypes of rice selected from this study can be recommended to be grown in the As-contaminated soils.     

Soil microalgae modulate grain arsenic accumulation by reducing dimethylarsinic acid and enhancing nutrient uptake in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Background and aims

Microalgae are ubiquitous in paddy soils. However, their roles in arsenic (As) accumulation and transport in rice plants remains unknown.

Methods

Two green algae and five cyanobacteria were used in pot experiments under continuously flooded conditions to ascertain whether a microalgal inoculation could influence rice growth and rice grain As accumulation in plants grown in As-contaminated soils.

Results

The microalgal inoculation greatly enhanced nutrient uptake and rice growth. The presence of representative microalga Anabaena azotica did not significantly differ the grain inorganic As concentrations but remarkably decreased the rice root and grain DMA concentrations. The translocation of As from roots to grains was also markedly decreased by rice inoculated with A. azotica. This subsequently led to a decrease in the total As concentration in rice grains.

Conclusions

The results of the study indicate that the microalgal inoculation had a strong influence on soil pH, soil As speciation, and soil nutrient bioavailability, which significantly affected the rice growth, nutrient uptake, and As accumulation and translocation in rice plants. The results suggest that algae inoculation can be an effective strategy for improving nutrient uptake and reducing As translocation from roots to grains by rice grown in As-contaminated paddy soils.

     

Zinc nutrition in rice production systems: a review

Background

Zinc (Zn) deficiency is one of the important abiotic factors limiting rice productivity worldwide and also a widespread nutritional disorder affecting human health. Given that rice is a staple for populations in many countries, studies of Zn dynamics and management in rice soils is of great importance.

Scope

Changing climate is forcing the growers to switch from conventional rice transplanting in flooded soils to water-saving cultivation, including aerobic rice culture and alternate wetting and drying system. As soil properties are changed with altered soil and water management, which is likely to affect Zn solubility and plant availability and should be considered before Zn management in rice. In this review, we critically appraise the role of Zn in plant biology and its dynamics in soil and rice production systems. Strategies and options to improve Zn uptake and partitioning efficiency in rice by using agronomic, breeding and biotechnological tools are also discussed.

Conclusions

Although soil application of inorganic Zn fertilizers is widely used, organic and chelated sources are better from economic and environmental perspectives. Use of other methods of Zn application (such as seed treatment, foliar application etc., in association with mycorrhizal fungi) may improve Zn-use efficiency in rice. Conventional breeding together with modern genomic and biotechnological tools may result in development of Zn-efficient rice genotypes that should be used in conjunction with judicious fertilization to optimize rice yield and grain Zn content.     

Differential responses of system of rice intensification (SRI) and conventional flooded-rice management methods to applications of nitrogen fertilizer

Background

Rising food demand, slowing productivity growth, poor N-use efficiency in rice, and environmental degradation necessitate the development of more productive, environmentally-sound crop and soil management practices. The system of rice intensification (SRI) has been proposed as a methodology to address these trends. However, it is not known how its modified crop-soil-water management practices affect efficiency of inorganic nitrogen applications.

Methods

Field experiments investigated the impacts of SRI management practices with different N-application rates on grain yield, root growth and activity, uptake of N and its use-efficiency, leaf chlorophyll content, leaf N-concentration, and photosynthetic rate in comparison with standard management practices for transplanted flooded rice (TFR).

Results

Overall, grain yield with SRI was 49 % higher than with TFR, with yield enhanced at every N application dose. N-uptake, use-efficiency, and partial factor productivity from applied N were significantly higher in SRI than TFR. Higher leaf nitrogen and chlorophyll contents during the ripening-stage in SRI plants reflected delayed leaf-senescence, extension of photosynthetic processes, and improved root-shoot activities contributing to increased grain yield.

Conclusions

Rice grown under SRI management used N fertilizer more efficiently due to profuse root development and improved physiological performance resulting in enhanced grain yield compared to traditional flooded rice.     

Carbon mineralization in soil of roots from twenty crop species,as affected by their chemical composition and botanical family

Background and aims

Plant growth-promoting rhizobacteria (PGPR) have been widely studied for agricultural applications. One aim of this study was to isolate cadmium (Cd)-tolerant bacteria from nodules of Glycine max (L.) Merr. grown in heavy metal-contaminated soil in southwest of China. The plant growth-promoting (PGP) traits and the effects of the isolate on plant growth and Cd uptake by legume and non-legume plants in Cd-polluted soil were investigated.

Methods

Cd-tolerant bacteria were isolated by selective media. The isolates were identified by 16S rRNA gene and phylogenetic analysis. The PGR traits of the isolates were evaluated in vitro. Cd in soil and plant samples was determined by ICP-MS.

Results

One of the most Cd-tolerant bacteria simultaneously exhibited several PGP traits. Inoculation with the PGPR strain had positive impacts on contents of photosynthesis pigments and mineral nutrients (Fe or Mg) in plant leaves. The shoot dry weights of Lolium multiflorum Lam. increased significantly compared to uninoculated control. Furthermore, inoculation with the PGPR strain increased the Cd concentrations in root of L. multiflorum Lam. and extractable Cd concentrations in the rhizosphere, while the Cd concentrations in root and shoot of G. max (L.) Merr. significantly decreased.

Conclusions

This study indicates that inoculation with Cd-tolerant PGPR can alleviate Cd toxicity to the plants, increase Cd accumulation in L. multiflorum Lam. by enhancing Cd availability in soils and plant biomass, but decrease Cd accumulation in G. max (L.) Merr. by increasing Fe availability, thus highlighting new insight into the exploration of PGPR on Cd-contaminated soil.     

Fe isotope fractionation caused by translocation of iron during growth of bean and oat as models of strategy I and II plants

Background

The determination of the plant-induced Fe-isotopic fractionation is a promising tool to better quantify their role in the geochemical Fe cycle and possibly to identify the physiological mechanisms of Fe uptake and translocation in plants. Here we explore the isotope fractionation caused by translocation of Fe during growth of bean and oat as representatives of strategy I and II plants.

Methods

Plants were grown on a nutrient solution supplemented with Fe(III)-EDTA and harvested at three different ages. We used the technique of multi-collector ICP-MS to resolve the small differences in the stable iron isotope compositions of plants.

Results

Total bean plants, regardless of their age, were found to be enriched in the light iron isotopes by ?1.2‰ relative to the growth solution throughout. During growth plants internally redistributed isotopes where young leaves increasingly accumulated the lighter isotopes whereas older leaves and the total roots were simultaneously depleted in light iron isotopes. Oat plants were also enriched in the light iron isotopes but during growth the initial isotope ratio maintained in all organs at all growth stages.

Conclusions

We conclude that isotope fractionation in bean as a representative of strategy I plants is a result of translocation or re-translocation processes. Furthermore we assume that both uptake and translocation of Fe in oat maintains the irons’ ferric state, or that Fe is always bound to high-mass ligands, so that isotope fractionation is virtually absent in these plants. However, in contrast to our previous study in which strategy II plants were grown on soil substrate, oat plants grown on Fe(III)-EDTA contain iron that enriches ⁵⁴Fe by 0.5 permil over ⁵⁶Fe. A possible explanation for the enrichment is the prevalence of a constitutive reductive uptake mechanism of iron in the nutrient solution used which is non-deficient in iron.     

The effects of water regime on phosphorus responses of rainfed lowland rice cultivars

Background and Aims

Soil phosphorus (P) solubility declines sharply when a flooded soil drains, and an important component of rice (Oryza sativa) adaptation to rainfed lowland environments is the ability to absorb and utilize P under such conditions. The aim of this study was to test the hypothesis that rice cultivars differ in their P responses between water regimes because P uptake mechanisms differ.

Methods

Six lowland rice cultivars (three considered tolerant of low P soils, three sensitive) were grown in a factorial experiment with three water regimes (flooded, moist and flooded-then-moist) and four soil P levels, and growth and P uptake were measured. Small volumes of soil were used to maximize inter-root competition and uptake per unit root surface. The results were compared with the predictions of a model allowing for the effects of water regime on P solubility and diffusion.

Key Results

The plants were P stressed but not water stressed in all the water regimes at all P levels except the higher P additions in the flooded soil. The cultivar rankings scarcely differed between the water regimes and P additions. In all the treatments, the soil P concentrations required to explain the measured uptake were several times the concentration of freely available P in the soil.

Conclusions

The cultivar rankings were driven more by differences in growth habit than specific P uptake mechanisms, so the hypothesis cannot be corroborated with these data. Evidently all the plants could tap sparingly soluble forms of P by releasing a solubilizing agent or producing a greater root length than measured, or both. However, any cultivar differences in this were not apparent in greater net P uptake, possibly because the restricted rooting volume meant that additional P uptake could not be converted into new root growth to explore new soil volumes.Key words: Oryza sativa, rainfed lowland, phosphorus efficiency, root morphology, solubilization, rice cultivar     

Does radial oxygen loss and iron plaque formation on roots alter Cd and Pb uptake and distribution in rice plant tissues?

Background and Aims

Metal (e.g. Cd and Pb) pollution in agricultural soils and crops have aroused considerable attention in recent years. This study aimed to evaluate the effects of ROL and Fe plaque on Cd and Pb accumulation and distribution in the rice plant.

Methods

A rhizobag experiment was employed to investigate the correlations among radial oxygen loss (ROL), Fe plaque formation and uptake and distribution of Cd and Pb in 25 rice cultivars.

Results

Large differences between the cultivars were found in rates of ROL (1.55 to 6.88 mmol O₂ kg^?1 root d.w. h^?1), Fe plaque formation (Fe: 6,117–48,167 mg kg^?1; Mn: 127–1,089 mg kg^?1), heavy metals in shoot (Cd: 0.13–0.35 mg kg^?1; Pb: 4.8–8.1 mg kg^?1) and root tissues (Cd: 1.1–3.5 mg kg^?1; Pb: 45–199 mg kg^?1), and in Fe plaque (Cd: 0.54–2.6 mg kg^?1; Pb: 102–708 mg kg^?1). Rates of ROL were positively correlated with Fe plaque formation and metal deposition on root surfaces, but negatively correlated with metal transfer factors of root/plaque and distributions in shoot and root tissues.

Conclusions

ROL-induced Fe plaque promotes metal deposition on to root surfaces, leading to a limitation of Cd and Pb transfer and distribution in rice plant tissues.     

Arbuscular mycorrhizas are beneficial under both deficient and toxic soil zinc conditions

Background and aims

Arbuscular mycorrhizas (AM) play different roles in plant Zn nutrition depending on whether the soil is Zn-deficient (AM enhancement of plant Zn uptake) or Zn-toxic (AM protection of plant from excessive Zn uptake). In addition, soil P concentration modifies the response of AM to soil Zn conditions. We undertook a glasshouse experiment to study the interactive effects of P and Zn on AM colonisation, plant growth and nutrition, focusing on the two extremes of soil Zn concentration—deficient and toxic.

Methods

We used a mycorrhiza-defective tomato (Solanum lycopersicum) genotype (rmc) and compared it to its wild-type counterpart (76R). Plants were grown in pots amended with five soil P addition treatments, and two soil Zn addition treatments.

Results

The mycorrhizal genotype generally thrived better than the non-mycorrhizal genotype, in terms of biomass and tissue P and Zn concentrations. This was especially true under low soil Zn and P conditions, however there was evidence of the ‘protective effect’ of mycorrhizas when soil was Zn-contaminated. Above- and below-ground allocation of biomass, P and Zn were significantly affected by AM colonisation, and toxic soil Zn conditions.

Conclusions

The relationship between soil Zn and soil P was highly interactive, and heavily influenced AM colonisation, plant growth, and plant nutrition.     

The effect of rate and Cd concentration of repeated phosphate fertilizer applications on seed Cd concentration varies with crop type and environment

Background and aims

Limited information is available on how cadmium (Cd) applied in phosphate fertilizer interacts with soil and environmental conditions over time to affect crop Cd concentrations.

Methods

Field studies from 2002 to 2009 at seven locations evaluated the cumulative effects of P fertilizer rate and Cd concentration on seed Cd concentration of durum wheat (Triticum turgidum L.) and flax (Linum usitatissiumum L.).

Results

Soil characteristics and environment affected Cd availability. Durum wheat grain Cd increased with P fertilizer rate but effect on flaxseed Cd concentration was smaller. Cadmium concentration in fertilizer had a greater effect on flaxseed than durum wheat Cd concentration. Seed Cd concentration of both crops was greatest with the highest rate P fertilizer containing the highest Cd concentration. There was not a strong cumulative effect of fertilization over the 8 years of the study, indicating attenuation of Cd availability over time.

Conclusions

Cadmium in phosphate fertilizer increases Cd available for crop uptake, but crop Cd concentration is also affected by soil characteristics and annual environmental conditions. Type of crop produced and soil and environmental characteristics that affect phytoavailability must be taken into account when assessing the Cd risk from P fertilization.     

Considerations on the shuttle mechanism of FeEDDHA chelates at the soil-root interface in case of Fe deficiency

Aim

A mechanism of action for the performance of Fe chelates as soil-applied fertilizer has been hypothesized by Lindsay and Schwab (J Plant Nutr 5:821–840, 1982), in which the ligand participates in a cyclic process of delivering Fe at the root surface and mobilizing Fe from the soil. This “shuttle mechanism” seems appealing in view of fertilizer efficiency, but little is known about its performance. The chelate FeEDDHA is a commonly used Fe fertilizer on calcareous soils.

Methods

In this study, the performance of the shuttle mechanism has been examined for FeEDDHA chelates in soil interaction and pot trial experiments.

Results

The specificity of EDDHA ligands for chelating Fe from soils of low Fe availability is limited. Experimental support for a shuttle mechanism in soil-plant systems with FeEDDHA was found: specific metal mobilization only occurred upon FeEDDHA-facilitated Fe uptake. The mobilized metals originated at least in part from the root surface instead of the soil.

Conclusion

The results from this study support the existence of a shuttle mechanism with FeEDDHA in soil application. If the efficiency of the shuttle mechanism is however largely controlled by metal availability in the bulk soil, it is heavily compromised by complexation of competing cations: Al, Mn and particularly Cu.     

Influence of CdCl2 and CdSO4 supplementation on Cd distribution and ligand environment in leaves of the Cd hyperaccumulator Noccaea (Thlaspi) praecox

Background and aims

The aim was to investigate whether different Cd salts in the nutrient solution of the Cd/Zn hyperaccumulator Noccaea (Thlaspi) praecox alter leaf Cd distribution and Cd ligand environment, and plant fitness.

Methods

Plants were grown for 8 weeks with 100/300 μM CdCl₂ or CdSO₄. Leaf biomass, and total chlorophyll, anthocyanin, Cd, Cl, S and P concentrations were monitored. Cd localisation and ligand environment in leaves were analysed using quantitative synchrotron-based micro-X-ray fluorescence imaging, and Cd K-edge X-ray absorption fine structure and Cd L₃-edge micro-X-ray absorption near-edge structure measurements.

Results

Cd uptake and plant fitness were comparable for CdCl₂ and CdSO₄ treatments, and depended on applied Cd concentration. In all treatments, Cd preferentially accumulated with high concentrations of Cl in vacuoles of large vacuolarised epidermal cells, bound mainly to oxygen-based (O)-ligands. In the mesophyll of CdCl₂? treated plants, Cd was preferentially sequestered in vacuoles, while for CdSO₄, Cd accumulated preferentially in the apoplast. In the symplast, O-ligands increased with increasing Cd concentrations; in the apoplast, sulphur-based (S)-ligands prevailed.

Conclusions

Cd partitioning between leaf mesophyll apoplast and symplast and the Cd ligand environment in N. praecox depend on the Cd salt type and concentration added to the nutrient solution.     

Root morphology, hydraulic conductivity and plant water relations of high-yielding rice grown under aerobic conditions

Background and Aims

Increasing physical water scarcity is a major constraint for irrigated rice (Oryza sativa) production. ‘Aerobic rice culture’ aims to maximize yield per unit water input by growing plants in aerobic soil without flooding or puddling. The objective was to determine (a) the effect of water management on root morphology and hydraulic conductance, and (b) their roles in plant–water relationships and stomatal conductance in aerobic culture.

Methods

Root system development, stomatal conductance (g_s) and leaf water potential (Ψ_leaf) were monitored in a high-yielding rice cultivar (‘Takanari’) under flooded and aerobic conditions at two soil moisture levels [nearly saturated (> –10 kPa) and mildly dry (> –30 kPa)] over 2 years. In an ancillary pot experiment, whole-plant hydraulic conductivity (soil-leaf hydraulic conductance; K_pa) was measured under flooded and aerobic conditions.

Key Results

Adventitious root emergence and lateral root proliferation were restricted even under nearly saturated conditions, resulting in a 72–85 % reduction in total root length under aerobic culture conditions. Because of their reduced rooting size, plants grown under aerobic conditions tended to have lower K_pa than plants grown under flooded conditions. Ψ_leaf was always significantly lower in aerobic culture than in flooded culture, while g_s was unchanged when the soil moisture was at around field capacity. g_s was inevitably reduced when the soil water potential at 20-cm depth reached –20 kPa.

Conclusions

Unstable performance of rice in water-saving cultivations is often associated with reduction in Ψ_leaf. Ψ_leaf may reduce even if K_pa is not significantly changed, but the lower Ψ_leaf would certainly occur in case K_pa reduces as a result of lower water-uptake capacity under aerobic conditions. Rice performance in aerobic culture might be improved through genetic manipulation that promotes lateral root branching and rhizogenesis as well as deep rooting.     

OsNRAMP1 transporter contributes to cadmium and manganese uptake in rice

Rice is a major dietary source of the toxic metal, cadmium (Cd). Previous studies reported that the rice transporter, OsNRAMP1, (Natural resistance-associated macrophage protein 1) could transport iron (Fe), Cd and arsenic (As) in heterologous yeast assays. However, the in planta function of OsNRAMP1 remains unknown. Here, we showed that OsNRAMP1 was able to transport Cd and manganese (Mn) when expressed in yeast, but did not transport Fe or As. OsNRAMP1 was mainly expressed in roots and leaves and encoded a plasma membrane-localized protein. OsNRAMP1 expression was induced by Cd treatment and Fe deficiency. Immunostaining showed that OsNRAMP1 was localized in all root cells, except the central vasculature, and in leaf mesophyll cells. The knockout of OsNRAMP1 resulted in significant decreases in root uptake of Cd and Mn and their accumulation in rice shoots and grains, and increased sensitivity to Mn deficiency. The knockout of OsNRAMP1 had smaller effects on Cd and Mn uptake than knockout of OsNRAMP5, while knockout of both genes resulted in large decreases in the uptake of the two metals. Taken together, OsNRAMP1 contributes significantly to the uptake of Mn and Cd in rice, and the functions of OsNRAMP1 and OsNRAMP5 are similar but not redundant.     

Successive straw biochar application as a strategy to sequester carbon and improve fertility: A pot experiment with two rice/wheat rotations in paddy soil

Aims

A pot study spanning four consecutive crop seasons was conducted to compare the effects of successive rice straw biochar/rice straw amendments on C sequestration and soil fertility in rice/wheat rotated paddy soil.

Methods

We adopted 4.5 t ha^?1, 9.0 t ha^?1 biochar and 3.75 t ha^?1 straw for each crop season with an identical dose of NPK fertilizers.

Results

We found no major losses of biochar-C over the 2-year experimental period. Obvious reductions in CH₄ emission were observed from rice seasons under the biochar application, despite the fact that the biochar brought more C into the soil than the straw. N₂O emissions with biochar were similar to the controls without additives over the 2-year experimental period. Biochar application had positive effects on crop growth, along with positive effects on nutrient (N, P, K, Ca and Mg) uptake by crop plants and the availability of soil P, K, Ca and Mg. High levels of biochar application over the course of the crop rotation suppressed NH₃ volatilization in the rice season, but stimulated it in the wheat season.

Conclusions

Converting straw to biochar followed by successive application to soil is viable for soil C sequestration, CH₄ mitigation, improvements of soil and crop productivity. Biochar soil amendment influences NH₃ volatilization differently in the flooded rice and upland wheat seasons, respectively.     

Effects of silicon on aluminum toxicity in upland rice plants

Aims

This study aimed to determine the capacity of Si to mitigate Al toxicity in upland rice plants (Oryza sativa L.) by evaluating plant growth and the Si and Al uptake kinetics.

Methods

Plants were grown for 40 days, after which the Si and Al uptake kinetics (Cmin, Km and Imax) were analyzed. Then, the shoots and roots were separated, and the dry matter, root morphology and Si and Al concentration and accumulation in the plant were evaluated.

Results

Aluminum decreased plant growth and the Si uptake capacity by decreasing the root growth and Si transport system efficiency in the upland rice roots (> Km and > Cmin). Silicon mitigated Al toxicity in the upland rice plants by decreasing Al transport to the plant shoots, although it did not reduce the Al uptake rate (Imax). Si treatment increased the growth of upland rice plant shoots grown in the presence of Al without influencing the root growth. The alleviation of Al toxicity by Si is more evident in the susceptible upland rice cultivar Maravilha.

Conclusions

Silicon mitigated Al toxicity in the upland rice plants by decreasing Al transport to the plant shoots but did not reduce the Al uptake rate by roots.

     

Effects of waterlogging on the solubility and redox state of Sb in a shooting range soil and its uptake by grasses: a tank experiment

Aims

The effects of waterlogging on redox state and solubility of antimony (Sb) in a calcareous shooting range soil and its uptake by forage grass Lolium perenne L. and pasture weed Holcus lanatus L. were investigated.

Methods

Grasses were grown on semi-waterlogged or waterlogged shooting range soil in a laboratory tank. The soil solution was sampled at various depths over time and analyzed for the concentrations of Sb(III), Sb(V) and total Sb, as well as other trace elements.

Results

Although the reduction of Sb(V) to Sb(III) under increased waterlogging time decreased Sb solubility, it increased Sb uptake by L. perenne from 1.1 to 1.7 mg?kg^?1 (and to a lesser extent H. lanatus), implying preferential uptake of Sb(III) by this grass. The tank showed considerable variation in redox conditions with depth and plant treatment. The soil root zone (30 cm for L. perenne and 15 cm for H. lanatus) instead of the water saturated bottom, showed the highest manganese (Mn) and iron (Fe) concentrations in solution, accompanied by a higher proportion of Sb(III) in solution than the bottom zone of the tank.

Conclusions

Waterlogging can increase the risk of Sb entering the food chain from shooting range soil.