Iron‐manganese interactions among clones of Nilegrass

Tetraploid clones of Nilegrass (Acroceras macrum, Stapf.) develop a chlorosis resembling iron (Fe) deficiency on acid (pH 5.0) soils in the Midlands of KwaZulu, Natal, South Africa. Hexaploid and pentaploid clones appear more resistant to the disorder. Iron deficiency would not be expected in such acid soils, but foliar sprays of Fe sulfate reduce the symptoms within 24 hours. Aluminum (Al) toxiciry has been ruled out as a cause of this chlorosis on the basis of soil tests. Manganese (Mn)‐induced Fe deficiency has been postulated. Six Nilegrass clones, differing in ploidy levels, were grown under low Fe or high Mn levels in nutrient solutions, in Mn‐toxic soil, in calcareous soil and in a standard potting soil at pH 7.0. Differential chlorosis symptoms, similar to those observed in the field, were reproduced in plants grown in low Fe or high Mn solutions, in neutral potting soil and in calcareous soil at pH 7.8. Based on plant symptoms and dry weights, the tetraploids were generally more sensitive to these conditions than hexaploid or pentaploid clones. However, in Mn‐toxic soil, plants had leaf tip necrosis rather than the chlorosis typical of Fe deficiency. When grown in a standard potting soil at pH 7.0, plants showing chlorosis accumulated higher concentrations of phosphorus (P), Al, copper (Cu), Mn, Fe, and zinc (Zn) than non‐chlorotic plants. Differential susceptibility to chlorosis is apparently associated with interference of such elements in Fe metabolism, and not with differential Fe concentrations in plant shoots. Additional studies are needed to determine the chemical states of Fe and Mn in root zones and within plant shoots of these clones. Resolution of the differential chlorosis phenomenon would contribute to fundamental knowledge in mineral nutrition and could be helpful in tailoring plant genotypes to fit problem soils.     

Distribution of sludge‐borne manganese in field‐grown maize

Abstract

The uptake and distribution of manganese (Mn) in field‐grown maize (Zea mays L.) was studied in a long‐term sewage sludge field trial on an acid sandy soil at Bordeaux. Since 1974, sewage sludge had been applied at levels of 101 dry matter (DM) ha^‐1 year^‐1 (SS 10) and 1001 DM ha^‐1 per 2 years (SS 100) on annually cropped maize plots. Treatment with farmyard manure (FYM) at a rate of 10 t DM ha^‐1 year^‐1 served as unpolluted control. Five replicate plants per treatment were examined at six different growth stages. At each stage, the whole plant was separated into its different organs and the Mn distribution was determined in at least 12 different plant parts. Manganese concentrations were always higher in SS 100 plants compared to FYM and SS 10 treated plants. Significant treatment‐dependent differences occurred almost all in the roots and in the different leaf levels while we found similar Mn concentrations in the stalk and in the reproductive organs. In the different stalk levels and in the ear composites we determined low Mn concentrations with critical deficiency values in FYM and SS 10 plants while Mn concentrations in SS 100 plants were in the normal range. Soil treatment also significantly influenced the initial absorption by the roots. Despite low absolute Mn concentrations in the roots of FYM plants, the Mn transfer coefficient (plant Mn concentration/soil Mn concentration) was highest in FYM plants and lowest in SS 100 plants indicating a relatively low Mn plant availability in the sludge‐treated plots.     

Microbial DNA extraction and analyses of soil iron–manganese nodules

Iron–manganese (Fe–Mn) nodules and concretions are soil new growth, reflecting soil environmental conditions during their formation. Bacteria play a dominant role in the oxidation of dissolved Mn(II) in aqueous systems and the formation of marine and freshwater Fe–Mn nodules. However, the role and significance of bacteria in soil Fe–Mn nodule formation have not been well recognized. In this paper, microbial DNA was directly extracted from two Fe–Mn nodule samples collected from Wuhan and Guiyang in central China. The extracted DNA was amplified by polymerase chain reaction (PCR) and cloned. The clones were then screened by amplified ribosomal DNA restriction analysis (ARDRA). Twenty patterns were obtained for Wuhan sample and Guiyang sample, respectively. DNA sequencing and phylogenetic analyses revealed that the bacterial compositions of the Fe–Mn nodules were mainly belonged to Firmicutes, β-proteobacteria, γ-proteobacteria branches of the domain bacteria. These divisions had close relativeness with Mn(II)-oxidizing bacteria identified from marine Fe–Mn nodules, implying the possible contributions of these bacteria to soil Fe–Mn nodule formation.     

Soybean leaf analysis of washed versus unwashed samples from boron‐manganese studies

Abstract

Elemental analyses of soybean leaf tissue from B & Mn field studies Indicate that washing tissue in deiontzed water did not appreciably change the concentration of most elements in the tissue. An exception was N which was decreased 0.54 per cent for one location and 0.33 per cent for the average of 3‐ sites when washed in deionized water prior to analyses. Although the tissue did not Indicate appreciable change tn K content when washed, the water In which the tissue had been washed Increased In K content by 6 ppm. The content of four of the micro elements in the plant tissue was affected by washing as compared to the unwashed samples. Mo and Ni were decreased while Zn and Cu were Increased.     

Soybean response to the application of several elements on a low‐manganese soil

Abstract

Certain soils in the Lower Atlantic Coastal Plain are Mn‐deficient and because of their inherent properties, deficiencies of other elements might be expected. The response of soybean [Glycine max (L.) Merr. cv. ‘Ransom'] to annual soil applications of B, Cu, Fe, Mo, S, and Zn with and without Mn was examined. The study was conducted on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) in 1975, 1976, and 1977. Seed yields, and soil and plant tissue concentrations of certain of the applied elements were determined. Soil pH increased from 6.4 in 1975 to 7.0 in 1977 as a result of lime applications.

Of the seven elements studied, only Mn significantly increased soybean seed yield compared to the check. Leaf concentrations of the respective elements were higher where the element was added than they were in plants grown on the check plots. In 1977, after three years of elemental additions, plant concentrations of Mn, Cu, and Zn were higher, relative to checks, than in 1975. In 1977, with the higher soil pH levels, plants from check plots had lower concentrations of Mn, but unexpectedly equal levels of Cu and higher levels of Zn than in 1975. This unexplained increase in plant Zn was also found in Other experiments in the same field during the same time period. Double acid extracted more soil Mn, Cu, and Zn than did DTPA from similar treatments during all three years. The DTPA‐extractable soil Mn correlated much better with plant Mn than did double acid Mn values, especially over years where a change in soil pH occurred. Correlation coefficients comparing extractable soil versus plant values for Cu and Zn data combined over years were higher for double acid than DTPA, although coefficients for the Cu and Zn data were still generally much lower than for the Mn data.     

Short‐term effects of manganese toxicity on ribulose 1,5 bisphosphate carboxylase in tobacco chloroplasts

The short‐term effects of manganese (Mn) toxicity on ribulose 1,5 bisphosphate carboxylase EC 4.1.1.39 (Rubisco) activity and concentration in tobacco (Nicotiana tabacum L. ‘KY 17') chloroplasts were examined. The activity of the enzyme from both Mn‐treated and control plants was determined 6,12,18, 24, and 48 h after introduction of Mn (80 mg/L). Enzyme activity was determined by monitoring rates of carbon dioxide (¹⁴CO₂) fixation into acid stable products. A decrease in the enzyme's activity in experimental plants was noted after 48 h of exposure. Visible symptoms, such as chlorosis and decreased leaf size, were also observed after 48 h of Mn exposure in experimental plants. Using Rocket Immunoelectrophoresis, no appreciable differences between Rubisco concentration levels of the experimental plants and the control plants were noted indicating that the effect on Rubisco activity is a post‐translational phenomenon and that Rubisco is not being degraded at an accelerated rate. Manganese accumulated in the experimental plants to concentrations as high as 3282 μg/g dry wt as determined by atomic absorption spectrophotometry. A shuttling mechanism for Mn between young and old leaves was indicated by an observed decrease in the concentration of Mn in the young leaf tissue between 12 and 18 h after treatment.     

Effects of phosphate,nitrate and chloride on calcium,magnesium and manganese content of cigar‐wrapper tobacco

Abstract

Nutrient solutions containing three levels of phosphate, nitrate, and chloride were applied to cigar‐wrapper tobacco (Nicotiana tabacum L.) plants growing in sand culture for a period of 18 days. Concentrations of other nutrient elements in the nutrient solutions were held constant and the solutions were applied to pots as needed to maintain favorable moisture conditions for plant growth. Plants were in the two leaf stage when transplanted and were maintained on a single nutrient solution for 38 days before treatments were started. At the end of an eight weeks growing period, plant leaves were harvested and analyzed for Ca, Mg, and Mn. Dry matter yield was significantly (P=0.01) increased when 2 mM/1 of Ca(NO₃)₂ replaced an equivalent amount of Ca(H₂PO₄)₂ or CaCl₂ in the nutrient solution. Nitrate significantly (P=0.05) increased Ca and Mg content and decreased Mn concentration in leaf tissue in comparison to chloride. Calcium and Mg content were significantly (P=0.05) decreased and Mn content of tobacco leaves was increased by phosphate in comparison to nitrate and chloride.     

Differential expression of iron deficiency‐induced genes in barley genotypes with differing manganese efficiency

The expression of two barley genes, Ids1 and Ids2, that were induced specifically by iron (Fe) deficiency stress in solution culture, was examined in two barley genotypes differing in manganese (Mn) efficiency. Plants were grown in a calcareous soil supplied with two levels of Mn (15 and 100 mg/kg soil). Ids1 was expressed at equal levels in the roots of both genotypes, and this expression was not affected by Mn supply. These results suggest that the expression of Ids1 probably does not contribute to Mn efficiency. A contrasting result was obtained for Ids2, which was expressed at a higher level in the roots of the Mn‐inefficient genotype than in the Mn‐efficient genotype. However, the expression levels also were not affected by Mn supply. The differential expression of Ids2 may indicate that this gene plays a role both in the Fe deficiency response and in the Mn efficiency mechanism. An interesting observation made on the time course of expression of the two genes. Initially, both genes had low expression in two week old plants and then much higher expression in three week old plants. The timing of this increase probably relates to the exhaustion of the seed Fe reserves. Therefore, our results indicate a need to consider the effect of seed nutrient content in research on the molecular basis for micronutrient acquisition.     

Effect of elevated manganese on the ultraviolet‐ and blue light‐absorbing compounds of cucumber cotyledon and leaf tissues

The effect of manganese [Mn(II)] on the pigments of cucumber (Cucumis sativus L., cv Poinsett 76) leaf and cotyledon tissues was investigated. Tissue disks (7 mm) were exposed to increasing Mn(II) concentrations from 100 μM to 2.5 mM. Acetone (carotenoid‐rich fraction) and acidified methanol (flavonoid‐rich fraction) extracts were analyzed by high performance liquid chromatography. Although none of the Mn(II)‐treated tissues showed visible damage, Mn(II) at concentrations of 250 μM and above significantly reduced (60%) the ß‐carotene levels of light‐incubated leaf tissues. A major Mn(II)‐induced, UV‐absorbing compound was observed in methanol extracts of cotyledonary tissues exposed to Mn(II) in the dark. In leaf tissues, Mn(II) reduced the levels of certain UV‐absorbing compounds under both light conditions. These results demonstrate that excess leaf Mn(II) can rapidly impair isoprenoid metabolism, altering tissue carotenoid composition. Furthermore, Mn(II) may also modify phenylpropanoid metabolism, changing the tissue flavonoid composition. Both situations could sensitize plant tissues to oxidative stresses, particularly enhanced solar UV‐B radiation, and may reduce the nutritional quality of leafy vegetables.     

Microdistribution of aluminum and manganese in the tea leaf tissues as revealed by X‐ray microanalyzer

Abstract

Tea plants (Thea sinensis L.) were found to accumulate large amount of Al (4457 ppm, D.W.) in their old leaves. The results showed that Mn stimulated the Al uptake and increased the Al content in the leaves. High concentrations of Ca and Mg in the soils decreased the Al and Mn and increased the Ca and Mg contents in the leaves. No phosphorus and aluminum interaction was found in the leaves of tea plants.

Microdistribution patterns of Al and Mn in the tea leaf tissues were also studied by means of a wavelength dispersive type X‐ray microanalyzer in conjunction with cryostage. The results of X‐ray micrographs showed that Al was densely deposited on the cell walls of the adaxial epidermis and palisade parenchyma cells of the old leaf tissues, and this distribution pattern of Al was different than that of Mn which was found mostly concentrated in the epidermal cells.     

Iron–manganese concretions contribute to benthic release of phosphorus and arsenic in anoxic conditions in the Baltic Sea

Purpose

Deposits of iron–manganese (Fe, Mn) concretions forming a large storage of phosphorus (P) and arsenic (As) are frequently under pressure of oscillating oxygen conditions in the eutrophic Gulf of Finland, the Baltic Sea. Yet, there is a poor understanding how anaerobic microbial processes regulate the cycling of elements in the concretions. The objective of this study was to highlight how the microbial processes control the release of elements from the concretions to brackish water during anoxia.

Materials and methods

Spherical concretions were collected from the oxic bottoms of the Gulf of Finland in the summer. Concretions and autoclaved controls were incubated in anoxic artificial brackish seawater with and without labile carbon, plus supplied with ammonium at 5, 10, and 20 °C for 15 weeks. Concentrations of Fe, Mn, P, and As were measured from the intact concretions and the ambient solutions during the experiment. Also, the consumption of the added ammonium and organic carbon and the formation of dissolved inorganic carbon were measured.

Results and discussion

At near-bottom temperature 5 °C, the concretions released at highest 0.12, 0.42, 0.02, and 0.0002 μmol g^?1 day^?1 of Fe, Mn, P, and As, respectively. The rates were significant only in the microcosms with added labile carbon, and only minor proportions (0.1–0.4 %) of their total contents were released during the incubations. The concretions removed completely the supplied ammonium only without carbon addition. We find that concretion deposit may form a local hot spot for the microbial reduction of Fe and Mn and release significant amounts of P and As, and participate in N cycling besides the bottom sediments of the Gulf of Finland during prolonged anoxia. However, the concretions may maintain their binding capacity for P and As longer than the fine-grained organic-rich sediment during anoxia.

Conclusions

During anoxia concretion deposits may form a temporal source of bioavailable P having ecological significance in the Gulf of Finland when concretions have access to labile organic carbon. Concretions from the Baltic Sea, the oceans, lakes, and soils contain high concentrations of Mn and Fe, but their proportions vary considerably. Anaerobic microbial processes may thus affect the stability of concretions from the different environments, but the outcome may depend on the ambient geochemical conditions.

     

Phytosiderophore release from manganese‐induced iron deficiency in barley

An experiment was conducted in the phytotron with barley (Hordeum vulgare L. cv. Minorimugi) grown in nutrient solution to compare iron (Fe) deficiency caused by the lack of Fe with manganese (Mn)‐induced Fe deficiency. Dark brown spots on older leaves and stems, and interveinal chlorosis on younger leaves were common symptoms of plants grown in either Mn‐toxic or Fe‐deficient treatments. Dry matter yield was affected similarly by Fe deficiency and Mn toxicity. The Mn toxicity significantly decreased the translocation of Fe from roots to shoots, caused root browning, and inhibited Fe absorption. The rate of Fe translocated from roots to shoots in the 25.0 μM Mn (toxic) treatment was similar to the Fe‐deficient treatment. Manganese toxicity, based on the release of phytosiderophore (PS) from roots, decreased from 25.0>250>2.50 uM Mn. The highest release of PS from roots occurred 7 and 14 days after transplanting (DAT) to Mn‐toxic and Fe‐deficient treatments, respectively; but was always higher in the Fe‐deficient treatment than the Mn‐toxic treatments. The release of PS from roots decreased gradually with plant age and with severity of the Mn toxicity symptoms. The PS content in roots followed the PS release pattern.     

Extractability of manganese and iron oxides in typical Japanese soils by 0.5 mol L−1 hydroxylamine hydrochloride (pH 1.5)

We investigated the extractability of manganese (Mn) and iron (Fe) oxides from typical Japanese soils (Entisols, Inceptisols, and Andisols) by 0.5?mol?L^?1 hydroxylamine hydrochloride (NH₂OH-HCl) extraction (pH 1.5; 16?h shaking at 25°C; soil:solution ratio 1:40), referred as to HH_mBCR, which is Step 2 (used for the reducible fraction) of the modified BCR (Community Bureau of Reference) sequential extraction procedure. The HH_mBCR procedure extracted almost all Mn oxides from the non-Andisol samples, but failed to extract a part of the Mn oxides from some Andisol samples. The procedure extracted most short-range ordered Fe oxides from non-Andisol samples, but it extracted only 7.5% and 13% of the short-range ordered Fe oxides from allophanic and non-allophanic Andisol samples, respectively. This remarkably low extractability of Fe oxides suggests that the HH_mBCR method is not suitable for extracting oxide-occluded heavy metals from Andisols. Since the extraction rate of short-range ordered Fe oxides from various soils with the extractant was negatively correlated with the amounts of oxalate- and pyrophosphate-extractable Al even when the variability of the extraction pH was reduced by increasing the soil:solution ratio from 1:40 to 1:500, the extractability of Fe oxides would be negatively affected by the presence of active Al, including allophane/imogolite, amorphous Al, and Al-humus complexes. Because these Al constituents are abundant in Andisols, they would be at least partially responsible for the lower extractability of Fe oxides by HH_mBCR from Andisols.     

Application of Electrochemical Degradation of Wastewater Composed of Mixtures of Phenol–Formaldehyde

The industrial wastewater from resin production plants contains as major components phenol and formaldehyde, which are traditionally treated by biological methods. As a possible alternative method, electrochemical treatment was tested using solutions containing a mixture of phenol and formaldehyde simulating an industrial effluent. The anode used was a dimensionally stable anode (DSA?) of nominal composition Ti/Ru_0.3Ti_0.7O₂, and the solution composition during the degradation process was analyzed by liquid chromatography and the removal of total organic carbon. From cyclic voltammetry, it is observed that for formaldehyde, a small offset of the beginning of the oxygen evolution reaction occurs, but for phenol, the reaction is inhibited and the current density decreases. From the electrochemical degradations, it was determined that 40?mA?cm^?2 is the most efficient current density and the comparison of different supporting electrolytes (Na₂SO₄, NaNO₃, and NaCl) indicated a higher removal of total organic carbon in NaCl medium.     

Horizontal variability in DTPA‐extractable iron,manganese, copper,and zinc in deep loess hill soils at the mey research station

Abstract

Soil is a heterogenous mixture of solids, and therefore, has significant amount of horizontal variability in DTPA‐extractable iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn). Such variability, if too high and random, may cause difficulties in interpreting the experimental data at a research station. But the level of variability of Fe, Mn, Cu, and Zn, and whether it is random or spatially correlated, has not been determined. Therefore, to determine the coefficient of variation and whether it is random or spatially correlated, fields at the MEY Research Station were divided into small plots and a composite sample was collected from each plot and analyzed for DTPA‐extractable Fe, Mn, Cu, and Zn. The weighted mean of the coefficient of variation for the whole station for Fe, Mn, Cu, and Zn was 47, 60, 38, and 47%, respectively. In addition, the variation in Fe, Mn, Cu, and Zn levels in each field, as small as 0.3 ha, was random and not spatially correlated. To reduce the effect of this random variability on treatments of an experiment at a research station, a fertilizer recommendation scheme which includes coefficient of variation as a factor is recommended.     

Cadmium sulfate application to sludge‐amended soils: III. Relationship between treatment and plant available cadmium,zinc, and manganese1

Abstract

Swiss chard (Beta vulgarisvar. cicla) and corn (Zea maysL.) were used as biological indicators of Cd, Zn and Mn availability in 12 soils amended with and without sludge, CdSO₄and CaCO₃. Soil Cd, Zn and Mn were partitioned into six fractions: soluble, exchangeable, adsorbed, organically bound, carbonate bound and sulfide bound, by the use of H₂O, KNO₃, H₂O, NaOH, EDTA and HNO₃, respectively. The data indicate that the major portion of total Cd was found in the carbonate, residual and organic fractions. Addition of CaCO₃caused an increase in the soluble and exchangeable fractions of Cd in the soils. The concentrations of Cd in the saturation extracts of the limed soils were significantly greater than those of the unlimed soils; however, this was not reflected in greater plant uptake of Cd from limed soils.     

The impact of earthworms on the abundance of Collembola: improvement of food resources or of habitat?

I assessed the direct influence of earthworm excretions, and the impact of earthworms through their action on the soil structure (increased macroporosity), on the population dynamics of the collembolan species Heteromurus nitidus. The intestinal content of Collembola arising from cultures on different soil types was observed, and two experimental cultures of H. nitidus were run: (1) a culture performed on an inert substrate supplied either with earthworm casts or with soil as food resource, (2) an experiment using microcosms with cores of two humus forms (moder and calcic mull), in the presence or absence of earthworms. The observation of gut contents revealed that H. nitidus feeds on excrements, the composition of which (ratio organic matter/mineral matter) varies according to the humus form where it lived. Slightly aged (10–15 days) organo-mineral casts of earthworms appeared to be a better food than calcic mull aggregates or organic material from moder. Densities of H. nitidus cultured in cores of calcic mull were higher than in moder, except when cores of moder were inhabited by an anecic earthworm for 2 months. The humus form strongly influenced populations of H. nitidus, firstly because densities of predators were higher in moder than in calcic mull, and probably also because of soil macroporosity. It was concluded that earthworms would affect predation on H. nitidus by creating a network of interconnected macropores in which Collembola can move and find shelter.     

Fractionation of Zinc in Paddy Soils of China

The rice fields in China amount to 25.4 million hectares of which low yield paddy soils areabout 26％(Xu,1981;Xiao,1981).One of the most important causes of low yield is the defi-ciency in nutrients including zinc.Zinc deficiency usually occurs in calcareous paddy soils withpH>6.5(Zhu and Liu,1981).And the availability of zinc in calcareous paddy soils is lowerthan that in neutral and acid paddy soils.