Uptake of zinc by Brassica napus as affected by sulphur supply

Industrial crops provide a possibility for utilization of heavy metal polluted soils. Knowledge of the factors which affect metal uptake by crops is therefore essential in order to develop concepts for the management of such soils. In pot experiments the uptake of Zn by oilseed rape increased considerably with the Zn supply. The increase of Zn uptake was counteracted partly by S. This protective effect of S was, however, not related to Zn retention in the roots.     

Uptake of Cu2+ by starch granules as affected by counterions

Potato and wheat starch granules were soaked in 1% aqueous solutions of copper(II) salts: acetate, chloride, and sulfate. Such treatment caused sorption of Cu(2+) ions at the granule surface and their penetration into the granule interior as was proven, for sectioned granules of investigated starch, by scanning electron microscopy combined with an X-ray microanalysis system (energy dispersive spectroscopy). Copper ions incorporated into the granules influenced the starch thermal stability. Uptake of Cu(2+) by potato, determined by flame atomic absorption spectrometry, was much higher than obtained for the wheat starch. Moreover, it was dependent on copper counteranions present in the solution. In all investigated granules, the most effective sorption occurred in the acetate solution. Starch dehydration or/and freezing and thawing, affecting the water-dependent inner structure of the granules, also influenced the amount of Cu(2+) taken from the solutions. Thus, compared to that in native starch, this value was considerably higher in Cu(CH 3COO)2, almost unchanged in CuSO4, and significantly lower in the case of CuCl2 solution. The influence of chloride and sulfate anions seemed to correlate with their water structure-making and structure-breaking ability, affecting the migration of Cu(2+) in the amorphous parts of the granules. However, high Cu uptake observed for acetate solution could be explained on the basis of acetate anion hydrolysis activating the polysaccharide matrix for cation binding. The obtained results provide new information about interactions of starch granules with salt solution and therefore support our understanding of starch properties.     

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.     

Mineral Elements Uptake and Growth of Strawberry as Influenced by Organic Substrates

Pot experiment was conducted in a greenhouse to compare the effect of four organic substrates [S1: Persian turpentine trees leaf mold (50%) + Soil (50%); S2: Oak leaf mold (50%) + Soil (50%); S3: Cypress leaf mold (50%) + Soil (50%) and S4: liquorice processing wastes (50%) + Soil (50%)] application on strawberry growth, yield, and nutrient concentration, and on some soil properties. Results showed that leaves mold and liquorice wastes application decreased pH, increased soil organic matter, and increased soil concentrations in all mineral elements studied, except for potassium (K). The amount of mineral elements in substrates had also a great influence on the leaf nutrient concentrations. High levels of nitrogen (N), K, iron (Fe), manganese (Mn), and zinc (Zn) were obtained in leaves; while phosphorus (P) concentration was lower than sufficient levels. Although, strawberry fresh and dry weights and leaf chlorophyll content were significantly higher in plants grown in S4 with no added fertilizer, the highest fruit yield was obtained in combination substrates with 50% fertilizer. Our results indicate that use of leaf mold and liquorice wastes in soil mixtures can reduce the amount of fertilizer required for optimum strawberry plant growth and yield.     

油冬菜对水凝胶包裹~(14)C-多菌灵的吸收及其在土壤-油冬菜体系中的可提态残留和结合残留

利用高吸水树脂(SAP)和农药解决干旱半干旱地区抗旱保水及虫害问题是行之有效的农业生产措施,研究并阐明SAP与农药共存下的农药环境行为规律以保障环境安全性具有重要的实际意义。本文以具有缓释特性的水凝胶包覆多菌灵(H-MBC)为研究对象,应用同位素示踪法研究14C标记H-MBC在水中的释放特性及其与原药(14C-MBC)在土壤-油冬菜体系中的结合残留、可提态残留、矿化及挥发物总量的异同性,同时考察油冬菜对14C标记H-MBC的吸收利用规律。结果表明,H-MBC可以实现多菌灵缓慢释放,48 h释放了总量的60%,至360 h时释放量达到了总量的96%;14C标记H-MBC及14CMBC在土壤中可提态残留均随着时间递减,至培养34 d时分别占引入量的10.70%和6.95%;14C标记H-MBC及14C-MBC在土壤中的结合残留随着时间先增后降,其拐点分别出现在28 d和14 d,其中14C标记H-MBC的结合残留约占引入量35.71%~52.51%,而对照14C-MBC的结合残留约为引入量的23.87%~43.26%;油冬菜对14C标记H-MBC和14C-MBC的吸收均较少,仅占引入量的0.08%~1.64%,表明2种施药方式下多菌灵均不会在植物中产生大量残留。根据质量平衡得到的14C标记HMBC和14C-MBC降解产生的挥发性物质(可能为14C-CO2和/或14C-甲酸)的量分别为30.17%~52.66%和32.26%~65.75%,凝胶的包覆减少了多菌灵挥发性物质的产生。本研究为干旱地区安全、科学使用SAP和农药提供了科学依据。     

Uptake of cations by annual ryegrass as related to cations adsorbed onto root exchange sites

Abstract

Previously published results on exchange capacities for Ca²⁺, Mg²⁺, Mn²⁺, and K⁺ in the Donnan free space of roots of two ryegrass cultivars (Lolium multiflorum Lam. cv. Marshall and Wilo) grown at two Al levels in the nutrient solution (0 and 74 μM) were correlated with the average net uptakes of the same cations. For Al‐treated plants regressed separately, significant correlations r=0.906 and r=0.963 were found for Mn²⁺ and Ca²⁺/Mg²⁺, respectively. No significant correlations were observed for these cations in control plants. In contrast, when data of control and Al‐treated plants were combined, significant linear correlations r=0.805, r=0.924, and r=0.968 were found for Ca²⁺, K⁺, and K⁺/(Ca²⁺+Mg²⁺)^1/2, respectively. The influence of cations adsorbed onto the root exchange sites and the effect of Al on the cation uptake processes were discussed.     

Yield,Nutrient Uptake,and Quality of Stevia as Affected by Organic Sources of Nutrient

A field experiment was conducted during 2008 and 2009 at the Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur, India, to study the effect of organic sources of nutrient on yield, nutrient uptake, fertility status of soil, and quality of stevia crop in the western Himalayan region. The experiment comprised eight different combinations of organic manure [farmyard manure (FYM), vermicompost (VC), and apple pomace manure (AP)]. Total leaf dry biomass increased by 149% over the control with application of VC 1.5 t ha^?1 + AP 5 t ha^?1. Application of organic manures enhanced organic carbon and available nutrient status of soil more than the control. Nitrogen (N) and phosphorus (P) content in stem were significantly affected by the application of organic manures over the control. Stevia plants supplied with FYM 10 t ha^?1 + AP 2.5 t ha^?1 recorded more total glycoside than other treatments. Stevioside yield (kg ha^?1) was greater with application of FYM 10 t ha^?1 + AP 2.5 t ha^?1.     

Uptake of uranium by vegetables and rice

The uptake of U by vegetables from soil and water has been studied in pots by spiking the soil and the irrigation water with U. An increase in the U level in vegetables has been observed with an increase of U content in the irrigation water and not with soil U. However, the concentration factor for the uptake of U by vegetables decreases with increase of U in water. The study of distribution of U in rice (Oryza saliva) indicates the discrimination of U by different parts of the crop. Among root, stem, and grain, the lowest concentration of U has been observed in grain (rice).     

Methylmercury production in the anoxic hypolimnion of a Dimictic Seepage Lake

Experimental results and field data indicated that methyl-Hg was produced within a layer of bacterioplankton near the top of the anoxic hypolimnion of Pallette Lake. In situ incubations at ambient Hg concentrations indicated that the net flux of methyl-Hg from the layer was between 50 and 100 pmol/m^2*d. This input was sufficient to account for the summer accumulation of methyl-Hg in the entire hypolimnion and it exceeded atmospheric inputs by 2 orders of magnitude. Maximum rates of net methylation occurred in the same region of the water column where we observed maximum rates of sulfate reduction. The measured rates were: 100 fmol rriethyl-Hg/L^*d and 90 nmol SO₄/L^*d. Sulfate reducing enrichment cultures isolated from the hypolimnion were also able to methylate Hg in the laboratory. Sulfate reduction did not occur in anoxic profundal sediments during summer and we infer from ancillary data that methylation in profundal sediments was also low. Whole-lake rates of sulfate reduction in the hypolimnetic layer and shallow sediments were roughly equivalent, but we cannot yet compare methylation rates at these sites due to large uncertainties in the littoral flux of methyl-Hg. We propose that zones of Hg methylation and SO4 reduction follow the oxic/anoxic boundary in both the watercolumn and sediments. The relative importance of watercolumn and sediment processes will depend on the physical and chemical structure of a given lake.     

Kinetics of Zinc Uptake and Anatomy of Roots and Leaves of Coffee Trees as Affected by Zinc Nutrition

Abstract

The influence of silicon (Si) (2.5 mM), sodium chloride (NaCl) (100 mM), and Si (2.5 mM) + NaCl (97.5 mM) supply on chlorophyll content, chlorophyll fluorescence, the concentration of malondialdehyde (MDA), H₂O₂ level, and activities of superoxide dismutase (SOD; E.C.1.15.1.1.), ascorbate peroxidase (APx; E.C.1.11.1.11.), catalase (CAT; E.C.1.11.1.6.), guaiacol peroxidase (G-POD; E.C.1.11.1.7.) enzymes, and protein content were studied in tomato (Lycopersicon esculentum Mill c.v.) leaves over 10-day and 27-day periods. The results indicated that silicon partially offset the negative impacts of NaCl stress with increased the tolerance of tomato plants to NaCl salinity by raising SOD and CAT activities, chlorophyll content, and photochemical efficiency of PSII. Salt stress decreased SOD and CAT activities and soluble protein content in the leaves. However, addition of silicon to the nutrient solution enhanced SOD and CAT activities and protein content in tomato leaves under salt stress. In contrast, salt stress slightly promoted APx activity and considerably increased H₂O₂ level and MDA concentration and Si addition slightly decreased APx activity and significantly reduced H₂O₂ level and MDA concentration in the leaves of salt-treated plants. G-POD activity was slightly decreased by addition of salt and Si. Enhanced activities of SOD and CAT by Si addition may protect the plant tissues from oxidative damage induced by salt, thus mitigating salt toxicity and improving the growth of tomato plants. These results confirm that the scavenging system forms the primary defense line in protecting oxidative damage under stress in crop plants.     

Cadmium and Nutrient Heavy Metals Uptake by Rice,Barley, and Spinach as Affected by Four Ammonium Salts

This experiment was conducted to investigate the influence of ammonium salts on the uptake of cadmium (Cd) and nutritional heavy metals (copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe)) by rice, barley, and spinach. These plants were grown in Cd, Cu, and Zn contaminated entisol (ES) or andisol (AS). The following ammonium salts were used: ammonium nitrate (NH₄NO₃), ammonium sulfate ((NH₄)₂SO₄), ammonium chloride (NH₄Cl), and ammonium dihydrogen phosphate (NH₄H₂PO₄). In ES, the Cd concentrations in three plant shoots were higher with NH₄Cl than with the other salts. The concentrations of Cd in soil solutions collected from ES were higher with NH₄Cl. Thus, the increase of Cd uptake by three plants with NH₄Cl treatment would be caused by the increased concentration of Cd in the soil solution. In contrast, in AS, the concentrations of the heavy metals in the shoots of all plants were not different among NH₄ applications, with one exception, the Mn concentration in rice increased with NH₄Cl in both ES and AS.     

Uptake of tritiated water vapor by bean leaves

When bean leaves were exposed to tritiated water (HTO) vapor in a wind tunnel, the concentration of HTO in the leaves approached equilibrium in a few hours. The results are in good agreement with a model proposed by Belot, who assumed that HTO exchange is controlled by the rate of diffusion of the vapor through the boundary layer of the leaf and the stomata, and that the resistances for HTO and for water vapor are equal.     

Simultaneous Uptake of Multiple Amino Acids by Wheat

ABSTRACT

Recent research has proven that higher plants can utilize amino acids as nitrogen (N) and carbon (C) sources. Most studies have focused on single amino acids with or without inorganic N, but a range of amino acids may be expected under conditions where the main N input derives from turnover of organic N sources. This study investigated the uptake of multiple amino acids by plant roots and further the active versus passive uptake was determined. Under minimum microbial activity conditions, seedlings of wheat (Triticum aestivum L. cv. ‘Baldus’) were exposed to a series of different concentrations of seven mixed amino acids solutions. Samples of the depleted solutions were periodically collected over a period of ten hours to measure the concentration of amino acids. For all tested amino acids passive uptake was a minor contribution compared to the total uptake. The uptake rates of the amino acids were well described by single Michaelis-Menten kinetic equations with R² ranging from 0.87 to 0.96. All of the tested amino acids showed a similar uptake pattern. Wheat plants had the highest affinity (lowest K _m values) for glutamine followed by tryptophan, alanine, arginine, glycine, and serine. The V _max values for amino acids uptake by wheat ranged from 2.26 for tryptophan to 16.6 μmol g^?1 root FW h^?1 in case of serine.     

Rhizosphere Phosphorus Solubility and Plant Uptake as Affected by Crop in a Clay Soil from the Central Plateau Region of Haiti

Phosphorus (P) is commonly a limiting nutrient affecting crop yields in tropical cultivated systems, and a high P-sorption capacity in many of these soils can decrease the effectiveness of fertilizer use. Smallholder farmers, such as those in rural Haiti who do not have sufficient access to P fertilizers, may benefit from crops that are efficient at scavenging for P. To evaluate commonly grown and potentially useful plants for this purpose, a pot study was conducted in a controlled-environment chamber set to approximate ambient May–June conditions in Haiti's Central Plateau with seven treatments (six legume and one grass species) using soil from an Ustalf taken in the region. Velvet bean (Mucuna pruriens [L.] DC) produced the largest amount of biomass, though no difference in P uptake among treatments was observed. Phosphorus uptake and rhizosphere P were positively correlated, indicating plants with a larger capacity to solubilize P took up more P.     

Root Growth,Nutrient Uptake,and Nutrient-Use Efficiency by Roots of Tropical Legume Cover Crops as Influenced by Phosphorus Fertilization

Roots are important organs that supply water and nutrients to growing plants. Data related to root growth and nutrient uptake by tropical legume cover crops are limited. The objective of this study was to evaluate root growth of tropical legume cover crops and nutrient uptake and use efficiency under different phosphorus (P) levels. The P levels used were 0 (low), 100 (medium), and 200 (high) mg kg^?1 of soil, and five cover crops were evaluated. Root dry weight, maximum root length, and specific root length were significantly influenced by P and cover crop treatments. Maximum values of these root growth parameters were achieved with the addition of 100 mg P kg^?1 soil. The P?×?cover crops interactions for all the macro- and micronutrients, except manganese (Mn), were significant, indicating variation in uptake pattern of these nutrients by cover crops with the variation in P rates. Overall, uptake pattern of macronutrients was in the order of nitrogen (N) > calcium (Ca) > potassium (K) > magnesium (Mg) > P and micronutrient uptake pattern was in the order of iron (Fe) > Mn > zinc (Zn) > copper (Cu). Cover crops which produced maximum root dry weight also accumulated greater amount of nutrients, including N, compared to cover crops, which produced lower root dry weight. Greater uptake of N compared to other nutrients by cover crops indicated that use of cover crops in the cropping systems could reduce loss of nitrate (NO₃ ^?) from soil–plant systems. Increase in root length and root dry weight with the addition of P can improve nutrient uptake from the soil and lessen loss of macro- and micronutrients from the soil–plant systems.     

Lead Phytostabilization and Cationic Micronutrient Uptake by Maize as Influenced by Pb Levels and Application of Low Molecular Weight Organic Acids

ABSTRACT

Phytoremediation is a promising technique to clean up toxic heavy metals including lead (Pb). A greenhouse trial was conducted to evaluate the effectiveness of citric, succinic, malonic and oxalic acids on micronutrient uptake and phytoremediation of Pb contaminated soil by maize under different Pb levels. Mean root and shoot dry weights of maize decreased with increasing Pb levels. At the lowest Pb level, application of citric and oxalic acids caused increase effects on root and shoot dry weight, respectively, as compared to the absence of organic acid. As Pb levels increased, micronutrient uptake in maize shoot decreased. Among the studied organic acids, only the application of oxalic acid increased uptake of all micronutrients in maize shoot as compared to control at the lowest Pb level. Mean root and shoot Pb concentration and uptake and also uptake index noticeably increased at the highest Pb level. All tested acids increased Pb concentration and uptake in maize root. At the highest Pb level, organic acids, except for citric acid, significantly increased shoot Pb uptake and uptake index as compared to the absence of organic acid. Translocation factors less than 1, demonstrated that most of Pb taken up by maize accumulated in root as compared to shoot. According to results reported herein, application of malonic, succinic and oxalic acids is a good strategy to enhance phytostabilization potential of Pb by maize in pb-polluted soils.     

Calcium Sulphate versus Lime as Fertilizer Filler: Effects on Ammonium and Nitrate Uptake by Perennial Ryegrass

Abstract

The recovery of ¹⁵N‐labelled nitrogen (N) by perennial ryegrass can be significantly increased by mixing gypsum (CaSO₄ · 2H₂O) into soil rooting medium at rates equivalent to 0.7 t ha^?1. Similar improvements in fertilizer N efficiency might be achieved, at less cost and more conveniently, by applying smaller amounts of CaSO₄ anhydrite more strategically to fertilizer microsites as a fertilizer filler or diluting agent, in calcium ammonium nitrate (CAN), in place of CaCO₃. With this in mind, two complementary pot experiments were conducted under simulated spring conditions in a controlled environment chamber. Use of CaSO₄ as diluting agent, in place of CaCO₃, appreciably enhanced (>30%) the uptake of labeled N by perennial ryegrass plants within the second week of regrowth, but thereafter, because losses of ¹⁵N‐labeled NO₃ ^?‐N from pots by denitrification or leaching had been minimal, plants in both treatments eventually recovered equal amounts of this N form from the soil.     

Mercury and Methylmercury Dynamics in the Hyporheic Zone of an Oregon Stream

The role of the hyporheic zone in mercury (Hg) cycling has received limited attention despite the biogeochemically active nature of this zone and, thus, its potential to influence Hg behavior in streams. An assessment of Hg geochemistry in the hyporheic zone of a coarse-grained island in the Coast Fork Willamette River in Oregon, USA, illustrates the spatially dynamic nature of this region of the stream channel for Hg mobilization and attenuation. Hyporheic flow through the island was evident from the water-table geometry and supported by hyporheic-zone chemistry distinct from that of the bounding groundwater system. Redox-indicator species changed abruptly along a transect through the hyporheic zone, indicating a biogeochemically reactive stream/hyporheic-zone continuum. Dissolved organic carbon (DOC), total Hg, and methylmercury (MeHg) concentrations increased in the upgradient portion of the hyporheic zone and decreased in the downgradient region. Total Hg (collected in 2002 and 2003) and MeHg (collected in 2003) were correlated with DOC in hyporheic-zone samples: r ²?=?0.63 (total Hg-DOC, 2002), 0.73 (total Hg-DOC, 2003), and 0.94 (MeHg-DOC, 2003). Weaker Hg/DOC association in late summer 2002 than in early summer 2003 may reflect seasonal differences in DOC reactivity. Observed correlations between DOC and both total Hg and MeHg reflect the importance of DOC for Hg mobilization, transport, and fate in this hyporheic zone. Correlations with DOC provide a framework for conceptualizing and quantifying Hg and MeHg dynamics in this region of the stream channel, and provide a refined conceptual model of the role hyporheic zones may play in aquatic ecosystems.