The native subspecies of Juncus effusus (Juncaceae) in western North America

Juncus effusus s. str. has two native representatives on the coast of western North America. A new combination is provided forJuncus effusus subsp.pacificus, ranging from California to British Columbia.Juncus effusus subsp.austrocalifornicus is newly described from southernmost California, Arizona, and Baja California, México. It differs from subsp.pacificus by its pale sheaths, with less thickened and less overlapping margins, and its disjunct distribution. A key is provided for the subspecies ofJ. effusus in North America.     

Response to Waterlogging and Differing Sensitivity to Divalent Iron and Manganese in Clones of Dactylis glomerata L. derived from Well-drained and Poorly-drained Soils

Clonally propagated plants of Dactylis glomerata derived froma well-drained, heavily grazed cliff habitat (clone L) and froman undergrazed poorly-drained soil (clone A) were tested forwaterlogging tolerance in soil-culture. Water-logging did notaffect the two clones differentially, a result, which contrastedstrongly with that of a previous experiment in which simulatedgrazing (clipping to 20 cm) unexpectedly caused clone A to beless tolerant of waterlogging than clone L. Maximum leaf andleaf sheath length was reduced more by water-logging in cloneL than in clone A (P < 0.05). In solution-culture when providedwith factorial combinations of 0.5, 5 and 50 mg dm^–2 ofFe²⁺ and Mn²⁺ the shoot dry weight yield of the dry-soil clonewas reduced more than that of the wet-soil clone by 50 mg Fedm^–3 irrespective of Mn²⁺ concentration (P < 0.01)but the reduction of growth was less at higher Mn²⁺ concentrations.Fifty milligrams of Mn²⁺ dm^–3 reduced the growth of thedry soil clone but increased the growth of the wet soil clonewith Fe²⁺ at 5 mg dm^–2 (P < 0.05). Iron at 0.5 mg dm^–2was suboptimal for shoot growth of both clones at any levelof Mn²⁺ and caused more severe leaf chlorosis in the wet soilclone. Leaf tissue of clone L contained more iron than thatof clone A after waterlogging (P < 0.01) but in solutionculture, though increasing iron from 0.5 to 50 mg dm^–3almost doubled leaf iron content (P < 0.001), the interactionClones x Mn x Fe just failed to reach significance at P <0.05. The manganese content of leaf tissue from the two clonesvaried differently in response to solution manganese (Clonesx Mn P < 0.01), clone A showing a slightly greater increaseof manganese content at high solution concentration. Iron at50 mg dm^–3 suppressed Mn uptake (Mn x Fe, P < 0.001)in both clones. The two clones thus show marked environmentaladaptation to the chemistry of wet and dry soils. Dactylis glomerata, Cocksfoot grass, Orchard grass, waterlogging, iron, manganese, toxicity, deficiency, ecotypes     

Effect of external oxygen demand on radial oxygen loss by Juncus roots in titanium citrate solutions

Radial oxygen loss (ROL) from the roots of two semiaquatic rushes, Juncus effusus L. and Juncus inflexus L., was studied in reducing titanium citrate buffer, using both closed incubations and a flow-through, titrimetric system. In closed experiments, roots released oxygen at a constant rate over a wide range of external oxygen demands, with the ROL rate only depending on sink strength at low demands, and no oxygen release into oxidized solutions. In the titrimetric experiments, roots continued to release oxygen at constant rates when provided with a constant external oxygen demand. ROL was higher in J. effusus (9·5 ± 1 × 10^?7 mol O₂ h^?1 root^?1) than in J. inflexus (4·5 ± 0·5 × 10^?7 mol O₂ h^?1 root^?1). Light and dark changes around the shoots did not affect the ROL rate in J. inflexus, whereas in J. effusus ROL was ≈ 1·75 times higher in the light than in the dark, presumably due to changes in stomatal aperture. These results suggest that ROL is controlled by the external oxygen demand at low to moderate reducing intensities, but that structural limitations to oxygen diffusion rates prevent ROL from continuing to increase at higher external oxygen demands.     

Chemical composition studies on some aquatic macrophytes in three scottish lochs. II. Potassium,sodium, calcium,magnesium and iron

The potassium, sodium, calcium, magnesium and iron levels in seven species of freshwater macrophytes (Juncus effusus L., Iris pseudacorus L., Carex rostrata Stokes, Glyceria maxima (Hartm.) Holmberg, Nuphar lutea (L.) Sm., Polygonum amphibium L. and Schoenoplectus lacustris (L.) Pallas) in three Scottish lochs of different trophic levels were studied during 1975 and the results obtained were compared with similar studies in other areas.     

Growth and nutrition of small Betula pendula plants at different relative addition rates of iron,manganese and zinc

In order to investigate the dependence of growth rate upon plant concentrations of iron, manganese and zinc, Betula pendula seedlings were cultivated in a hydroponic system. In three different experiments, all essential nutrient elements except iron, manganese or zinc, were titrated in non-growth limiting amounts at low external concentrations. The solution was continuously recirculated and sprayed on the roots. The micronutrients (Fe, Mn and Zn) were added as addition rates, R_A (day^-1), relative to the calculated internal amount in the plants. No chelates were added to the culture solution.At steady-state nutrition, plant relative growth rate showed a linear dependence upon the internal concentration of the limiting micronutrient. These data do not support the Steenbjerg effect where negative correlations between growth and plant nutrient concentrations have been reported. Steady-state nutrition was associated with very different growth responses to the different limiting nutrients.     

Manganese and iron interactions on their uptake and distribution in soybean (Glycine max (L.) Merr.)

Summary The uptake and distribution of iron and manganese were studied in a manganese-sensitive soybean cultivar (‘Bragg’) grown over a range of supply levels of these nutrients in solution culture. At high (90 and 275 μM) manganese levels, increasing the iron concentration in solution from 2 to 100 μM partially overcame the effects of manganese toxicity. Interactions between manganese and iron occurred for dry matter yields, rate of Mn absorption by the roots, and the proportions of manganese and iron transported to the tops. No interaction was observed for the rate of root absorption of iron. The percentage distribution of manganese in the plant top increased with increasing iron, despite a reduced rate of Mn uptake. On the other hand, iron uptake was independent of solution Mn concentration and increased with increasing solution Fe. Also more iron was retained in the roots at high Mn and/or Fe levels in solution. Concentrations of manganese and iron in roots, stems and individual leaves were affected independently by the manganese and iron supplyi.e. without any interaction occurring between the two elements. In general, the concentration in a plant part was related directly to the solution concentration. Symptoms resembling iron deficiency correlated poorly with leaf Fe concentrations whereas high levels of manganese were found in leaves displaying Mn toxicity symptoms.     

Catalase Activity and Post-anoxic Injury in Monocotyledonous Species

Three anoxia-intolerant species, Glyceria maxima, Juncus effususand Iris germanica (var. Quechei), and three anoxia-tolerantspecies Schoenoplectus lacustris, Acorus calamus and Iris pseudacoruswere chosen for investigation. Rhizomes of anoxia-intolerantspecies show increased catalase activities when returned toair after periods of prolonged anoxia. Levels of catalase remainedfairly constant in anoxia-tolerant species under the same conditions.In the anoxia intolerant G. maxima, the post-anoxic increasein catalase activity was reduced by circulating the anaerobicatmosphere. This treatment also reduced the ethanol contentof the tissue under incubation, and increased the survival ofthe rhizomes as seen in their ability to resume growth in thepost-anoxic phase. Exposure of anaerobic G. maxima rhizomesto ethanol vapour increased post-anoxic levels of catalase activityand when this produced a 5-fold increase always resulted indeath of the rhizomes. Acetaldehyde vapour applied in the sameway gave rise to increases in catalase activity followed byrapid death of the rhizomes. It is suggested that post-anoxic oxidation of anaerobicallyaccumulated ethanol may result in a surge of acetaldehyde production,which could exert a toxic effect on the recovering tissues.The possible role of catalase in an ethanol-oxidation reaction,which is well documented in animals, is discussed in the lightof the association between the natural accumulation of largeconcentrations of ethanol and subsequent post-anoxic death insome plant tissues. Key words: Catalase, post-anoxia, ethanol     

Mineral Ion Nutrition of Developing Barley Grains 1. Effect of Magnesium Deficiency on Ion Content of Immature Embryos and Endosperms

The effect on the mineral ion nutrition of developing barleyembryos and endosperms was studied when both Mg and Mn werewithdrawn simultancously from the rooting medium. Both embryosand endosperms had lower Mg levels, on average 40 and 50 percent, respectively, over the developmental period, than thosefrom control plants grown in complete nutrient solution. Comparedto the controls, higher levels of Mn (average 20 per cent) andCa (average 20 per cent) were found in Mg-deficient embryosfrom test plants, but Mn levels were lower (average 30 per cent)and Ca levels unaffected in Mg-deficient endosperms. K levelsin both embryos and endosperms were not changed. The endospermsfrom test plants had lower total N levels than the controls. Hordeum vulgare L., barley, embryo, endosperm, sand culture, magnesium, manganese, calcium, potassium, nitrogen, mineral nutrition     

Injection of hydrogen gas stimulates acid mine drainage treatment in laboratory‐scale hydroponic root mats

The environmentally benign disposal of acid mine drainage (AMD) is still a technical challenge. In the present study, artificial AMD was treated in a laboratory‐scale floating hydroponic root mat of soft rush, Juncus effusus. This ecotechnological system was operated with hydrogen injection and water recirculation but without an external carbon supply. It achieved a mean increase of ΔpH = 3.3 up to pH ≈ 8.2, high sulfate removal of up to 87%, and efficient removal of iron (100%), aluminum (99.8%), manganese (97.4%), and zinc (99.6%). Sulfide was not detected in the outflow. Treatment performance correlated with the amount of hydrogen loading. Daily oscillations of the redox potential up to amplitudes of ΔE_h ≈ 450 mV in a mean range of E_h ≈ ?150 to +300 mV indicated a correlation of plant physiology and removal processes. Apparently, sulfate and metal removal were the result of chemolithotrophic microbial sulfate reduction supported by the externally provided H₂ and chemoorganotrophic sulfate reduction driven by rhizodeposits. Bicarbonate generated in the microbial transformation of such plant‐derived organic carbon contributed to pH neutralization. The effluent's pH increase was governed further by recirculation of the treated AMD. The flow regime and the injection of hydrogen at the ground of the root mat caused concentration gradients where the most efficient removal occurred in the deepest zone of the root mat. Further investigations should target long‐term stability, plant growth dynamics, load variations, balances of carbon and sulfur, the removal of H₂S and metal precipitates from the system as well as efficient hydrogen supply.     

Presence and possible origin of positive Eu anomaly in shoot samples of Juncus effusus L

BackgroundThe rare earth elements (REE) are non-essential elements for plants. They stimulate plant growth at low doses, but at high levels are phytotoxic. There are differences in concentrations of REE in various organs of the same plant species, but the normalized REE patterns can be very similar in samples of the same species collected in different locations. Here we compare normalized REE curves in above-ground samples of Juncus effusus L. (common rush, soft rush) collected from sites with different land-use types.MethodsThe concentrations of rare earth elements were measured in 55 shoot samples of J. effusus L. The samples were collected from 15 sampling sites located in the Holy Cross Mts., south-central Poland and analyzed with the use of inductively coupled plasma mass spectrometry (ICP-MS). The results were normalized to the North American Shale Composite and anomalies of different elements were calculated.ResultsTotal REE concentrations varied from 0.028 mg/kg to 2.7 mg/kg. The samples were enriched in the light REE (from La to Eu) with the highest concentrations of La and Ce. The North American Shale Composite (NASC)-normalized REE curves were roughly similar in all samples except for two samples collected in the acid mine drainageaffected areas.ConclusionAll samples showed positive europium anomalies in NASC-normalized REE concentration patterns. The most probable explanation of this is that the uptake and translocation of Eu in J. effusus (and possibly in other wetland plants) is caused by a short-term decrease of the redox potential in a rhizosphere favoring reduction of Eu³⁺ to Eu²⁺ and thus enhancing Eu mobility in the soil-plant environment.     

九州虫草菌丝体对Mn的耐性及富集

重金属耐性真菌的研究是生物修复的重要研究内容。本文研究了九州虫草（Cordyceps kyusyuensis）对于Mn的耐性及富集。在液体培养基中添加不同浓度（0—60 g/L）的Mn离子,测定其菌丝生物量、菌丝Mn含量、菌丝抗氧化酶活性和过氧化水平以及菌体细胞离子交换量、Mn在细胞中的分布的变化情况。实验结果表明九州虫草菌丝生物量与Mn浓度呈显著负相关,Mn浓度60 g/L为九州虫草菌丝生长极限浓度。菌丝中Mn含量随培养基中Mn浓度的增大而显著升高,10 g/L Mn时,菌丝细胞中Mn积累量达到细胞干重的1.0013%。九州虫草菌丝中过氧化产物丙二醛（MDA）、可溶性蛋白（SP）含量、可溶性糖浓度与培养基中Mn浓度呈负相关,实验组与对照组差异显著。抗氧化酶（过氧化氢酶（CAT）、过氧化物酶（POD）、超氧化物歧化酶（SOD））活性随着培养基中Mn浓度增大而显著升高,但变化趋势不同。九州虫草菌丝细胞不可溶性组分中Mn的量（91.51%—98.6%）显著高于可溶部分（1.40%—8.49%）。九州虫草菌丝细胞壁离子交换量（CEC）随着培养基中Mn浓度的升高变化不明显。说明在九州虫草菌丝对Mn的富集过程中,其细胞壁、细胞膜和细胞器对于Mn结合发挥了主要作用,细胞质中可溶性成分对Mn的结合发挥次要作用。在Mn的胁迫下,增强抗氧化酶系统的协同作用以清除大量自由基是细胞对锰耐性的重要机制。     

Soil Solution Chemistry Controlling the Field Distribution of Melica ciliata L.

Germination, establishment and growth of Melica ciliata L.,an 'acidifuge' species of rocky habitats in Europe, were studiedexperimentally and related to chemical properties of the soilsolution, including pH, base cation composition, Al concentrationand speciation, and Mn concentration. M. ciliata failed to establishin acid leptite soil. However, it was able to grow in solutionat pH 3·6 and exhibited vigorous growth at pH 3·9,a typical soil solution pH of leptite sites, which Melica isunable to colonize. Higher concentrations of Mn than those measuredin any leptite soil solutions did not influence growth. Exposureto 0·037 mmol l^-1 (1 mg l^-1) of Al³⁺, a concentrationusually exceeded in the soil solution of leptite sites, severelyretarded root growth. Speciation technique applied to Al insoil solutions obtained by centrifugation demonstrated a closerelationship between H⁺ and Al concentrations and, in particular,between H⁺ and free ionic (quickly reacting) Al species. Soilsolution concentrations of free ionic Al proved to be < 0·002mmol l^-1 in sites lacking Melica , but often > 0·10mmol l^-1 in site lacking Metalica . It is concluded that theinability of M. ciliata to establish in acid soils is not primarilydue to the high H⁺ concentration but to the high soil solutionconcentrations of Al, especially free Al ionic species at lowsoil pH.Copyright 1993, 1999 Academic Press Melica ciliata, distribution, soil solution, pH, aluminium speciation, manganese, base cations, iron     

A comparative study of the tolerance of salt marsh plants to manganese

Summary Salicornia europaea, Puccinellia maritima, Triglochin maritima, Aster tripolium, Plantago maritima, Armeria maritima, Juncus gerardii andFestuca rubra, collected as seed from a salt marsh at Portaferry, County Down, were grown on saline (340 mM NaCl) and non saline nutrient solutions at five concentrations of manganese sulphate (0.025–10.0 mM). After an eight week growing period, shoot and root yields and the concentrations of sodium, potassium, calcium and manganese in the shoots were determined.Except forS. europaea the saline treatments had a strongly limiting effect on plant growth. Each of the species investigated showed a degree of tolerance to high concentrations of manganese which was similar to that of calcifuge species and plants characteristic of waterlogged sand dune slack communities, but which was very much greater than that ofArrhenatherum elatius a species usually excluded from acidic soils. There was little evidence to support the hypothesis that tolerance of high manganese concentrations was correlated with the position of the experimental plants in the salt marsh ecotone or that the manganese nutrition of halophytic and glycophytic marsh species differs. Whilst manganese uptake increased proportionally with solution manganese concentration, there were few other major effects of manganese on the balance of shoot cation concentrations in the plants investigated. Both antagonistic and synergistic effects of sodium on manganese uptake were recorded for different species.     

不同种植模式下重金属污染对牧草叶片光合特性和重金属含量的影响

为探索不同种植模式下重金属污染对牧草生理特性的影响,皇竹草(Pennisetum sinese)、黑麦草(Lolium perenne)和龙须草(Juncus effusus)采用单作和间作模式,研究了重金属污染对其叶片光合参数、光合色素和重金属含量的影响.结果表明,与单作相比,间作下皇竹草叶片的叶绿素(Chl)a、C...     

Influence of potassium and manganese on growth and uptake of magnesium by soybeans (Glycine max (L.) Merr. cv. Bragg)

Summary Soybean (Glycine max (L) Merr. cv. Bragg) seedlings were grown in nutrient solutions to evaluate the response to manganese nutrition as affected by potassium supply. In solutions containing 275 M manganese, increasing the solution concentration of potassium from 1 mM to 10 mM alleviated symptoms of manganese toxicity, decreased manganese concentrations in the leaves and increased dry matter yields of the plants. The reduction in manganese toxicity was brought about by a reduced rate of root absorption of manganese at high potassium supply levels.Increasing the supply of either potassium or manganese decreased the leaf concentration of magnesium although there were no apparent symptoms of magnesium deficiency in any treatment. The reduced concentration of magnesium in the leaves was due to effects of potassium and manganese on the rate of root absorption of magnesium.Under manganese deficiency conditions, growth was reduced and manganese concentrations in plant parts were very low; there was no effect of potassium supply when manganese was absent from the nutrient solution.     

Effect of calcium carbonate and organic matter on the growth and concentration of iron and manganese in sorghum (Sorghum bicolor)

Summary The effect of CaCO₃ and organic matter on the availability of iron and manganese was studied on sorghum (Sorghum bicolor). Addition of calcium carbonate caused significant decrease in dry matter and grain yield. But yields tended to increase with the addition of organic matter at the rate of 15 t/ha. The iron concentration decreased with the addition of CaCO₃ at all the stages of crop growth. Like iron, concentration of manganese also decreased with the increase in added CaCO₃. Organic matter increased the iron concentration both at seedling and flowering stage. The concentration of manganese was, however, dependent on the stage of the crop.     

Manganese Nutrition of Lupinus spp. Especially in Relation to Developing Seeds

Patterns of transport and accumulation of manganese were studiedin Lupinus albus L. and Lupinus angustifolius L. in a wide rangeof availability levels in the rooting medium. The recently described‘split seed’ disorder, involving discolouration,splitting, and deformity of seeds, was reproduced in sand cultureusing critically low levels of manganese. The disorder was preventedby maintaining adequate manganese in the medium and its incidencein field and glasshouse was quantitatively related to the managneselevel in seed and fruit phloem sap. The use of phloem sap analysisfor early diagnosis of the disorder is suggested. High levelsof manganese in parent seed is suggested to afford protectionagainst the disorder by improving early vegetative growth ina manganese deficient situation. Direct carry-over of manganesefrom one seed generation to the next was insignificant. Manganese proved to be fully mobile in xylem but only sparinglymobile in phloem from vegetative structures to seed. It wasaccumulated in massive amounts in leaves and fruits when availabilitywas high. Seed manganese content increased 80–100 foldas the level in the rooting medium was increased from 0•1to 500 mg Mn 1^–1. L. albus was superior to L. angustifoliusin accumulating manganese in leaves and pods, and more efficientin translocating the element to its seeds. These differenceswere greatest at low or moderate manganese levels. Xylem intakeby a fruit was small relative to phloem intake when manganeseavailability was low, but became increasingly important as thesupply in the rooting medium was raised.     

Changes in a Juncus effusus community on Handa, 1966–1974

Summary

Changes in frequency of species in a Juncus effusus community were observed over a period of ten years. The community was shown to contain two groups of associated species and the members of one of these groups showed a decline in frequency during this period. It is suggested that these changes result from changes in the drainage régime.     

Effect of calcium carbonate and iron on the availability and uptake of iron,manganese, phosphorus and calcium in pea (Pisum sativum L.)

Summary The effect of CaCO₃ and iron on the availability of iron, manganese phosphorus and calcium was studied in the greenhouse on pea (Pisum sativum L.) crop on a light textured soil, which was marginal in exchangeable calcium. Addition of calcium carbonate caused significant increase in dry matter yield with no added iron at both the stages of crop growth. But yeild intended to decrease with 8% CaCO₃ at 75 days of crop growth. Dry matter yield also increased with the addition of iron upto 10 ppm at 45 days and upto 5 ppm at 75 days. The iron concentration and uptake decreased with the increase in CaCO₃ and increased with the application of iron at both the stages of crop growth. The application of iron and CaCO₃ decreased concentration and uptake of phosphorus significantly at both the stages.Like phosphorus, concentration and uptake of manganese also decreased with the increase in added CaCO₃ upto 8% and iron upto 20 ppm at 45 and 75 days. The concentration of calcium increased with the addition of CaCO₃ to the extent of 50 and 40% with 8% CaCO₃ at 45 and 75 days, while the uptake of calcium increased more than 3 folds at 45 days and more than 2 folds at 75 days. The concentration of calcium decreased with the application of iron upto 20 ppm but the uptake at 45 days increased upto 10 ppm and at 75 days upto 5 ppm and then decreased.The concentration of Fe, P and Ca decreased at 75 days and that of Mn increased while the uptake of all these nutrients increased at 2nd stage due to higher dry matter.     

Induction of tetraploidy in Juncus effusus by colchicine

Tetraploidy was induced in vitro in mat rush (Juncus effusus L.) cultivar Nonglin-4 by exposure to colchicine (0, 50, 100 and 500 mg dm^?3) for 6, 12 and 24 h. Flow cytometric analysis was used to confirm the ploidy level. Anatomical and ultrastructural analyses at cellular and subcellular levels in tetraploid and diploid control plants revealed differences between diploid and tetraploid plants. The leaf epidermis had larger stomata but lower stomatal density in tetraploid plants. In addition, mesophyll cells in tetraploid plants appeared more compact and showed less intercellular spaces along with increased size of vascular bundles. However, a significant reduction of chlorophyll content was observed in tetraploid plants that might be the result of structural modification in the lamellar membranes of chloroplasts.