共查询到20条相似文献,搜索用时 350 毫秒
1.
Rita M. Godinho Carlos Vale Miguel Caetano Luis C. Alves Teresa Pinheiro 《Plant and Soil》2014,376(1-2):129-137
Aim
This study presents a micrometre-scale map of the elemental distribution within roots and surrounding sediment of Halimione portulacoides of a contaminated salt marsh in the Tagus estuary.Methods
Microprobe particle induced X-ray emission analysis was performed in sediment slices containing roots with tubular rhizoconcretions attached to host sediments.Results
Strong concentration gradients were found particularly in the inner part of rhizoconcretions adjacent to the root wall. Local enrichment was observed in sediment interstices with Fe precipitates and other associated elements. A maximum of 55 % of Fe was measured near the concretion–root interface, with a decrease to <5 % in the host sediment. Maximum concentrations of P (3 %), As (1,200 μg g?1) and Zn (3,000 μg g?1) were registered in concretions, one order of magnitude above the values of the host sediment. The elemental concentration profiles across roots showed that the epidermis was an efficient selective barrier to the entrance of elements. Fe and As were retained in the epidermis. The highest Cu and Zn concentrations were also observed in the epidermis. However, the concentrations of Mn, Cu and Zn increased in the inner root.Conclusions
As and Fe were mostly retained in the concretion, whereas P, Mn, Cu and Zn were mobilised by the root. 相似文献2.
Liske Versieren Elke Smets Karel De Schamphelaere Ronny Blust Erik Smolders 《Plant and Soil》2014,381(1-2):131-142
Background and aims
The biotic ligand model (BLM) is a bioavailability model for metals based on the concept that toxicity depends on the concentration of metal bound to a biological binding site; the biotic ligand. Here, we evaluated the BLM to interpret and explain mixture toxicity of metals (Cu and Zn).Methods
The mixture toxicity of Cu and Zn to barley (Hordeum vulgare L.) was tested with a 4 days root elongation test in resin buffered nutrient solutions. Toxicity of one toxicant was tested in presence or absence of a low effect level of the other toxicant or in a ray design with constant toxicant ratios. All treatments ran at three different Ca concentrations (0.3, 2.2 and 10?mM) to reveal ion interaction effects.Results
The 50 % effect level (EC50) of one metal, expressed as the free ion in solution, significantly (p?<?0.05) increased by adding a low level effect of the other metal at low Ca. Such antagonistic interactions were smaller or became insignificant at higher Ca levels. The Cu EC10 was unaffected by Zn whereas the Zn EC10 increased by Cu at low Ca. These effects obeyed the BLM combined with the independent action model for toxicants.Conclusions
The BLM model explains the observed interactions by accounting for competition between both metals free ions and Ca2+ at the Cu and Zn biotic ligands. The implications of these findings for Cu/Zn interactions in soil are discussed. 相似文献3.
Aliaksandr Kolbas Lilian Marchand Rolf Herzig Erika Nehnevajova Michel Mench 《Plant and Soil》2014,376(1-2):377-397
Background and aims
The potential use of a metal-tolerant sunflower mutant line for both biomonitoring and phytoremediating a Cu-contaminated soil series was investigated.Methods
The soil series (21–1,170 mg Cu kg?1) was sampled in field plots at control and wood preservation sites. Sunflowers were cultivated 1 month in potted soils under controlled conditions.Results
pH and dissolved organic matter influenced Cu concentration in the soil pore water. Leaf chlorophyll content and root growth decreased as Cu exposure rose. Their EC10 values corresponded to 104 and 118 μg Cu L?1 in the soil pore water, 138 and 155 mg Cu kg?1 for total soil Cu, and 16–18 mg Cu kg?1 DW shoot. Biomass of plant organs as well as leaf area, length and asymmetry were well correlated with Cu exposure, contrary to the maximum stem height and leaf water content.Conclusions
Physiological parameters were more sensitive to soil Cu exposure than the morphological ones. Bioconcentration and translocation factors and distribution of mineral masses for Cu highlighted this mutant as a secondary Cu accumulator. Free Cu2+ concentration in soil pore water best predicted Cu phytoavailability. The usefulness of this sunflower mutant line for biomonitoring and Cu phytoextraction was discussed. 相似文献4.
Ylva Gårdinger Joanna Hlebowicz Ola Björgell Magnus Dencker 《Cardiovascular ultrasound》2014,12(1):1-5
Objective
Left ventricular wall stress has been investigated in a variety of populations, but the effect of food intake has not been evaluated. We assessed whether left ventricular wall stress is affected by food intake in healthy subjects.Methods
Twenty-three healthy subjects aged 25.6?±?4.5 years were investigated. Meridional end-systolic wall stress (ESS) and circumferential end-systolic wall stress (cESS) were measured before, 30 minutes after, and 110 minutes after a standardised meal.Results
Both ESS and cESS decreased significantly (P?<?0.001) from fasting values 30 minutes after the meal, and had not returned to baseline after 110 minutes. ESS decreased from 65?±?16 kdynes/cm2 (fasting) to 44?±?12 kdynes/cm2 30 minutes after, and to 58?±?13 kdynes/cm2 110 minutes after eating. cESS decreased from 98?±?24 kdynes/cm2 to 67?±?18 kdynes/cm2 30 minutes after, and to 87?±?19 kdynes/cm2 110 minutes after the meal.Conclusion
This study shows that left ventricular wall stress is affected by food intake in healthy subjects. 相似文献5.
Kyotaro Noguchi Junko Nagakura Bohdan Konôpka Tadashi Sakata Shinji Kaneko Masamichi Takahashi 《Plant and Soil》2013,364(1-2):159-169
Aims
Nitrogen deposition affect fine-root dynamics, a key factor in forest carbon and nutrient dynamics. This study aimed to elucidate the effects of increased soil inorganic nitrogen (N) levels on the fine-root dynamics of Cryptomeria japonica, which is tolerant to excess N load.Methods
An ammonium nitrate solution (28 kg ha?1 month?1) was applied for 3 years to plots (1 m?×?2 m) in a C. japonica plantation. The elongation and disappearance of the fine roots were examined using the minirhizotron technique.Results
The N fertilization increased soil inorganic N content and lowered the soil pH. Fine-root elongation rates increased with fertilization, whereas patterns of their seasonal changes were not affected. The ratio of cumulative disappearance to cumulative elongation of fine roots was lower in the N-fertilized plots than in the control plots. The mean diameter of the fine roots was not affected by N fertilization.Conclusions
Our results suggest that C. japonica can respond to increased levels of soil inorganic N by increasing both the production and residence time of the fine roots. However, the effects of the changing soil N content are less evident for the phenology and morphology of the fine roots in C. japonica. 相似文献6.
Gregory van der Heijden Arnaud Legout Andrew J. Midwood Carol-Ann Craig Benoît Pollier Jacques Ranger Etienne Dambrine 《Plant and Soil》2013,369(1-2):33-45
Background and aims
The sustainability of forest ecosystems may be at stake especially in forests on base-poor soils due to reduced nutrient deposition and intensified silvicultural practices. Understanding nutrient availability and cycling is therefore essential to manage forest soil fertility. This study aims to assess in a beech plot Mg and Ca vertical transfer in soil and root uptake using an isotopic tracing experiment.Methods
A simulated rainfall containing a small amount (960 g?Mg.ha?1; 530 g Ca.ha?1) of highly enriched 26Mg and 44Ca was sprayed on the forest floor of a 35-yr-old beech plot. The isotopic composition of fine roots and of the soil exchangeable Mg and Ca pool was monitored during 1 year. A pool and flux model (IsoMod) was developed to predict the labeling of the soil and vertical transfer of tracers.Results
Tracers (44Ca and 26Mg) were immediately retained in the thin litter layer. During the following year, Mg and to a lesser extent Ca were progressively released. After 1 year, the exchangeable Mg and Ca pools of the upper mineral layer (0–5 cm) were strongly labeled (~660?‰, representing ~55 % of the tracer input and ~370?‰, ~41 % of the tracer input respectively). A significant proportion (~8 % 26Mg, ~2 % 44Ca) of tracer was leached through the soil, below 10 cm. This amount was much larger than what was predicted using a simple mixing model. The Ca and Mg isotopic composition of fine roots at all depths was close or lower than that of exchangeable Ca and Mg respectively.Conclusions
An in situ ecosystem-scale 26Mg and 44Ca isotopic tracing experiment was successfully carried out. Tracers were at first strongly retained in the litter layer, then progressively transferred to soil horizons below. Nutrient cycling of Mg and Ca were proven to be very different. Mg had a higher mobility in the soil than Ca, and nutrient uptake sources were proven to be different. 相似文献7.
Background and aims
The roots of tussock-forming plants contribute to the formation of microtopographic features in many ecosystems, but the dynamics of such roots are poorly understood. We examined the spatial heterogeneity of tussock fine root dynamics to investigate allocation patterns and the role of root productivity in the persistence of tussock structures.Methods
We compared the spatial variability of fine root (<1 mm, 1–2 mm) density, biomass, % live, allocation, turnover rate (using bomb 14C), and productivity of four Carex stricta Lam.-dominated tussock meadows in the upper Midwest, USA (3 reference, 1 restored site).Results
Relative to underlying microsites, tussocks were warm, dry, and high in root density, productivity, % live biomass, and turnover. Root productivity averaged 649 g?m?2 yr?1 (±208) in reference sites, comprised 57 % (±10) of total net production, and was concentrated in tussocks (70 %?±?4). Root turnover rate averaged 0.63 yr?1 (±0.08), but tussocks had ~50 % faster root turnover than the underlying soil, and <1 mm roots turned over ~40 % faster than 1–2 mm roots.Conclusions
Our detailed analysis of the spatial heterogeneity of tussock root dynamics suggests that high allocation and elevated turnover of tussock roots facilitates organic matter accumulation and tussock persistence over time. 相似文献8.
9.
Aims
We characterized the runoff and erosion from a volcanic soil in an Austrocedrus chilensis forest affected by a wildfire, and we evaluated the effects of a mitigation treatment.Methods
Rainfall simulations were performed in the unburned and burned forest, with and without vegetation cover, and under a mitigation treatment.Results
After the wildfire, the mean infiltration rate decreased from 100 mm?h?1 in unburned soils to 51 and 64 mm?h?1 in the burned with and without litter and vegetation cover, respectively. The fast establishment of bryophytes accelerated the recovery of soil stability. Sediment production was negligible in the control plots (4.4 g?m?2); meanwhile in the burned plots, it was 118.7 g?m?2 and increased to 1026.1 g?m?2 in the burned and bare plots. Total C and N losses in the control plots were negligible, while in the burned and bare plots the organic C and total N removed were 98.25 and 1.64 g?m2, respectively. The effect of mitigation treatment was efficient in reducing the runoff, but it did not affect the sediment production.Conclusions
These fertile volcanic soils promoted the recovery of vegetation in a short time after the wildfire, diminishing the risk of erosion. 相似文献10.
Aims
Root elongation tests are sensitive bioassays for testing metal toxicity in nutrient solutions. The metal speciation and, hence, metal exposure conditions are little controlled in the traditional set-up. A resin buffered solution system was developed to overcome this issue.Methods
Barley (Hordeum vulgare L.) root elongation was tested in aerated 140 mL solution batch systems supplied with 3.3 g Dowex resin for two plants. Copper toxicity was measured in presence or absence of the resin (+R/?R) and in presence or absence of a metal complexing ligand (+NTA; nitrilotriacetic acid/?NTA). In addition, the toxicity in the traditional set without resin and with daily solution replacement was included as a reference.Results
Metal desorption from the resin is fast in these systems (k?=?0.82 h?1). Total dissolved Cu roughly halved during 4 days in ?R/?NTA systems due to uptake, while it increased by 30 % in the +R/?NTA, probably due to complexation reactions by root-derived molecules. The toxicity (50 % reduction in root length, EC50) of the initial free Cu2+ was equal in all resin or chelate buffered systems and in the solutions with daily replacement, whereas this threshold was significantly larger in the ?R/?NTA due to Cu2+ uptake and complexation reactions.Conclusion
The resin method is a convenient system for high throughput screening of metal toxicity and avoids uncertainties in metal speciation inherent to chelator buffered systems. Details are given how to prepare the resin to obtain a target metal ion activity. 相似文献11.
Background and aims
Studies have found significant differences in methane (CH4) emissions among rice cultivars; however, it is unclear whether this difference is related to radial oxygen loss (ROL) from the roots.Methods
Based on a 2-year in situ field study and solution culture experiments on 16 rice cultivars, we investigated CH4 emission levels and their dependence on ROL.Results
We detected significant differences in CH4 emission and ROL among rice cultivars. The lowest and highest CH4 emission levels were 4.10 and 7.35 g m?2 for early rice, and 14.36 and 23.33 g m?2 for late rice, respectively. The maximum and minimum ROL values were 3.77 and 1.73 mmol plant?1 h?1 for early rice, and 4.18 and 2.08 mmol plant?1 h?1 for late rice, respectively. Seasonal total CH4 emission was negatively correlated with ROL in the early rice season (p?<?0.01), and (p?<?0.01) in the late rice season. ROL was positively correlated with the number of roots per plant (RN), root tips per plant (RT), and root volume per plant (RV).Conclusions
We suggest that ROL can be used as a predictive index for CH4 emissions. RN, RT, and RV were the most important factors influencing ROL in rice cultivars.12.
Standing fine root mass and production in four Chinese subtropical forests along a succession and species diversity gradient 总被引:2,自引:0,他引:2
Cong Liu Wenhua Xiang Pifeng Lei Xiangwen Deng Dalun Tian Xi Fang Changhui Peng 《Plant and Soil》2014,376(1-2):445-459
Background and aims
The influences of succession and species diversity on fine root production are not well known in forests. This study aimed to investigate: (i) whether fine root biomass and production increased with successional stage and increasing tree species diversity; (ii) how forest type affected seasonal variation and regrowth of fine roots.Methods
Sequential coring and ingrowth core methods were used to measure fine root production in four Chinese subtropical forests differing in successional stages and species diversity.Results
Fine root biomass increased from 262 g·m?2 to 626 g·m?2 with increasing successional stage and species diversity. A similar trend was also found for fine root production, which increased from 86 to 114 g·m?2 yr ?1 for Cunninghamia lanceolata plantation to 211–240 g·m?2 yr ?1 for Choerospondias axillaries forest when estimated with sequential coring data. Fine root production calculated using the ingrowth core data ranged from 186 g·m?2 yr ?1 for C. lanceolata plantation to 513 g·m?2 yr ?1 for Lithocarpus glaber – Cyclobalanopsis glauca forest.Conclusions
Fine root biomass and production increased along a successional gradient and increasing tree species diversity in subtropical forests. Fine roots in forests with higher species diversity exhibited higher seasonal variation and regrowth rate. 相似文献13.
Growth,physiological, biochemical and ionic responses of pistachio seedlings to mild and high salinity 总被引:1,自引:0,他引:1
Roghieh Hajiboland Fahimeh Norouzi Charlotte Poschenrieder 《Trees - Structure and Function》2014,28(4):1065-1078
Key message
Depending on salt concentrations, different mechanisms are involved in the tolerance of pistachio and an acclimation to salinity conditions occurs in the leaves that develop in the presence of salt.Abstract
Pistachio (Pistacia vera L.) is a salt tolerant species that is considered an alternative crop for cultivation in salinzied orchard soils. In this work, 12-week-old pistachio seedlings cultivated in soil under greenhouse conditions were treated with five levels of salinity including control (0.63 dSm?1), low (2 and 4 dSm?1) and high (8 and 10 dSm?1) salt concentrations for further 12 weeks. Plant growth parameters were not affected by mild salinity; a significant reduction was only observed from 8 dSm?1. Considerable differences were observed between the young and mature leaves regarding osmotic and ionic stress effects of salt. Main compatible solutes were proline in mature leaves, proline and soluble sugars in young leaves, and soluble sugars and amino acids, other than proline, in roots. Concentration and content of Na in the leaves were not significantly increased at low levels of salinity and the K:Na and Ca:Na ratio of leaves were affected only by higher salt concentrations. Using the sequential extraction procedure for cell wall isolation, we observed that both absolute and relative amounts of Na in the cell wall fraction increased under low salinity, while decreased under higher levels of salt supply. Stable water relations, photochemistry and CO2 assimilation rates particularly of young leaves, as well as ion homeostasis were mechanisms for maintenance of plants growth under mild salinity. Under severe saline conditions, the impaired ability of mature leaves for synthesis of assimilates, preferent allocation of carbohydrates to roots for maintenance of osmotic homeostasis and finally, reduction of protein synthesis caused growth inhibition in pistachio. 相似文献14.
Sebastian Pfautsch Pablo L. Peri Craig Macfarlane Floris van Ogtrop Mark A. Adams 《Trees - Structure and Function》2014,28(1):125-136
Key message
This study is the first to quantify tree water use below 50°S. Tree morphology differs markedly among the two investigated species, reflecting adjustment to different environmental cues.Abstract
A pronounced environmental gradient dictates the dominance of Nothofagus in the foothills on the eastern side of the Andes Mountains in Patagonia, Argentina. Below 50° southern latitude, open forests of Nothofagus antarctica (ñire) dominate the landscape towards the Patagonian steppe where annual rainfall is low. With increasing rates of annual rainfall, corresponding with an increase in elevation, closed forests of N. pumilio (lenga) replace those of ñire. During a short-term study we assessed differences in stand structure and examined environmental, structural and functional traits related to tree water use of ñire and lenga. Sap velocity reached similar maximum rates (95–100 L m?2 sapwood h?1), but whole-tree water use (Q) was significantly lower in ñire (8–13 L day?1 tree?1) compared to lenga (20–90 L day?1 tree?1) resulting in lower stand transpiration (ñire: 0.51 mm day?1; lenga: 3.42 mm day?1) despite similar tree densities. Related to this, wind speed had a particularly significant impact on Q of ñire, but not lenga. The ratio of leaf area to sapwood area (A L/A S) clearly identified ñire to be more structurally proficient at conserving water. While stem diameter (DBH) and crown area (A C) were well related in both species, only lenga exhibited relationships between variables related to tree allometry and physiology (A C/Q, DBH/Q). Our results provide the first ecophysiological characterization of the two Nothofagus species that define important and widespread ecosystems in southern Patagonia (not only below 50°S), and provide useful data to scale water use of both species from tree to stand. 相似文献15.
Does radial oxygen loss and iron plaque formation on roots alter Cd and Pb uptake and distribution in rice plant tissues? 总被引:5,自引:0,他引:5
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. 相似文献16.
A putative recombinant enzyme from Dictyoglomus turgidum was characterized and immobilized on Duolite A568 beads. The native enzyme was a 46 kDa tetramer. Its activity was highest for l-rhamnose, indicating that it is an l-rhamnose isomerase. The maximum activities of both the free and immobilized enzymes for l-rhamnose isomerization were at pH 8.0 and 75 °C in the presence of Mn2+. Under these conditions, the half-lives of the free and immobilized enzymes were 28 and 112 h, respectively. In a packed-bed bioreactor, the immobilized enzyme produced an average of 130 g l-rhamnulose l?1 from 300 g l-rhamnose l?1 after 240 h at pH 8.0, 70 °C, and 0.6 h?1, with a productivity of 78 g l?1 h?1 and a conversion yield of 43 %. To the best of our knowledge, this is the first report describing the enzymatic production of l-rhamnulose. 相似文献
17.
Fine root biomass and turnover of two fast-growing poplar genotypes in a short-rotation coppice culture 总被引:1,自引:0,他引:1
Background and aims
The quantification of root dynamics remains a major challenge in ecological research because root sampling is laborious and prone to error due to unavoidable disturbance of the delicate soil-root interface. The objective of the present study was to quantify the distribution of the biomass and turnover of roots of poplars (Populus) and associated understory vegetation during the second growing season of a high-density short rotation coppice culture.Methods
Roots were manually picked from soil samples collected with a soil core from narrow (75 cm apart) and wide rows (150 cm apart) of the double-row planting system from two genetically contrasting poplar genotypes. Several methods of estimating root production and turnover were compared.Results
Poplar fine root biomass was higher in the narrow rows than in the wide rows. In spite of genetic differences in above-ground biomass, annual fine root productivity was similar for both genotypes (ca. 44 g DM m?2 year?1). Weed root biomass was equally distributed over the ground surface, and root productivity was more than two times higher compared to poplar fine roots (ca. 109 g DM m?2 year?1).Conclusions
Early in SRC plantation development, weeds result in significant root competition to the crop tree poplars, but may confer certain ecosystem services such as carbon input to soil and retention of available soil N until the trees fully occupy the site. 相似文献18.
David M. Deery John B. Passioura Jason R. Condon Asitha Katupitiya 《Plant and Soil》2013,368(1-2):483-492
Aims
To determine soil water diffusivity, D(θ), on undisturbed field soil at medium to low water content (suction range from 10 to 150 m of water), for the purpose of modeling the uptake of water by plant roots.Methods
The method is based on the analysis of one-step outflow induced by a turbulent stream of dry air over the exposed end of a soil core, with the other end of the core enclosed. The outflow is measured through time as the change in the weight of the core as it sits on a recording balance. D(θ) is calculated by deconvoluting the measured outflow function.Results
Over the suction range of 10 to 150 m of water, D(θ) calculated on the undisturbed soil ranged from 20?×?10?9 to 10?×?10?9 [m2?s?1], substantially higher than other published estimates over this range in suction.Conclusions
These unusually large values cast doubt on the view that flow of water to roots limits uptake of water from the targeted subsoil. 相似文献19.
Nitrogen deposition promotes ecosystem carbon accumulation by reducing soil carbon emission in a subtropical forest 总被引:1,自引:0,他引:1
Houbao Fan Jianping Wu Wenfei Liu Yinghong Yuan Rongzhen Huang Yingchun Liao Yanyan Li 《Plant and Soil》2014,379(1-2):361-371
Background and aims
Tropical and subtropical forests are experiencing high levels of atmospheric nitrogen (N) deposition, but the responses of such forests ecosystems to N deposition remain poorly understood.Methods
We conducted an 8-year field experiment examining the effect of experimental N deposition on plant growth, soil carbon dioxide efflux, and net ecosystem production (NEP) in a subtropical Chinese fir forest. The quantities of N added were 0 (control), 60, 120, and 240 kg ha?1 year?1.Results
NEP was lowest under ambient conditions and highest with 240 kg of N ha?1 year?1 treatment. The net increase in ecosystem carbon (C) storage ranged from 9.2 to 16.4 kg C per kg N added in comparison with control. In addition, N deposition treatments significantly decreased heterotrophic respiration (by 0.69–1.85 t C ha?1 year?1) and did not affect plant biomass. The nitrogen concentrations were higher in needles than that in fine roots.Conclusions
Our findings suggest that the young Chinese fir forest is carbon source and N deposition would sequester additional atmospheric CO2 at high levels N input, mainly due to reduced soil CO2 emission rather than increased plant growth, and the amount of sequestered C depended on the rate of N deposition. 相似文献20.