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41.
A.K.M. Zakir Hossain M. Alamgir Hossain Hiroyuki Koyama Tetsuo Hara 《Soil Science and Plant Nutrition》2013,59(2):189-199
Aluminum toxicity and boron deficiency are the major factors that limit plant growth and development in acid soils and in B-deficient soils. Root growth inhibition is an early symptom of AI toxicity and B deficiency. Effects of AI and B supply and their interaction on the growth of wheat (Triticum aestivum L.) seedlings were investigated using hydroponics. Fifteen wheat cultivars commonly grown in Bangladesh were used and found to differ considerably in their tolerance to AI toxicity and B deficiency. The relative root length of all the wheat cultivars at 50 µM AI (pH 4.5) ranged from 27 to 71% relative to the control (0 µM AI). Among the cultivars, Inia66 and Kalyansona were found to be the most Al-tolerant and sensitive cultivars, respectively, based on the data of relative root length, malate exudation and AI content of roots. Malate was detected in all the cultivars in the presence of 100 µM AI (pH 4.3). Inia66 exuded a 6-fold larger amount of malate and the AI content of roots was 4 times lower than that in Kalyansona. The vigorous seedling growth was observed at 40 µM B among the series of B treatments. Considerable cultivar differences in response to 40 µM B were observed among the 15 cultivars. Kalyansona was considered to be the most sensitive and Kheri the most tolerant to B deficiency. The interaction effects of B ( 40 and 200 µM) and AI (50 µM) on seedling growth were also examined in Inia66 and Kalyansona. Root growth was inhibited in the presence of Al but B supply especially at 200 µM B in the Kalyansona cultivar caused a slight improvement. 相似文献
42.
Mathias?FosuEmail author Ronald?F.?Kühne Paul?L.?G.?Vlek 《Biology and Fertility of Soils》2003,39(2):117-122
In order to understand the efficiency of residue-N use and to estimate the minimum input required to obtain a reasonable level of crop response, it is important to quantify the fate of the applied organic-N. The recovery of N from 15N-labelled Crotalaria juncea was followed in the soil and the succeeding maize crop. Apparent N recovery (ANR) by maize from unlabelled Crotalaria juncea, Crotalaria retusa, Calopogonium mucunoides, Mucuna pruriens and mineral fertilizer at three locations were also evaluated. The maize crop recovered 4.7% and 7.3% of the 15N-labelled C. juncea-N at 42 days after sowing (DAS) and at final harvest, respectively. The corresponding 15N recovery from the soil was 92.4% and 58.5%. The highest mean ANR of 57.4% was with mineral fertilizer, whereas the mean ANR of 14.3% from C. retusa was the lowest. A large pool substitution and added-N interaction effect was observed when comparing N recovery from the labelled and unlabelled C. juncea. The amount of residue-N accounted for by the isotope dilution method at 42 DAS was 97.1% and at final harvest 65.8%. The large residue-N recovery in the soil organic-N pool explains the residual effect usually observed with organic residue application. 相似文献
43.
Sari?JuutinenEmail author Tuula?Larmola Rainer?Remus Edith?Mirus Wolfgang?Merbach Jouko?Silvola Jürgen?Augustin 《Biology and Fertility of Soils》2003,38(1):10-14
The contribution of Phragmites australis (Cav.) Trin. ex Steud. (common reed) litter as an origin of CH 4-C was studied in a microcosm experiment. 14C-labelled, dried and ground P. australis root and shoot litter was buried in waterlogged, planted or non-planted fen microcosms. The evolution of 14CO 2 and 14CH 4 from the pots was monitored during the 35-day experiment. The 14C activity in the shoots and roots of the plants, soil, and inundation water was also analysed at the end of the experiment. Up to 40% of the released CH 4-C originated from the added litter, whereas the rest originated from old soil organic matter. The comparison of planted and non-planted pots suggested that the contribution of recent plant-derived C (i.e. root exudates) to CH 4 emission was negligible. The proportion of litter-derived CH 4-C was significantly higher in the planted pots, suggesting that the presence of plants enhanced the formation of CH 4 from litter. The major part of the initial 14C activity was recovered from the soil. About 3% was recovered from the inundation water, about 10% was emitted as CO 2, and only <0.01% as CH 4. However, these results demonstrated that plant litter and old soil organic matter are the major sources of CH 4-C in fens during the early growth stage of P. australis. 相似文献
44.
Carolina?Delavechia Eugenio?Hampp Adriana?Fabra Stella?CastroEmail author 《Biology and Fertility of Soils》2003,38(2):110-114
The Sinorhizobium -legume interaction is sensitive to a number of environmental factors, soil acidity being one of the most important. In the typic Hapludoll soil of the central-southern region of Córdoba (Argentine) it was found that the nodulation of alfalfa ( Medicago sativaL.) roots was impaired with a reduction in shoot dry matter under conditions of soil acidity (pH 5.5) Our results showed that the addition of lime as dolomitic limestone at a concentration of 1 t ha -1to acid soil caused a significant increase in the nodulation of alfalfa roots inoculated with the strain Sinorhizobium meliloti SEMIA 116 (recommended inoculum for alfalfa) in the greenhouse experiments. The success of the lime treatment may be related not only to an increase in the pH values but also to an increase in the Ca concentration, improving the growth of S. meliloti and its nodulation ability under acidic conditions. In this study, we also demonstrated an increment in the bacterial growth rate as well as in the production of exopolysaccharides and lipopolysaccharides under low pH (5.5) and a high Ca concentration (5 mM) in the culture medium. 相似文献
45.
Effects of genetically modified plants on microbial communities and processes in soil 总被引:16,自引:0,他引:16
M.?Bruinsma G.?A.?Kowalchuk J.?A.?van?VeenEmail author 《Biology and Fertility of Soils》2003,37(6):329-337
The development and use of genetically modified plants (GMPs) has been a topic of considerable public debate in recent years. GMPs hold great promise for improving agricultural output, but the potential for unwanted effects of GMP use is still not fully understood. The majority of studies addressing potential risks of GMP cultivation have addressed only aboveground effects. However, recent methodological advances in soil microbial ecology have allowed research focus to move underground to try to gain knowledge of GMP-driven effects on the microbial communities and processes in soil that are essential to key terrestrial ecosystem functions. This review gives an overview of the research performed to date on this timely topic, highlighting a number of case studies. Although such research has advanced our understanding of this topic, a number of knowledge gaps still prevent full interpretation of results, as highlighted by the failure of most studies to assign a definitively negative, positive or neutral effect to GMP introduction. Based upon our accumulating, yet incomplete, understanding of soil microbes and processes, we propose a synthesis for the case-by-case study of GMP effects, incorporating assessment of the potential plant/ecosystem interactions, accessible and relevant indicators, and tests for unforeseen effects. 相似文献
46.
Annemie?ElsenEmail author Raf?Beeterens Rony?Swennen Dirk?De?Waele 《Biology and Fertility of Soils》2003,38(6):367-376
In this study, the effect of an arbuscular mycorrhizal fungus (AMF) and two migratory endoparasitic nematodes on Musa plant growth, including the root system, were examined. In addition, the AMF-nematode interaction was studied. Seven Musa genotypes with different root systems were selected. Based on their relative mycorrhizal dependency, two genotypes (Calcutta 4 and Obino l'Ewai) were selected for AMF-nematode interaction studies. The experiments were performed under greenhouse conditions. Mycorrhization with Glomus mosseae resulted in a significantly better plant growth even in the presence of nematodes. The effect of AMF on the root system was genotype-dependent and seemed to be related to the relative mycorrhizal dependency of the genotype. The nematodes also affected the root system, decreasing branching. Nematode population densities were significantly reduced in the presence of AMF, except for Pratylenchus coffeae in Obino l'Ewai. In the root system, it appeared that the decreased branching caused by the nematodes was counterbalanced by the increased branching caused by the AMF. 相似文献
47.
Jason?M.?ConderEmail author Roman?P.?LannoEmail author 《Journal of Soils and Sediments》2003,3(1):13-20
Background. Earthworm heavy metal concentrations (critical body residues, CBRs) may be the most relevant measures of heavy
metal bioavailability in soils and may be linkable to toxic effects in order to better assess soil ecotoxicity. However, as
earthworms possess physiological mechanisms to secrete and/or sequester absorbed metals as toxicologically inactive forms,
total earthworm metal concentrations may not relate well with toxicity.
Objective The objectives of this research were to: i) develop LD50s (total earthworm metal concentration associated with 50% mortality) for Cd, Pb, and Zn; ii) evaluate the LD50 for Zn in a lethal Zn-smelter soil; iii) evaluate the lethal mixture toxicity of Cd, Pb, and Zn using earthworm metal concentrations
and the toxic unit (TU) approach; and iv) evaluate total and fractionated earthworm concentrations as indicators of sublethal
exposure.
Methods Earthworms (Eisenia fetida (Savigny)) were exposed to artificial soils spiked with Cd, Pb, Zn, and a Cd-Pb-Zn equitoxic mixture to estimate lethal CBRs
and mixture toxicity. To evaluate the CBR developed for Zn, earthworms were also exposed to Zn-contaminated field soils receiving
three different remediation treatments. Earthworm metal concentrations were measured using a procedure devised to isolate
toxicologically active metal burdens via separation into cytosolic and pellet fractions.
Results and Discussion Lethal CBRs inducing 50% mortality (LD50, 95% CI) were calculated to be 5.72 (3.54-7.31), 3.33 (2.97-3.69), and 8.19 (4.78-11.6) mmol/kg for Cd, Pb, and Zn, respectively.
Zn concentrations of dead earthworms exposed to a lethal remediated Zn-smelter soil were 3-fold above the LD50 for Zn and comparable to earthworm concentrations in lethal Zn-spiked artificial soils, despite a 14-fold difference in total
soil Zn concentration between lethal field and artificial soils. An evaluation of the acute mixture toxicity of Cd, Pb, and
Zn in artificial soils using the Toxic Unit (TU) approach revealed an LD50 (95% CI) of 0.99 (0.57-1.41) TU, indicating additive toxicity.
Conclusions Total Cd, Pb, and Zn concentrations in earthworms were good indicators of lethal metal exposure, and enabled the calculation
at LD50s for lethality. The Zn-LD50 developed in artificial soil was applicable to earthworms exposed to remediated Zn-smelter soil, despite a 14-fold difference
in total soil Zn concentrations. Mixture toxicity evaluated using LD50s from each single metal test indicated additive mixture toxicity among Cd, Pb, and Zn. Fractionation of earth worm tissues
into cytosolic and pellet digests yielded mixed results for detecting differences in exposure at the sublethal level
Recommendation and Outlook CBRs are useful in describing acute Cd, Pb, and Zn toxicity in earthworms, but linking sublethal exposure to total and/or
fractionated residues may be more difficult. More research on detoxification, regulation, and tissue and subcellular partitioning
of heavy metals in earthworms and other invertebrates is needed to establish the link between body residue and sublethal exposure
and toxicity. Keywords: Bioavailability; Cd; critical body residues; earthworms; metals; Pb; soil; Zn
An erratum to this article is available at . 相似文献
48.
Background, Aims and Scope Disposal of dredged material in subaqueous depots is increasingly considered an economic and ecologically sound option in
managing contaminated dredged material. The concept of subaqueous disposals capped with active barrier systems has been developed
to minimize this risk of contaminant release. As such a depot represents a permanent installation within a sensitive ecosystem,
it requires a thorough monitoring concept. It is the goal of this work to develop such a concept regarding general considerations
and results of laboratory and field investigations.
Methods In addition to the state-of-the-art techniques developed for other under-water constructions, this monitoring concept is developed
with particular respect to the chemical isolation of the dredged material from the overlying water body. It comprises the
use of seepage meters, dialysis samplers, and DGT gel probes for determining the migration of selected target solutes. The
capability of the dialysis samplers is demonstrated by comparing field results with model calculations. The appropriateness
of DGT probes to assess the impact of humic substances on trace metal speciation and on copper toxicity is demonstrated with
the aid of laboratory experiments.
Results and Discussion The experimental results show that, by using dialysis samplers, the temporal changes in concentration-depth-profiles of heavy
metals in the pore solution can be monitored. Additionally, the application of DGT probes facilitates the in situ detection
of labile species of a metal in the presence of dissolved humic substances, which serves to reflect its toxicity. Conclusions.
Three subsequent monitoring phases are distinguished on the basis of both general considerations and the findings from field
results: A hydraulic phase that is characterized by compaction and pore water expulsion, a geochemical phase in which the
demobilization of pollutants can occur due to substantial changes in the physico-chemical conditions (pH, EH), and a steady-state-phase
where pore water flow and geochemical conditions are approaching their minimum.
Recommendations and Outlook The monitoring concept suggested here provides a versatile tool to assess the chemical isolation of subaqueous sediment depots
and other contaminated sediment sites. This is of great importance as subaqueous disposal is increasingly considered a future
management strategy as space for upland disposal is limited and treatment, in general, proves to be too costly. 相似文献
49.
Kay?HamerEmail author Astrid?Hadeler Thomas?Muschalla Jürgen?Schr?ter Günter?Timmer 《Journal of Soils and Sediments》2003,3(4):284-291
Goal
Annually, 400.000 m3 harbour sediments are dredged to maintain the water depth in the harbours of Bremen and Bremerhaven. The sediment contains organic and inorganic pollutants and hence is deposited on a landfill. Because of the limited capacity of that landfill alternative treatment techniques are investigated. This study aims to evaluate the production of Light Weight Aggregates (LWA) from harbour sediments with respect to the product quality and environmental aspects of the use of the LWA. 相似文献50.
Piet?C.?N.?GroenewaldEmail author Carin?S.?Viljoen 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(1):75-83
This article aims to determine the effect of certain covariates, such as season of kidding, parity, and time of kidding on
the characteristics of the lactation curve of Saanen dairy goats. Characteristics investigated are peak milk yield, time of
peak milk yield, total milk production, persistency, and the relationship between fat and protein in milk composition, as
well as between lactation curves of the same animal in successive years. The analysis is carried out using a hierarchical
Bayesian approach, together with Wood’s model, to model lactation. Posterior distributions of quantities of interest are obtained
by means of the Markov chain Monte Carlo (MCMC) methods. These clearly illustrate the significant effect of especially parity,
but also season and time of kidding on the characteristics of the lactation curve. Total and peak milk yield increase with
increasing parity up to about the third or fourth parity, while peak yield is later for first than for later parities. The
analysis also enables estimation of lactation characteristics of untested animals, prediction of future characteristics and
identification of exceptional animals. 相似文献