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1.
Arbuscular mycorrhizal fungus (AMF) can enhance plant growth and resistance to toxicity produced by heavy metals (HMs), affect the bioavailability of HMs in soil and the uptake of HMs by plants, and thus has been emerged as the most prominent symbiotic fungus for contribution to phytoremediation. A greenhouse pot experiment was conducted to assess the effect of Glomus versiforme BGC GD01C (Gv) on the growth and Cd accumulation of Cd-hyperaccumulator Solanum nigrum in different Cd-added soils (0, 25, 50, 100 mg Cd kg−1 soil). Mycorrhizal colonization rates were generally high (from 71% to 82%) in Gv-inoculated treatments at all Cd levels. Gv colonization enhanced soil acid phosphatase activity, and hence elevated P acquisition and growth of S. nigrum at all Cd levels. Moreover, the presence of Gv significantly increased DTPA-extractable (phytoavailable) Cd concentrations in 25 and 50 mg Cd kg−1 soils, but did not affect phytoavailable Cd in 100 mg Cd kg−1 soil. Similarly, inoculation with Gv significantly increased Cd concentrations of S. nigrum in 25 and 50 mg Cd kg−1 soils, but decreased Cd concentrations of the plants in 100 mg Cd kg−1 soil. Overall, inoculation with Gv greatly improved the total Cd uptakes in all plant tissues at all Cd levels. The present results indicated that S. nigrum associated with Gv effectively improved the Cd uptake by plant and would be a new strategy in microbe-assisted phytoremediation for Cd-contaminated soils. 相似文献
2.
Junli Hu Fuyong Wu Shengchun Wu Junhua Wang Xiangui Lin Ming Hung Wong 《Journal of Soils and Sediments》2016,16(9):2195-2202
Purpose
Fruiting vegetables are generally considered to be safer than other vegetables for planting on cadmium (Cd)-contaminated farms. However, the risk of transferring Cd that has accumulated in the stems and leaves of fruiting vegetables is a major issue encountered with the usage of such non-edible parts. The objective of this study was to resolve the contribution of arbuscular mycorrhizal (AM) fungi to the production of low-Cd fruiting vegetables (focusing on the non-edible parts) on Cd-contaminated fields.Materials and methods
An 8-week pot experiment was conducted to investigate the acquisition and translocation of Cd by cucumber (Cucumis sativus L.) plants on an unsterilized Cd-contaminated (1.6 mg kg?1) soil in response to inoculation with the AM fungus, Funneliformis caledonium (Fc) or Glomus versiforme (Gv). Mycorrhizal colonization rates of cucumber roots were assessed. Dry biomass and Cd and phosphorus (P) concentrations in the cucumber shoots and roots were all measured. Soil pH, EC, total Cd, phytoavailable (DTPA-extractable) Cd, available P, and acid phosphatase activity were also tested.Results and discussion
Both Fc and Gv significantly increased (P?<?0.05) root mycorrhizal colonization rates and P acquisition efficiencies, and thus the total P acquisition and biomass of cucumber plants, whereas only Fc significantly increased (P?<?0.05) soil acid phosphatase activity and the available P concentration. Both Fc and Gv significantly increased (P?<?0.05) root to shoot P translocation factors, inducing significantly higher (P?<?0.05) shoot P concentrations and shoot/root biomass ratios. In contrast, both Fc and Gv significantly decreased (P?<?0.05) root and shoot Cd concentrations, resulting in significantly increased (P?<?0.05) P/Cd concentration ratios, whereas only Gv significantly decreased (P?<?0.05) the root Cd acquisition efficiency and increased (P?<?0.05) the root to shoot Cd translocation factor. Additionally, AM fungi also tended to decrease soil total and phytoavailable Cd concentrations by elevating plant total Cd acquisition and soil pH, respectively.Conclusions
Inoculation with AM fungi increased the P acquisition and biomass of cucumber plants, but decreased plant Cd concentrations by reducing the root Cd acquisition efficiency, and resulted in a tendency toward decreases in soil phytoavailable and total Cd concentrations via increases in soil pH and total Cd acquisition by cucumber plants, respectively. These results demonstrate the potential application of AM fungi for the production of fruiting vegetables with non-edible parts that contain low Cd levels on Cd-contaminated soils.3.
《Pedobiologia》2014,57(4-6):223-233
Mycorrhizal fungi and earthworms can individually or interactively influence plant growth and heavy metal uptake. The influence of earthworms and arbuscular mycorrhizal (AM) fungi either alone or in combination on maize (Zea mays L.) growth and cadmium (Cd) uptake was investigated in a calcareous soil artificially spiked with Cd. Soils were contaminated with Cd (10 and 20 mg Cd kg−1), inoculated or un-inoculated with the epigeic earthworm Lumbricus rubellus and two AM fungal species (Rhizophagus irregularis and Funneliformis mosseae) for two months of growth under greenhouse conditions. Generally, earthworms alone increased both shoot P uptake and biomass but decreased shoot Cd concentration and root Cd uptake. AM fungi individually often increased total maize P uptake, declined shoot Cd concentration, and consequently produced higher total biomass. However, R. irregularis enhanced shoot Cd uptake at low Cd level and root Cd uptake at high Cd level. In plants inoculated with F. mosseae species, earthworms increased shoot biomass and Cd uptake, decreased root biomass and Cd uptake at all Cd levels, and increased shoot Cd concentration at low Cd level. In plants colonized by R. irregularis species, however, earthworm addition decreased maize biomass only at high Cd level and root Cd concentration and total maize Cd uptake at both Cd levels. Earthworm activity decreased Cd transfer from the soil to maize roots at low Cd level, but this was counterbalanced in the presence of F. mosseae. Mycorrhizal symbiosis significantly reduced the transfer of Cd from roots to shoots, independence of earthworm effect. Overall, it is concluded that L. rubellus and AM fungi, in particular F. mosseae isolate, improved maize tolerance to Cd toxicity both individually and interactively by increasing plant growth and P nutrition, and restricting Cd transfer to the aboveground biomass. Consequently, the single and interactive effects of the two soil organisms might potentially be important not only in protecting maize plants against Cd toxicity, but also in Cd phytostabilization in soils polluted by this highly toxic metal. 相似文献
4.
Soil contamination with Cd is of primary concern and beneficial soil restoration strategies urge. The aim of this work is to evaluate the response of two different genotypes of Pinus pinaster (wild and selected) to Cd contamination and to assess how inoculation with ectomycorrhizal fungi, Suillus bovinus and Rhizopogon roseolus, influenced each genotype. Seedlings were exposed to soil contaminated at 15 and 30 mg Cd kg−1. Plant growth, mycorrhizal traits and Cd accumulation in different tissues of the plant were determined at harvest. The fungal community was assessed by denaturing gradient gel electrophoresis. At 15 mg Cd kg−1 S. bovinus increased aboveground development in both genotypes. At 30 mg Cd kg−1 non-inoculated wild genotype accumulated more Cd in the shoots (1.7-fold) than the selected genotype; inoculation with R. roseolus decreased Cd concentration in the roots of the selected genotype whereas the opposite occurred in the wild genotype. Cd concentration in the root system was the parameter most influenced by the interaction between the three studied variables. The fungal community established was affected by the Cd concentration in the soil. Results show that different genotypes of P. pinaster react differently to Cd exposure depending on the mycorrhizal association. The importance of considering the combination between plant genotype and its symbiotic partners when aiming at the forestation of degraded land is highlighted. 相似文献
5.
The ultimate goal of soil remediation is to restore soil health. Soil microbial parameters are considered to be effective indicators of soil health. The aim of this study was to determine the effects of phytoextraction on microbial properties through the measurement of soil microbial biomass carbon, soil basal respiration and enzyme activities. For this purpose, a pre-stratified rhizobox experiment was conducted with the Cd hyperaccumulator Sedum alfredii H. for phytoextraction Cd from an artificial contaminated soil (15.81 mg kg−1) under greenhouse conditions. The plant and soil samples were collected after growing the plant for three and six months with three replications. The results indicated that the ecotype of S. alfredii H. originating from an ancient silver mining site was a Cd-hyperaccumulator as it showed high tolerance to Cd stress, the shoot Cd concentration were as high as 922.6 mg kg−1 and 581.9 mg kg−1 at the two samplings, and it also showed high BF (58.4 and 36.8 after 3 and 6 months growth), and TF (5.8 and 5.1 after 3 and 6 months growth). The amounts of Cd accumulated in the shoots of S. alfredii reached to an average of 1206 μg plant−1 after 6 months growth. Basal respiration, invertase and acid phosphatase activities of the rhizosphere soil separated by the shaking method were significantly higher (P < 0.01) than that of the near-rhizosphere soil and the unplanted soil after 3 months growth, so were microbial biomass carbon, urease, invertase and acid phosphatase activities of the rhizosphere soil after 6 months growth. Acid phosphatase activity of the 0–2 mm sub-layer rhizosphere soil collected by the pre-stratified method after 3 months growth was significantly higher (P < 0.05) than that of other sub-layer rhizosphere soils and bulk soil, and so were microbial biomass carbon, basal respiration, urease, invertase and acid phosphatase activities of the 0–2 mm sub-layer rhizosphere soil after 6 months growth. It was concluded that phytoextraction by S. alfredii could improve soil microbial properties, especially in rhizosphere, and this plant poses a great potential for the remediation of Cd contaminated soil. 相似文献
6.
This study evaluated the interactive effect of arbuscular mycorrhizal fungi (AMF) inoculation and exogenous phosphorus supply on soil phosphotases, plant growth, and nutrient uptake of Kandelia obovata (Sheue, Liu & Yong). We aimed to explore the ecophysiological function of AMF in mangrove wetland ecosystems, and to clarify the possible survival mechanism of mangrove species against nutrient deficiency. K. obovata seedlings with or without AMF inoculation (mixed mangrove AMF), were cultivated for six months in autoclaved sediment medium which was supplemented with KH2PO4 (0, 15, 30, 60, 120 mg kg−1). Then the plant growth, nitrogen and phosphorus content, root vitality, AMF colonization and soil phosphatase activity were analyzed. The inoculated AMF successfully infected K. obovata roots, developed intercellular hyphae, arbuscular (Arum-type), and vesicle structures. Arbuscular mycorrhizal fungi colonization ranged from 9.04 to 24.48%, with the highest value observed under 30 and 60 mg kg−1 P treatments. Soil P supply, in the form of KH2PO4, significantly promoted the height and biomass of K. obovata, enhanced root vitality and P uptake, while partially inhibiting soil acid (ACP) and alkaline phosphotase (ALP) activities. Without enhancing plant height, the biomass, root vitality and P uptake were further increased when inoculated with AMF, and the reduction on ACP and ALP activities were alleviated. Phosphorus supply resulted in the decrease of leaf N–P ratio in K. obovata, and AMF inoculation strengthened the reduction, thus alleviating P limitation in plant growth. Arbuscular mycorrhizal fungi inoculation and adequate P supply (30 mg kg−1 KH2PO4) enhanced root vitality, maintained soil ACP and ALP activities, increased plant N and P uptake, and resulted in greater biomass of K. obovata. Mutualistic symbiosis with AMF could explain the survival strategies of mangrove plants under a stressed environment (waterlogging and nutrient limitation) from a new perspective. 相似文献
7.
Earthworms and arbuscular mycorrhizal fungi (AMF) are known to independently affect soil microbial and biochemical properties, in particular soil microbial biomass (SMB) and enzymes. However, less information is available about their interactive effects, particularly in soils contaminated with heavy metals such as cadmium (Cd). The amount of soil microbial biomass C (MBC), the rate of soil respiration (SRR) and the activities of urease and alkaline phosphatase (ALP) were measured in a calcareous soil artificially spiked with Cd (10 and 20 mg Cd kg−1), inoculated with earthworm (Lumbricus rubellus L.), and AMF (Glomus intraradices and Glomus mosseae species) under maize (Zea mays L.) crop for 60 days. Results showed that the quantity of MBC, SRR and enzyme activities decreased with increasing Cd levels as a result of the elevated exchangeable Cd concentration. Earthworm addition increased soil exchangeable Cd levels, while AMF and their interaction with earthworms had no influence on this fraction of Cd. Earthworm activity resulted in no change in soil MBC, while inoculation with both AMF species significantly enhanced soil MBC contents. However, the presence of earthworms lowered soil MBC when inoculated with G. mosseae fungi, showing an interaction between the two organisms. Soil enzyme activities and SRR values tended to increase considerably with the inoculation of both earthworms and AMF. Nevertheless, earthworm activity did not affect ALP activity when inoculated with G. mosseae fungi, while the presence of earthworm enhanced urease activity only with G. intraradices species. The increases in enzyme activities and SRR were better ascribed to changes in soil organic carbon (OC), MBC and dissolved organic carbon (DOC) contents. In summary, results demonstrated that the influence of earthworms alone on Cd availability is more important than that of AMF in Cd-polluted soils; and that the interaction effects between these organisms on soil microorganism are much more important than on Cd availability. Thus, the presence of both earthworms and AMF could alleviate Cd effects on soil microbial life. 相似文献
8.
《Applied soil ecology》2007,35(1):163-173
Two pot experiments were conducted to investigate the effect of inoculation with the arbuscular mycorrhizal (AM) fungus Glomus intraradices on Pb uptake by two clones of Nicotiana tabacum plants. Non-transgenic tobacco plants, variety Wisconsin 38, were compared in terms of Pb uptake with transgenic plants of the same variety with inserted gene coding for polyhistidine anchor in fusion with yeast metallothionein. Bioavailability of Pb in experimentally contaminated soil was enhanced by the application of a biodegradable chelate ethylenediaminedissuccinate (EDDS).EDDS addition (2.5 and 5.0 mmol kg−1 substrate) increased Pb uptake from the substrate and enhanced Pb translocation from the roots to the shoots, with shoot Pb concentrations reaching up to 800 mg kg−1 at the higher chelate dose. Application of a single dose of 5 mmol kg−1 proved to be more efficient at increasing shoot Pb concentrations than two successive doses of 2.5 mmol kg−1, in spite of a marked negative effect on plant growth and phytotoxicity symptoms. Pb amendment (1.4 g kg−1 substrate) connected with either dose of EDDS decreased significantly plant biomass as well as reduced the development of AM fungi. AM inoculation promoted the growth of tobacco plants and partly alleviated the negative effect of Pb contamination, mainly in the case of root biomass.No consistent difference in Pb uptake was found between transgenic and non-transgenic tobacco plants. The effect of AM inoculation on Pb concentrations in plant biomass varied between experiments, with no effect observed in the first experiment and significantly higher root Pb concentrations and increased root–shoot ratio of Pb concentrations in the biomass of inoculated plants in the second experiment. Due to probable retention of Pb in fungal mycelium, the potential of AM for phytoremediation resides rather in Pb stabilisation than in phytoextraction. 相似文献
9.
Vani Mittal Onkar Singh Harsh Nayyar Jagdeep Kaur Rupinder Tewari 《Soil biology & biochemistry》2008,40(3):718-727
The effect of six phosphate-solubilizing fungi (PSF, two strains of Aspergillus awamori, and four of Penicillium citrinum) isolated from rhizosphere of various crops, was observed on the growth and seed production of chickpea plants (Cicer arietinum L. cv. GPF2) in pot experiments. The phosphate (P) solubilizing activity of PSF in liquid varied from 38 to 760 μg ml?1 for tricalcium phosphate (TCP) and 28–248 μg ml?1 for mussoorie rock phosphate (MRP). All PSF isolates were biocompatible and produced growth-promoting hormone, Indole acetic acid (IAA), varying in concentration from 2.5 to 9.8 μg ml?1. Of the various pot experiments carried out in green house, maximum stimulatory effect on chickpea plants growth was observed by inoculation of two A. awamori strains. This treatment resulted in 7–12% increase in shoot height, nearly three-fold increase in seed number and two-fold increase in seeds weight as compared to the control (un-inoculated) plants. Inoculation of four strains of P. citrinum exhibited lesser stimulatory effect. It showed 7% increase in shoot height, two-fold increase in seed number and 87% increase in seeds weight as compared to the control plants. However, a consortium of all the six fungal isolates showed no stimulatory effect on chickpea plants growth. 相似文献
10.
Phytates represent a significant pool of organic phosphorus (Po) that is largely unavailable to plants. This study deals with phytate-mineralizing (PM), organic-acid-producing (OAP) rhizobacterial isolates, their characterization and their effect on plant growth. Their genetic diversity was assessed by 16S rRNA amplified ribosomal DNA restriction analysis (ARDRA) and selected isolates were identified by partial sequencing of 16S rRNA gene. Na-phytate and Po rich poultry farm manure (PFM) used as sources of phosphorus in semi-solid-agar (SSA) medium and soil respectively, for plant inoculation studies, where Cajanus cajan (pigeon pea) used as plant. Of thirty-nine rhizobacterial isolates, nineteen were proficient at releasing phosphate (Pi) (up to 85 μg/ml) from sparingly soluble calcium (Ca)-phytate and concomitantly decreasing the pH of minimal medium with 100 mM glucose from 8.0 to below 5. When the medium contained glycerol in place of glucose, Ca-phytate remained undissolved with no significant Pi released and no decline in pH. Genetic diversity of phytate-mineralizing (PM) rhizobacterial isolates suggests that the isolates mainly fall in two populations: acid-producing (AP) population (mainly represented by members of Enterobacteriaceae) and non-AP population. OAP-PM rhizobacterial isolates were identified as Citrobacter, Pantoea, Klebsiella and Enterobacter species. Organic acids (OAs) secreted by PM isolates were detected by HPLC, showed secretion of gluconic and acetic acids. Importance of OAs in Ca-phytate dephosphorylation was demonstrated in vitro using A. ficuum phytase. Gluconate and acetate additions enhanced phytase catalyzed dephosphorylation of Ca-phytate in vitro. Sonicated cell lysates of isolates showed significant Pi release from Ca-phytate compared to whole cells, indicating inaccessibility of Ca-phytate due to poor solubility. Selected isolates showed that they possess cell-associated acid phytase and modulators of phytase activity suggested that the enzymes are histidine acid phosphatase (HAP) type of phytase. OAP-PM isolates PP1 and DHRSS showed significant increase in dry shoot/root ratio and P content of shoot in Na-phytate containing semi-solid agar (SSA) medium, but isolate DHRSS did not increase dry shoot/root ratio in soil experiments containing poultry farm manure as source of P, although it significantly increased shoot P content of plants. The inoculation of isolates enhanced the shoot P content and dry shoot/root ratio, but did not increase the dry weight in SSA medium. It may be concluded that some OAP-PM rhizobacterial isolates that release P from Ca-phytate show increase in shoot P content in phytate containing SSA medium and in soils. 相似文献
11.
This paper reports the results of a study focused on the metal (Cd, Co, Cr, Cu, Ni, Pb, Sb, U and Zn) distribution in soils and uptake and accumulation by earthworms Nicodrilus caliginosus (Savigny) from urban, peri-urban, green-urban and non-urban zones of Siena municipality (central Italy). The main goal was to define the influence of soil properties and metal soil contents on the uptake of these contaminants by earthworms. Data indicated that Cd, Cu, Pb, Sb and Zn soil contents increased in the following order: non-urban < green-urban < peri-urban < urban soils, suggesting that vehicular traffic affects the distribution of these metals. Pb and Sb were the main soil contaminants and their highest enrichments were found in urban sites where stop-and-go traffic occurs. Concentrations of these traffic-related metals in earthworms showed a distribution pattern similar to that in soil, suggesting that soil contamination influenced the uptake of Cd, Cu, Pb, Sb and Zn by N. caliginosus. There were significant positive correlations between Cd, Pb and Sb earthworm concentrations and their soil contents. The lack of correlation for Cu and Zn could be due to the physiological regulation of these elements by earthworms. Statistical analysis pointed out that the uptake and accumulation of Cd, Cu, Pb, Sb and Zn by earthworms were affected by some soil physicochemical properties such as the organic carbon and carbonate contents that are able to rule the bioavailability of metals in soils. 相似文献
12.
《Applied soil ecology》2003,22(1):1-14
Studies were conducted to evaluate the survival and persistence of Sinorhizobium meliloti 104A14 and two acid phosphatase-negative mutants in Kirkland (fine, mixed, thermic Udertic Paleustolls) silt loam soils with various fertility levels, and to assess the impact of inoculation on nodule occupancy and soil microbial community structure in the inoculated alfalfa (Medicago sativa L.) rhizosphere. Recovery of the inoculated strains was 100% (in the order of 108 cells g−1 soil) immediately following inoculation to soils, but decreased from 108 cells g−1 soil to undetectable levels in a nutrient-poor soil within 32 days. In a nutrient-rich soil, approximately 2–3% (4.7–7.43×106 cells g−1 soil) of the mutants and 23% (5.84×107 cells g−1 soil) of the wild-type inocula persisted for more than 64 days. Survivability and persistence of the wild-type S. meliloti were significantly greater than that of the genetically modified acid phosphatase negative mutants in all the soils tested. The persistence and nodule occupancy of the introduced S. meliloti in sterile and non-sterile soils were also tested for two repeated alfalfa growth periods in the same plant growth units, with a 1 month interval in between and no additional inoculation for the second period. Nodule occupancy of the introduced S. meliloti in non-sterile soils ranged from 30 to 60% for the first period and 85 to 100% for the second period. Our results suggest that survival and persistence of S. meliloti was enhanced by alfalfa cultivation and increased soil fertility, but impaired by mutation of acid phosphatase genes regardless of phosphorus nutritional levels. Moreover, inoculation with genetically modified S. meliloti strain 104A14 promoted indigenous bacterial growth in soil (increased bacterial population from 1.4×106 to 4.3×106 cells g−1 soil), but not the growth of fungi and yeast. However, inoculation of the wild-type S. meliloti or genetically modified mutants did not result in significant changes in microbial community structure as indicated by EP indices and ratios of r/K strategists. 相似文献
13.
《European Journal of Soil Biology》2006,42(1):13-22
A pot experiment was conducted to investigate the impact of high carbon dairy factory effluent application on the growth of perennial ryegrass (Lolium perenne L.), plant nutrient uptake, soil microbial biomass carbon and nitrogen, populations of soil-microorganisms, root colonising fungi and the microbial functional diversity. The effluent was added at rates of 0, 100,000, 200,000 and 300,000 l ha–1. These rates are equivalent to 0, × 1, × 2 and × 3 normal field application rates. The added effluent contained (g l–1), C; 19.42, total P; 0.65; S, 0.75, K; 1.33, Na; 4.55, Mg; 0.11, NH4; 0.073, total N; 0.073 and had a pH of 4.33. Replicate pots (incubated in a controlled-environment room at 20 °C, with 16 h light/8 h dark) were harvested at 32, 61, and 130 days after setting up of the experiment. In the first sampling, shoot dry matter levels declined significantly (P < 0.01) with increased effluent. By the third sampling the trend was reversed with treated pots having greater amounts of shoot dry matter. The initial depression of growth was possibly due to a combination of factors including excess levels of available carbon (C) for microbes leading to immobilisation of nutrients, particularly nitrogen (N) and sulphur (S). Shoot N and S concentrations were lower (P < 0.001) and the phosphorus concentrations were higher in effluent-treated samples. Soil microbial biomass-C (480 and 770 μg g−1 of biomass C in untreated and treated soil, respectively) and microbial-N (81 and 123 μg g–1 of microbial-N in untreated and treated soil, respectively) were significantly (P < 0.001) greater in effluent-treated pots at all times. Populations of total culturable bacteria were higher (P < 0.01) in the treated pots in the first sample (log10 populations g–1 were 7.3 in untreated pots compared to 8.0 averaged across three treatments) but there were no differences in the subsequent two samples. Effluent also increased yeast populations (log10 numbers g–1 were 0.6 in untreated pots and 3.1 in treated pots averaged across treatments and times P < 0.01) at all three sampling times. The Shannon-Weiner Diversity Index of root fungi decreased with increasing effluent application (P < 0.01) while the species richness decreased with effluent as well as with time (P < 0.1). Potential root pathogens Fusarium oxysporum, total Fusarium spp. and Pythium spp. significantly increased (P < 0.05) in treated samples but in the final sampling, Codinaea fertilis significantly (P < 0.05) decreased with effluent treatment. The microbial functional diversity pattern and the average well colour development (AWCD) in soil were significantly changed by the effluent application but effects were not detectable after 130 days. 相似文献
14.
《Applied soil ecology》2007,35(1):1-9
Wheat production (Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha−1 during the last 5 years, and 164 kg P ha−1 applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot−1), and nitrogen (N) fertilization (0 and 150 mg N pot−1). A range of soil P between 6 and 60 mg P kg−1 was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content (r2 = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0–27 mg P kg−1 (a decrease of 2.8% mg P−1 kg−1). Above 27 mg P kg soil−1, AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil−1. The soil P range that ensures high wheat production without deterring indigenous AMC is discussed. 相似文献
15.
《Soil biology & biochemistry》2012,44(12):2359-2367
As, Cd, Cu, Pb, Sb and Zn concentrations were determined in two earthworm species (Allolobophora rosea and Nicodrilus caliginosus) from a mining and industrial area in northern Kosovo and compared with their contents in the bulk soil and the main soil fractions. Earthworm specimens were collected at fifteen sites located at different distances from a Pb–Zn smelter along a gradient of decreasing contamination. Individuals of A. rosea and N. caliginosus showed similar tissue levels of As, Cd, Cu, Pb, Sb and Zn, suggesting that earthworm species belonging to the same eco-physiological group have a similar propensity to uptake and bioaccumulate heavy elements. Cd, Pb, Sb and Zn concentrations in both earthworm species were positively correlated with the respective total soil contents and generally decreased with distance from the smelter. The bioaccumulation factor (BAF) revealed that Cd and Zn were the only elements bioaccumulated by earthworms. The rank order of BAF values for both species was as follows: Cd > > Zn > > Cu > As = Pb = Sb. The absorption of Cd, Pb, Sb and Zn by earthworms mostly depended on the extractable, reducible and oxidable soil fractions, suggesting that the intestine is likely the most important uptake route. The extractable soil fraction constantly influenced the uptake of these heavy elements, whereas the reducible fraction was important mainly for Pb and Zn. The water soluble fraction had an important role especially for the most mobile heavy elements such as Cd and Zn, suggesting that dermal uptake is not negligible. As a whole, the analytical data indicate that soil fractionation patterns influence the uptake of heavy elements by earthworms, and the extractable fraction is a good predictor of heavy element bioavailability to these invertebrates in soil. 相似文献
16.
The endogeic earthworm Pontoscolex corethrurus (Müller, 1857) was the most abundant species (75%) in soil contaminated with hydrocarbons, mostly benzo(a)pyrene (BaP), in the state of Tabasco (Mexico). The earthworm P. corethrurus was tested for its capacity to remove 100 mg BaP kg−1 from an Anthrosol soil (sterilized or not) and amended with legume Mucuna pruriens (L.) DC. var. utilis (Wall. ex Wight) Baker ex Burck (3%) or the grass Brachiaria humidicola (L.) DC (3%) (recently renamed as Urochloa humidicola (Rendle) Morrone & Zuloaga) in an aerobic incubation experiment. P. corethrurus removed 26.6 mg BaP kg−1 from the sterilized soil and application of B. humidicola as feed increased this to 35.7 mg BaP kg−1 and M. pruriens to 34.2 mg BaP kg−1 after 112 days. The autochthonous microorganisms removed 9.1 mg BaP kg−1 from the unsterilized soil and application of B. humidicola increased this to 18.0 mg BaP kg−1 and M. pruriens to 11.2 mg BaP kg−1. Adding P. corethrurus to the unsterilized soil accelerated the removal of BaP and 36.1 mg kg−1 was dissipated from soil. It was found that the autochthonous microorganisms removed BaP from soil, but addition of P. corethrurus increased the dissipation 4-fold. The endogeic earthworm P. corethrurus can thus be used to remediate hydrocarbon-contaminated soils in tropical regions. 相似文献
17.
Germinability and virulence of sclerotia of Sclerotium rolfsii were assessed after 50 days of exposure of 14C-labeled sclerotia to soil at 0, −5 and −15 kPa and pH 6.9, or to soil at 15, 25 or 30 °C, pH 5 or 8 and −1 kPa. Evolution of 14CO2 accounted for the greatest share of endogenous carbon loss from sclerotia under all soil conditions, except in water-saturated soil (0 kPa), in which sclerotial exudates contributed the major share of carbon loss. Total evolution of 14CO2 from sclerotia in soil at −15 kPa (42.4% of total 14C) and at −5 kPa (38%) was significantly higher than at 0 kPa (23.8%). Evolution of 14CO2 in soil at 25 or 30 °C was more rapid than at 15 °C with regardless of pH. Loss of endogenous carbon by sclerotia was the greater after 50 days of exposure to soil at 0 kPa, or at 25 or 30 °C and pH 8, than at other soil conditions. Sclerotia exposed to water-saturated soil (0 kPa) showed a more rapid decline in nutrient independent germinability, viability and virulence, than to those exposed to −5 or −15 kPa. Sclerotia became dependent on nutrient for germination and lost viability and virulence within 30–40 days in soil at 25 or 30 °C, pH 8. However, more than 60% of sclerotia retained viability in soil at 15 °C regardless of pH, even after 50 days. Radish shoot growth was increased significantly by the sclerotia that had been exposed to soil at 0 kPa, or to soil at 25 or 30 °C and pH 8 for 50 days. In conclusion, carbon loss by sclerotia during incubation on soil at different pH levels, temperatures and water potentials was inversely correlated with sclerotial ability to infect radish seedlings. The relationship between carbon loss by sclerotia and radish shoot length was positive. 相似文献
18.
The combination of nitrogen and Azospirillum can ensure greater nutrient absorption and crop yield in agricultural areas using high technology. Thus, the objective was to evaluate maize response to Azopirillum brasilense (AZ) inoculation and nutrient (macronutrients and micronutrients) application under greenhouse and field conditions in clay and sandy soils of the Brazilian Cerrado. In the greenhouse assays, the following parameters were measured: shoot dry weight (SDW), root dry weight (RDW), and root volume (RV). In the field experiments, the maize yield was determined after drying the grains at 60 °C for 48 h. In clay soil, there was a significant increase in the SDW, RDW and RV in the treatment with AZ concentrated (1011 cells ml−1 of inoculum) when compared with the control treatment and the treatment with AZ diluted (106 cells ml−1 of inoculum). In this soil, adding micronutrients did not affect the maize response under greenhouse conditions. In sandy soil, there was no difference between the AZ treatment and the control, except for treatments where nutrients and AZ were both added leading to a significant increase in the maize response. In both soils, the RV:RDW ratio was higher in the treatment with AZ concentrated compared to that in the treatment with AZ diluted, but the yield response depended on the addition of nutrients. Inoculation with A. brasilense gave comparable yield to the nitrogen treatment. The grain production was increased by 29% in the treatment with A. brasilense and nitrogen compared to nitrogen fertilization alone. In this study, the yield response was affected significantly when maize was inoculated with A. brasilense, but this response was dependent on the soil type under greenhouse conditions. 相似文献
19.
《Applied soil ecology》2006,31(3):215-225
The effect of forest fire on soil enzyme activity of spruce (Picea balfouriana) forest in the eastern Qinghai-Tibetan Plateau was assessed. Six specific enzymes were chosen for investigation: invertase, acid phosphatase, proteinase, catalase, peroxidase and polyphenoloxidase. It was found that the activities of invertase and proteinase were reduced by burning, but the activities of acid phosphatase, polyphenoloxidase and peroxidase increased. Meanwhile, burning significantly (P < 0.05) resulted in the decrease of concentrations of available N and K of 0–20 cm depth layer soil, and significantly (P < 0.05) decreased concentrations of organic matter content, total N and P, as well as available N, P and K in soil at both 20–40 and 40–60 cm depths except for available P at 20–40 cm soil depth. These results illustrated that burning could influence the enzyme activities and chemical properties of soil not only of upper but also lower soil layers. Correlation analysis indicated that invertase activities in 0–20 cm depth layer soil were significantly positively correlated with organic matter, total N and P, as well as available N and P. Furthermore, all six enzymes studied were sensitive to fire disturbance, and thus could be used as indicators of soil quality. Our study also showed that soil enzyme activities were associated with soil depth, decreasing from top to bottom in both burned and unburned spruce forests. The distribution pattern of soil enzyme activities suggested that the rate of organic matter decomposition and nutrient cycling depended on soil depth, which had important structural and functional characteristics in nutrient cycling dynamics and implications in plantation nutrient management. The finding that burning effects on enzyme activities and soil properties between different soil layers were homogenized was attributed to the 8-years’ regeneration of forest after burning. 相似文献
20.
《European Journal of Soil Biology》2007,43(4):207-215
The purpose of this study was to investigate the effects of high cadmium and nickel soil concentrations on selected physiological parameters of Arundo donax L. A 2-year pot experiment was held in the field and the pots were irrigated with aqueous solutions of Cd and Ni in concentrations of 5, 50 and 100 ppm, against the control (tap water). At the end of the cultivation periods the pots soil was divided into three equal zones and total and NH4OAc extractable Cd and Ni concentrations were determined. The top zone exhibited the highest metal content. Cadmium and nickel total concentrations at the end of the experiment were up to 973.8 mg kg−1 and 2543.3 mg kg−1 respectively, while NH4OAc extractable Cd was up to 291.7 mg kg−1 and Ni up to 510.3 mg kg−1. Stomatal conductance ranged between 0.3 and 0.8 mol CO2 m−2 s−1, intercellular CO2 concentration ranged between 212.9 and 243.0 ppm CO2, stomatal resistance between 0.6 and 1.3 s cm−1, chlorophyll content (SPAD values) between 46.3 and 57.0 and chlorophyll fluorescence (Fv/Fm) ranged between 0.8 and 0.9. All studied physiological parameters did not show statistically significant differences among control and heavy metal treated plants for both years; therefore, high soil cadmium and nickel concentration did not inhibit stomatal opening and did not affect the function of the photosynthetic machine of A. donax plants. 相似文献