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1.
Phytohormones have an essential ability to adapt to abiotic stresses, including drought stress (DS), by mediating physiological and molecular processes. Arbuscular mycorrhizas (AMs) can enhance tolerance of DS, but the information regarding phytohormone changes in AM plants exposed to DS is little known. Trifoliate orange (Poncirus trifoliata) seedlings colonized by an AM fungus Funneliformis mosseae were subjected to DS and well-watered for 6 weeks. Plant growth performance, gas exchange, indole-acetic acid (IAA), gibberellins (GAs), brassinosteroids (BRs), abscisic acid (ABA), methyl jasmonate (MeJA) and zeatin riboside (ZR) were determined. The 6-week DS treatment strongly restricted root mycorrhizal colonization. Mycorrhizal inoculation significantly increased plant growth parameters under DS, as compared with non-mycorrhizal treatment. Mycorrhizal treatment also induced significantly higher leaf-relative water content, net photosynthetic rate, transpiration rate and stomatal conductance but lower intercellular CO2 concentration and leaf temperature under DS, compared with non-mycorrhizal treatment. Mycorrhizal plants under DS condition represented significantly higher leaf ABA, IAA, GAs, BRs and ZR levels than non-mycorrhizal plants. The study, hence, suggested that mycorrhizal inoculation induced the changes of gas exchange and endogenous phytohormone levels to enhance drought tolerance in trifoliate orange.  相似文献   

2.
In order to analyze the effectiveness of colonization by arbuscular mycorrhizal fungi (AMF) at the nursery stage on the growth and nutrient concentration of wetland rice after transplanting, the experiments were conducted under glasshouse conditions using two types of soil, namely (i) sterilized paddy soil (PS) and (ii) sterilized paddy soil diluted with sterilized Andosol subsoil 5 times (DS) under two water regimes, (i) flooded conditions changed to non-flooded conditions 30 d before harvest (F-NF) and (ii) continuous flooding (CF) up to harvest. Treatments consisting of mycorrhizal inoculation (+AMF) and non-inoculation ( — AMF) were applied only at the nursery stage when the seedlings were produced under dry nursery (60% moisture of maximum water holding capacity) conditions.

Seedlings grown in PS showed a significantly higher biomass yield and nutrient concentrations than in DS. At 90 and 105 d after transplanting, the mycorrhizal plants showed a higher biomass than non-mycorrhizal plants in PS whereas there were no differences in DS except for roots. Mycorrhizal colonization at the transplanting stage was higher in DS than in PS. However, after transplanting opposite results were obtained, the level in PS being relatively higher than in DS. Grain yield and P concentration of unhulled grain and shoots in PS were higher in the +AMF treatments than in the -AMF treatments under both water regimes. Contents of micronutrients (Zn, Cu, Fe, and Mn) were higher in the +AMF plants than in the -AMF ones at all growth stages up to maturation irrespective of soil fertility and water regimes. These results suggest that AMF inoculation at the nursery-stage was beneficial for wetland rice after transplanting to flooded conditions in terms of growth promotion and increase of nutrient concentrations.  相似文献   

3.
It is well known that arbuscular mycorrhizal fungi (AMF) effects on plant growth largely depend on fungus identity. The objective of this study was to test whether three individual AMF isolates and their mixture mitigate drought stress (DS) differentially in soybean (Glycine max) genotype, predicting that under DS, the mixture of the AMF isolates would provide greater benefits to soybean plants than individual ones. In a greenhouse experiment, a drought-susceptible soybean genotype was inoculated with Septoglomus constrictum, Glomus sp., and Glomus aggregatum, known to be among the most abundant in agricultural and natural soils from central Argentina, and their mixture (Mx). Whereas under well-watered (WW) conditions, individual isolates and Mx treatment were similarly infective; under DS conditions, the Mx treatment showed lower rates of root colonization. Between WW and DS conditions, biomass was decreased in all treatments, although this effect was more marked in non-AM plants. Moreover, AMF strains improved water content and P and N concentrations. Under DS, the Mx treatment was unable to exceed the highest contents that were recorded by AMF isolates. However, under WW conditions, the Mx treatment showed a higher N content than individual isolates. Under both watering conditions, AM plants reduced oxidative damage evaluated as malondiadehyde and chlorophyll content and keep constant osmotic metabolites such as soluble sugars and proline content, without significant differences between AMF isolates and the Mx treatment. These results show that AMF play an important role in mitigating drought impacts on soybean, but that mixtures of AMF isolates did not perform as well as the best single strain inoculum, excluding complementarity effects and suggesting selection effect of AMF on DS alleviation in soybean.  相似文献   

4.
Arbuscular mycorrhizal fungi (AMF) can act as an extension of the root system of their host plants. In Desmoncus orthacanthos Martius (Arecaceae), which has thick and unbranched roots (i.e., magnolioid roots) and low densities of root hairs, this association may be essential to reach a maximum growth with minimum fertilizers. This is important because of the potential in the south of Mexico to use D. orthacanthos' shoots as a raw material to build handcrafts. To evaluate the effect of arbuscular mycorrhizae on phosphorus (P) uptake and initial growth of D. orthacanthos seedlings, a 160-day bi-factorial experiment was carried out in which plants were subject to one of two levels of mycorrhizal colonization (with or without) and one of three levels of P substrate addition (4, 12, and 24 ppm). Our results show that total dry weight (DW) and leaf area (LA) responded significantly to P addition but not to mycorrhizal colonization. Phosphorus concentration in plant tissues (Pt) was increased by both factors (mycorrhizae and P addition). Mycorrhizae increased relative growth rate (RGR) at low P level. Our results indicate that AMF play an important role in early growth and P uptake by D. orthacanthos seedlings; therefore, the AMF must be considered in plantations of this potentially economically important palm.  相似文献   

5.
The mycorrhizal enhancement of plant growth is generally attributed to increased nutrients uptake. A greenhouse experiment was conducted to investigate the effect of arbuscular mycorrhizal fungi (AMF) inoculation on the growth and nutrient uptake of directly seeded wetland rice. Seeds were germinated and inoculated with arbuscular mycorrhizal fungi or left uninoculated. The plants were grown at 60% of ‐0.03 MPa to establish the mycorrhizas. After 5 weeks, half of the pots were harvested and the rest were flooded with deionized water to maintain 3–5 cm of standing water until harvesting (122 days after sowing). Mycorrhizal fungal colonization of rice roots was 36.2% at harvest. Mycorrhizal fungi inoculated rice seedlings grew better compared to uninoculated seedlings and had increased grain yield (10%) at the harvesting stage. Shoot and root growth were effectively increased by AMF inoculation at the harvesting stage. The nitrogen (N) and phosphorus (P) acquisition of direct seeding wetland rice were significantly increased by AMF inoculation. The AMF enhanced N and P translocation through the hyphae from soils to roots/shoots to grains effectively.  相似文献   

6.
Densely branched lateral roots (DBLRs) in Sesbania cannabina are formed in response to patchily distributed phosphorus (P) in volcanic soils. Little attention has been paid to morphological and physiological responses of DBLRs. Here, we investigated the relation between plant growth and DBLR development, enzymatic activities involved in P acquisition, and the influence of arbuscular mycorrhizal fungi (AMF), which contribute to P uptake, to clarify the function of DBLRs. We investigated DBLR development induced by localized application of P fertilizer and we compared the activities of phosphoenolpyruvate carboxylase (PEPCase) and acid phosphatase (APase) between DBLRs and non‐DBLRs. Additionally, plants were grown with or without AMF to investigate the effect of AMF colonization on the numbers of DBLRs and plant P uptake, and we compared AMF colonization between DBLRs and non‐DBLR roots. Secondary to quaternary lateral DBLRs were produced after the primary lateral roots passed near P fertilizer. Pi content per DBLR increased as DBLRs developed, promoting higher shoot growth. Under P deficiency, PEPCase and APase activities increased in non‐DBLR, but were significantly lower in DBLRs in the same plants. AMF inoculation changed the root system architecture by significantly decreasing the number of DBLRs, and AMF colonization was lower in DBLRs than in non‐DBLRs. Our results indicate that DBLR formation is a P‐coacquisition strategy of S. cannabina grown in P‐deficient andosolic soil. Roots that form DBLR are clearly different from non‐DBLR roots in morphological and biochemical response and AMF symbiosis.  相似文献   

7.
Common mycorrhizal network (CMN) links up several coexisting plant individuals via underground root communication for resource sharing, while it is not known whether phytohormones participate in such communication. A two-chambered rootbox separated through 37-μm mesh was used to establish the CMN by Diversispora spurca between trifoliate orange (TO) and white clover (WC). After 20 weeks of inoculation, the CMN was established, as evident from high mycorrhizal buildup under supplier (mycorrhizal inoculation) TO–target (non-mycorrhizal inoculation) WC association. This CMN was eventually responsible for the significant increase in plant biomass of these associated plants. CMN decreased root abscisic acid (ABA) level in supplier and target plants, but increased root indole-3-acetic acid (IAA) level in supplier plant alone. CMN mediated significantly higher gibberellins (GAs) and zeatin riboside (ZR) concentration in roots of target plant, leaving supplier plant unaffected. Root ZR was bidirectionally transferred through the CMN. A higher root methyl jasmonate (MeJA) concentration was observed in supplier WC–target TO or supplier TO–supplier WC association, indicating an unidirectional communication from WC to TO. It suggested that except IAA, GAs, brassinosteroid (BR), and ABA, root MeJA and ZR were apparently involved in the underground communication by CMN.  相似文献   

8.
Crocus sativus L. cultivation is expanding to areas with low soil fertility, where mycorrhizal fungi are supposed to be essential for plants growth and ecosystems functioning. Agricultural practices applied under these conditions should lead to good saffron productivity and quality. Our objective was to study the density and diversity of mycorrhizal fungi populations associated with saffron grown in Taliouine (Morocco) under different agricultural management practices (fertilization type, age and plantation method). Morpho-anatomical studies identified rhizospheric mycorrhizal spores and assessed root colonization by arbuscular mycorrhizal fungi (AMF). Molecular identification of AMF was realized by sequencing the Large Subunit (LSU) rDNA gene region. Among the eleven species of AMF spores identified, Funneliformis and Rhizoglomus species were the most abundant (> 35%). Modern saffron plantation showed higher roots colonization rates (mycorrhization intensity (100%) and frequency (51.6%)), while in traditional plantations lower mycorrhization frequency values were found (17.4%). LSU sequencing identified five AMF genera and three unknown genomic groups, whereas Shannon diversity index indicated that AMF community composition changed significantly according to plantation age and fertilization type. Our results contribute to a better knowledge of saffron AMF communities and open new perspectives for a rational utilization of the agricultural practices for organic saffron production.  相似文献   

9.
Arbuscular mycorrhizal fungi (AMF) differ in their rate and extent of colonization of both plant roots and soil but the mechanism responsible for these differences is unclear. We compared the external mycelium of three AMF isolates (Glomus intraradices, Glomus etunicatum and Gigaspora gigantea) during early colonization of plant roots. We investigated whether an AMF with the most rapid colonization would have higher numbers of infective structures (i.e., infection hyphae and contact points), an AMF with extensive root colonization would have more infection units, and (3) AMF with extensive soil colonization would have large numbers of all external features (including absorptive hyphae, runner hyphae and hyphal bridges). Using specially designed soil and root observation chambers, we followed the development of the external mycelium for 7 weeks. We found that rapid colonization rate was due, in part, to the presence of more infective structures, in particular more infection hyphae and root contact points. Second, the extensive root colonizer had more, larger infection units. Third, data did not support the hypothesis that the extensive soil colonizer had more external structures. These results show that differences in the architecture of the external mycelium are responsible, in part, for variation in the colonization strategy of AMF.  相似文献   

10.
Arbuscular mycorrhizal fungi (AMF) influence soil aggregate stability through their hyphae, roots, and glomalin-related soil protein (GRSP); however, the individual effect of these factors is difficult to distinguish. Pots separated by a 37-μm mesh bag buried in the middle of each pot was used to establish root zone (root + hyphae) and hyphae zone (roots free), where the Poncirus trifoliata seedlings were colonized by Funneliformis mosseae or Paraglomus occultum in root zone. AMF inoculation significantly increased shoot, root, and plant’s total biomass, soil organic carbon, GRSP fractions, 2–4 and 1–2 mm size water-stable aggregates, and mean weight diameter (MWD) in root or hyphae zone. Within root zone, root colonization and biomass presented stronger relationship with MWD than GRSP fractions. While, within hyphae zone, total of GRSP fraction was significantly correlated with MWD. The study, suggested further that root biomass and colonization were the main mechanisms in root zone for improving aggregate stability, whereas total of GRSP fractions was of paramount importance in hyphae zone. Mycorrhizal effect on aggregate stability was observed to be contrastingly different between root zone and hyphae zone.  相似文献   

11.
菌根对紫色土上间作玉米生长及磷素累积的影响   总被引：4，自引：2，他引：4  
丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)在土壤与植物系统的磷素循环中发挥着关键的作用。本文通过盆栽模拟试验研究了不同AMF接种状况[不接种(NM)、接种Glomus mosseae(GM)、接种G.etunicatum(GE)]和玉米/大豆间作体系不同根系分隔方式(不分隔、尼龙网分隔、塑料膜分隔)对间作玉米植株生长及磷素吸收累积的影响。研究结果表明:GM处理下的间作玉米根系侵染率在不同根系分隔方式之间的差异不显著,而GE处理则在塑料膜分隔处理下对玉米的侵染率最高。接种不同AMF对间作玉米促生效果不同,GM和GE处理在不同根系分隔情况下表现出各自的优势,与未接种处理相比,GM处理能使玉米生物量、株高有一定程度增加并在根系不分隔处理下玉米磷吸收较多、生长较好;GE处理能使植株生物量有一定程度增加并在尼龙网分隔处理下的玉米磷吸收较多、生长较好。间作体系不同根系分隔方式对玉米的影响也不同,其中玉米地上部生物量在根系分隔处理下普遍小于不分隔处理,但根系生物量的大小情况则刚好相反。另外,无论何种接种状况,玉米根系磷含量及吸收量均以尼龙网分隔处理显著较高。而根系磷吸收效率则以接种G.mosseae且不分隔根系处理显著高于分隔处理。所有复合处理中,以接种G.etunicatum与尼龙网分隔根系组合处理对间作玉米的生长及磷素累积的促进作用最好,若应用于滇池流域,可望有效控制坡耕地土壤磷素的迁移。  相似文献   

12.
Soil acidification has become a serious problem for citrus cultivation in China. As a soil amendment, biochar is expected to increase soil pH as well as soil fertility. In this study, we assessed the effect of biochar on Trifoliate orange, the most frequently used citrus rootstock, in a pot experiment using acidic red soil from the Gannan citrus production area. Plant height and shoot diameter of Poncirus trifoliata (L.) Raf. seedlings increased significantly after biochar was added to soils. This positive effect was further evidenced by the increased plant biomass and leaf net photosynthetic rate. The root system architecture (RSA) was evaluated based on root length, root surface area, root volume and root tip. Biochar amendment significantly increased the total absorptive surface area of the root system. Due to the significant role of arbuscular mycorrhizal fungi (AMF) in citrus root nutrient uptake, the AMF colonization and community in Poncirus roots were investigated. The AMF colonization rate was not significantly affected by biochar, whereas AMF diversity increased upon biochar treatment. In addition, the biochar treatment resulted in increases in soil pH, organic matter and mineral nutrients. Together, our results suggest that the positive effects of biochar on the growth performance of Poncirus seedlings can be attributed to the substantial augmentation of soil fertility, increased soil pH, optimized RSA and improved AMF species composition.  相似文献   

13.
A greenhouse pot experiment was conducted to investigate heavy metal [copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd)] uptake by two upland rice cultivars, ‘91B3’ and ‘277’, grown in a sterilized field soil contaminated by a mixture of Cu, Zn, Pb, and Cd. Rice plants were inoculated with each of three arbuscular mycorrhizal fungi (AMF), Glomus versiforme (GV), Glomus mosseae (GM), and Glomus diaphanum (GD), or remained noninoculated (NM). Both rice cultivars could be colonized by the three AMF used in this experiment. The percentage of mycorrhizal colonization by the three AMFs on the two rice cultivars ranged from 30% to 70%. Mycorrhizal colonization of both upland rice cultivars had a large influence on plant growth by increasing the shoot and root biomass compared with non-inoculated (NM) plants. The results indicate that mycorrhiza exert some protective effects against the combined toxicity of Cu, Zn, Pb, and Cd in the contaminated soil. This conclusion is supported by the partitioning of heavy metals (HMs) in the two cultivars. In the two cultivars, colonization by AMF reduced the translocation of HMs from root to shoot (except that the colonization of AMF increased the Cu translocation of HMs in cultivar ‘277’). Immobilization of the HMs in roots can alleviate the potential toxicity to shoots induced by the mixture of Cu, Zn, Pb, and Cd. The two rice cultivars showed significant differences in uptake of Cu, Zn, Pb, and Cd when uninoculated. GM inoculation gave the most protective effects on the two cultivars under the combined soil contamination.  相似文献   

14.
Mycorrhiza-released glomalin-related soil protein (GRSP) influences rhizosphere properties, but it is not clear whether exogenous GRSP enhances drought tolerance of plants. In this work, easily extracted GRSP (EE-GRSP) was isolated from Satsuma mandarin soil, and half-strength EE-GRSP (0.007 mg protein mL?1) was weekly applied into rhizosphere of potted trifoliate orange (Poncirus trifoliata) exposed to well watered (WW) and drought stress (DS). After four months, EE-GRSP-treated seedlings exhibited significantly higher plant growth (plant height, leaf number and fresh weight) and root growth-related parameters (lateral root numbers and root morphology) than non-EE-GRSP-treated seedlings under both WW and DS conditions. Exogenous EE-GRSP generally significantly increased leaf water potential, net photosynthesis rate, transpiration rate, stomatal conductance and intercellular CO2 concentration, while dramatically decreased leaf temperature, regardless of soil water status. The seedlings treated with exogenous EE-GRSP observed significantly higher activities of leaf Fe-SOD and root Mn-SOD, Cu/Zn-SOD, and Fe-SOD than untreated control under DS. Leaf abscisic acid, indole-acetic acid and methyl jasmonate concentrations were significantly higher in EE-GRSP-treated seedlings than untreated control under DS. This work firstly reported that exogenous application of EE-GRSP improved drought tolerance of trifoliate orange, thereby, offering a strong possibility in favour of EE-GRSP to be used as a plant growth regulator.  相似文献   

15.
采用盆栽试验研究了不同浓度NaCl（03%、06%和10%）胁迫下,接种丛枝菌根真菌Glomus mosseae-2 对番茄内源激素的影响。结果表明：（1）盐胁迫下,植株生长受抑,生长促进物质IAA、GA3和Zeatin含量下降,生长抑制物质ABA含量增加,接种Glomus mosseae-2增加了植株干物质量和这些激素的含量;（2）菌根形成过程中,Glomus mosseae-2参与调节内源激素平衡, 降低了叶片ABA/IAA、ABA/GA3、ABA/Zeatin及ABA/ (IAA+GA3+Zeatin)的比值; （3）气孔导度（gs））和ABA/Zeatin值呈极显著负相关,同一盐浓度胁迫下,接菌株有较高gs和较低的ABA/Zeatin值。 ABA和Zeatin共同调节气孔对盐胁迫的响应,维持接菌株较高的气孔导度,增强了番茄的耐盐性。  相似文献   

16.
The production of fine roots is one of the principal means by which carbon, fixed during photosynthesis, enters the soil, and quantifying the production for particular combinations of environmental and biotic factors is important for predicting the sequestration of carbon in the soils of grassland ecosystems. Arbuscular mycorrhizal fungi (AMF) can have a major effect on the production of roots, and we studied how colonization by AMF affects the lifespan of roots. Twenty per cent of control roots of Trifolium repens survived for longer than 42 days whereas 37% survived that long in AMF‐colonized plants. The overall survival of the roots of Lolium perenne was less than in T. repens: around 10% of roots survived beyond 42 days and this was not affected by AMF colonization. Previous studies have shown that lifespans of roots can be affected by temperature. We tested the hypothesis that these observations are linked to a change in the morphology of the root system caused by temperature and also by AMF. We found that inoculation with AMF in a microcosm study using Plantago lanceolata grown at various temperatures, with and without AMF, showed no clear effect of AMF on branching patterns. Temperature had a significant effect on total lengths, numbers and branching rates of some higher orders of roots. Total lengths of both secondary and tertiary roots grown at 27°C were about double those of plants grown at 15°C. Colonization by AMF tended to reduce this effect. Evidently the effect of colonization by AMF on root lifespan depends on the species. Increased branching, and thus a greater proportion of ephemeral roots, was responsible for shortening the lives of the roots at increased temperature, which suggests a strong link between lifespan and morphology.  相似文献   

17.
人工石质边坡构树根系抗剪特性研究   总被引：1，自引：0，他引：1  
研究构树根系抗剪切特性,可为岩石边坡生态防护提供理论依据。采用室内单根抗剪切试验分析了上、下坡向,一级、二级、三级侧根的抗剪切强度和应力—应变曲线。结果表明:下坡向根系数量、根径大于上坡向,根系平均长度小于下坡向;根系的剪切力-应变曲线与其生长方位、根径、根系分级有相似的曲线形状;分级根系的剪切力为一级>二级,下坡向一级根系剪切力大于上坡向,但二级根系剪切力反而小,最大剪切力随根径增加而增大;根系的抗剪强度随着根径的增大而减小,呈线性关系;抗剪强度值随着根径的而增大;下坡向根系平均抗剪强度大于上坡向,各根系平均抗剪强度为一级>二级>三级,但上下坡向和各级根系间无显著差异。抗剪强度是影响边坡稳定的重要因素,它既可以加固土体,又能影响植物的锚固作用。  相似文献   

18.
Soil replant disease is the main bottleneck interfering with tree growth of peach in soils with poor traits. A potted study was conducted to evaluate the effects of inoculation with an arbuscular mycorrhizal fungus (AMF), Acauloapora scrobiculata, on plant growth, mineral nutrients, soil enzyme activities, soil microbial populations, and root exudate compositions of peach (Prunus persica L. Batsch) seedlings grown in replant soil and non-replant soil. After 15 weeks in AMF inoculation, replant soil heavily inhibited root mycorrhizal colonization. In replant soil, AMF inoculation significantly increased shoot biomass and root phosphorus, potassium, calcium, copper, zinc, iron, and boron concentrations. Mycorrhizal peach seedlings showed a higher number of soil bacteria and total microbes but a lower number of soil fungi under replant conditions, as well higher soil urease and acid phosphatase activity and lower soil sucrase and catalase activity. Greater soil aggregate stability was observed in mycorrhiza-inoculated replant soil than in non-mycorrhizal soil due to the increase of water-stable aggregates in 2–4 mm and 1–2 mm size. In addition, a total of 92 substances were identified in root exudates, and the mycorrhizosphere had considerably more root exudate compositions. AMF inoculation had a significantly inhibitive effect on the relative abundance of allelochemical substances, including benzoic acid, benzaldehyde, diisooctyl phthalate, phenols, and sterols, while there was an increase in diphenyl-ethanedione and à-(benzoyloxy)-benzeneacetonitrile in replanted peach. It was concluded that AMF inoculation could partly mitigate soil replant disease of peach through modulating soil microbe balance, improving soil aggregate stability, and changing root exudate compositions.  相似文献   

19.
Two microcosm experiments were conducted to study the role of extraradical mycelium (ERM) of arbuscular mycorrhizal fungi (AMF) in establishment and growth of tree species used for revegetation in anthropogenic substrates. Inoculated or non-inoculated Acer pseudoplatanus, Alnus glutinosa or Salix purpurea seedlings were grown with Calamagrostis epigejos (a grass spontaneously colonising degraded ecosystems) in two substrates (fly ash and coal mine spoil) either in direct root contact or in rhizoboxes with interaction only via ERM network. In both experiments, inoculation with AMF mostly had a positive effect on the growth of trees and increased the aggregation of fly ash. When plants grew in direct root-to-root contact, grass presence negatively affected tree growth, but it significantly improved mycorrhizal development (colonization of tree seedlings, spore number and ERM length). When grass and tree roots interacted via the ERM network, tree seedlings were successfully colonised by the ERM spreading from the C. epigejos roots. Mechanical disturbance of the ERM links between plants reduced AMF development and tree height in both substrates, but tree shoot biomass was not affected. In fly ash, inoculated, non-disturbed treatments showed significant transfer of 32P from the grass to the tree seedlings. It can be concluded that roots of A. pseudoplatanus, A. glutinosa or S. purpurea seedlings can be colonised from the ERM network radiating from quickly growing grasses, which can act as important agents for AMF distribution and facilitate mycorrhization of planted trees. In particular for willow, grass seems to be an essential nurse plant to achieve successful root colonisation.  相似文献   

20.
Heavy metal(HM) contamination in soils is an environmental issue worldwide that threatens the quality and safety of crops and human health. A greenhouse experiment was carried out to investigate the growth, mycorrhizal colonization, and Pb and Cd accumulation of pakchoi(Brassica chinensis L. cv. Suzhou) in response to inoculation with three arbuscular mycorrhizal(AM) fungi(AMF), Funneliformis mosseae, Glomus versiforme, and Rhizophagus intraradices, aimed at exploring how AMF inoculation affected safe crop production by altering plant-soil interaction. The symbiotic relationship was well established between pakchoi and three AMF inocula even under Pb or Cd stress, where the colonization rates in the roots ranged from 24.5% to 38.5%. Compared with the non-inoculated plants, the shoot biomass of the inoculated plants increased by 8.7%–22.1% and 9.2%–24.3% in Pb and Cd addition treatments, respectively. Both glomalin-related soil protein(GRSP) and polyphosphate concentrations reduced as Pb or Cd concentration increased. Arbuscular mycorrhizal fungi inoculation significantly enhanced total absorbed Pb and Cd(except for a few samples) and increased the distribution ratio(root/shoot) in pakchoi at each Pb or Cd addition level. However, the three inocula significantly decreased Pb concentration in pakchoi shoots by 20.6%–67.5% in Pb addition treatments, and significantly reduced Cd concentration in the shoots of pakchoi in the Cd addition treatments(14.3%–54.1%), compared to the non-inoculated plants.Concentrations of Pb and Cd in the shoots of inoculated pakchois were all below the allowable limits of Chinese Food Safety Standard.The translocation factor of Pb or Cd increased significantly with increasing Pb or Cd addition levels, while there was no significant difference among the three AMF inocula at each metal addition level. Meanwhile, compared with the non-inoculated plants, AMF inocula significantly increased soil p H, electrical conductivity, and Pb or Cd concentrations in soil organic matter in the soils at the highest Pb or Cd dose after harvest of pakchoi, whereas the proportion of bioavailable Pb or Cd fraction declined in the AMF inoculated soil. Our study provided the first evidence that AM fungi colonized the roots of pakchoi and indicated the potential application of AMF in the safe production of vegetables in Pb or Cd contaminated soils.  相似文献   

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