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1.
以滇西北香格里拉亚高山地区生态严重退化的荒草坡植被类型和基本实现恢复的近原生林地植被类型中主要植物的丛枝菌根真菌(AMF)作为研究对象,对这些植物根系的AMF感染率及其根际土壤中的AMF孢子密度进行了调查研究。结果表明,荒草坡的10种植物和近原生林地的9种植物,均形成典型的丛枝菌根(AM)。荒草坡和近原生林植物根际土壤中的平均孢子密度分别为674±221(SE)个/100g土和290±72个/100g土。单因素方差分析表明,两植被类型的主要植物在根系AMF菌丝感染率以及根际土壤中AMF孢子密度方面的差异都极显著。同种植物在近原生林地具有较高的AMF感染率,而根际土壤中的孢子密度则是在荒草坡为高。相关性分析表明,所调查植物的根系AMF菌丝感染率与根际土壤中的AMF孢子密度间不存在相关性。  相似文献   

2.
为探明不同套种模式核桃根际丛枝菌根(AM)与土壤因子之间的相关关系,采用菌根形态学的研究方法,研究了核桃根系中丛枝菌根真菌(AMF)定殖状况和根际土壤中AMF的孢子密度,运用相关分析、主成分分析和通径分析方法,研究了核桃AMF与土壤因子的相关性。结果表明:核桃根系能与AMF形成良好的共生关系,不同套种模式之间核桃根系中AMF定殖率以及孢子密度差异显著,套种茶树的种植园中AMF的侵染率和孢子密度最高,套种豌豆的种植园中AMF侵染率和孢子密度最低;AMF孢子密度与土壤有机质、pH值、碱性磷酸酶和脲酶活性显著正相关;AMF总侵染率与pH值显著正相关;AMF总侵染率、菌丝侵染率和孢子密度与全磷显著负相关;丛枝侵染率与全氮和碱性磷酸酶活性显著正相关;菌丝侵染率与pH值极显著正相关;菌丝圈侵染率与全氮和碱性磷酸酶活性显著正相关;泡囊侵染率与过氧化氢酶活性显著正相关,与水解氮和速效钾极显著负相关,与土壤有机质和全氮显著负相关。土壤中的有机质、全氮和全磷是云南高原山区核桃菌根真菌定殖和发育的主要影响因子。  相似文献   

3.
In Argentina, the Yungas forests are among the ecosystems most affected by human activity, with loss of biodiversity. To assess the mycorrhizal status in these ecosystems, the roots of 41 native plant species belonging to 25 families were collected throughout the year from two sites of the Yungas forests. Roots were washed and stained to study the presence of arbuscular mycorrhizas (AM). Morphological types of arbuscular mycorrhizas (Arum and Paris-type) and colonization patterns were identified and photographed. All plants presented AM colonization. The AM colonization patterns varied from single intracellular aseptate hyphae, coils, appresoria, to vesicles and/or arbuscules. Among the species studied, the Paris-type colonization showed to be dominant. Results confirmed that AM hosts are predominant in the Yungas of South American forests.  相似文献   

4.
Polylepis forests are one of the most endangered high mountain ecosystems of South America and reforestation with native Polylepis species has been highly recommended. Greenhouse bioassays were set up to determine the influence of three different soils on growth and phosphorous nutrition of Polylepis australis seedlings. Soils were collected from a grassland, a rare mature forest and a forest degraded due to repeated fires. We identified the arbuscular mycorrhizal fungi (AMF) present in the three soils and after 12 months we harvested the seedlings to evaluate root and shoot biomass, plant P content and root colonization by native AMF and dark septate endophytes (DSE). The soil inocula contained 26 AMF morphospecies. Grassland inoculum showed the highest AMF richness, and mature forest showed a different AMF community assembly from grassland and degraded forest inocula. Root biomass and root colonization were highest in seedlings inoculated with mature forest soil, meanwhile shoot biomass and plant P content were similar between all treatments. AMF colonization correlated negatively with DSE and root biomass was negatively correlated with DSE colonization, thus these fungal symbionts could be competing for resources. Our results indicate that AMF inoculum from the mature forest stand has the potential to improve P. australis performance, probably due to the dominance of Glomeraceae and Acaulosporaceae families. However, other soil microorganisms could be together with AMF in the natural inocula, affecting the growth response of P. australis seedlings. Future studies evaluating the effect of these inocula under field conditions should be carried out.  相似文献   

5.
广东清远石灰岩3个植物群落菌根及土壤AMF孢子多样性   总被引:1,自引:0,他引:1  
以广东省清远市清新县石灰岩山区风水林、次生草坡和旱作耕地的退化植被群落为主要研究对象,比较研究了3个植物群落常见植物的菌根感染率和根际土丛枝型菌根真菌(AMF)孢子的密度和丰富度。结果如下:在所检测的29种常见植物中,除凹头苋(Amaranthus blitum)外,其余植物均具有典型的丛枝型菌根结构;次生草坡植物的菌根感染强度和频度均较高,风水林次之,旱作耕地杂草的菌根感染强度和频度相对较低;在3个植物群落土样中共分离出70种AMF孢子,以球囊霉属(Glomus)最为丰富,无梗囊霉属(Acaulospora)次之;林相保护较完整、植物较丰富的风水林拥有最丰富的AMF孢子类型和最高的密度,而结构退化、物种贫乏的次生草坡和旱作耕地中的AMF孢子类型少,密度也明显降低。研究表明植物群落的物种多样性与其根际土AMF孢子丰富度和多样性具有密切的联系。  相似文献   

6.
This study assessed the arbuscular mycorrhizal (AM) status of Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands in relation to season, management and soil depth in Ethiopia. We studied 43 woody species in 52 plots in three areas. All woody species were colonized by AM fungi, with average root colonization being relatively low (16.6% – ranging from 0% to 95%). Mean spore abundance ranged from 8 to 69 spores 100 g−1 of dry soil. Glomus was the dominant genus in all study sites. Season had a strong effect on root colonization and spore abundance. While spore abundance was higher (P < 0.001) in the dry season in all three study sites, root colonization showed a more variable response. Root colonization was reduced in the dry season in the site that was least subject to stress, but increased in the dry season in the harshest sites. Management in the form of exclosures (that exclude grazing) had a positive effect on spore abundance in one of the two sites considered. Spore abundance did not significantly differ (P = 0.17) between the two soil depths. Our results show that in this arid region all trees are mycorrhizal. This has profound consequences for rehabilitation efforts of such dry deciduous woodlands: underground processes are vital for understanding species adaptation to pulsed resource availability and deserve increasing attention.  相似文献   

7.
The biodiversity of arbuscular mycorrhizal fungi (AMF) was surveyed in the Kolm region of Iran in three adjacent sites, a natural stand, a 10-year-old and a 15-year-old plantation of Amygdalus scoparia. To date, there have been few studies of AMF biodiversity in Iran, especially in the western forests of the country. For this study, soil and root samples were taken from A. scoparia rhizosphere soil in spring and autumn. Almost half of the root length was colonized by AMF. We identified 13 AMF species belonging to Glomeraceae, Claroideoglomeraceae or Diversisporaceae. The three plantations differed in terms of soil electrical conductivity, organic C and P. Spore density was significant correlated with P concentration. Root length colonization was correlated only with soil Ca. Species diversity and richness were significantly correlated with soil N, P, organic C and spore density. AMF diversity in 15-year-old plantations was more similar to that in the natural stand than in the 10-year-old plantation. We confirmed that a 15-year-old plantation is not similar in terms of AMF colonization to natural stands. We conclude that more than 15 years are required for AMF colonization of plantations to resemble that of natural stands.  相似文献   

8.
This paper investigates the distribution of arbuscular mycorrhizal fungi (AMF) spores and AMF colonization in a field study in southeastern Brazil. Response to AMF and rhizobial inoculation was studied in monocultures of Plathymenia reticulata and mixed plantations with both Tabebuia heptaphylla and Eucalyptus camaldulensis in a sandy soil during two consecutive years. P. reticulata height and diameter and mycorrhizal colonization and AMF diversity were measured in dry and rainy periods. The inoculated treatment of E. camaldulensis, T. heptaphylla and P. reticulata mixed plants showed higher height and diameter growth of P. reticulata used as well as increased root colonization and AMF spore numbers. Spore populations were found to belong to five genera: Acaulospora, Entrophospora, Glomus, Gigaspora and Scutellospora, with Glomus dominating. Agroforestry practices including use of leguminous tree P. reticulata effectively maintained AMF spore numbers in soils and high AMF colonization levels compared with monocultures, proving an efficient system for productivity and sustainability.  相似文献   

9.
The biodiversity of arbuscular mycorrhizal fungi(AMF) was surveyed in the Kolm region of Iran in three adjacent sites, a natural stand, a 10-year-old and a 15-yearold plantation of Amygdalus scoparia. To date, there have been few studies of AMF biodiversity in Iran, especially in the western forests of the country. For this study, soil and root samples were taken from A. scoparia rhizosphere soil in spring and autumn. Almost half of the root length was colonized by AMF. We identified 13 AMF species belonging to Glomeraceae, Claroideoglomeraceae or Diversisporaceae. The three plantations differed in terms of soil electrical conductivity, organic C and P. Spore density was significant correlated with P concentration. Root length colonization was correlated only with soil Ca.Species diversity and richness were significantly correlated with soil N, P, organic C and spore density. AMF diversity in 15-year-old plantations was more similar to that in the natural stand than in the 10-year-old plantation. We confirmed that a 15-year-old plantation is not similar in terms of AMF colonization to natural stands. We conclude that more than 15 years are required for AMF colonization of plantations to resemble that of natural stands.  相似文献   

10.
A survey of 35 tree species(belonging to 28 genera in 19 families) in Aliyar,South India was carried out to ascertain their arbuscular mycorrhizal(AM) and dark septate endophyte(DSE) fungal status.All the tree species examined had AM association.AM and DSE colonization is reported for the first time in 20 and 14 species respectively.Cooccurrence of AM and DSE was observed in 14(40%) tree species.The extent of DSE colonization was inversely related to the extent of AM fungal colonization.Six tree species had Arum-type,18 had intermediatetype and 11 had typical Paris-type AM morphology.AM fungal spore morphotypes belonging to 11 species in two genera were isolated from the rhizosphere soil.AM fungal spore numbers were not related to the extent of AM colonization and Glomus dominated spore diversity.AM association individually and along with DSE were found respectively in the 63% and 44% of the economically important tree species.The occurrence of AM and DSE fungal association in economically important indigenous tree species indicates the possibility of exploiting this association in future conservation programmes of these species.  相似文献   

11.
Studies were carried out on the arbuscular mycorrhizal (AM) fungal association in four potential timber yielding tree species from four forest areas of the Western Ghat region of Goa, India. The edaphic factors selected for the study varied within the four study sites. Significant positive and negative correlations were exhibited between spore density and root colonization of AM fungi at two sites, Collem and Dharbandoda. The study recorded the presence of 21 AM fungal species belonging to three genera—viz., Acaulospora, Gigaspora, and Glomus. The present study suggests that there is a site specific variation in root colonization (except at Mollem) and spore density as well as edapho-specific variation in association, composition, and distribution of AM fungi associated with potential timber yielding trees from four forest areas in the Western Ghat region of Goa. Further investigations of AM fungal dynamics if carried out can help elucidate the ecological significance of AM fungal associations in the Western Ghat region of Goa. To add, learning more about the ecology and intricacies of the AM association is crucial for attaining a good understanding of its life cycle and functions in edapho-climatic conditions of the Western Ghat region of Goa to further use it in the management of reforestation practices.  相似文献   

12.
The level of colonization by ectomycorrhizae (ECM) and arbuscular endomycorrhizae (AM) of 23 species of native trees and shrub legumes was studied. Root samples were obtained from different regions of Uruguay. Colonization level was determined by observing AM fungal structures (hyphae, arbuscules, vesicules) in stained root segments. The number and morphological type of spores were determined in 100 g of rhizosphere soil. Ectomycorrhizal colonization was evaluated by direct and microscopic observation of root tips. All species had a high level of AM colonization. In Papilionoideae colonization varied between 62% and 78%, in the Mimosoideae between 18% and 69% and in the Caesalpinioideae the variation was larger (6–74%). These results show a significant presence of fungi that form arbuscular mycorrhizae in our soils. The number of spores forming AM in rhizosphere soil (280–l.620 spores/100 g of dry soil) was also highly relative to references for other leguminous trees. Spores were grouped in three principal morphological types Acaulospora, Glomus and Sclerocystis. Presence of ECM fungi was evident only when observed under the microscope. 26% of the plant species exhibited this type of mycorrhizae, reaching a maximal value of 36% in Mimosoideae. Only six plant species exhibited both types of mycorrhizae. Dual colonization could help in the colonization of poor soils and for their use in agroforestry systems.  相似文献   

13.
Mycorrhizal associations of important tree species were investigated within the research area of the Tropenbos Cameroon Programme (TCP), situated on the western portion of the Atlantic Biafrean forest of south Cameroon. Ninety-seven tree species of economic, social, and ecological importance, and three lianas were selected in three sites that differed in altitude, soil clay content, and soil pH. In each site plots were laid out in undisturbed forest. In each plot, seedlings, saplings, juvenile, and mature trees were identified to species level and counted; girth at breast height measured and basal area calculated; root samples were taken and examined for mycorrhizal type and extent of mycorrhizal colonization.

All 100 species investigated were mycorrhizal. Tree of 74 species formed exclusively arbuscular mycorrhizas (AM); 23 trees and three Gnetum species formed ectomycorrhizas (ECM). Five of these ECM plants also harbored AM structures. Extent of mycorrhizal root colonization showed large differences for various AM trees; however, colonization of more than half of these trees was less than 25%. Colonization of ECM trees was often higher than 75%. The contribution of ECM trees to basal area varied between 19 and 35%. ECM trees often occurred in small to large clumps. In sustainable forest management plans, existing ECM forest clumps should be given special conservation value.  相似文献   


14.
Mexican montane rainforests and adjacent disturbed areas were studied for disturbance-related spatio-temporal changes to the arbuscular mycorrhizal fungal (AMF) community and soil glomalin concentration. The AMF community functions to both improve plant growth and soil conditions and is thus an important component to the restoration of this forest type to disturbed areas. The study areas included mature rainforests that were converted to pine forests, milpas, pastures and shrub/herbaceous plant communities via burning and logging. Seasonal patterns in AMF spore species richness and sporulation significantly differed across disturbance types at two of the three sites surveyed. Contrasting patterns of sporulation among AMF families across different disturbance types helped to explain how species richness and composition were maintained despite dramatic changes to the host plant community. Meaning, in most cases, disturbance induced changes in when different AMF taxa sporulated but not what taxa sporulated. Only conversion from mature pine–oak–LiquidambarPersea forests to pine-dominated stands severely reduced AMF spore richness and total sporulation. Surprisingly, in pine-dominant stands no concomitant negative impacts on soil glomalin (MAb32B11 immunoreactive soil protein) concentrations were detected. However, soils of mature forests containing no pines had the highest concentration of glomalin. Conversion to pasture and milpa (diverse cornfield) had a strong negative impact on the concentration of soil glomalin concentrations. In sharp contrast, the same disturbance types improved AMF sporulation and AMF spore richness. It appears that disturbance type, and not AMF community measures used herein, best predicts changes in soil glomalin concentration.  相似文献   

15.
9 mycorrhizal fungi, including 4 ectomycorrhizal fungi (ECMF) and 5 arbuscular mycorrhizal fungi (AMF), were used to explore their effect on seedling growth of Mytilaria laosensis. The study shows that M. laosensis is one of the species with both VAM and ECM. Mycorrhizal infection rate of all ECM inoculation methods reached level 3, and that of AMF infection rate was 88%-93%, of which AM91 became the highest. In different periods, different inoculation treatment expressed different effects on seedling growth. At the end of the experiment, the height, ground diameter, underground dry mass and upper ground dry mass of seedling inoculated with PX0801 and 9006 respectively increased by 71%, 45%, 128%, 184%, and 65%, 54%,150%, 208%, which exhibited the best overall effect. Coinoculated seedlings with AM90036, AM3008 and AM91 had advantages over uninoculated ones in all the tested growth indicators, which suggest to significantly promote the growth of M.laosensis. The results obtained provide reference for mycorrhizal fungi application on M. laosensis.  相似文献   

16.
Establishment of Polylepis forests endemic to the mountains of South America may be affected by seed dispersal, site characteristics and livestock density. Polylepis australis (“tabaquillo”) grows in the high mountains of central Argentina, where we set up 76 square study plots of 900 m2. To determine dispersal distance, we distributed 6 seed traps per plot in and around 20 plots. To determine the best site characteristics and livestock stoking rates, at two river basins differing in historic stocking rates, we analyzed the presence of seedlings in 56 plots and recorded topography, vegetation types and indicators of livestock activity. We also measured microsite characteristics in a sample of 32 comparable pairs of 1 m2 quadrats, with and without seedlings. Maximum recorded dispersal distance of P. australis seeds was 6 m, and seedlings were found no more than 10 m from seed trees. The numbers of seedlings and seed trees were 3.5 and 4 times higher, respectively, in the basin with less livestock. At the 900 m2 plot scale, a Poisson regression indicated a positive relationship between seedling number and P. australis canopy cover. At the quadrat scale (1 m2), seedlings were found in quadrats with significantly lower evidence of soil erosion than comparison quadrats without seedlings. We conclude that the main limitations to recruitment are short seed dispersal distances, lack of seed trees and extreme soil erosion. Management should therefore aim at preserving seed trees and reducing livestock density to prevent erosion.  相似文献   

17.
The tree species Alnus acuminata and Morella pubescens, native to South America, are candidates for soil quality improvement and afforestation of degraded areas and may serve as nurse trees for later inter-planting of other trees, including native crop trees. Both species not only form symbioses with arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF), but also with N2-fixing actinobacteria. Because tree seedlings inoculated with appropriate mycorrhizal fungi in the nursery resist transplanting stress better than non-mycorrhizal seedlings, we evaluated for A. acuminata and M. pubescens the potential of inoculation with mycorrhizal fungi for obtaining robust tree seedlings. For the first time, a laboratory-produced mixed AMF inoculum was tested in comparison with native soil from stands of both tree species, which contains AMF and EMF. Seedlings of both tree species reacted positively to both types of inocula and showed an increase in height, root collar diameter and above- and belowground biomass production, although mycorrhizal root colonization was rather low in M. pubescens. After 6 months, biomass was significantly higher for all mycorrhizal treatments when compared to control treatments, whereas aboveground biomass was approximately doubled for most treatments. To test whether mycorrhiza formation positively influences plant performance under reduced water supply the experiment was conducted under two irrigation regimes. There was no strong response to different levels of watering. Overall, application of native soil inoculum improved growth most. It contained sufficient AMF propagules but potentially also other soil microorganisms that synergistically enhance plant growth performance. However, the AMF inoculum pot-produced under controlled conditions was an efficient alternative for better management of A. acuminata and M. pubescens in the nursery, which in the future may be combined with defined EMF and Frankia inocula for improved management practices.  相似文献   

18.
Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas.We assessed arbuscular mycorrhizal fungi(AM)status of Faidherbia albida(Del.)A.Chev.trees grown on different land uses.We quantified the growth and nutrient uptake of F.albida seedlings inoculated with AM from different sources.These efforts were based on soil and fine root samples from the rhizosphere soils of F.albida trees.AM root colonization was determined using the gridline intersect method.Spores were extracted by the wet sieving and decanting method and identified to genus level.The seedling experiment had a completely randomized onefactorial design with four treatments and five replications.Faidherbida albida seedlings were grown in a greenhouse.All in situ F.albida trees were colonized by AM fungi.AM root colonization of F.albida trees was significantly higher(P<0.0086)in area exclosures than on lands used for grazing or cultivation.Spore abundance was significantly higher(P<0.0014)in area exclosures followed by cultivated land and grazing land.Glomus was the dominant genus in all land-uses.AM-inoculated F.albida seedlings grew better(P<0.05)than non-inoculated controls.Seedlings inoculated with AM from area exclosure had significantly(P<0.05)higher growth and nutrient uptake than those inoculated with AM from grazing and cultivated land.This emphasizes the importance of the native soil AM potential for better establishment of seedlings to achieve optimum plant growth improvement and assist in rehabilitation of degraded arid lands.  相似文献   

19.
The integration of N2 fixing trees into stable agroforestry systems in the tropics is being tested due to their ability to produce high biomass N and P yields, when symbiotically associated with rhizobia and mycorrhizal fungi. The growth of Centrolobium tomentosum Guill. ex Benth, a native leguminous tree from the Brazilian Atlantic Forest, was assessed with dual inoculation of Rhizobium spp and mycorrhizal fungi under field conditions. Complete fertilization was compared to treatments of inoculation with selected rhizobia strains BHICB-Ab1 or BHICB-Ab3, associated or not to arbuscular mycorrhizal (AM) fungi. The dual inoculation increased the height and growth in relation to the plants treated with rhizobia alone. Plants inoculated with strain BHICB-Ab1 and arbuscular mycorrhizal fungi (AMF) exhibited an increase of 56% dry matter over uninoculated control and nitrogen accumulation was greater than with BHICB-Ab3 inoculated plants. Strain BHICB-Ab1 presented a synergetic relationship with mycorrhizal fungi since the combined inoculation with BHICB-Ab1 enhanced plant height and dry weight more than single inoculation while the growth of BHICB-Ab3 plants was not modified by AMF inoculation. Arbuscular mycorrhizal fungi enhanced plants survival and seemed to favour the nodule occupation by rhizobia strains as compared to the non-mycorrhizal plants. Inoculation with selected rhizobia and AMF improved the growth of C. tomentosum under field conditions. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

20.
Effects of mycorrhizal association on improving tolerance of host plant under stress environments have received attentions in recent years. In this paper, six isolates of AMF (arbuscular mycorrhizal fungus) were inoculated to Casuarina equisetifolia seedlings under glasshouse conditions to investigate the effects of AMF on growth and drought tolerance of host plants. All the six isolates which belong to Glomus showed high mycorrhizal colonization (88.5–96.0%) with C. equisetifolia seedlings. Seedlings were subjected to drought stress without watering for 7 days and survival of the seedlings inoculated with Glomus caledonium Gc90068, G. versiforme Gv9004 and G. caledonium Gc90036 increased by 36.6, 23.3 and 16.6%, respectively compared with uninoculated seedlings. Limited influence of AMF on seedling height growth was found, but the effects of AMF on total biomass increment were very significant; the increment ranged from 25.7 to 118.9% compared with uninoculated treatment, and it was noted that AMF exerted more influences on root biomass than shoot biomass. Based on the changes in physiological and biochemical parameters among different treatments caused by drought stress, it was concluded that AM (arbuscular mycorrhizal) associations improve the drought tolerance of C. equisetifolia seedlings by means of some physiological and biochemical responses, such as lowering permeability of plasma membrane and MDA (malondialdehyde) contents, enhancing concentrations of P nutrition, soluble sugar, soluble protein and activities of POX (Peroxidase) of C. equisetifolia seedlings.  相似文献   

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