Rates and quantities of carbon flux to ectomycorrhizal mycelium following 14C pulse labeling of Pinus sylvestris seedlings: effects of litter patches and interaction with a wood-decomposer fungus

We used a novel digital autoradiographic technique that enabled, for the first time, simultaneous visualization and quantification of spatial and temporal changes in carbon allocation patterns in ectomycorrhizal mycelia. Mycorrhizal plants of Pinus sylvestris L. were grown in microcosms containing non-sterile peat. The time course and spatial distribution of carbon allocation by P. sylvestris to mycelia of its mycorrhizal partners, Paxillus involutus (Batsch) Fr. and Suillus bovinus (L.): Kuntze, were quantified following 14C pulse labeling of the plants. Litter patches were used to investigate the effects of nutrient resource quality on carbon allocation. The wood-decomposer fungus Phanerochaete velutina (D.C.: Pers.) Parmasto was introduced to evaluate competitive and territorial interactions between its mycelial cords and the mycelial system of S. bovinus. Growth of ectomycorrhizal mycelium was stimulated in the litter patches. Nearly 60% of the C transferred from host plant to external mycorrhizal mycelium (> 2 mm from root surfaces) was allocated to mycelium in the patches, which comprised only 12% of the soil area available for mycelial colonization. Mycelia in the litter patch most recently colonized by mycorrhizal mycelium received the largest investment of carbon, amounting to 27 to 50% of the total 14C in external mycorrhizal mycelium. The amount of C transfer to external mycelium of S. bovinus following pulse labeling was reduced from a maximum of 167 nmol in systems with no saprotroph to a maximum of 61 nmol in systems interacting with P. velutina. The 14C content of S. bovinus mycelium reached a maximum 24-36 h after labeling in control microcosms, but allocation did not reach a peak until 56 h after labeling, when S. bovinus interacted with mycelium of P. velutina. The mycelium of S. bovinus contained 9% of the total 14C in the plants (including mycorrhizae) at the end of the experiment, but this was reduced to 4% in the presence of P. velutina. The results demonstrate the dynamic manner in which mycorrhizal mycelia deploy C when foraging for nutrients. The inhibitory effect of the wood-decomposer fungus P. velutina on C allocation to external mycorrhizal mycelium has important implications for nutrient cycling in forest ecosystems.     

Effect of ammonium on glutamine synthetase activity in ectomycorrhizal fungi, and in mycorrhizal and non-mycorrhizal Scots pine seedlings

The influence of ammonium on glutamine synthetase activity (GS, EC 6.3.1.2) was studied in three species of ectomycorrhizal fungi, Paxillus involutus (Batsch:Fr) Fr, Piloderma croceum Erikss. and Hjortst. and Suillus variegatus (Fr) O Kuntze growing in pure culture, as well as in the roots and needles of nursery-grown, non-mycorrhizal and mycorrhizal Scots pine (Pinus sylvestris L.) seedlings inoculated with Paxillus involutus or Piloderma croceum as the symbiont. In response to increasing concentrations of ammonium in the nutrient solution, GS activity (expressed on a dry weight basis) increased slightly in Suillus variegatus but not in the other fungi. Glutamine synthetase activity increased in the roots and decreased in the needles of non-mycorrhizal seedlings as the ammonium concentration in the nutrient solution was increased from 0 to 1 mM, but no response was noted with further increases from 1 to 12 mM. Interspecies differences in GS activity were noted among the fungi growing in pure culture, but no significant interspecies differences were observed among the same fungi in the mycorrhizal state.     

Growth and nutrient uptake of ectomycorrhizal Pinus sylvestris seedlings in a natural substrate treated with elevated Al concentrations

Models of the effects of elevated concentrations of aluminum (Al) on growth and nutrient uptake of forest trees frequently ignore the effects of mycorrhizal fungi. In this study, we present novel data indicating that ectomycorrhizal mycelia may prevent leaching of base cations and Al. Mycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings were grown in sand obtained from the B-horizon of a local forest. In Experiment 1, non-mycorrhizal seedlings and seedlings inoculated with Hebeloma cf. longicaudum (Pers.: Fr.) Kumm. ss. Lange or Laccaria bicolor (Maire) Orton were provided with nutrient solution containing 2.5 mM Al. Aluminum did not affect growth of non-mycorrhizal seedlings or seedlings inoculated with L. bicolor. Seedlings colonized by H. cf. longicaudum had the highest biomass production of all seedlings grown without added Al, but the fungus did not tolerate Al. Shoots of seedlings colonized by L. bicolor had the lowest nitrogen (N) concentrations but the highest phosphorus (P) concentrations of all seedlings. The treatments had small but significant effects on shoot and root Al concentrations. In Experiment 2, inoculation with L. bicolor was factorially combined with the addition of a complete nutrient solution, or a solution lacking the base cations K, Ca and Mg, and solutions containing 0 or 0.74 mM Al. Seedling growth decreased in response to 0.74 mM Al, but the effect was significant only for non-mycorrhizal seedlings. Mycorrhizal seedlings generally had higher P concentrations than non-mycorrhizal seedlings. Aluminum reduced P uptake in non-mycorrhizal plants but had no effect on P uptake in mycorrhizal plants. Mycorrhizal colonization increased the pH of the soil solution by about 0.5 units and addition of Al decreased the pH by the same amount. We conclude that the presence of ectomycorrhizal mycelia decreased leaching of base cations and Al from the soil.     

毛白杨苗期VA菌根菌与外生菌根菌接种的研究

1998～1999年在田间条件下布置了毛白杨VA菌根(包括根内球囊霉菌和单孢球囊霉菌)与外生菌根硬皮马勃混合接种试验.结果表明接种菌根菌对毛白杨苗高生长量有促进作用,且以根内球囊霉菌作用最明显,单孢球囊霉菌处理次之,硬皮马勃处理最差.水涝大大降低人工接种菌根菌的效果,严重影响VA菌根和外生菌根菌单独接种及混合接种的效应,根内球囊霉菌甚至会抑制毛白杨苗木的高生长,VA菌根和外生菌根间的负交互作用也不对苗高生长产生影响.菌根真菌的感染率随时间变化出现较大的波动和变化.     

The effect of Paxillus involutus Fr. on aluminum sensitivity of Norway spruce seedlings

Non-mycorrhizal Norway spruce seedlings (Picea abies Karst.) and Norway spruce seedlings colonized with Paxillus involutus Fr. were grown in an axenic silica sand culture system. After successful mycorrhizal colonization, the seedlings were exposed to 200 or 800 micro M AlCl(3) for 10 weeks. In both non-mycorrhizal and mycorrhizal seedlings, exposure to Al significantly reduced root growth and the uptake of Mg and Ca. After 5 weeks of exposure to 800 micro M Al, the mycorrhizal seedlings had significantly higher chlorophyll concentrations than the non-mycorrhizal seedlings, although no difference in Mg nutrition was apparent. After 10 weeks of exposure to Al, both non-mycorrhizal and mycorrhizal seedlings exhibited needle chlorosis and reduced photosynthetic activity. However, the aluminum-induced reduction in shoot growth was largely ameliorated by colonization with P. involutus. We conclude that mycorrhizal colonization modifies the phytotoxic effects of Al in Norway spruce seedlings. However, differences in physiological responses to Al between mycorrhizal and non-mycorrhizal seedlings may be largely reduced in the long term as a result of impaired mineral nutrient uptake.     

丛枝菌根对喜树幼苗的生长效应

2005年2月精选喜树种子培养无菌根幼苗,生长90天以后分别接种3种丛枝菌根真菌,即蜜色无梗囊霉(Acaulospora mellea)、透光球囊霉(Glomus diaphanum)和弯丝硬囊霉(Sclerocystis sinuosa),探讨了菌根真菌对喜树幼苗株高、生物量以及氮、磷吸收的影响。结果表明,丛枝菌根的形成显著促进了菌根幼苗的高生长和生物量的积累,对喜树幼苗氮素营养的吸收影响不大,但却有利于喜树幼苗对磷素营养的吸收。从植株高度和生物量来看,菌根幼苗优于无菌根幼苗,蜜色无梗囊霉菌根幼苗尤为突出,分别达到无菌根幼苗(CK)的1.2和1.6倍,差异显著。丛枝菌根的形成对喜树幼苗氮素营养的吸收影响不大。从全株的氮含量来看,菌根幼苗与无菌根幼苗相近,只有在根、茎和叶片中Am菌根幼苗的氮含量才有明显变化,而透光球囊霉和弯丝硬囊霉菌根幼苗与无菌根幼苗之间则没有显著差异。丛枝菌根的形成总体上促进了喜树幼苗对磷素营养的吸收,并且主要体现在根的磷含量上。与无菌根幼苗比,所有菌根幼苗根的氮、磷分配比例增加,而茎和叶片的氮、磷分配比例减少。图2表2参13。     

浙江天童常绿阔叶林中马尾松菌根研究

通过对浙江天童常绿阔叶林中马尾松的菌根研究,比较分析了马尾松在不同样地及不同季节菌根感染率的状况,结果表明,菌根感染率与季节及样地类型有密切的联系,12月份左右,在裸地中菌根感染率较低,只有2.67%;而7月份左右,在马尾松林中,菌根感染率达到了76%.其次,通过一年多对各样地子实体的采集研究和实验室分析,确定在这个阔叶林中与马尾松共生的菌根真菌共4科6属8种,其中硬皮马勃科（Scleroderrnataceae）豆马勃属（Pisolithus）的彩色豆马勃（P.tinctorius（Pers.））和大包硬皮马勃（S.bovista Fr.）以及红菇科（Russulacese）乳菇属（Lactarius Dcex Gray）的松乳菇（L.deliciosus（L.ex.Fr）Gery）分布较广泛,在多数样地中均可找到相应的子实体.最后,本文通过菌根在生态系统中的作用,初步探讨了菌根与常绿阔叶林整体退化机制之间的关系.     

Nutrient uptake by intact mycorrhizal Pinus sylvestris seedlings: a diagnostic tool to detect copper toxicity

We developed a nondestructive method for detecting early toxic effects of inflethal copper (Cu) concentrations on ectomycorrhizal and non-mycorrhizal (NM) Scots pine (Pinus sylvestris L.) seedlings. The fungal symbionts examined were Paxillus involutus (Fr.) Fr., Suillus luteus (Fr.) S.F. Gray and Thelephora terrestris (Ehrh.) Fr. The accumulation of Cu in needles and fungal development (ergosterol) in roots and infstrate were assessed. Inorganic phosphate (P(i)) and ammonium (NH(4) (+)) uptake capacities were determined in a semi-hydroponic cultivation system on intact P-limited plants that were exposed for 3 weeks to 0.32 (control), 8 or 16 &mgr;moles Cu(2+). Short-term effects of a 1-hour exposure to 32 &mgr;moles Cu(2+) on nutrient uptake rates were also determined. None of the Cu(2+) treatments affected plant growth or root ergosterol concentrations. The active fungal biomass in infstrate invaded by S. luteus was reduced by 50% in the 16 &mgr;M Cu(2+) treatment compared with the control treatment; however, colonization by S. luteus prevented an increased accumulation of Cu in the needles. In contrast, the 16 &mgr;M Cu(2+) treatment caused a 2.2-fold increase in needle Cu concentration in NM plants. Ergosterol concentrations in the infstrate colonized by P. involutus and T. terrestris were not affected by 16 &mgr;molar Cu(2+). Although P. involutus and T. terrestris were less sensitive to Cu(2+) than S. luteus, T. terrestris did not prevent the accumulation of Cu in needles of its host plant in the 16 &mgr;molar Cu(2+) treatment. Mycorrhizal plants consistently had higher P(i) and NH(4) (+) uptake capacities than NM plants. In the control treatment, specific P(i) uptake rates were almost 10, 4 and 3 times higher in plants associated with P. involutus, S. luteus and T. terrestris, respectively, than in NM plants, and specific NH(4) (+) uptake rates were about 2, 2 and 5 times higher, respectively, than those of NM seedlings. Compared with the corresponding control plants, a 3-week exposure to 8 &mgr;M Cu(2+) had no effect on the nutrient uptake potential of plants. In contrast, the 16 &mgr;M Cu(2+) treatment significantly reduced P(i) uptake capacity of all plants and decreased NH(4) (+) uptake capacity of seedlings colonized by S. luteus or T. terrestris. The 32 &mgr;M Cu(2+) 1-h shock treatment reduced specific NH(4) (+) and P(i) uptake rates of roots colonized by S. luteus to 39 and 77%, respectively, of the original rates. The Cu(2+) 1-h shock treatment reduced the NH(4) (+) uptake rate of NM plants by 51%.     

Effect of the arbuscular mycorrhizae <Emphasis Type="Italic">Glomus fasciculatum</Emphasis> and <Emphasis Type="Italic">G. macrocarpum</Emphasis> on the growth and nutrient content of <Emphasis Type="Italic">Cassia siamea</Emphasis> in a semi-arid Indian wasteland soil

The effect of two arbuscular mycorrhizal (AM) fungi, Glomus fasciculatum and G. macrocarpum on shoot and root dry weights and nutrient content of Cassia siamea in a semi-arid wasteland soil was evaluated. Under nursery conditions, mycorrhizal inoculation improved growth of seedlings. Root and shoot dry weights were higher in mycorrhizal than non-mycorrhizal plants. The concentration of P, K, Cu, Zn and Na was significantly higher in AM inoculated seedlings than in non-inoculated seedlings. Mycorrhization led to decrease in alkalinity of the rhizosphere soil from pH 8.5 to 7.4. Under nursery conditions, the degree of mycorrhizal dependency increased with age of C. siamea seedling. On transplantation to the field, the survival rate of mycorrhizal seedlings (75%–90%) was higher than that of non-mycorrhizal seedlings (40%). Besides better survival rate, AM inoculation improved the growth performance of seedlings in terms of height and stem diameter. Among the two AM fungi used, the efficiency of Glomus macrocarpum was higher than that of G. fasciculatum under both nursery and field conditions.This revised version was published online in May 2005 with corrected page numbers.     

Synergistic effects between Suilllus luteus and Trichoderma virens on growth of Korean spruce seedlings and drought resistance of Scotch pine seedlings

Korean spruce(Picea koraiensis Sieb. El Zucc.)is one of the main afforestation species in northern China.Seedling quality is a critical factor at planting time. To test whether the synergistic growth enhancement of Scotch pine(P. sylvestris var. mongolica) seedlings brought by the plant beneficial fungus Trichoderma virens(J.H. Mill., Giddens and A.A. Foster) Arx and ectomycorrhizal fungus(Suillus luteus(L.) Roussel.) can also benefit Korean spruce seedlings, we examined the effects of S. luteus and T. virens on the growth of P. koraiensis seedlings and drought resistance of P. sylvestris var. mongolica in peat soils. The two fungi were added to sterilized peat soil in pots, and the plants were grown for 4 months. Seedling growth and physiological variables, including mycorrhizal colonization rate of roots,biomass, and chlorophyll content, were examined. The colonization rate of the mycorrhizal fungus on P. koraiensis exceeded 65 %, and the synergism between S. luteus and T.virens enhanced most of the variables for P. koraiensis seedlings after inoculation with S. luteus then 30 days later with T. virens as in our published results for seedlings of P.sylvestris var. mongolica. When seedlings of P. sylvestris var. mongolica were inoculated with this sequence, they became more drought tolerant. T. virens also induced S.luteus to produce-1,3-glucanase and chitinase. This inoculation sequence at planting can thus improve the quality of P. sylvestris var. mongolica and P. koraiensis seedlings and substantiates our previous results.     

Effect of raw humus under two adult Scots pine stands on ectomycorrhization, nutritional status, nitrogen uptake, phosphorus uptake and growth of Pinus sylvestris seedlings

Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth.     

Screenhouse performance of VAM-inoculated seedlings of Leucaena leucocephala (Lam.) De wit. in a phosphorus-deficient and aluminum sulfate-treated medium

The effect of 3 species of vesicular-arbuscular mycorrhizal (VAM) fungi on the growth of Leucaena leucocephala (Lam.) De Wit. in a phosphorus-deficient and aluminumsulfate (AIS)-treated medium was investigated in a screenhouse experiment. Plant height, root length, nodulation, phosphorus uptake and nitrogen fixation were used as indices of plant performance.While there were significant differences among mycorrhizal plants with respect to these indices, they outperformed their non-mycorrhizal counterparts in all respects except in nitrogen content. Of the 3 mycorrhizal species studied, Glomus etunicatum (Becker and Gerd) was the most efficient, followed by Glomus fasciculatum (Thaxter) Gerd and Trappe, and finally, Gigaspora margarita (Becker and Hall). Both aluminumsulfate and mycorrhizal treatments increased shoot dry weight.     

水分胁迫下外生菌根对马尾松幼苗养分吸收的影响

利用接种褐环乳牛肝菌、鸡油菌、彩色豆马勃、土生空团菌的马尾松苗,在温室采用盆栽方法,研究水分胁迫下,不同菌根化苗对养分的吸收情况.结果表明:在水分胁迫下,外生菌根能显著提高马尾松幼苗对N、P、K的吸收.随胁迫加剧,菌根化苗N、P含量和磷酸酶活性均呈先增后降趋势,在中度胁迫时达最大,其中,接种褐环乳牛肝菌l的苗对N、P吸收效果最好,分别比对照增加56.65％和44.32％;接种彩色豆马勃和褐环乳牛肝菌1的马尾松苗的K含量随胁迫的加剧先增后降,在轻度胁迫时达最大,分别比对照增加221.99％和200.00％.N和K主要分布在叶中,而P在根、茎、叶中分布较均匀,菌根的形成有利于马尾松幼苗N、K的上行运输.在轻度和中度胁迫下,接种褐环乳牛肝菌1对提高马尾松苗N、P、K的吸收和含量效果最好,同时也促进了马毛松幼苗生长和抗旱能力的增强.     

应用RAPD分析快速鉴定外生菌根蘑菇分离物的真伪

采用DNA指纹比较技术对部分外生菌根蘑菇分离菌株的真伪进行了鉴定，结果表明：不同来源的点柄乳牛肝菌Suillus granulatus子实体之间的DNA相似系数为0.939。但各菌丝体分离菌株与其来源子实体的DNA相似系数为1.000，每个供试引物获得的RAPD指纹图谱全部对应相同，证实分离物为真正的牛肝菌分离菌株。试验还鉴定与子实体DNA具极高同源性的细裂硬皮马勃Sclerodema areolatum的组织分离菌丝体是真正的分离菌株。供试大红菇Russula rubra分离培养物与供试子实体之间存在很大的DNA异质性，因此判定该分离物为杂菌或其它生物体分离物，并非大红菇的分离菌株。试验结果显示：RAPD指纹技术是外生菌根蘑菇分离物真伪鉴定的一种快速可靠的方法。文章就RAPD鉴定共生真菌分离菌株的可靠性与技术范围进行了讨论。     

Effect of different nitrogen and carbon sources and concentrations on the mycelial growth of ectomycorrhizal fungi under in-vitro conditions

Effect of different nitrogen and carbon sources and their concentrations in liquid media on the mycelial growth of six different ectomycorrhizal (ECM) fungal species was studied. Differences were found in the utilization of the different nitrogen and carbon sources between the fungal species. All the species showed better mycelial growth in the medium containing ammonium as nitrogen source. Growth was low in all species in medium in which nitrogen was supplied in nitrate form. All the ECM isolates investigated showed reduced growth in the medium containing maleic acid as the carbon source. The effect of glucose and di-ammonium hydrogen orthophosphate concentrations on mycelia growth of all the six fungal species was studied with ranges for glucose of 2–40 g/l, and for di-ammonium hydrogen orthophosphate of 2–20 g/l. Cortinarius fulvoconicus and Cortinarius flexipes showed maximal mycelial growth at a glucose concentration greater than 20 g/l. Suillus luteus, Scleroderma citrinum, Laccaria laccata, and Tricholoma aurantium showed maximal growth at a glucose concentration of 20 g/l. All six species showed maximal mycelial growth at 5–10 g/l of di-ammonium hydrogen orthophosphate concentration and with increased concentration mycelial growth in all species decreased.     

Integrating mycorrhiza in a complex model system: effects on ecosystem C and N fluxes

During the last decades, ectomycorrhiza has been identified to be of major importance for ecosystem carbon (C) and nitrogen (N) cycling and tree growth. Despite this importance, mycorrhiza has largely been neglected in ecosystem models or regarded only implicitly by a static mycorrhiza term. In order to overcome this limitation, we integrated the dynamic mycorrhiza model MYCOFON (Meyer et al. in Plant Soil 327:493–517, 2010a, Plant Soil 327:519, 2010b) into the ecosystem modelling framework MoBiLE (Modular Biosphere simuLation Environment) and coupled it to available forest growth and development process models. Model testing was done for different beech and spruce forest sites in Germany. Simulation results were compared to a standard model set-up, that is, without explicit consideration of mycorrhiza. Parameters were set in order not to violate previous findings about C partitioning into aboveground and belowground biomasses. Nevertheless, the explicit consideration of mycorrhiza let to considerable differences between sites and deposition scenarios with respect to simulated root biomass, plant nitrogen supply, and gaseous soil C and N emissions. The latter was mainly a result of differences in soil N concentration and dynamics. Our simulation results also show that the C supply to mycorrhizal fungi by plants as well as the importance of mycorrhizal fungi for plant N uptake, that is, the allocation of C and N between plants and fungi, depends on the magnitude of N deposition. This effect is neglected by standard model approaches so far. Therefore, explicit consideration of mycorrhiza in ecosystem models has a high potential to improve model simulations of ecosystem C and N cycling and associated biosphere–hydrosphere–atmosphere exchange processes and consequently simulation of soil CO₂ and N trace gas emissions from forest sites.     

Cultured arbuscular mycorrhizal fungi and native soil inocula improve seedling development of two pioneer trees in the Andean region

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.     

外生菌根在高寒地区造林中的效果

1988～1990年利用引进和分离的菌根菌对落叶松Larix gmelirai和樟子松(Pinus sylvestris var.mongolica)苗木进行人工接种及其造林试验研究。试验结果证明,造林用苗菌根化能够提高成活率和生长量。1988年秋造落叶松菌根苗平均成活率为97.7％,比对照的提高13.2％;1989年春造落叶松菌根苗的成活率平均为95.2％,比对照提高13.4％;同年春造的樟子松菌根苗成活率平均为87.2％,比对照的提高17.5％;1990年一年生落叶松菌根苗造林成活率为90％,比对照的提高40％。它们的生长能力比对照的好很多。本次试验筛选出的优良菌种有Suillus grevillei,Boletus sp.Cortinarius russus,Xerocmus chrysenteron。     

Mycorrhizal status of an ozone-sensitive poplar clone treated with the antiozonant ethylene diurea

The antiozonant ethylene diurea is proven to prevent growth reductions in forest trees induced by ozone. The community of mycorrhizal fungi could be useful indicator of environmental stress. In this study, response of mycorrhizal fungi and fine roots to a 4-year exposure to ambient ozone and treatment with antiozonant was investigated in ozone-sensitive poplar clone under field conditions. The community of ectomycorrhizal fungi and root length colonization with ectomycorrhizal, arbuscular mycorrhizal fungi, and root endophytic fungi was analyzed in antiozonant-treated poplar plants and in poplar plants irrigated with water. In general, plants protected by antiozonant showed higher total number of fine roots, number of ectomycorrhizal types, Shannon–Weaver diversity index, and Species richness index compared to the plants treated with water. The ectomycorrhizal community shifted from contact exploration type in the trees irrigated with water to short-distance exploration type in ethylene diurea-treated trees. Ozone protectant may beneficially affect the belowground community of mycorrhizal fungi colonizing roots of ozone-sensitive poplar clone.     

Dual inoculation of a woody legume (Centrolobium tomentosum) with rhizobia and mycorrhizal fungi in south-eastern Brazil

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.