Effect of mycorrhizal inoculation and soluble phosphorus fertilizer on growth and phosphorus uptake of pearl millet

Summary Six mycorrhizal fungi were tested as inoculants for pearl millet (Pennisetum americanum Leeke) grown in pots maintained in a greenhouse. VAM fungi varied in their ability to stimulate plant growth and phosphorus uptake. Inoculation withGigaspora margarita, G. calospora andGlomus fasciculatum increased shoot drymatter 1.3 fold over uninoculated control. In another pot trial, inoculation withGigaspora calospora andGlomus fasciculatum resulted in dry matter and phosphorus uptake equivalent to that produced by adding phosphorus at 8 kg/ha.The influence of inoculatingGigaspora calospora on pearl millet at different levels of phosphorus fertilizer (0 to 60 kg P/ha) as triple superphosphate in sterile and unsterile alfisol soil was also studied. In sterile soil, mycorrhizal inoculation increased dry matter and phosphorus uptake at levels less than 20 kg/ha. At higher P levels the mycorrhizal effect was decreased. These studies performed in sterilized soil suggest that inoculation of pearl millet with efficient VAM fungi could be extremely useful in P deficient soils. However, its practical utility depends on screening and isolation of fungal strains which perform efficiently in natural (unsterilized) field conditions.     

Interactions between vesicular-arbuscular mycorrhizal fungi and asparagus

Summary The vesicular-arbuscular mycorrhizal (VAM) fungus,Glomus versiforme increased significantly the growth ofAsparagus officinalis under controlled conditions using Turface as the growth medium. The growth responses, including increases in root fresh weight, numbers of shoots, shoot dry weight, and shoot height follow a pattern similar to other mycorrhizal systems. Indigenous VAM fungi appeared to have negative effects on average shoot fresh and dry weight, number of shoots per pot and average shoot height on one year oldA. officinalis seedlings obtained from the field and grown under controlled conditions. These results may be due either to the high levels of soluble phosphate present in the soil or the ineffectiveness of the particular indigenous fungi as mycorrhizal fungi in asparagus. Indigenous mycorrhizal fungi overwinter in asparagus root crown as vesicles and as external and internal hyphae. Soil obtained from the same fields as the one year old crowns was a good source of mycorrhizal inoculum for sterile seedlings.     

Screening and selecting arbuscular mycorrhizal fungi for inoculating micropropagated apple rootstocks in acid soils

Santa Catarina state is the largest producer of apples in Brazil. Soils in this region have low pH and high levels of aluminum and manganese, requiring high inputs of fertilizers and amendments increasing costs of apple production. Inoculation of arbuscular mycorrhizal fungi can improve the establishment of micropropagated apple plants in such adverse soil conditions. Soil samples were collected from apple orchards in the Caçador, Fraiburgo and São Joaquim regions to develop a corn bioassay to identify mycorrhizal communities with high infectivity. Eleven fungal species were identified from one Caçador soil with the highest infectivity. Glomus etunicatum SCT110, Scutellospora pellucida SCT111, Acaulospora scrobiculata SCT112 and Scutellospora heterogama SCT113 were brought into single-species culture and used in a plant growth and nutrient uptake experiment using micropropagated apple (Malus prunifolia), cultivated at three soil pH. Colonization by fungal isolates significantly affected plant height, shoot and root dry weights, and root:shoot ratio. Soil pH also significantly affected all growth parameters except shoot dry weight. Mycorrhizal inoculation also significantly altered tissue concentrations of P, Zn, Cu, Ca, S, Na, N, K, Fe and Al. Association with mycorrhizal fungi increased P concentration and also decreased Al concentrations in the shoots. Overall, G. etunicatum and S. pellucida were the most effective isolates to promote plant growth and nutrient uptake. Inoculation of apple rootstock with selected fungal isolates during the acclimatization stage represents a useful strategy for producing micropropagated apples that can withstand acidic soil conditions.     

Effect of soil liming and vesicular-arbuscular-mycorrhizal inoculation on the growth and micronutrient content of the teff plant

In a greenhouse experiment involving an acid soil teff [Eragrostis tef (Zucc.) Trotter] plants failed to grow unless the soil was limed or inoculated with either of two vesicular-arbuscular-mycorrhizal (VAM) fungi,Glomus mosseae orGlomus macrocarpum. Plant growth increased by liming and to a lesser extent by VAM fungal inoculation. Liming also enhanced root colonization by VAM fungi. Shoot micronutrient content generally increased as a result of inoculation, and decreased by increased lime applications.     

Diversity of Arbuscular Mycorrhizal Fungi Associated with Plants Growing in Fly Ash Pond and Their Potential Role in Ecological Restoration

Root colonization and diversity of arbuscular mycorrhizal fungi (AMF) were analyzed in plants growing in fly ash pond. Eight species could be separated morphologically, while phylogenetic analyses after PCR amplification of the ITS region followed by RFLP and sequencing revealed seven different AM fungal sequence types. Phylogenetic analysis showed that these sequences cluster into four discrete groups, belonging to the genus Glomus and Archaeospora. Inoculation of plants with spores of AM fungal consortia (Glomus etunicatum, Glomus heterogama, Glomus maculosum, Glomus magnicaule, Glomus multicaule, Glomus rosea, Scutellospora heterogama, and Scutellospora nigra) along with colonized root pieces increased the growth (84.9%), chlorophyll (54%), and total P content (44.3%) of Eucalyptus tereticornis seedlings grown on fly ash compared to non-inoculated seedlings. The growth improvement was the consequence of increased P nutrition and decreased Al, Fe, Zn, and Cu accumulations. These observations suggested that the inoculation of tree seedlings with stress adapted AM fungi aid in the reclamation of fly ash ponds.     

Effect of combined inoculation ofAzospirillum brasilense and vesicular-arbuscular mycorrhiza on pearl millet (Pennisetum americanum)

Summary Growth and phosphorus uptake of pearl millet (Pennisetum americanum) on an unsterile, phosphorus-deficient soil was improved by the seed inoculation withAzospirillum brasilense or soil inoculation with the vesicular-arbuscular mycorrhizal fungi (Acaulospora,Gigaspora margarita, Glomus fasciculatum). These microorganisms acted synergistically when added simultaneously and the response was significant withAzospirillum brasilense + Gigaspora margarita andAzospirillum brasilense + Glomus fasciculatum combinations over uninoculated control as far as the dry matter content of shoots, root biomass and phosphorus uptake of the millet was concerned.     

Stimulation of Growth and Nutrient Uptake by VAM Fungi in Brassica Oleracea Var. Capitata

Cabbage (Brassica oleracea, var. capitata, cv. Hercules) seedlings were inoculated with vesicular-arbuscular mycorrhizal (VAM) fungi Glomus fasciculatum, G. aggregatum, and G. mosseae. Differential efficiency in mycorrhizal colonization and the specificity of fungal symbiont to stimulate the growth and nutrient uptake of the host were observed. In addition, there was an increase in phenol, protein, reducing sugar contents, and peroxidase activity in the VAM inoculated seedlings. Since these compounds are known to confer resistance against fungal pathogens, the use of VAM as a biological control agent to protect cabbage against several root diseases is suggested.     

Dual inoculation with Aspergillus fumigatus and Glomus mosseae enhances biomass production and nutrient uptake in wheat (Triticum aestivum L.) supplied with organic phosphorus as Na-phytate

In a pot experiment, wheat was grown for 50 days in two heat-sterilized low-phosphorus (P) soils supplied with organic P as Na-phytate. Seed inoculation with the phosphatase-producing fungus (PPF) Aspergillus fumigatus or soil inoculation with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae increased shoot and root dry weight and root length, phosphatase activity in the rhizosphere and shoot concentrations of P and to a lesser extent of K and Mg. As a rule, the greatest effects on those parameters were most in the combined inoculation treatment (PPF + VAM). Shoot concentrations of Cu and Zn were only enhanced by VAM, not by PPF. At harvest, depletion of organic P in the rhizosphere soil increased in the order of: sterilized soil < PPF < VAM < PPF + VAM which corresponded with the enhanced P concentrations in the plants. The results demonstrate that organic P in form of Na-Phytate is efficiently used by VAM and that use of organic P can be increased by simultaneous inoculation with phosphatase-producing fungi.     

五指山常见热带树种的丛枝菌根真菌多样性

采用野外调查的方法,分析了五指山不同海拔高度7个科10种常见热带树种形成丛枝菌根(Arbuscular Mycorrhizal,AM)的状况及其根际土壤中AM真菌的多样性。结果表明,所调查的10种热带常见树种都能形成AM共生体,其菌根侵染率随寄主植物的不同,从21.8%～90.5%变化不等,同时,在10种常见植物的根系中也都观察到了AM真菌的典型结构——丛枝和泡囊。从10种植物的根际土壤中共分离到36种AM真菌,隶属于Acaulospora,Glomus,Gigaspora和Scutellospora4个属,其中,Glomus属的真菌是该地区的优势类群,其出现频度和相对多度分别为84%和56%。在所调查的10种热带常见树种中,Swietenia macrophylla根际AM真菌的孢子最丰富,密度高达7.32;Machilus namu根际的AM真菌种类则最为丰富,多样性指数达到1.6548。通过对不同海拔高度Swietenia macrophylla根际AM真菌分布的分析表明,海拔高度显著影响着AM真菌的分布,Gigaspora属的真菌随海拔高度的增加显著升高,Scutellospora属的真菌则显著降低。     

Species richness and spore abundance of arbuscular mycorrhizal fungi across distinct land uses in Western Brazilian Amazon

Arbuscular mycorrhizal fungi (AMF) were surveyed for species richness and abundance in sporulation in six distinct land uses in the western Amazon region of Brazil. Areas included mature pristine forest and sites converted to pasture, crops, agroforestry, young and old secondary forest. A total of 61 AMF morphotypes were recovered and 30% of them could not be identified to known species. Fungal communities were dominated by Glomus species but Acaulospora species produced the most abundant sporulation. Acaulospora gedanensis cf., Acaulospora foveata, Acaulospora spinosa, Acaulospora tuberculata, Glomus corymbiforme, Glomus sp15, Scutellospora pellucida, and Archaeospora trappei sporulated in all land use areas. Total spore numbers were highly variable among land uses. Mean species richness in crop, agroforestry, young and old secondary forest sites was twice that in pristine forest and pasture. fungal communities were dominated in all land use areas except young secondary forest by two or three species which accounted for 48% to 63% of all sporulation. Land uses influenced AMF community in (1) frequency of occurrence of sporulating AMF species, (2) mean species diversity, and (3) relative spore abundance. Conversion of pristine forest into distinct land uses does not appear to reduce AMF diversity. Cultural practices adopted in this region maintain a high diversity of arbuscular mycorrhizal fungi.     

Increased Sporulation of Vesicular-Arbuscular Mycorrhizal Fungi by Manipulation of Nutrient Regimens

Adjustment of pot culture nutrient solutions increased root colonization and sporulation of vesicular-arbuscular mycorrhizal (VAM) fungi. Paspalum notatum Flugge and VAM fungi were grown in a sandy soil low in N and available P. Hoagland nutrient solution without P enhanced sporulation in soil and root colonization of Acaulospora longula, Scutellospora heterogama, Gigaspora margarita, and a wide range of other VAM fungi over levels produced by a tap water control or nutrient solutions containing P. However, Glomus intraradices produced significantly more spores in plant roots in the tap water control treatment. The effect of the nutrient solutions was not due solely to N nutrition, because the addition of NH₄NO₃ decreased both colonization and sporulation by G. margarita relative to levels produced by Hoagland solution without P.     

西藏高原针茅草地土壤因子对丛枝菌根真菌物种多样性的影响

在对西藏高原北部针茅草地根围土壤中的丛枝菌根(AM)真菌种类分离鉴定基础上,研究了藏北针茅草地的土壤质地、pH、有机质和有效磷含量对AM真菌孢子密度、分离频度、相对多度、重要值、物种多样性指数和均匀度的影响.结果表明: 针茅草地根围土壤中共分离鉴定出AM真菌3属15种,其中,球囊霉属9种、无梗囊霉属6种、盾巨孢囊霉属1种.球囊霉属和无梗囊霉属为藏北针茅草地AM真菌的优势属;近明球囊霉和光壁无梗囊霉为藏北高寒草原针茅属植物根围AM真菌的优势种.不同质地土壤中AM真菌孢子密度、分离频度、相对多度和重要值均表现出球囊霉属＞无梗囊霉属＞盾巨孢囊霉属的趋势;土壤pH值对AM真菌种群组成无明显影响,球囊霉属和无梗囊霉属真菌分离频度、相对多度和重要值随土壤pH升高而增加,盾巨孢囊霉属则呈现相反趋势;不同土壤有机质含量范围内,AM真菌孢子密度等各项指标均呈球囊霉属＞无梗囊霉属＞盾巨孢囊霉属,而AM真菌属的分布没有明显规律;土壤有效磷含量对AM真菌种丰度和孢子密度影响较小.研究区域内AM真菌物种多样性指数和均匀度随着土壤有效磷含量升高而增加.     

Host genotype dependency and growth enhancing ability of VA-mycorrhizal fungi for Eleusine coracana (finger millet)

Inoculation of finger millet (Eleusine coracana Gaertn.) plants with one of six different vesicular, arbuscular, mycorrhizal (VAM) fungi increased plant biomass, height, leaf area and absolute growth rate; however, effectiveness of the various VAM fungi varied significantly. Maximum root colonization and mycorrhizal efficacy was observed with plants inoculated with Glomus caledonicum. Among five host genotypes tested for mycorrhizal dependency against G. caledonicum, genotype HR-374 gave the highest plant biomass, mycorrhizal efficacy and root colonization, the inoculation resulting in increased mineral (phosphate, nitrogen, Zn²⁺ and Cu²⁺) content and uptake in shoots.     

Establishment of Vesicular-Arbuscular Mycorrhizal Fungi and Other Microorganisms on a Beach Replenishment Site in Florida

Beach replenishment is a widely used method of controlling coastal erosion. To reduce erosional losses from wind, beach grasses are often planted on the replenishment sands. However, there is little information on the microbial populations in this material that may affect plant establishment and growth. The objectives of this research were to document changes in the populations of vesicular-arbuscular mycorrhizal (VAM) fungi and other soil microorganisms in replenishment materials and to determine whether roots of transplanted beach grasses become colonized by beneficial microbes. The study was conducted over a 2-year period on a replenishment project in northeastern Florida. Three sampling locations were established at 1-km intervals along the beach. Each location consisted of three plots: an established dune, replenishment sand planted with Uniola paniculata and Panicum sp., and replenishment sand left unplanted. Fungal and bacterial populations increased rapidly in the rhizosphere of beach grasses in the planted plots. However, no bacteria were recovered that could fix significant amounts of N₂. The VAM fungi established slowly on the transplanted grasses. Even after two growing seasons, levels of root colonization and sporulation were significantly below those found in the established dune. There was a shift in the dominant VAM fungi found in the planted zone with respect to those in the established dunes. The most abundant species recovered from the established dunes were Glomus deserticola, followed by Acaulospora scrobiculata and Scutellospora weresubiae. The VAM fungi that colonized the planted zone most rapidly were Glomus globiferum, followed by G. deserticola and Glomus aggregatum.     

我国北方VA菌根真菌某些属和种的生态分布

虽然VA真菌遍布全球,但其属和种的分布是不均衡的,常有程度不同的地域性。以新疆、北京和吉林三地为代表的我国北方土壤中的VA真菌大都为球囊霉属Glomns。对摩西球囊霉G.mosseae、地表球囊霉G.versilorme及未发表种Glomus sp.9等菌种和某些生态因子的统计分析表明:土壤pH、土壤有机质含量和采集地海拔高度对三菌种的分布影响显著。在pH5—9.5范围内,球囊霉属所占比例随土壤pH增高而加大;无梗囊霉属Acaulospora所占比例则随土壤pH降低而加大。pH大于9的土壤中完全没有盾巨囊霉属Scutellospora。虽然球囊霉属主要分布在有机质含量低的土壤中,但其未发表种Glomus sp.9却较多发现于有机质丰富处。无梗囊霉属的某些种对土壤有机质含量在一定选择性。盾巨囊霉属多见于有机质含量为5—10％的土壤中。海拔3000米以上土壤中球囊霉属和无梗囊霉属显著减少,盾巨囊霉属则已绝迹。球囊霉属中某些种对海拔高度较敏感。摩西球囊霉是我国北方土壤中的常见种,也是北京污灌土壤中的优势种。由于对环境的适应能力及地域性的差异,将VA真菌总结为“广谱生态型”和“窄谱生态型”两类。     

Response of citronella Java (Cymbopogon winterianus Jowitt) to VA mycorrhizal fungi and soil compaction in relation to P supply

Nutrient acquisition and growth of citronella Java (Cymbopogon winterianus Jowitt) was studied in a P-deficient sandy soil to determine the effects of mycorrhizal symbiosis and soil compaction. A pasteurized sandy loam soil was inoculated either with rhizosphere microorganisms excluding VAM fungi (non-mycorrhizal) or with the VAM fungus, Glomus intraradices Schenck and Smith (mycorrhizal) and supplied with 0, 50 or 100 mg P kg^-1 soil. The soil was compacted to a bulk density of 1.2 and 1.4 Mg m^-3 (dry soil basis). G. intraradices substantially increased root and shoot biomass, root length, nutrient (P, Zn and Cu) uptake per unit root length and nutrient concentrations in the plant, compared to inoculation with rhizosphere microorganisms when the soil was at the low bulk density and not amended with P. Little or no plant response to the VAM fungus was observed when the soil was supplied with 50 or 100 mg P kg^-1 soil and/or compacted to the highest bulk density. At higher soil compaction and P supply the VAM fungus significantly reduced root length. Non-mycorrhizal plants at higher soil compaction produced relatively thinner roots and had higher concentrations and uptake of P, Zn and Cu than at lower soil compaction, particularly under conditions of P deficiency. The quality of citronella Java oil measured in terms citronellal and d-citronellol concentration did not vary appreciably due to various soil treatments.     

The Vesicular Arbuscular Mycorrhiza Associated with Three Cultivars of Rice (Oryza sativa L.)

The present study deals with the occurrence of vesicular arbuscular mycorrhizal fungi in three cultivars of rice in Barak valley. Three cultivars of rice were Pankaj, Malati and Ranjit. The results revealed the association of VAM fungi in all the cultivars of rice. The association was maximum in Pankaj cultivar followed by Malati, and Ranjit, respectively, in all the three sampling phases. All the three cultivars of rice crop showed maximum soil spore population and number of VAM fungal species at the harvesting phase (135 DAS) and minimum at the phase of maturation (90 DAS). Glomus species were found dominating followed by Acaulospora species. Glomus microcarpum, Glomus claroideum, Glomus mosseae and Acaulospora scrobiculata were found in all the three fields.     

Screening of arbuscular mycorrhizal fungi for the revegetation of eroded red soils in subtropical China

Some acidic red soils in hilly regions of subtropical China were degraded as a result of slope erosion following the removal of natural vegetation, primarily for fuel. Revegetation is important for the recovery of the degraded ecosystem, but plant growth is limited by the low fertility of eroded sites. One factor contributing to the low fertility may be low inoculum density of arbuscular mycorrhizal (AM) fungi. Compared to red soils under natural vegetation or in agricultural production, substrates on eroded sites had significantly lower AM fungal propagule densities. Thus, the management and/or application of AM fungi may increase plant growth and accelerate revegetation. Thirteen species of AM fungi were identified in red soils by spore morphology. Scutellospora heterogama, Glomus manihotis, Gigaspora margarita, Glomus aggregatum and Acaulospora laevis were among the most common according to spore numbers. Pot cultures were used to isolate and propagate 14 isolates of AM fungi indigenous to red soil. The effectiveness of each fungus in promotion of growth of mungbean was evaluated in red soil. For comparison, three isolates from northern China, known to be highly effective in neutral soils, and two isolates from Australia, known to be from acidic soil were used. Effectiveness was positively related to root infection (r ² = 0.601). For two of these isolates, Glomus caledonium (isolated from northern China) and Glomus manihotis (an isolate indigenous to red soil), the applied P concentration giving the highest infection and response to infection was approximately 17.5 mg P kg^–1 soil. In field experiments in which this concentration of P was applied, the five most effective isolates were tested on mungbean. The Glomus caledonium isolate from northern China was the most effective, followed by the indigenous Glomus manihotis isolate. The Glomus caledonium isolate was also shown to be effective on Lespedeza formosa, which is commonly used in revegetation efforts. We conclude that inoculation of plants with selected isolates of AM fungi may aid in revegetation efforts on eroded red soils in subtropical China.     

Mycorrhizal responsiveness of aerobic rice genotypes is negatively correlated with their zinc uptake when nonmycorrhizal

Plant Zn uptake from low Zn soils can be increased by Zn-mobilizing chemical rhizosphere processes. We studied whether inoculation with arbuscular mycorrhizal fungi (AMF) can be an additional or an alternative strategy. We determined the effect of AMF inoculation on growth performance and Zn uptake by rice genotypes varying in Zn uptake when nonmycorrhizal. A pot experiment was conducted with six aerobic rice genotypes inoculated with Glomus mosseae or G. etunicatum or without AMF on a low Zn soil. Plant growth, Zn uptake and mycorrhizal responsiveness were determined. AMF-inoculated plants produced more biomass and took up more Zn than nonmycorrhizal controls. Mycorrhizal inoculation, however, significantly increased Zn uptake only in genotypes that had a low Zn uptake in the nonmycorrhizal condition. We conclude that genotypes that are less efficient in Zn uptake when nonmycorrhizal are more responsive to AMF inoculation. We provide examples from literature allowing generalization of this conclusion on a trade off between mycorrhizal responsiveness and nutrient uptake efficiency.     

Effect of aromatic plant species on vesicular-arbuscular mycorrhizal establishment in Pistacia terebinthus

The inoculation of Pistacia terebinthus with vesicular-arbuscular mycorrhizal (VAM) fungi and the spread of the infection were studied using a mixed cropping system, under glasshouse conditions, with Salvia officinalis, Lavandula officinalis and Thymus vulgaris colonized by Glomus mosseae as an inoculation method. This method was compared with soil inoculum placed under the seed or distributed evenly in the soil. Indirect inoculation with all the aromatic plants tested significantly increased VAM root colonization of P. terebinthus compared with the use of soil inoculum, although the effect on plant growth was different for each one of the aromatic species used as inoculum source. Inoculation with L. officinalis and T. vulgaris were the best treatments resulting in high VAM colonization and growth enhancement of P. terebinthus.