Seed source and vesicular-arbuscular mycorrhizal symbiont affects growth of Juglans nigra seedlings

Seedlings of Juglans nigra from three seed sources were grown in fumigated soil without vesicular-arbuscular mycorrhizal (VAM) fungi or inoculated with Gigaspora margarita, Glomus deserticola or Glomus etunicatum. Vesicular-arbuscular mycorrhizal development varied significantly between fungal symbionts within a black walnut source. Glomus deserticola and G. etunicatum produced the highest levels of root colonization in all sources. Significant differences in seedling shoot and root growth were attributed to root colonization by specific VAM fungi in each black walnut source. Glomus deserticola stimulated seedling leaf area and root weight 26 and 52%, respectively, in one seed source. Seedling leaf N, P and K concentrations were significantly improved by VAM in two seed sources. Juglans nigra seedlings respond favorably to VAM colonization. However, differences between seed sources suggest a strong host-symbiont interaction.     

Growth and Mycorrhizal Dependency of Acacia mangium Willd. Inoculated with Three Vesicular Arbuscular Mycorrhizal Fungi in Lateritic Soil

Three VA-mycorrhizal fungi; Glomus occultum, Glomus aggregatum (local isolates) and G. mosseae (strain from Bangalore, India) were inoculated to assess their effect on growth of Acacia mangium in lateritic soil. All inoculations enhanced growth with respect to shoot height, root diameter, leaf area, chlorophyll content and biomass of A. mangium significantly compared to uninoculated control seedlings. G. occultum proved most efficient among the three. The mycorrhizal dependency factor indicated that the growth of A. mangium was 57% dependent on G. occultum, 47% on G. mosseae and 46% on Glomus aggregatum.     

Selection of efficient VA mycorrhizal fungi for Casuarina equisetifolia—second screening

An investigation was carried out to screen and select efficient vesicular arbuscular mycorrhizal (VAM) fungi for inoculating the forest tree species, Casuarina equisetifolia. The seedlings were inoculated with 10 different VAM fungi, obtained from various sources. Inoculated seedlings generally had greater plant height, stem girth, biomass and P content than uninoculated plants. They also had more mycorrhizal root colonization and spore numbers in root zone soil. C. equisetifolia seedlings responded best (in biomass) to inoculation with Glomus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, closely followed by Acaulospora laevis Gerdemann and Trappe and G. fasciculatum (Thaxter Sensu Gerdemann) Gerdemann and Trappe; all the three being statistically on par with each other.     

Vesicular-arbuscular mycorrhiza effects on Gliricidia sepium and Senna siamea in a fallowed alley cropping system

Nitrogen fixing and non-N₂ fixing legumes such as Gliricidia speium and Senna siamea have been used in alley cropping systems for soil improvement and source of N for food crops. However their establishments could be limited by P and moisture deficiencies in degraded soils. Vesicular-arbuscular mycorrhizal fungi can help to overcome these deficiencies. We examined the effects of a vesicular-arbuscular mycorrhizal (VAM) fungus, Glomus deserticola, on the performance of sole hedgerow trees of Gliricidia sepium and Senna siamea and their mixtures (interplanted) in a fallowed alley cropping experiment on a degraded Alfisol in southwestern Nigeria. Percentage root infection by VAM fungi was higher in inoculated plants than in uninoculated ones irrespective of whether they were interplanted or non-interplanted. Inoculation with G. deserticola increased dry matter accumulation and nutrient uptake (N. P, Mg and K) but there was no significant interaction between mycorrhizal inoculation and interplanting for growth and nutrient uptake except for the uptake of P, Mg and K in G. sepium. Inoculation with G. deserticola reduced leaf shedding of G. sepium by 50% but did not have the same effect for S. siamea. For both tree species inoculated plants extracted more water from 0–30 cm depth than the uninoculated ones.     

Improvement of early growth of two tropical peat-swamp forest tree species Ploiarium alternifolium and Calophyllum hosei by two arbuscular mycorrhizal fungi under greenhouse conditions

Tropical peat-swamp forests are one of the largest near-surface reserves of terrestrial carbon. However, many peat-swamp forest tree species have resulted in the reduction due to over-exploitation, forest fires and conversion into agricultural land in Indonesia. The objective of this study was to determine the effects of two arbuscular mycorrhizal (AM) fungi, Glomus clarum and G. aggregatum, on the early growth of two slow-growing peat-swamp forest tree species, Ploiarium alternifolium and Calophyllum hosei, under greenhouse conditions. Cuttings of P. alternifolium and C. hosei were uninoculated or inoculated with G. clarum and G. aggregatum and grown under greenhouse conditions for 6 months. Percentage AM colonization, plant growth, phosphorus (P) concentration and survival rate were measured. The AM colonization of P. alternifolium and C. hosei ranged from 27 to 32% and 18 to 19%, respectively. Colonization by G. clarum and G. aggregatum increased shoot height, stem diameter, leaf number, and shoot and root dry weights. Cutting shoot P content were increased by AM fungal colonization. The survival rates of inoculated plants were higher (100%) than those of control plants (67%). The results suggest that inoculation with AM fungi improves early growth of P. alternifolium and C. hosei in a tropical peat-swamp forest and can therefore contribute to rehabilitation of peat-swamps.     

Growth of Nursery-grown Bamboo Inoculated with Arbuscular Mycorrhizal Fungi and Plant Growth Promoting Rhizobacteria in two Tropical Soil Typeswith and without Fertilizer Application

A nursery experiment was conducted to assess the effect of bioinoculants (Glomus aggregatum, Bacillus polymixa, Azospirillum brasilense) on seedling growth promotion of bamboo (Dendrocalamus strictus (Roxb.) Nees.) in two soil types (alfisol, vertisol) with or without fertilizer application. Bamboo seedlings were grown in the presence or absence of bioinoculants either individually or in all combinations for 180 days in field soil under tropical nursery conditions. Shoot, rhizome and root length, dry masses, nutrient concentrations and arbuscular mycorrhizal (AM) colonized root lengths were determined at harvest. Under the experimental condition tested combined inoculation of AM fungi, PSB and A. brasilense resulted in maximum growth response both under fertilized and unfertilized conditions in both soil types. Fertilizer application enhanced the efficiencies of N, P and K uptake, whereas reduced their usage efficiencies. Though soil type did not affect microbial inoculation response, fertilizer application significantly affected plant response to microbial inoculation.     

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.     

Functional compatibility of two arbuscular mycorrhizae with thirteen fruit trees in Senegal

Functional compatibility between thirteen tropical fruit trees (Afzelia africana Smith., Adansonia digitata L., Aphania senegalensis Radlk., Anacardium occidentale L., Cordyla pinnata (Lepr. ex A. Rich.) Milne-Redhead, Dialium guineensis Wild., Landolphia heudelottii A.DC., Sclerocarya birrea (A.Roch.) Hochst., Saba senegalensis (A. DC.) Pichon and four reference hosts Balanites aegyptiaca (L.) Del., Parkia biglobosa (Jacq.), Tamarindus indica L. and Zizyphus mauritiana Lam.) and two arbuscular mycorrhizal fungi (AMF) (Glomus aggregatum Schenck and Smith emend. Schenck and Glomus intraradices Schenck and Smith), was investigated. Marked differences were found between them in terms of mycorrhizal formation, root colonization, relative mycorrhizal dependency (RMD) and phosphorus concentrations in shoot tissues. A. africana, L. heudelottii and S. senegalensis did not form symbiotic associations, and the growth of A. africana decreased following mycorrhizal inoculation, while L. heudelottii and S. senegalensis showed no dependency. In contrast, A. digitata, A. senegalensis, A. occidentale, B. aegyptiaca and S. birrea were well colonized with AMF, but did not significantly increase in biomass production. Five fruit trees did, however, show dependency by a positive interaction with G. aggregatum, the most effective AMF. Z. mauritiana was found to be very highly dependent (RMD > 75%), T. indica was highly dependent (50–75% RMD), and D. guineensis, P. biglobosa and C. pinnata were moderately dependent (25–50% RMD). Phosphorus absorption probably contributed to this dependency more than the absorption of potassium. These results indicate that some tropical fruit trees do derive benefits from AM inoculation, while others do not.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of endomycorrhizae (VAM) on bamboo seedling growth and biomass productivity

The role of vesicular-arbuscular mycorrhizae (VAM) fungi symbiosis with bamboo seedling was investigated. VAM species Glomus aggregatum, G. fasciculatum and G. mosseae were inoculated individually and in combinations with the bamboo seedlings. The percentage of infection and various growth parameters such as the number of shoots, number of rhizome, internodal distance, leaf length and breadth and total biomass production were studied in myocorrhizal and non-mycorrhizal infected plants. The above findings indicated a significant increase in the growth rate and biomass productivity.     

Ectomycorrhizal inoculation of Douglas-fir transplanted container seedlings with commercially produced inoculum

Commercially produced vegetative inocula of Laccaria laccata and Hebeloma crustuliniforme successfully formed ectomycorrhizae with Douglas-fir transplanted container (plug+1) seedlings. After 4.5 months in containers, 83% and 90%, respectively, of short roots were mycorrhizal. L. laccata- or H. crustuliniforme-inoculated seedlings had significantly more mycorrhizal and total short roots than Pisolithus tinctorius-inoculated (4% mycorrhizal root tips) or uninoculated control seedlings. No significant differences were detected in seedling growth at the end of the container phase.After transplantation and growth in nursery beds for 17 months, mean new short root colonization of all seedlings was 80%. H. crustuliniforme persisted as a dominant mycorrhizal fungus on seedlings initially inoculated with this fungus. L. laccata-inoculated seedlings had 40% of their short roots colonized by L. laccata and another 40% by native fungi Rhizopogon and Thelephora spp. All mycorrhizae of control seedlings and those inoculated with P. tinctorius were formed by fungi native to the nusery beds. A significant fungal treatment effect was detected for shoot height only. Control seedlings were significantly taller than L. laccata-inoculated seedlings after transplanting.This article is part of senior author's thesis in partial fulfillment of the Ph.D. degree in the Department of Forest Science at Oregon State University, Corvallis.     

非灭菌条件下VA菌根菌对肉桂苗生长发育的影响

研究了在非灭菌条件下接种木薯球囊霉 (GlomusmanihotisHoweler ,Sieverding&Schenck)对肉桂 (CinnamomumcassiaPresl.)营养袋幼苗生长的影响。结果表明 ,接种组幼苗具有较高的VA菌感染率 ,幼苗的高、径、冠幅生长及根长、叶片数、生物量、叶绿素含量均比非接种对照组高 ,差异达显著水平。     

Effect of Arbuscular Mycorrhiza on the Drought Tolerance of Poncirus trifoliata Seedlings

The effects of Glomus mosseae colonization on the plant growth and drought tolerance of 1-year-old trifoliate Poncirus trifoliata seedlings in potted culture were studied in natural water stress and rewatering conditions. Results showed that arbuscular mycorrhizal (AM) inoculation significantly improved the height, stem diameter, and fresh weight of P. trifoliata seedlings before natural water stress. By the end of the experiment, the survival percentage of AM-transplanted seedlings was 8% higher than those of non-AM ones. During water stress and rewatering, AM significantly increased the contents of soluble sugars and proteins in leaves, and enhanced the activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POD), and catalase (CAT) in either seedling leaves or roots, which indicated that AM colonization could improve the osmotic adjustment response of P. trifoliata, enhance its defense system, and alleviate oxidative damages to membrane lipids and proteins. These results demonstrated that the drought tolerance of P. trifoliata seedlings was increased by inoculation with AM fungi. The functional mechanism underlying the observation that mycorrhizas increased the host’s drought tolerance was closely related to enzymatic and nonenzymatic antioxidant defense systems such as SOD, G-POD, CAT, and soluble protein. Translated from Chinese Journal of Applied Ecology, 2005, 16(3) (in Chinese)     

Mycorrhizal dependency and growth responses of Acacia nilotica and Albizzia lebbeck to inoculation by indigenous AM fungi as influenced by available soil P levels in a semi-arid Alfisol wasteland

A series of available phosphorus (Olsen) levels ranging from 10 to 40 ppm were achieved in a semi-arid soil. The influence of the levels of phosphorus on the symbiotic interaction between two subtropical tree species, Acacia nilotica and Albizzia lebbeck, and a mixed inoculum of indigenous arbuscular mycorrhizal (AM) fungi was evaluated in a greenhouse study. The extent to which the plant species depended on AM fungi for dry matter production decreased as the levels of soil P increased, but the degree of this decrease differed in the two species tested. Acacia nilotica colonized by AM fungi showed a significant increase in shoot P and dry matter at a soil P level of 10 ppm whereas in Albizzia lebbeck, such increase occurred at 20 ppm. Mycorrhizal inoculation response disappeared beyond soil P levels of 25 ppm in Acacia nilotica and 30 ppm in Albizzia lebbeck. Levels of soil P greater than 25 ppm suppressed AM fungus colonization in both species. Soil P levels of 30 and 40 ppm and 40 ppm caused negative mycorrhizal dependencies (MD) in Acacia nilotica and Albizzia lebbeck respectively. Values of MD for both species were negatively correlated with soil P levels. Based on the MD values, regression equations were developed to predict MD for given levels of available P.     

蓝桉和尾叶桉混合菌根研究 Ⅰ.菌根合成及真菌间的相互作用

采用蜡磨菌与ＶＡ 菌根真菌分别对蓝桉和尾叶桉进行单接种或混合接种,研究结果表明,两种菌根类型的真菌均能在桉树苗木根系上成功地定殖,分别合成了外生菌根、ＶＡ 菌根和混合菌根,证实了桉树不仅是菌根营养型树种,而且能形成多种菌根类型。ＶＡ 菌根感染率在接种初期较高,但随时间的推移有降低的趋势;而外生菌根菌初期合成菌根的速度较慢,但单位长度根段内菌根根尖数目有明显增加的趋势。与单接种ＶＡ菌根真菌苗木相比,外生菌根真菌抑制了ＶＡ 菌根菌在根系上的进一步侵染,体现在较低的ＶＡ 菌根感染率;而外生菌根菌显示出了较强的竞争能力,并能在接种后９ 周时开始形成子实体。在混合菌根中,外生菌根有逐步替代ＶＡ 菌根的发展趋势,两种类型的菌根真菌间存在一定的竞争性作用关系。基质磷（Ｐ）素水平对菌根的形成也有一定的影响     

Seasonal pattern of nitrogen mineralization and soil moisture beneath Faidherbia albida (synAcacia albida) in central malawi

On fertile alluvial soils on the lakeshore plain of Malawi, maize (Zea mays L.) yields beneath canopies of large Faidherbia albida (synAcacia albida) trees greatly exceed those found beyound tree canopies, yet there is little difference in soil nutrients or organic matter. To investigate the possibility that soil nutrient dynamics contribute to increased maize yields, this study focused on the impact of Faidherbia albida on nitrogen mineralization and soil moisture from the time of crop planting until harvest. Both large and small trees were studied to consider whether tree effects change as trees mature.During the first month of the rainy season, a seven-fold difference in net N mineralization was recorded beneath large tree canopies compared to rates measured in open sites. The initial pulse beneath the trees was 60 g N g^–1 in the top 15 cm of soil. During the rest of the cropping cycle, N availability was 1.5 to 3 times higher beneath tree canopies than in open sites. The total production of N for the 4-month study period was 112 g N g^–1 below tree canopies compared to 42 g N g^–1 beyond the canopies. Soil moisture in the 0–15 cm soil layer was higher under the influence of the tree canopies. The canopy versus open site difference grew from 4% at the beginning of the season to 50% at the end of the cropping season.Both N mineralization and soil moisture were decreased below young trees. Hence, the impact of F. albida on these soil properties changes with tree age and size. While maize yields were not depressed beneath young F. albida, it is important to realize that the full benefits of this traditional agroforestry system may require decades to develop.     

Source of mycorrhizal inoculum influences growth of Faidherbia albida seedlings

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.     

Effect of the inoculation and distribution of mycorrhizae in <Emphasis Type="Italic">Plathymenia reticulata</Emphasis> Benth under monoculture and mixed plantation in Brazil

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.     

Plant recovery from seedling-derived shoot tips ofFaidherbia albida grown in vitro

In vitro cultures were initiated from shoots taken from seedlings ofFaidherbia albida on Murashige and Skoog based medium supplemented with different combinations of 6-benzylaminopurine (BA) and -naphthaleneacetic acid (NAA). The shoots grew and rooted on all media. Rooting and vigorous growth were most successful on medium supplemented with 10^–7M NAA alone on which 87% of the shoots formed roots. Seventy-one percent of plantlets which were transferred to soil were successfully established and nodulated with the nativeRhizobium. The procedures provide a basis for the development of in vitro techniques for rapid multiplication and physiological studies of the species.     

Response of Acacia senegal (L.) Willd. to inoculation with arbuscular mycorrhizal fungi isolates in sterilized and unsterilized soils in Senegal

The benefits of inoculation with six arbuscular mycorrhizal fungi (AMF) isolates (Glomus aggregatum, G. fasciculatum, G. intraradices, G. manihotis, G. mosseae, and G. verriculosum) were investigated on seedlings of Acacia senegal (L.) Willd., a multipurpose tree legume highly valued for arabic gum production. Mycorrhizal root colonization, plant growth and relative mycorrhizal dependency (RMD) were measured in A. senegal seedlings growing in soils from three geographical sites in Senegal (Dahra, Bambey and Goudiry) and two soil conditions (sterilized vs unsterilized) in the glasshouse. The impact of inoculation on mycorrhizal root colonization and plant growth depended on AMF isolates, soil origins and soil conditions. Mycorrhizal root colonization and plant growth were increased in sterilized soils regardless of soil origin and AMF isolates. The degree of RMD of A. senegal seedlings varied with soil origin, soil condition and AMF isolates. A. senegal showed the highest RMD values, reaching a maximum of 45 %, when inoculated with G. manihotis. However, in unsterilized soils, no significant effect of AMF inoculation on plant growth was observed despite significant root colonization with certain AMF isolates in Dahra and Goudiry soils. This indicates that the most infective AMF isolates were not the most effective and unsterilized soils may contain effective mycorrhizal propagules. In conclusion, it is important to consider the native mycorrhizal component of the soils before harnessing mycorrhizal inoculation programs for sustainable agroforestry systems.     

The influence of Desert False Indigo, <Emphasis Type="Italic">Amorpha fruticosa</Emphasis>, and three arbuscular mycorrhizae fungi on the growth of <Emphasis Type="Italic">Populus ussuriensis</Emphasis> seedlings

The influence of Desert False Indigo, Amorpha fruticosa, on the growth of Populus ussuriensis seedlings inoculated with three arbuscular mycorrhizae (AM) fungi (Glomus mosseae, Glomus intraradices, Glomus sinuosa) was studied using the nylon net method. The results showed that all three AM fungi infected P. ussuriensis seedlings and G. intraradices and also G. mosseae infected A. fruticosa. The AM fungi promoted growth of P. ussuriensis and Desert False indigo seedlings. Moreover, under co-cultivation with A. fruticosa, the biomass of P. ussuriensis increased significantly. The concentration of nitrogen in P. ussuriensis grown with A. fruticosa and the concentration of soluble nitrogen in the rhizosphere were also higher than when grown alone. Hypha were found on the two plant seedlings inoculated with G. mosseae and G. intraradices, suggesting that AM fungi may transport nutrients from seedlings of A. fruticosa to the rhizosphere of P. ussuriensis seedlings, which may have promoted the growth of P. ussuriensis. The AM fungi played a critical role on the effect of A. fruticosa on growth of P. ussuriensis.