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K. Udaiyan - One of the best experts on this subject based on the ideXlab platform.
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Seasonality of Vesicular-Arbuscular Mycorrhizae in sedges in a semi-arid tropical grassland
Acta Oecologica, 2002Co-Authors: Thangavelu Muthukumar, K. UdaiyanAbstract:Abstract Vesicular-Arbuscular mycorrhizal (VAM) colonization and spore numbers in the rhizosphere of Cyperus iria L. and C . rotundus L., growing in a semi-arid tropical grassland, was studied during the 1993 and 1994 monsoons. In addition, climatic and chemical properties of the soils were determined in order to investigate their influence on mycorrhizal variables. VAM fungal association in the sedges was confirmed by plant- and root-trap culture techniques. The soil nutrients exhibited seasonal variations, but were highly variable between years. Intercellular hyphae and vesicles with occasional intraradical spores characterized mycorrhizal association in sedges. Dark septate fungi also colonized roots of sedges. Temporal variations in mycorrhizal colonization and spore numbers occurred, indicating seasonality. However, the patterns of mycorrhizal colonization and spore numbers were different during both the years. The VAM fungal structures observed were intercellular hyphae and vesicles. Changes in the proportion of root length with VAM structures, total colonization levels and spore numbers were related to climatic and edaphic factors. However, the intensity of influence of climatic and soil factors on VAM tended to vary with sedge species.
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Vesicular-Arbuscular Mycorrhizae in tropical sedges of southern India
Biology and Fertility of Soils, 1996Co-Authors: Thangavelu Muthukumar, K. Udaiyan, S. ManianAbstract:Twenty-four species of sedges (representing six genera) from different vegetation types in Western Ghats, South India, were examined for Vesicular-Arbuscular mycorrhizal (VAM) associations. All the sedges had VAM fungal infections with hyphae and vesicles, but arbuscules were observed only in 42% of the total species. The VAM fungal colonization varied considerably between species, ranging from 9 to 62%. Root colonization was positively and negatively correlated with root diameter and root hair length, respectively. The number of VAM fungal spores in the rhizosphere varied from 5 to 86 g-1 soil. No significant relationship was found between spore numbers or root colonization and either soil pH or moisture. Four Glomus spp., one Acaulospora sp., one Sclerocystis spp., and one Gigaspora sp. were identified among the VAM fungal spores. The results reflect a high incidence of VAM in sedges occurring in Western Ghats and emphasize the need to assess the VAM status of plant species from different ecosystems to understand their mycorrhizal status.
Thangavelu Muthukumar - One of the best experts on this subject based on the ideXlab platform.
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Seasonality of Vesicular-Arbuscular Mycorrhizae in sedges in a semi-arid tropical grassland
Acta Oecologica, 2002Co-Authors: Thangavelu Muthukumar, K. UdaiyanAbstract:Abstract Vesicular-Arbuscular mycorrhizal (VAM) colonization and spore numbers in the rhizosphere of Cyperus iria L. and C . rotundus L., growing in a semi-arid tropical grassland, was studied during the 1993 and 1994 monsoons. In addition, climatic and chemical properties of the soils were determined in order to investigate their influence on mycorrhizal variables. VAM fungal association in the sedges was confirmed by plant- and root-trap culture techniques. The soil nutrients exhibited seasonal variations, but were highly variable between years. Intercellular hyphae and vesicles with occasional intraradical spores characterized mycorrhizal association in sedges. Dark septate fungi also colonized roots of sedges. Temporal variations in mycorrhizal colonization and spore numbers occurred, indicating seasonality. However, the patterns of mycorrhizal colonization and spore numbers were different during both the years. The VAM fungal structures observed were intercellular hyphae and vesicles. Changes in the proportion of root length with VAM structures, total colonization levels and spore numbers were related to climatic and edaphic factors. However, the intensity of influence of climatic and soil factors on VAM tended to vary with sedge species.
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Vesicular-Arbuscular Mycorrhizae in tropical sedges of southern India
Biology and Fertility of Soils, 1996Co-Authors: Thangavelu Muthukumar, K. Udaiyan, S. ManianAbstract:Twenty-four species of sedges (representing six genera) from different vegetation types in Western Ghats, South India, were examined for Vesicular-Arbuscular mycorrhizal (VAM) associations. All the sedges had VAM fungal infections with hyphae and vesicles, but arbuscules were observed only in 42% of the total species. The VAM fungal colonization varied considerably between species, ranging from 9 to 62%. Root colonization was positively and negatively correlated with root diameter and root hair length, respectively. The number of VAM fungal spores in the rhizosphere varied from 5 to 86 g-1 soil. No significant relationship was found between spore numbers or root colonization and either soil pH or moisture. Four Glomus spp., one Acaulospora sp., one Sclerocystis spp., and one Gigaspora sp. were identified among the VAM fungal spores. The results reflect a high incidence of VAM in sedges occurring in Western Ghats and emphasize the need to assess the VAM status of plant species from different ecosystems to understand their mycorrhizal status.
Paul Widden - One of the best experts on this subject based on the ideXlab platform.
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the morphology of Vesicular Arbuscular Mycorrhizae in clintonia borealis and medeola virginiana
Botany, 1996Co-Authors: Paul WiddenAbstract:During a survey of the Vesicular–Arbuscular mycorrhizal (VAM) associations of forest herbs in a deciduous forest in the southern Laurentian mountains in Quebec, two liliaceous species, Clintonia borealis and Medeola virginiana, revealed very distinctive morphology. In both species, once the epidermis was penetrated, the fungus spread towards the centre of the root via intracellular hyphae until the innermost layer of the cortex was reached, at which point the fungus spread laterally and tangentially through the cortical cells adjacent to the endodermis via a series of banana-shaped projections (bobbits). These eventually differentiated into the arbuscules and the VAM might spread from this inner cortical layer back into the outer cortical layers. In C. borealis, the hyphae coiled in the cortex, and vesicles were formed in the upper cortical cells. In M. virginiana, no coiling took place, but extensive diverticulae were produced by the intracellular hyphae in the cortical cells, close to their point of exi...
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Effect of ozone on the development of Vesicular-Arbuscular Mycorrhizae in sugar maple saplings
Mycologia, 1994Co-Authors: Lynn Duckmanton, Paul WiddenAbstract:We examined the effects of ozone on the incidence of Vesicular-Arbuscular Mycorrhizae in the roots of sugar maple {Acer saccharum) seedlings using a modified grid-line intersect method. The presence of vesicles, arbuscules, hyphal coils and internal my? celium was recorded. As the concentration of ozone
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development of Vesicular Arbuscular Mycorrhizae in sugar maple acer saccharum and effects of base cation ammendment on vesicle and arbuscule formation
Botany, 1993Co-Authors: Margaret A Cooke, Paul Widden, I P OhalloranAbstract:The development, condition, and incidence of Vesicular–Arbuscular Mycorrhizae of Acer saccharum (sugar maple) seedlings grown in the greenhouse in natural sugar maple forest soil substrate were examined. The effects of the addition of a cation mixture containing calcium, magnesium, and potassium were also studied. The mycorrhizal structures observed were similar to those found in natural field conditions. Mycorrhizae developed intracellularly via hyphal coils, and arbuscules usually developed from these coils, forming arbusculate coils. This development is different from that observed in most annual crop plants. Vesicular–Arbuscular mycorrhizal structures appeared within 30 days. The rate of mycorrhizal infection decreased, along with plant health, as the quantity of the added cations was increased, but the amendment did not affect the morphology of the infection. More vesicles were observed in the lowest level of application than in controls, suggesting a stress response and possible relationship between...
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morphology incidence and fertilization effects on the Vesicular Arbuscular Mycorrhizae of acer saccharum in a quebec hardwood forest
Mycologia, 1992Co-Authors: Margaret A Cooke, Paul Widden, I P OhalloranAbstract:The condition and incidence of Vesicular-Arbuscular Mycorrhizae of Acer saccharum (sugar maple) in a natural hardwood forest in the Lower Laurentians of Quebec was examined. The effects of forest fertilization on the Mycorrhizae were also studied. Microscopic examination revealed VAM structures which included hyphal coils, vesicles, and arbuscules. Vesicles and hyphal coils were the most frequently observed structures, whereas arbuscules were rarely seen. Seasonal differences in the incidence of Vesicular-Arbuscular Mycorrhizae were observed but these differences were not consistent from year to year. Generally, infection rates were lowest in mid-summer. Fertilization of forest soil with a base cation mixture did not appear to affect either the condition or the incidence of VAM.
David P Janos - One of the best experts on this subject based on the ideXlab platform.
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Vesicular Arbuscular Mycorrhizae in two tropical monodominant trees
Journal of Tropical Ecology, 1997Co-Authors: Sylvia D Torti, Phyllis D Coley, David P JanosAbstract:Mycorrhizae, symbioses between plant roots and fungi, are found in virtually all terrestrial plant ecosystems. Substantial evidence indicates that mycorrhizal associations are beneficial to both partners. In most systems, the fungus benefits the host plant by effectively scavenging nutrients and in return, utilizes carbohydrates produced by the plant (Allen 1991, Harley & Smith 1983). Moreover, both major types of Mycorrhizae, Vesicular-Arbuscular Mycorrhizae (VAM) and ectoMycorrhizae (EM), can alter the outcome of competitive interactions between host plants (Allen & Allen 1984, Hartnett et al. 1993, Hetrick et al. 1989, Newman et al. 1992, Perry et al. 1989). Early studies focused primarily on temperate Mycorrhizae, but more recently, ecologists have turned toward the tropics. In contrast to the temperate zone, where trees tend to be EM, the majority of tropical tree species surveyed thus far form VAM (Janos 1983). Some notable exceptions of tropical trees forming EM occur in the plant families Dipterocarpaceae, Caesalpiniaceae, Euphorbiaceae, Fagaceae and Myrtaceae. Although tropical forests are typically diverse, many tree species in these five families grow in persistent, monodominant stands which can extend for hundreds of hectares (Connell & Lowman 1989). Janos (1983, 1985) has suggested that under low nutrient or seasonal conditions, EM may be more efficient than VAM at scavenging nutrients. Furthermore, EM may be able to absorb organic nitrogen (Alexander 1983), decompose organic litter (Trojanowski et al. 1984) and/or protect the host's roots from herbivory or pathogen attack (Marx 1972). Hence, the ability of some tropical trees to associate with EM has been hypothesized to give them a competitive advantage by which they can achieve local or regional dominance
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Vesicular-Arbuscular Mycorrhizae of epiphytic and terrestrial Piperaceae under field and greenhouse conditions
Mycorrhiza, 1993Co-Authors: Blase Maffia, Nalini M. Nadkarni, David P JanosAbstract:We examined the roots of 27 epiphytic and terrestrial species of Piperaceae collected in primary and secondary habitats in Monteverde, Costa Rica. Terrestrial roots of only two of the nine Peperomia species, two of eight Piper species, and of Pothomorphe umbellatum contained internal vesicles and/or arbuscules. We did not find internal vesicles and/or arbuscules in 3024 cm of fine roots of epiphytic Piperaceae, even though 15% of these root segments had associated external typical glomalean hyphae. Glomus and Acaulospora spores, and Gigaspora auxiliary cells occurred in both canopy and terrestrial habitats. After inoculation of a low nutrient substrate, the facultatively epiphytic Peperomia costaricensis averaged 23% mycorrhizal root length. Relatively high atmospheric inputs of dissolved inorganic nutrients that alleviate the requirement for Mycorrhizae, and heterogeneity of mycorrhiza inocula in the canopy may explain the absence of Mycorrhizae from epiphytic Piperaceae. We suggest that the Piperaceae comprises predominantly facultatively mycotrophic species, and that facultative mycotrophism facilitates their radiation to the canopy.
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Vesicular-Arbuscular Mycorrhizae of epiphytes
Mycorrhiza, 1993Co-Authors: David P JanosAbstract:This article introduces reports concerning the occurrence of Mycorrhizae on epiphytes in Costa Rica, Ethiopia, Venezuela, Malaysia, and Mexico. Association of Vesicular-Arbuscular mycorrhizal fungi with the roots of epiphytes is not well known. Vesicular-Arbuscular mycorrhizal fungi (VAM) do occur in the canopy, but are uncommon except in certain sites and host taxa. Occurrence of VAM on epiphytes may be constrained by mineral nutrient availability and spatial heterogeneity in the canopy. Nevertheless, epiphytes present unique opportunities to study influences of Mycorrhizae on vascular plant community composition and on the evolution of mycorrhizal associations.
F B Reeves - One of the best experts on this subject based on the ideXlab platform.
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inland sand dune Mycorrhizae effects of soil depth moisture and ph on colonization of oryzopsis hymenoides
Mycologia, 1995Co-Authors: A K Alagely, F B ReevesAbstract:The occurrence of Vesicular Arbuscular Mycorrhizae was reconfirmed in Oryzopsis hymenoides, a major graminoid species on western sand dunes. A bioassay was used to determine the ability of soil fro...
