Arbuscular Mycorrhizae Effects on Growth of Two Hawaiian Species: Indigenous \u3cem\u3eOsteomeles anthyllidifolia\u3c/em\u3e (Rosaceae) and Invasive \u3cem\u3ePsidium cattleianum\u3c/em\u3e (Myrtaceae)

Two important plant species of Hawai\u27i, the indigenous Osteomeles anthyllidifolia (Sm.) Lindl., a component of Hawai\u27i\u27s most endangered habitat, and the highly invasive Psidium cattleianum Sabine were grown with or without arbuscular mycorrhizal fungi in a soilless mix at different soil-solution phosphorus (P) levels. At P levels similar to those in the field (0.007 mg P/liter), shoot biomass of inoculated plants of O. anthyllidifolia was 189% greater than that of controls, and that of P. cattleianum was 93% greater. Root weight of O. anthyllidifolia and leaf-tissue P of both species also were significantly higher in inoculated plants. At a higher concentration of soil-solution P (0.020 mg P/liter), inoculated plants of O. anthyllidifolia had 176% more biomass than controls, and those of P. cattleianum had 49% more. In a growth medium with soil-solution P equivalent to that of good agricultural soil (0.200 mg P/liter), inoculated plants of O. anthyllidifolia were 101% larger than controls. Results suggest that presence of arbuscular mycorrhizal fungi is of vital importance to establishment of O. anthyllidifolia in Hawaiian soils and that their absence may limit P. cattleianum invasion of sites that are highly deficient in available P

Colonização micorrízica e crescimento da videira (Vitis vinifera, Porta-Enxerto P1103) em solo com alto teor de cobre.

A aplicação de fungicidas cúpricos em vinhedos aumenta o teor de Cu no solo, potencializando a toxidez para a videira. Entretanto, tem sido relatado que os fungos micorrízicos arbusculares (FMA) podem propiciar efeito protetor às plantas em solos contendo excesso de metais pesados. O trabalho objetivou avaliar a colonização micorrízica e o crescimento da videira (porta-enxerto P1103) em solo contendo elevados teores de Cu. Avaliou-se seis tratamentos de inoculação com FMA (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus e R. irregularis), além de um não inoculado. Verificou-se que a colonização micorrízica da videira foi elevada (média de 33%), mesmo em solo contendo excesso de Cu. A inoculação dos isolados de FMA testados pouco influenciou o crescimento da videira, mas a inoculação com R. irregulares e R. clarus beneficiou a produção de massa seca das raízes das mudas.Resumo expandido

Vesicular-arbuscular Mycorrhizal Inoculation of Hawaiian Plants: A Conservation Technique for Endangered Tropical Species

Forty species of plants (including 28 species endemic to the Hawaiian Islands) were evaluated in the greenhouse for their response to inoculation with the vesicular-arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith. Seedlings, cuttings, and established plants were inoculated. Several kinds of growth media were used. Increased growth and survival most frequently occurred when plants were grown in a gravel or fine sand medium that included calcined clay (up to 50% by volume) or sphagnum peat (up to 20%). Significant increases in height, weight, leaf number and size, and survival were noted in 10 of 14 species of seedlings grown in media in which peat content was 20% or less. Mycorrhizae were only rarely present in the noninoculated plants except for plants grown from cuttings. The latter routinely formed mycorrhizae in the absence of added inoculum. Addition of mycorrhizal fungi to potting mixes appears to have value as a conservation technique for some plants that are difficult to propagate

Arbuscular mycorrhizal fungi species associated with rhizosphere of Phoenix dactylifera L. in Morocco

A survey of arbuscular mycorrhizal fungi (AMF) diversity and date palm (Phoenix dactylifera L.) tree root colonization in arid areas was undertaken in ten palm groves located along the Ziz valley (Tafilalet, south-west Morocco). The frequency and the mean intensity of root colonization reached 72 and 43% respectively and the spore population varied from 238 to 1840 spores/10g of soil. The AMF colonization levels of field date palm roots were found to be negatively correlated with soil phosphorus content (r2 =-0,64). A total of ten AMF species were trapped from the 10 studied sites with a population of 4 to 7 species per sites. The isolated species included: Glomus mosseae, G. fasciculatum, G. constrictum, G. aggregatum, G. macrocarpum, 3 undescribed species of Acaulospora and two of Scutellospora genera. The latter two species were trapped only at the second trapping cycle.Keywords: AMF, diversity, Morocco, palm grove, Phoenix dactylifer,

Effect of vermicompost and selected plant preparations on the development of arbuscular mycorrhizal symbiosis in lettuce (Lactuca sativa)

The aim of the pot experiment was to evaluate effect of vermicompost and promoting plant preparations application (Symbivit and Plantaktiv) on the development of arbuscular mycorrhizal symbiosis in lettuce, amount of extraradical mycelium of mycorrhizal fungi in soil and plant biomass production. Symbivit contains six species of mycorrhizal fungi and Plantaktiv contains magnesium sulfate activated by oxygen promoting activity of aerobic microorganisms in the soil. The application of vermicompost and promoting plant preparations did not have a statistically significant effect on lettuce root colonization by mycorrhizal fungi. The greatest length of extraradical mycelium was observed in variant with vermicompost application, in variant with addition of vermicompost and Symbivit, and in variant with vermicompost applied with both plant preparations. There was detected statistically significant difference when compared to control variant. Dry matter weight of aboveground biomass and root of the lettuce were statistically significantly increased in all variants, where vermicompost was applied, either alone or in combination with plant preparations. Separate application of Symbivit or Plantaktiv did not have a statistically significant effect either on the length of extraradical mycelium or dry matter weight of the lettuce.O

Mycorrhizal Status of Gunnera petaloidea in Hawai'i

Eight collections of the endemic Hawaiian angiosperm Gunnera petaloidea ssp. kauaiensis were examined for mycorrhizae. Soil-inhabiting roots of all specimens possessed extensive vesicular-arbuscular mycorrhizae 01AM). Aerial roots lacked mycorrhizae. Soil from the root zones of the plants contained propagules of VAM fungi, and spores of two species of VAM fungi were found in the soil. The discovery of mycorrhizae in Gunnera adds another symbiont to the Gunnera-Nostoc symbiosis

Impacto da retirada da palhada de áreas com cana-de-açúcar sobre os fungos micorrízicos arbusculares em solo de cerrado, em Dourados – MS.

FERTBIO 2010

Direct nitrogen and phosphorus limitation of arbuscular mycorrhizal fungi: a model and field test.

Since mycorrhizal fungi constitute an important component of the soil–plant interface, their responses to changes in nutrient availability may mediate shifts in ecosystem function. We tested the hypothesis that initial soil nutrient availability may determine effects of nitrogen (N) and phosphorus (P) additions on the growth and community of arbuscular mycorrhizal (AM) fungi. Extraradical hyphal lengths and degree of root colonization of AM fungi were measured in control and fertilized plots along a soil fertility gradient in Hawaii. Responses of individual AM genera were assessed through immunofluorescent labeling. The AM biomass was increased by N and P additions in the N- and P-limited sites, respectively, and reduced by P fertilization in the fertile site only. The abundance of Scutellospora was lower under N than under P fertilization, whereas the incidence of Glomus was higher in the fertile site than the N-limited site. Gigaspora and Acaulospora did not vary among sites or treatments. Our results indicate that a decrease in AM abundance following nutrient additions cannot be assumed to occur and the effects may differ among AM genera and ecosystems with varying soil nutrients. Limitation of N and P may be one possible explanation

Densidade de esporos e colonização radicular por fungos microrrízicos arbusculares em ecossistemas de Araucaria angustifolia (Bert.) O. Ktze. preservados e impactados

Araucaria angustifolia (Bert.) O. Ktze., a native forest tree from Brazil, is under extinction risk. This tree depends on arbuscular mycorrhizal fungi for growth and development, especially in tropical low-P soils but, despite being a conifer, Araucaria does not form ectomycorrhiza, but only the arbuscular endomycorrhiza. This study aimed at surveying data on the spore density and root colonization (CR) by arbuscular mycorrhizal fungi (AMF) in Araucaria angustifolia forest ecosystems, in order to discriminate natural, implemented, and anthropic action-impacted ecosystems, by means of Canonical Discriminant Analysis (CDA). Three ecosystems representative of the Campos do Jordão (SP, Brazil) region were selected: 1. a native forest (FN); 2. a replanted Araucaria forest (R); and 3. a replanted Araucaria forest, submitted to accidental fire (RF). Rhizosphere soil and roots were sampled in May and October, 2002, for root colonization, AMF identification, and spores counts. Root percent colonization rates at first collection date were relatively low and did not differ amongst ecosystems. At the second period, FN presented higher colonization than the other two areas, with much higher figures than during the first period, for all areas. Spore density was lower in FN than in the other areas. A total of 26 AMF species were identified. The percent root colonization and spore numbers were inversely related to each other in all ecosystems. CDA indicated that there is spatial distinction among the three ecosystems in regard to the evaluated parameters.A Araucaria angustifolia (Bert.) O. Ktze. é uma espécie florestal nativa do Brasil e encontra-se ameaçada de extinção. É altamente dependente de fungos micorrízicos arbusculares para seu desenvolvimento, principalmente em solos com baixos teores de fósforo. Embora sendo uma conífera, esta árvore não forma ectomicorriza, mas sim a endomicorriza arbuscular. O presente estudo teve como objetivo levantar dados sobre a densidade de esporos e a colonização radicular de fungos micorrízicos arbusculares (FMAs) em ecossistemas florestais de Araucaria angustifolia, visando discriminar os ecossistemas natural, implantado e impactado pela ação antrópica, através da Análise Canônica Discriminante (ACD). Foram selecionados três ecossistemas representativos da região de Campos do Jordão (SP): 1. floresta nativa (FN); 2. floresta replantada de araucária (R); e 3. floresta replantada de araucária, submetida a uma queima acidental (RF). As coletas de solo rizosférico e de raízes foram realizadas em maio e outubro de 2002. Determinaram-se a densidade de esporos, taxa de colonização radicular e identificaram-se os gêneros de FMAs presentes. O número de esporos na FN foi sempre inferior aos reflorestamentos. Foram identificadas ao todo 26 espécies de FMAs. A colonização radicular na primeira coleta apresentou valores os quais não diferiram entre as três áreas estudadas. Entretanto, na segunda coleta, a FN apresentou plantas com maior valor de colonização que aquelas dos reflorestamentos, sendo todos os valores superiores aos encontrados na primeira coleta. Houve uma relação inversa entre colonização e número de esporos em todas as áreas. Ocorreu uma separação espacial entre as três áreas de estudo, baseada em análise canônica discriminante das variáveis estudadas

Desenvolvimento de dendezeiro em área reabilitada com leguminosas arbóreas.

O objetivo desse trabalho foi avaliar o desenvolvimento de 8 cultivares de dendê, plantadas em tanques de deposição de rejeito de bauxita, anteriormente com um substrato de cerca de 50 cm de cinza vegetal e revegetado com leguminosas arbóreas fixadoras de nitrogênio