Crescimento de mudas de peroba rosa em resposta à inoculação com fungos micorrízicos arbusculares / Growth responses of peroba rosa seedlings due to arbuscular mycorrhizal fungi inoculation

O objetivo neste trabalho foi de avaliar o efeito da inoculação de fungos micorrízicos arbusculares no crescimento de mudas de peroba rosa (Aspidosperma polyneuron). O experimento foi conduzido em delineamento experimental, inteiramente casualizado, em casa de vegetação com seis repetições. Utilizou-se mistura de solo e areia (3:1), desinfestado como substrato, com os seguintes tratamentos de inoculação: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata e uma mistura de fungos micorrízicos arbusculares (FMA). Após 120 dias, observou-se que a colonização micorrízica radicular foi de 28,3 por cento a 48,4 por cento para a mistura de FMA e para G. margarita, respectivamente. As plantas inoculadas com G. margarita e G. clarum apresentaram maior crescimento, indicando o potencial da inoculação desses fungos na produção de mudas.

The aim of this study was to examine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on Aspidosperma polyneuron seedlings growth. The experiment was conducted under greenhouse conditions in a randomized design using a disinfected mixture of soil + sand (3:1) with the following treatments: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata, a mixture of arbuscular mycorrhizae fungi (AMF) and a non-inoculated control with six replicates. After 120 days of seed germination, it was observed that root colonization was from 28.3 percent to 48.4 percent for mixture of AMF and G. margarita, respectively. The plants inoculated with G. margarita or G. clarum showed higher growth than other treatments, which evidence the potential of AMF inoculation in seedlings production.

Antioxidant responses in bean (Phaseolus vulgaris) roots colonized by arbuscular mycorrhizal fungi.

• Degradation of reactive oxygen species in arbuscular mycorrhizas (AM) may be an efficient mechanism to attenuate the activation of plant defenses. Here, we evaluated the activities of superoxide dismutase (SOD), guaiacol-peroxidase (GPX) and catalase (CAT) in bean (Phaseolus vulgaris) mycorrhizal roots at different conditions and stages of symbiosis development. • Bean plants were inoculated with Glomus clarum (Gc) or G. intraradices (Gi), under low (LP) and high P (HP) concentrations, and grown under glasshouse conditions. In a second experiment, bean seeds were treated with formononetin and inoculated with Gc under LP and HP conditions. The activities of SOD, GPX and CAT were evaluated. • SOD was induced only in roots colonized by Gc, at a late stage of the symbiosis development under LP, and at an early stage under HP. GPX was induced in roots colonized by Gc at an early time point and suppressed later under LP. In general, CAT was induced in roots colonized by Gc under LP. CAT activities in roots were dependent on P and formononetin treatment. • The possible roles of SOD, GPX and CAT in AM are discussed.

Elevated CO2 and plant species richness impact arbuscular mycorrhizal fungal spore communities.

• We enumerated arbuscular mycorrhizal (AM) fungal spore communities for 3 yr as part of a long-term CO2 enrichment experiment at Cedar Creek, Minnesota, USA. Complete factorial combinations of two levels of CO2 and N, and 16 perennial plant species grown in monoculture and 16-species polyculture were arranged in a split-plot design. • In 1998-2000, spore communities were quantified under monocultures of eight plant species. In 2000, measurements were expanded to include monocultures and polycultures of all of the plant species. • Under plant monocultures, only Glomus clarum responded significantly to CO2 elevation out of 11 species present. This response was not detectable under plant polycultures. Glomus clarum was also significantly more abundant under plant polycultures. Nitrogen addition had small negative effects on AM fungal spore abundance and species richness in 2000. The interaction of CO2 and N did not affect arbuscular mycorrhizal fungal spore communities. • We show that CO2 enrichment and plant species richness impact arbuscular mycorrhizal fungal community structure. These findings are important because altered symbiotic functioning may result.

Fungos micorrízicos nativos e Glomus clarun no rendimento de trevo vesiculoso cultivado em condições naturais e modificadas pela calagem e aplicação de fósforo / Glomus clarun and native mycorrhizal fungi on yield of Trifolium spp. cultivated under natural and modified soil contitions with addition by phosphorus and liming

Em experimento desenvolvido na casa de vegetação na UFSM-RS, avaliou-se o efeito da introdução de fungos micorrizicos arbusculares (fMA) Glomus clarum e nativos no rendimento de massa seca (MS) e absorção de P pelo trevo vesiculoso (Trifolium spp.) e verificou-se a compatibilidade entre a espécie introduzida e os fMA nativos ocorrentes no solo estudado. Os tratamentos/oram constituídos defatorial 4x2x2 com quatro níveis de fMA: G. clarum, fungos nativos, mistura de ambas as populações e controle sem inoculação de fMA: com dois valores de pH: 4,4 e 5,4 e com dois níveis de fósforo disponível (Mehlich l): 6 e ISmg/kg de solo. A introdução de G. clarum isoladamente ou em conjunto com fMA nativos, na condição de pH 4,4, e em baixa disponibilidade de P, aumentou o rendimento de MS e absorção de P. Em disponibilidade intermediária de P (l5mg/kg de solo) e pH 5,4 não ocorreu diferença entre os tratamentos inoculados com fMA, mas destes ocorreu diferença para o tratamento sem inoculação, evidenciando a dependência do trevo pela micorrizaçâo. Tratamentos inoculados com G. clarum apresentaram maiores rendimentos de MS, absorção de P, colonização micorrizica e esporulação, mostrando que a introdução dessa espécie pode ser viável quando espécies nativas não são eficientes para a cultura ou tornam-se ineficientes quando a fertilidade do solo é modificada por aplicação de P e/ou calagem.

The experiment v/as conducted under greenhouse condition at the University of Santa Maria, RS, Brazil. The objectives were to evaluate the introduction of arbuscular mycorrhizalfúngi (AMF) Glomus clarum and natives fungi on the phosphorus uptake and dry matter (DM) production from Trifolium spp. and Io verify lhe compatibilily between introduced specie and lhe nativo AMF occurence in lhe studied soil. The treatments was constituled of 4x2x2 factorial withfour AMF leveis: G. clarum, AMf native, mixture of both populations of AMF andcontrai which was without inocutation of AMF: twopH leveis: 4.4 and 5.4 and two phosphorus leveis by Mehlich I extractor: 6 and l5mg/kg of soil. It was noticed that when G. clarum was introduced isolately or with native AMF with pH of 4.4 and low P availability increased DM production and P accumulation. At medium P availability (15mg/kg of soil) and pH 5.4 there were no diferences between inoculated treatments with AMF but from ones there was observed diferences on the contrai. These differences were due to the mycorrhizal dependence on Trifolium. Inoculated treatments with G. clarum showed higher DM production, Puptake, mycorrhizal colonization and number of spores. It can be concluded that the introduction of G. clariim can be viable when the nativo species are not efficient for the crop or become unefficient when the natural soilferlilily is modified by addition of phosphorus or liming.