ABSTRACT Arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSF) are symbionts that are associated with the roots of plants, including epiphytic lycophytes and ferns. Paris-type mycorrhiza and glomoid structures are the most common forms of colonization in these plants. This work aimed to evaluate the occurrence of these symbionts in the roots of epiphytic lycophytes and ferns as well as the diversity of AMF spores recovered from substrate associated with the roots of eleven species. Roots of Asplenium gastonis, Campyloneurum aglaolepis, C. nitidum, Niphidium crassifolium, Pecluma pectinatiformis, Phlegmariurus mandiocanus, Pleopeltis hirsutissima, P. pleopeltifolia andSelaginella microphyllahad hyphae and vesicles typical of AMF colonization, but not arbuscules.Campyloneurum nitidum, Pecluma pectinatiformis, Phlegmariurus mandiocanus, Pleopeltis pleopeltifolia and Selaginella microphyllahad melanized hyphae and microsclerotia typical of DSF. All species colonized by DSF were also colonized by AMF. Seventeen spore morphotypes of AMF were identified, of which six were acaulosporoid and eleven glomoid. Glomus aff. formosanum andAcaulospora aff. lacunosa were the most abundant and frequent species. Epiphytic lycophytes and ferns host concurrently AMF and DSF but colonization is scanty in their roots. For the first time, acaulosporoid spores and intraradical vesicles are reported for this group of plants.

Nenhum estudo prévio tem investigado o uso de grafite como substituto do carvão ativado em orquídeas. No presente trabalho, concentrações diferentes de carvão ativado ou de grafite foram adicionadas ao meio KC para escurecer o meio de cultura e estimular a propagação in vitro de Cattleya bicolor e de um duplo híbrido de orquídea ('BLC Pastoral Innocence'). As plântulas foram inoculadas em meio KC sem reguladores de crescimento; os efeitos de concentrações de carvão ativado (0,0; 1,5; 3,0; 4,5; 6,0 and 7,5 g L-1) e de grafite (0,0; 1,5; 3,0; 4,5; 6,0 and 7,5 g L-1) foram testados separadamente. Foram inoculadas quinze plântulas em cada frasco e os experimentos foram conduzidos sob esquema de planejamento fatorial com dois fatores: meios de cultura e luminosidade; o meio de cultura com onze níveis (diferentes concentrações de grafite ou de carvão ativado) e luminosidade com dois níveis (fotoperíodo de 14h e iluminação contínua). Para cada combinação do nível fatorial foram feitas três repetições. Após seis meses de cultivo, foram registrados os números médios de brotos e raízes induzidos em cada concentração de carvão ativado e de grafite. O maior número de brotos nas plântulas de C. bicolor foi observado no meio contendo 6,0 e 7,5 g L-1 de grafite, e o maior número de raízes foi verificado no meio contendo 6,0 g L-1 de carvão ativado. No duplo híbrido o maior número de brotos e raízes foi observado no meio contendo 4,5 g L-1 de carvão ativado. O grafite não pode ser recomendado para substituir o carvão ativado.

No previous studies have investigated the use of graphite instead of activated charcoal in orchids. In this work, different concentrations of activated charcoal or graphite were added to KC medium to darken the culture medium and stimulate the in vitro propagation of Cattleya bicolor and of a double hybrid orchid ('BLC Pastoral Innocence'). The seedlings were inoculated on growth regulator-free KC medium; the effects of activated charcoal (0.0, 1.5, 3.0, 4.5, 6.0, and 7.5 g L-1) and graphite (0.0, 1.5, 3.0, 4.5, 6.0, and 7.5 g L-1) concentrations were tested separately. Each flask contained fifteen seedlings, and the experiments had a randomised, two-way factorial design. The two tested variables were culture medium and illumination levels; eleven culture levels (different concentrations of graphite or activate charcoal) and two illumination levels (14-hr photoperiod or continuous illumination) were evaluated. Three replicates of each combination were utilised. After six months of culture, the average numbers of induced buds and roots per seedling were recorded for each concentration of activated charcoal or graphite. Whereas the largest number of buds in C. bicolor seedlings occurred on media containing 6.0 or 7.5 g L-1 graphite, the largest number of roots occurred on media containing 6.0 g L-1 activated charcoal. In the hybrid 'BLC Pastoral Innocence', the largest number of buds and roots was reported in medium with 4.5 g L-1 activated charcoal. When using graphite in place of activated charcoal, we obtained disparate the results in root formation that suggest that graphite is not a recommended substitute for activated charcoal.