Cyathea atrovirens (Langsd. & Fisch.) Domin, an intensely exploited tree fern, is found inside forests in several succession stages, as well as in swamps, roadsides and unused fields in the Rio dos Sinos basin, in the state of Rio Grande do Sul, southern Brazil. This study evaluated the in vitro germination and gametophyte development of C. atrovirens under different pH conditions, as well as spore viability after different storage times at 7 ºC. The lowest germination rate of spores was obtained at pH 7.0. At pH 5.0 to 6.5, laminar gametophyte development started at 20 to 30 days of culture. Antheridia and archegonia were first observed at 35 and 128 days, respectively. Storage at 7 o C did not affect germination rates. The capability of germination at different pH levels may explain the occurrence of the species in a wide range of habitats. The present study contributes to the understanding of the full life-cycle of C. atrovirens and to the analysis of the influence of abiotic components, providing information for the cultivation, management and conservation of the species.Keywords: tree ferns, gametophyte, pH, reproduction, conservation. Rechenmacher, C., Schmitt, JL. and Droste, A. through lens cleaning tissue. Part of the spores were stored in tubes at 7 ± 1 °C for later viability analysis. Spores did not undergo asepsis to keep experimental conditions close to those found in nature.
Germinação de esporos e desenvolvimento gametofítico deTo evaluate the effect of pH on germination and initial gametophyte development of fresh spores, seven different pH levels were used: 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; and 7.0. In a laminar flow hood, 10-mg samples of spores were distributed in flasks with 50-mL autoclaved Meyer solution (Meyer et al., 1955). Six replicates were used for each pH level, totalising 42 flasks. The cultures were maintained in a growth chamber at 26 ± 1 °C for a 16-hour photoperiod and photon flux density of 100 µmol.m -2.s -1 provided by cool white fluorescent tubes.Germination was scored at three, six, nine and 12 days of in vitro culture. Six slides (one slide per flask) from each treatment were analysed, verifying 100 spores on each slide. To follow up initial gametophyte development at different pH levels, 10 individuals on each slide (one slide per flask) were photographed and classified according to their developmental stage in the following categories at six, nine and 12 days of culture: a) rhizoid and chlorocyte; b) filamentous stage; and c) laminar stage. At 104, 128 and 150 days, the morphology of one individual from each flask was described.To describe the in vitro development of this species, only gametophytes obtained at pH 6.0 were evaluated at up to 128 days of culture. Representative individuals at different development stages were photographed, and the images were digitalised using a Canon EOS 220 camera coupled to an Olympus CX4 microscope.In a second experiment, the germinability rates of fresh and stored spores (90 and 180 days at 7 °C) were compared, using cultures w...