Este estudo foi desenvolvido com o objetivo de avaliar o efeito de 6-benzilaminopurina - BAP (0; 0,5 e 1,0 mg L-1) e espectros luminosos (branco, vermelho e azul), na indução de estruturas semelhantes à protocormos ("protocorm like bodies - PLBs") a partir de calos obtidos de explantes foliares. O delineamento experimental utilizado foi inteiramente casualizado e os tratamentos foram arranjados em esquema fatorial 3x3 (três concentrações de BAP e três espectros luminosos), com quatro repetições (frasco) contendo cinco explantes cada. Aos 60 dias de cultivo foram avaliados o número e o comprimento dos protocormos, número de folhas por protocormo, massa fresca total, percentual de explantes oxidados e coloração dos explantes, sendo nesta última, atribuídos os seguintes valores: 1 – branco/amarelado, 2 – verde claro e 3 - verde escuro. A partir dos resultados obtidos foi possível concluir que o cultivo dos calos de Cattleya nobilior em meio MS suplementado com 1,0 mg L-1 de BAP e sob espectro luminoso vermelho promove um aumento da massa fresca e diminui a oxidação dos protocormos,enquanto que, o cultivo em meio contendo 0,5 mg L-1 de BAP e sob espectro luminoso branco promove um leve aumento no comprimento dos protocormos. No entanto, para o número de protocormos, número de folhas por protocormo e coloração dos protocormos, os tratamentos realizados não promoveram alterações significativas sobre estas variáveis.

This study examines the in vitro growth and ex vitro establishment of Brassavola tuberculata in relation to the micropropagation system and sucrose concentration employed in the in vitro culture. A completely randomized experimental design was utilized, employing a 2 x 5 factorial arrangement. The experimental period began with seedlings cultivated in vitro for 180 days, which were subsequently transferred to Murashige and Skoog culture media containing sucrose concentrations of 0, 15, 30, 45, or 60 g L-1. The cultures were subjected to two micropropagation systems: conventional and gas exchange. After 90 days of in vitro cultivation, the plants were evaluated, transplanted into a substrate, and placed in a screened nursery for ex vitro cultivation. After 300 days of ex vitro cultivation, the survival and initial characteristics of the plants were assessed. The micropropagation system allowing gas exchange and sucrose concentrations up to 30 g L-1 enhanced the shoot and root growth of in vitro propagated plants. No noticeable anatomical differences were observed after 90 days of in vitro culture among the different sucrose concentrations and micropropagation systems used. In the ex vitro establishment, irrespective of sucrose concentration, the micropropagation system facilitating gas exchange positively influenced all evaluated characteristics.

One of the obstacles for the production of Orchidaceae plants is the seed propagation. Thus, in in vitro cultivation, luminosity and the type of sealing of the bottles are factors that influence germination and initial development of orchids. Therefore, the objective was to evaluate the light condition, the type of sealing of the bottles and the evaluation time in germination and initial in vitro development of Dendrobium nobile Lindl. After sowing, cultures were subjected to two irradiance conditions according to the sealing of the flasks: 7.0 µmol m-2 s-1 (threaded cap) and 19.0 µmol m-2 s-1 (plastic film) and two light conditions: white fluorescent lamp and red fluorescent lamp. At 30, 60 and 90 days, the percentage of germination, survival, of protocorms in stage 1, stage 2, stage 3 and stage were evaluated 4. DIC was used, in a sub-divided plot scheme for 30 and 60 days after sowing and in a 2 x 2 factorial scheme at 90 days. The highest germination percentage was observed when using white fluorescent lamp with a plastic film cover (70.33%) and at 30 days (70.13%). The highest survival percentage (100%) was observed when using plastic film cover and white fluorescent lamp at 90 days. The greatest development of propagules, reaching stage 4 was verified in the red fluorescent lamp with threaded cap (9.55%).

Orchids need measures for conservation of their species, among them the creation of seed banks. This study analyzes suitable methodologies to identify the viability of Cattleya seeds through the tetrazolium test. Seeds of Cattleya nobilior Rchb. and Cattleya walkeriana Gardn. were submitted to three preconditioning: no soaking (control); sucrose (10%); or distilled water. After 24 hours, they were submitted to tetrazolium solution with three types of conditioning: oven (40 °C); water bath (40 °C); or room temperature. Subsequently, the percentage of viable seeds (VS) was calculated and in vitro sowing was carried out. Germination percentage (G) was determined after 45 days. A completely randomized design was used for each species studied, with treatments arranged in a 3x3 factorial scheme (three preconditioning and three conditioning), with eight replicates of one tube each. The experiment was performed in duplicate. The highest viability values found in the tetrazolium test were close to those of germination (C. nobilior: VS = 88% e G = 97%; C. walkeriana: VS = 88% e G = 95%) for Cattleya species native to the Cerrado. The conditioning at ambient temperature had a greater effect on seed visualization for both species studied, suggesting that the tetrazolium test should be performed at this conditioning temperature.