-(In vitro germination and growth of Hadrolaelia tenebrosa (Rolfe) Chiron & V.P. Castro (Orchidaceae), an endangered species of the Brazilian flora). Orchids are seriously endangered species. For that reason, studies regarding their propagation and development are extremely important. Thus, the present study analyzed the influence of the culture medium on the in vitro germination of Hadrolaelia tenebrosa seeds, on the initial development of protocorms until they form seedlings and on seedling growth during the first twelve months in vitro. The results revealed that the ideal methodology for the in vitro culture of Hadrolaelia tenebrosa involves the use the Knudson's C medium for seed germination and seedling initial growth, and the subsequent transfer of six-month-old plants to VW medium where they should remain until acclimatization is carried out. The obtained data showed that the most efficient culture medium for seed germination of that species was not the most adequate for the development of their seedlings. Therefore, the outcomes of such studies are very important for the optimization of propagation techniques for orchid species. Key words: asymbiotic germination, in vitro culture, media culture, orchid RESUMO -(Estudo da germinação e crescimento in vitro de Hadrolaelia tenebrosa (Rolfe) Chiron & V.P. Castro (Orchidaceae), uma espécie da flora brasileira ameaçada de extinção). As orquídeas são espécies seriamente ameaçadas de extinção. Por isso, estudos sobre a propagação e desenvolvimento dessas plantas são extremamente importantes. Assim, este trabalho procurou estudar a influência do meio de cultura na germinação in vitro de sementes de Hadrolaelia tenebrosa, no desenvolvimento inicial dos protocormos até a formação das plântulas, bem como no crescimento dessas durante o primeiro ano de cultivo in vitro. Os resultados demonstraram que o método ideal para a multiplicação de Hadrolaelia tenebrosa é a utilização do meio Knudson C para a germinação das sementes. Após seis meses as plântulas devem ser transferidas para o meio VW e nele mantidas até o início da aclimatização. Ressalta-se o fato de que para essa espécie o meio de cultura mais eficaz para a germinação, não foi o mais adequado para o desenvolvimento das plantas. Estas informações são de grande importância para a otimização do processo de propagação de espécies de orquídeas. Palavras-chave: cultivo in vitro, germinação assimbiótica, meios de cultura, orquídea 1.

Comparative analysis of zygotic and somatic embryogenesis of Acca sellowiana showed higher amounts of sucrose, fructose, raffinose, and myo-inositol in zygotic embryos at different developmental stages than in corresponding somatic ones. These differences were mostly constant. In general, glucose levels were significantly lower than the other soluble carbohydrates analyzed, showing minor variation in each embryo stage. Despite the presence of sucrose in the culture medium, its levels conspicuously diminished in somatic embryos compared with the zygotic ones. Raffinose enhanced parallel to embryo development, regardless of its zygotic or somatic origin. Analysis of the soluble carbohydrate composition of mature zygotic cotyledon used as explant pointed out fructose, glucose, myoinositol, sucrose, and raffinose as the most important. Similar composition was also found in the corresponding somatic cotyledon. Total soluble carbohydrates varied inversely, decreasing in zygotic embryos and increasing in somatic embryos until the 24th d, at which time they increased rapidly about sixfold in zygotic embryos until the 27th d, a period coinciding with the zygotic proembryos formation. Such condition seems to reflect directly the variation of endogenous sucrose level, mainly because glucose and fructose diminished continuously during this time period. This means that, in terms of soluble sugars, zygotic embryo formation occurred under a situation represented by high sucrose amounts, simultaneously with low fructose and glucose levels, while in contrast, somatic embryo formation took place under an endogenous sugar status characterized by a substantial fructose enhancement. Starch levels increased continuously in zygotic embryos and decreased in somatic ones, the reverse to what was found in fructose variation. Starch accumulation was significantly higher in somatic torpedo and cotyledonary embryos than in the corresponding zygotic ones.

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In general, plant material grown in vitro has low photosynthetic ability to achieve positive carbon balances. Therefore, a continuous supply of carbohydrates from the culture medium is required, and sucrose has been the most commonly used carbon source. In this paper, we investigate the effects of different sucrose concentrations and the presence and absence of light on the endogenous levels of soluble carbohydrates and starch as well as on the proliferation and growth of Dendrobium Second Love (Orchidaceae) in vitro. The possibility of using etiolated stem segments as a means for micropropagating this hybrid was also verified. The results obtained indicated that the presence and absence of light and the sucrose concentrations used influenced the amounts of soluble carbohydrates and starch and the proliferation of D. Second Love shoots and roots. An increase in sucrose concentration caused a progressive increase in the amounts of total carbohydrates and starch. Under both light conditions, sucrose was the main sugar found in the shoots followed by glucose and fructose. The addition of sucrose to the culture medium up to 2% and 4% was advantageous to the number of shoots produced per explant and the root longitudinal growth in the presence and absence of light, respectively. Shoot and root dry matter and the number of roots formed per explant increased as sucrose concentration was raised up to 6% in both light treatments. The use of dark-grown shoot segments proved to be a useful and reliable alternative for the micropropagation of this hybrid.

-(In vitro germination and growth of Cattleya bicolor Lindley (Orchidaceae)). The technique of germinating orchid seeds in vitro has been used since the beginning of the last century. Nevertheless, the available knowledge regarding the nutritional composition of culture media that favor in vitro germination and growth of orchids is still scarce. Cattleya bicolor is a Brazilian threatened orchid species and very little is known about its seed germination and growth in vitro. For that reason, this study aimed at analyzing the influence of the culture medium on the in vitro germination of Cattleya bicolor seeds, on the initial development of its protocorms until they form seedlings, and on seedling growth during the first twelve months of in vitro culture. The results revealed that the Vacin & Went is the ideal culture medium for seed germination and initial seedling development of Cattleya bicolor in vitro. It is recommended that after six months the seedlings be transferred to MS or VW media, since they promote seedling development. They should be kept in one of those media until acclimatization. These results are very important for the optimization of propagation techniques of Brazilian orchid species. Key words: asymbiotic germination, in vitro culture, media culture, orchid RESUMO -(Germinação e crescimento in vitro de Cattleya bicolor Lindley (Orchidaceae)). A germinação de sementes de orquídeas in vitro vem sendo utilizada desde o início do século passado. Apesar disso, o conhecimento disponível a respeito da composição nutricional dos meios de cultura que favorecem a germinação e o crescimento in vitro de orquídeas ainda é bastante escasso. Diante da ameaça de extinção da Cattleya bicolor e devido à escassez de conhecimento a respeito da germinação e do crescimento in vitro dessa espécie, este trabalho teve como objetivo avaliar a influência do meio de cultura na germinação in vitro de suas sementes, no desenvolvimento inicial dos protocormos até a formação das plântulas, bem como avaliar o crescimento das plântulas até os primeiros doze meses de cultivo in vitro. Os resultados mostraram que o meio de cultura ideal para a germinação in vitro das sementes e para o desenvolvimento inicial das plântulas de Cattleya bicolor é o de Vacin & Went. Recomenda-se que após seis meses de cultivo as plântulas sejam transferidas para o meio MS ou VW, que promovem o desenvolvimento das plântulas, e mantê-las em um destes meios de cultura até o início da aclimatização. Tais informações são de grande importância para a otimização do processo de propagação das espécies de orquídeas nativas do Brasil. Palavras-chave: cultivo in vitro, germinação assimbiótica, meios de cultura, orquídea

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Catasetum macrocarpum is an epiphytic orchid that has been subjected to strong environmental pressure in the state of Tocantins. This investigation aimed at studying the germination, growth and morpho-anatomical development of C. macrocarpum under in vitro conditions. The effects of three culture media on the in vitro germination and on the multiplication and growth of 90-day-old seedlings were studied: Murashige & Skoog (full- and half-strength), Knudson C, and Vacin & Went. The effects of different concentrations of benzyladenine (BA) and naphthaleneacetic acid (NAA) on the multiplication and growth of 120-day-old plants were evaluated. Anatomical studies were conducted on protocorms at different developmental stages. Acclimatization was also carried out. Knudson C was the best medium for seed germination whereas Vacin & Went promoted the greatest protocorm development. Half-strength Murashige & Skoog was the most effective medium for seedling multiplication and growth. The results revealed that 1 mg L-1 BA was the best treatment for shoot proliferation and leaf production. NAA at 0.5 mg L-1 strongly favored root formation. The anatomical study revealed that the early stages of C. macrocarpum development do not always coincide with the morphological phases described. The acclimatization of C. macrocarpum plants provided successful results regarding plant survival.

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