In vitro growth and acclimatization of Cattleya loddigesii Lindley com carvao ativado sob dois espectros luminosos

The aim of this study was to evaluate the effect of different concentrations of activated charcoal in 1/2 MS (half concentration of macronutrients) culture medium under two light spectra on the in vitro growth of Cattleya loddigesii seedlings. Plantlets with approximately 90 days were subcultured under eight treatments, consisting of different active charcoal concentrations (0; 0.5; 1.0 and 2.0g [L.sup.-1]) in V2 MS medium combined with white and red light spectra. After 180 days of germination, biometric data, fresh weight, and the level of photosynthetic pigments were evaluated. Plantlets acclimatized in a greenhouse were evaluated for survival after 120 days. Total chlorophyll, chlorophyll a, and carotenoid concentrations were higher in treatments under white light, while red light promoted greater chlorophyll b, plantlets with fewer and shorter roots, and high ex vitro mortality. The addition of 2.0g [L.sup.-1] of active charcoal to the culture medium and the use of white light provided greater development efficiency both on in vitro culture and ex vitro plant survival. Key words: In vitro germination, luminosity, kinds of light, orchid, plantlets and ex vitro survival. O objetivo deste estudo foi avaliar a adicao de concentracoes de carvao ativado em meio de cultura 1/2 MS (com metade da concentracao dos macronutrientes) sob dois espectros luminosos para a obtencao de plantulas in vitro de Cattleya loddigesii. Plantulas com aproximadamente 90 dias foram subcultivadas em oito tratamentos, nos quais foi testada a adicao ao meio de cultura V2 MS com carvao ativado (0; 0,5; 1,0 e 2,0g [L.sup.-1]) e combinados sob espectro de luz branca e luz vermelha. Apos 180 dias da germinacao, foram mensurados dados biometricos (raiz e parte aerea), massa fresca e teores de pigmentos fotossinteticos. Em plantulas aclimatizadas em casa de vegetacao, foram avaliadas a taxa de sobrevivencia apos 120 dias. As concentracoes de clorofila total, clorofila a e carotenoides foram maiores nos tratamentos sob luz branca, enquanto a luz vermelha influenciou significativamente maior clorofila b, plantulas com menos raizes e de menor comprimento e elevada mortalidade ex vitro. A adicao de 2,0g [L.sup.-1] de carvao ativado ao meio de cultura e o uso de luz branca proporcionaram maior eficiencia de desenvolvimento tanto para as culturas in vitro quanto para a sobrevivencia ex vitro das plantas. Palavras-chave: germinacao in vitro, luminosidade, tipo de luz, orquidea, plantulas e sobre