Cultivo in vitro de orquídeas do grupo Cattleya, em diferentes meios de cultura e irradiâncias

Abstract

The propagation in vitro of orchids requires specific conditions to be cultivated. This work aimed to evaluate the effects of the methods of cultivation in the process of germination and growth of the species of the Cattleya group, and establish better levels of irradiation for the growth of vitroplants. We evaluated the effects of adding doses (0,0; 1,0; 2,0; 3,0 e 4,0 g L-1) of activated charcoal and of commercial brands in the means of culture GB5, MN, and Peter s. In the second step we evaluated four formulations in the means of culture (Peter s; MS; GB5; and B&G), with 0,0 and 2,0 g L-1 activated charcoal. Finally we studied the effects of the light irradiation (12; 25; 50; 100; and 150 µmol m-2 s-1). The seeds germination of the Laelia purpurata var. carnea, Cattleya amethystoglossa e Laelia anceps var. semia-alba occurred in less time (≈ 30 days) and in higher percentage level (80%) in means of culture without the addition of activated charcoal. In the same conditions, there were more green protocorms also, but the addition of activated charcoal increased the growth of the protocorms with roots. Simpler formulations, for example, the commercial fertilizer Peter s or B&G orchidée can substitute more complex means of culture as MS (1962) and GB5 (1968). Vitroplants of the Cattleya guttata Leopoldi x Lc. Guadalajara cultivated under light irradiation of the 65 µmol m-2 s-1 resulted in a better vegetative growth. In higher levels of irradiation, photo inhibitor effects were observed, but it was reversible in lower frequency, showing the plasticity of the hybrid studied.The propagation in vitro of orchids requires specific conditions to be cultivated. This work aimed to evaluate the effects of the methods of cultivation in the process of germination and growth of the species of the Cattleya group, and establish better levels of irradiation for the growth of vitroplants. We evaluated the effects of adding doses (0,0; 1,0; 2,0; 3,0 e 4,0 g L-1) of activated charcoal and of commercial brands in the means of culture GB5, MN, and Peter s. In the second step we evaluated four formulations in the means of culture (Peter s; MS; GB5; and B&G), with 0,0 and 2,0 g L-1 activated charcoal. Finally we studied the effects of the light irradiation (12; 25; 50; 100; and 150 µmol m-2 s-1). The seeds germination of the Laelia purpurata var. carnea, Cattleya amethystoglossa e Laelia anceps var. semia-alba occurred in less time (≈ 30 days) and in higher percentage level (80%) in means of culture without the addition of activated charcoal. In the same conditions, there were more green protocorms also, but the addition of activated charcoal increased the growth of the protocorms with roots. Simpler formulations, for example, the commercial fertilizer Peter s or B&G orchidée can substitute more complex means of culture as MS (1962) and GB5 (1968). Vitroplants of the Cattleya guttata Leopoldi x Lc. Guadalajara cultivated under light irradiation of the 65 µmol m-2 s-1 resulted in a better vegetative growth. In higher levels of irradiation, photo inhibitor effects were observed, but it was reversible in lower frequency, showing the plasticity of the hybrid studied.