Acclimatization of Phalaenopsis and Cattleya obtained by micropropagation 27 ARTÍCULO DE INVESTIGACIÓN Acclimatization of Phalaenopsis and Cattleya obtained by micropropagation Aclimatización de Phalaenopsis y Cattleya obtenidas por micropropagación Lucía Primitiva Díaz 1 , Jorge Julio Namur 2 , Sebastián Agustín Bollati 3 , Osvaldo Ernesto Antonio Arce 4 Abstract The quality of micropropagated plants relies on the acclimatization stage. This research intends to develop an efficient protocol to obtain the acclimatization of Phalaenopsis and Cattleya. Plants of Pha- laenopsis obtained from protocorms were selected. They came from flowering stalks grown at modified Murashige and Skoog (MS) (1962) medium and classified by growth ranks and put into moss, mesquite wood shaving and perlite (1:1:1), into a humidity chamber. The protocorms were multiplied at MS from Cattleya sown in Knudson C (1946) medium; regenerated plants of 1-2 cm were selected, and implanted in humidity chamber on: moss, coal and perlite (1:1:1) MCP; mesquite wood shavings, coal and perlite (1:1:1) ACP; moss and perlite (1:1) MP; mesquite wood shaving and perlite (1:1) AP. The following re- sults were obtained: Phalanopsis: a) Survival: 44% in R0 and 100% in RI and RII. b) Number of leaves: RI gave on average 1 more leaf than the range 0; c) Roots number and length: RI and RII gave on average 2 more roots than R0, and there were no significant differences in length. d) Height: RII presented greater growth than RI and Ro. Cattleya: a) The survival in MCP was 0%, MP 16 %, ACP 32% and AP 80%. b) The height in MP was significantly superior to the ones in ACP and AP. Plants from both genera need to achieve a 2 to 4 cm growth rank in vitro to endure the greenhouse conditions. MAP was the best subs- trate in Phalaenopsis and moss-perlite in Cattleya. Key words: Orchidaceae, substrates, in vitro culture. 1 Doctora en Agronomía. Profesora Asociada, Facultad Agronomía y Zootecnia, UN Tucumán,Argentina. 2 Ingeniero Agrónomo. Ayudante graduado, Facultad Agronomía y Zootecnia, UN Tucumán, Argentina. jorgenamur@hotmail. com 3 Becario alumno. Facultad Agronomía y Zootecnia, UN Tucumán, Argentina. sebastianbollati@hotmail.com 4 Magíster en Estadística Aplicada. Profesor Adjunto, Facultad Agronomía y Zootecnia, UN Tucumán, Argentina. ova.arce@ gmail.com Rev. Colomb. Biotecnol. Vol. XII No. 2 Diciembre 2010 27-40 27