Cattleya walkeriana Gardner (Orchidaceae) propagation: culture medium, sealing system and irradiance

This study aimed to evaluate the influence of culture media, irradiance, and sealing system on the in vitro and ex vitro growth of Cattleya walkeriana Gardner. We used MS medium as culture medium, supplemented with 30 g L-1 of sucrose and solidified with 7.0 g L-1 of bacteriological agar. This medium served as a control, while for the other treatments we supplemented the media as follows: 2) MS with 150 g L-1 of banana pulp = P150; 3) MS with 300 g L-1 of banana pulp = P300; 4) MS with 150 g L-1 of banana peel = PE150; and 5) MS with 300 g L-1 of banana peel = PE300. The irradiances were provided by 3000K LED lamps: 86 μmol m-2 s-1 (Irradiance-1) and 128 µmol m-2 s-1 (Irradiance-2) and the conventional sealing (CSS) and sealing systems that allow gas exchange (GESS). After 120 (in vitro) and 180 days (ex vitro) of cultivation, we evaluated them for pseudobulb (PN), leaf (LN) and root number (RN), plant height (PH), pseudobulb diameter (PD), longest leaf (LL) and root length (RL), fresh mass (TFM) and survival (%SURV). There was a significant interaction for all the variables analyzed. The CM x SS double interaction was significant for PH, LL, and RL. The CM x I x SS interaction was significant for PN, LN, RN, PD, TFM, and %SURV traits of C. walkeriana grown in vitro. There was a significant interaction between CM x I x SS for all C. walkeriana traits evaluated in ex vitro culture. Using the medium with up to 150 g L-1 of banana pulp combined with Irradiance-2 and CSS provided the highest values for in vitro plant growth. However, prior cultivation in MS medium, Irradiance-1, and CSS provided the greatest survival and establishment of this species plants in ex vitro culture.