Morfofisiologia de plântulas de Cattleya labiata Lindley e Cattleya eldorado Linden cultivadas in vitro sob influência de paclobutrazol

Abstract

The efficiency of in vitro cultivation of orchids is associated with culture media, and especially with the plant growth regulators. This study aimed to evaluate the influence of paclobutrazol (PBZ) in the development of in vitro plantlets of Cattleya labiata Lindley and Cattleya eldorado Linden. Plantlets from in vitro germination, with 1 ± 0.2 cm in length, were used in this study. In the experiment, hormone-free MS medium was used as the control. Treatments consisted of MS medium supplemented with 1, 2, 4 and 6 mg.L-1 of PBZ. PBZ at a concentration of 4 mg.L-1 combined with 1 mg.L-1 naphthalene acetic acid (NAA) and 1 mg.L-1 6-benzylaminopurine (BAP) was also tested. The experiment was completely randomized in a factorial arrangement in time, with six replicates per treatment. The morphological evaluations were performed at the onset of the experiment and at the subcultures every 40 days, during 160 days. Treatment with 1mg.L-1 PBZ for 40 days promoted further development and vigor of the root system and may contribute to the acclimatization phase of plantlets.