In vitro growth of Oncidium baueri (Orchidaceae) at different macronutrients and sucrose concentrations

Abstract

The propagation in vitro is an important method for orchids reproduction, because the seeds don't have endosperm and present low germination. The sugar is a important component in medium culture, serving as a source of carbon and energy. The objective of this study was to evaluate the growth in vitro of Oncidium baueri (Orchidaceae) in different macronutrients and sucrose concentrations. The treatments consisted: two formulations of the macronutrientes of the MS medium, in complete MS and MS modifed medium with half of the regular concentration of macronutrients, and different sucrose concentrations (30 gL-1, 40 gL-1e 60 gL-1), at pH 5,8. A randomized design with eight replications was used as statistical model and a fask with twenty plants composed each plot. Data were submitted to analysis of variance, complemented by the Tukey test at 5% of signifcance. The following variables were assessed six months after the beguining of the experiment: plant height, root length; number of roots, number of buds, dry mass and total fresh mass. The treatment that showed the best results was 40 gL-1 sucrose in a modifed MS medium with half of regular concentration of macronutrients, for vegetative development and rooting of Oncidium baueri orchid.