Source and concentration of carbohydrates on shoot growth and rooting of Miltonia flavescens Lindl.

Abstract

Miltonia flavescens is an epiphytic orchid native to southern Brazil threatened with extinction by extraction and destruction of their habitats. Type and concentration of carbohydrates are important for promoting growth and development of in vitro cultured orchids. This study aimed to evaluate the effect of different carbohydrate sources and concentrations on in vitro growth and rooting of M. flavescens. In vitro seed-derived plants used as explants were cultured in half-strength MS media containing sucrose, maltose and glucose as carbohydrate sources, at concentrations of 0, 15, 30, 45 and 60 g.L^-1. After six months in culture, plants were evaluated for aerial part height, root number, leaf number, shoot number and fresh weight. The experiment was arranged in a complete randomized design, with five replications per treatment and experimental unit consisting of ten plants per flask. Leaf number was the only variable that was not significantly affected by the source and concentration of carbohydrates. At the concentrations of 15 and 60 g.L^-1 of carbohydrate, no difference was found among sucrose, glucose and maltose for any variable tested. On the other hand, sucrose at concentrations of 30 and 45 g.L^-1 promoted in vitro growth of M. flavescens.

Miltonia flavescens is an epiphytic orchid native to southern Brazil threatened with extinction by extraction and destruction of their habitats. Type and concentration of carbohydrates are important for promoting growth and development of in vitro cultured orchids. This study aimed to evaluate the effect of different carbohydrate sources and concentrations on in vitro growth and rooting of M. flavescens. In vitro seed-derived plants used as explants were cultured in half-strength MS media containing sucrose, maltose and glucose as carbohydrate sources, at concentrations of 0, 15, 30, 45 and 60 g.L^-1. After six months in culture, plants were evaluated for aerial part height, root number, leaf number, shoot number and fresh weight. The experiment was arranged in a complete randomized design, with five replications per treatment and experimental unit consisting of ten plants per flask. Leaf number was the only variable that was not significantly affected by the source and concentration of carbohydrates. At the concentrations of 15 and 60 g.L^-1 of carbohydrate, no difference was found among sucrose, glucose and maltose for any variable tested. On the other hand, sucrose at concentrations of 30 and 45 g.L^-1 promoted in vitro growth of M. flavescens.