Efeito de diferentes concentrações de meio MS e de duas condições de luminosidade no crescimento in vitro de Cattleya nobilior (Rchb.f)

Abstract

The composition of the culture medium and the culture conditions are crucial for the success of in vitro propagation of orchids and plants can influence the quality of the seedlings. In order to study the in vitro growth of plants of Cattleya nobilior were evaluated 25 different salt concentrations in the culture medium, ranging from 0 to 100% (with intervals of 4%) under two light conditions: red light (V) and red and white light (VB). Plants were inoculated with approximately 1 cm long and the culture medium was supplemented with 30 g L-1 sucrose, 5.5 g L-1 bacteriological agar and the pH was adjusted to 5.8 ± 0.1. After 120 days of transplantation, the plants were evaluated for survival percentage, fresh weight, height and diameter of the clump, length of highest root of the clump, number of tillers, root and leaves of the clump. Was observed joint effect (p <0.01) on the lighting conditions and the salt concentration of MS medium on all variables. Isolated effect was also observed (p <0.01) of the salt concentration of MS medium on the variables analyzed, however the light conditions, alone, did not affect (p> 0.05) in the results of this work. The salt concentration of MS medium ranging from 60 to 75% increase provided in all variables regardless of lighting condition. The use of light of 15 mol m-2 s -1 afforded a white fluorescent lamp associated with a red fluorescent is efficient for in vitro growth C. nobilior minimizing production costs.