Efeito de reguladores de crescimento na germinação e crescimento in vitro de Brassavola cebolleta Rchb.F. (Orchidaceae)

Abstract

The aim of this study was to evaluate the responses associated with germination and plant growth of Brassavola cebolleta Rchb. F. in the presence of different combinations and concentrations of plant growth regulators in alternative culture medium. The experiment was conducted at the Laboratory of In vitro Cultivation of FCA/ UFGD in Dourados/MS during the period from February to November 2009. It was conducted in completely randomized design and treatments arranged in 3x3x3 factorial scheme (three concentrations of GA3, three concentrations of BA and three concentrations of NAA) with two repetitions. The culture medium was enriched with regulators BA and NAA. The GA3 was added in the seeds at the time of sowing. After nine months in a growth chamber with photoperiod and temperature controlled (12 hours and 23±2°C) the plants were removed from the flasks. It was evaluated the following characteristics: percentage of germination (%G); number of plants (NP), leaves (NF) and roots (NR); height of shoot (AP), length of largest root (CR), fresh and dry mass of shoots (MFA, MSA) and roots (MFR, MSR). The plant characteristics were submitted to variance analysis and when they were significant regression analysis were done. The single effects and combinations of growth regulators were significant (p <0.05) for most characteristics studied. According to the results obtained the use of GA3 combined or not with BA and NAA caused reduction in germination and the values of most vegetal characteristics evaluated. Although the use of growth regulators (BA and NAA) together have increased the values of some characteristics evaluated, the best results were observed when they were used alone.