Growth and flowering of Miltonia flavescens LINDL. (ORCHIDACEAE) plants treated with Gibberellic acid

Abstract

Gibbelleric acid (GA3) is a bioactive substance from gibberellin used as a stimulant for vegetal growth since it enhances cell lengthening and induces flowering in several species. Current assay evaluated the effect of different concentrations of gibberellic acid on the growth and flowering of Miltonia flavescens. Mature plants were sprayed manually with different GA3 concentrations (25, 50, 100 and 200 mg.L-1) and control was sprayed with water, intercalated by fortnightly spraying with leaf manure Biofert® (5 mL.L-1). Experiment was totally randomized, with 5 treatments and 28 repetitions per treatment. After 90 days the following were evaluated: height of aerial section, diameter of pseudobulb, length and width of leaves, shoots and flower stems, number of shoots and flower stems per plant. There was no significant difference between plants treated with GA3 and controls on variables height of aerial section, diameter of pseudobulb, number of shoots, length of shoots and leaves. On the other hand, significant differences among the treatments occurred for length of pseudobulb, number of leaves per plant and width of leaves. Plant spraying with 50 mg.L-1 of phytoregulator promoted the formation of a greater number of flowers per plant although GA3 failed to trigger their lengthening