Optimization of in vitro multiplication of Dendrobium sp. through application of Gibberellin (GA₃)

Dendrobium sp. is a widely popular ornamental orchid valued for its aesthetic appeal and diverse varieties. In vitro multiplication is a method of propagating new plants by stimulating shoot growth, either directly or via callus induction. Gibberellic acid (GA₃), a type of plant growth regulator (PGR), is commonly used to enhance plant growth and development. This study aimed to evaluate the effect and optimal concentration of GA₃ on the in vitro growth of Dendrobium sp. plantlets. The experiment was arranged in a Completely Randomized Design (CRD) with five concentrations of GA₃: 0 mg/L, 1 mg/L, 2 mg/L, 3 mg/L, and 4 mg/L. Each treatment was replicated five times, with one plantlet per replicate. Data were analyzed using one-way ANOVA in SPSS, followed by Tukey’s post hoc test at a 5% significance level. The results indicated that GA₃ application significantly affected plantlet survival rate, height, number of leaves, and number of roots. However, no significant effect was observed on total carbohydrate content. Among the tested concentrations, 2 mg/L GA₃ was identified as the most effective in promoting the growth and development of Dendrobium sp. plantlets in vitro.