Effects of Madagascar Periwinkle Leaf Extract (Catharanthus roseus (L.) G.Don, Apocynaceae) on the Agromorphophysiological Characteristics of Dendrobium sp. during Acclimatization Phase

Abstract

This study aimed to determine the effects of different concentrations of Catharanthus roseus leaf extract on the morphological characteristics of Dendrobium orchids. The research was conducted in the greenhouse of the Agronomy Laboratory, Faculty of Agriculture, University of Bengkulu. The experiment was arranged in a completely randomised block design (CRBD) consisting of seven concentrations of C. roseus leaf extract: 0%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, and 0.3%. Dendrobium orchid seedlings ready for acclimatisation were soaked in the extract solution for 15 minutes before planting. The observed parameters included plant height, plant diameter, number of leaves, leaf length, leaf width, number of roots, and stomatal density. Data were analysed using analysis of variance (ANOVA), followed by the least significant difference (LSD) test at the 5% significance level. The results showed that C. roseus leaf extract significantly affected stomatal density but had no significant effect on plant height, plant diameter, number of leaves, leaf length, leaf width, or number of roots. Compared with the control (46.12 stomata mm⁻²), the extract reduced stomatal density, with the lowest value recorded for the 0.05% treatment (33.02 stomata mm⁻²). Overall, the application of C. roseus leaf extract reduced stomatal density in Dendrobium orchids during the acclimatisation phase.