In vitro Polyploid Induction in Phalaenopsis Aphrodite by Pendimethalin

Phalaenopsis aphrodite is a type of orchid with high ornamental and economic value. However, its development for commercial needs in Indonesia is still hindered by the limited availability of varieties. Therefore, enhancing genetic diversity is necessary, one of which is through polyploid induction. Several previous studies reported that pendimethalin effectively duplicates the chromosome numbers of various plant species. The aim of this study was to induce polyploidy in Phalaenopsis aphrodite and to evaluate the effect of pendimethalin treatment at the early stages in vitro. This study was conducted from March to August 2024. The experimental design used was a Completely Randomized Design (CRD) with two factors, the concentration of pendimethalin and incubation time on the treatment media. A hundred of zygotic embryos were cultured on MS0 + pendimethalin at concentrations of 100, 300, and 1000 µM for 2, 4, and 6 days while the control was cultured on MS0 without pendimethalin. Polyploidy was confirmed through chromosome counting using the squash method. The results showed that treatment with 100 µM pendimethalin for 6 days resulted in 11.1% tetraploid Phalaenopsis aphrodite plants. Although tetraploid individuals were obtained, the induction efficiency was relatively low. In addition, the pendimethalin treatment was also associated with decline viability, reduced morphological parameters, and did not significantly affect the stomatal parameters. However, these findings serve as a preliminary data for further studies to optimize polyploid induction by pendimethalin treatment in Phalaenopsis aphrodite so it could be potentially applied to breeding programs and commercial production.