Effects of Paclobutrazol on the Growth of Periwinkle (Catharanthus roseus)

Abstract

Growing periwinkles as a potted plant often faces the problem of excessively rapid stem growth, requiring frequent repotting when plants showed increased growth. One effective method to control plant growth is the use of plant growth retardants, with widely used paclobutrazol. Therefore, the objective of this study was to evaluate suitable concentrations of paclobutrazol for controlling the growth of periwinkles at levels of 0, 62.5, 125, 250, and 500 ppm, using a Completely Randomized Design. The results showed that paclobutrazol significantly reduced height increase rate, branching rate, leaf area, plant and root weight, and flower number compared to the control treatment (p<0.01). However, paclobutrazol concentrations exceeding 125 ppm should not be used on periwinkle plants.