Vegetative Propagation of Six Pachyphytum Species as Influenced by Different LED Light Qualities

Pachyphytum, a slow-growing succulent genus, is considered a high-value ornamental plant in high demand as a potted plant. To facilitate and enhance its vegetative propagation, different light-emitting diode (LED) light qualities were used on leaf cuttings. Different light spectrum qualities, i.e., red (peak at 630 nm), blue (peak at 450 nm), purple (peaks at 450 and 650 nm), 3000 K white LED (peaks at 455 and 600 nm), 4100 K white LED (peaks at 455 and 590 nm), and 6500 K white LED (peaks at 450 and 545 nm), were used as treatments for six Pachyphytum species or cultivar, specifically P. compactum, P. glutinicaule, P. machucae, P. oviferum, P. viride, and P. cv. Oviride (P. oviferum × P. viride). The results of this study suggest that the different light qualities studied here significantly affected the growth and development of the Pachyphytum species. The use of blue and 6500 K white LED lights increased survival rates, rooting, and shooting success, while the use of white lights significantly improved shoot and root growth as well as the corresponding fresh and dry weights. However, in terms of the percentage moisture content, the effects of monochromatic red and blue lights, as well as the composite spectral distribution of purple light, were significantly higher compared to the effect of white light. The improvement in root growth and development, and the fresh and dry weights of Pachyphytum species under different light spectra are evidence that the effects of the light quality vary among plant species even when they belong to the same genus. Similarly, the use of different light qualities may be beneficial at certain growth stages for leaf cuttings to promote the optimal development of plant organs. The results of this study provide improved vegetative propagation techniques for Pachyphytum species and other slow-growing succulents propagated through leaf cuttings.