Light Quality Affects Protocorm-Like Body (PLB) Formation, Growth and Development of In Vitro Plantlets of Phalaenopsis pulcherrima

Abstract Light-emitting diodes (LEDs) can be used as a useful alternative to the in vitro culture of various plant species, which not only accelerates plantlet growth and development but also reduces illumination costs. In this study, the effect of different LEDs on the induction of protocorm-like bodies (PLBs) from the leaf segments, shoot propagation and rooting of Phalaenopsis pulcherrima plantlets on two medium of Vacin and Went (VW) and 1/2 Murashige and Skoog (MS) was investigated. The light treatments used included blue (B, 460 nm), red (R, 660 nm), a combination of red and blue (R : B, 1 : 1) and fluorescence (FLs) light. The results showed that the highest number and induction of PLBs were established in response to R : B LEDs. Under the same light treatments, the highest number and induction of PLBs were obtained from explants cultured on the VW medium. In the shoot propagation phase, R : B LEDs stimulated the shoot elongation, the number of shoots per explant, and the content of chlorophyll a and b. In the in vitro rooting phase, R : B LEDs stimulated the shoot elongation, the number of leaves per explant, and leaf area. However, LED lights reduced the dry and fresh weight of P. grandiflorum plantlets in both the in vitro shoot propagation and rooting phases. Therefore, the application of LEDs can be a practical and effective way to solve different problems, including the elongation of roots and shoots, and improve the photosynthetic pigments that often occur in the in vitro culture of P. pulcherrima under FLs lights.