Application of wide-spectrum light-emitting diodes in micropropagation of popular ornamental plant species: a study on plant quality and cost reduction

In the present study, the applicability of four wide-spectrum light-emitting diodes (LEDs) emitting warm light (AP67, AP673L, G2, and NS1) was determined for the micropropagation of five popular ornamental plant species: Chrysanthemum × grandiflorum, Gerbera jamesonii, Heuchera × hybrida, Ficus benjamina, and Lamprocapnos spectabilis. Plantlets were grown in a growth room with a 16-h photoperiod. The photosynthetic photon flux density was set at 62–65 μmol m−2 s−1. The composition of the media and subculture timing were adjusted to the needs of each species tested. The results were compared to the cool daylight-emitting fluorescent (FL) control (TLD 36W/54). In most of the species studied (except for F. benjamina), the highest propagation ratios, or ratios similar to the FL control, were observed under the red- and far-red-abundant G2 LEDs. NS1 spectrum (with the highest proportion of blue and green light) was also efficient for G. jamesonii and L. spectabilis, and it provided a similar propagation ratio as the FL control. Light quality affected shoot length, number of leaves, callus regeneration, and the biosynthesis of chlorophyll. This influence, however, was species-dependent. Lighting conditions did not affect the dry matter and rooting in most of the species tested, except for G. jamesonii. The substitution of FLs with G2 LEDs can result in a 50% reduction of annual electricity costs, while the application of NS1 lamps can generate savings of up to 75%. In conclusion, the G2 LED lighting system seemed to be the most suitable in terms of propagation efficiency, plantlet quality, and cost reduction.