Light spectrum influences adventitious root formation and shoot growth in Euphorbia leucocephala Lotsy stem cuttings

Euphorbia leucocephala Lotsy (commonly known as “pascuita”) is a popular ornamental species in Mexico, especially during the Christmas season. It is mainly propagated by stem cuttings; however, low rooting rates and poor plantlet quality limit its commercial potential. Light-emitting diode (LED) lighting has been shown to affect vegetative propagation in various species. This study evaluated the effects of different LED light spectra on adventitious root formation and shoot development in apical and basal cuttings of E. leucocephala. A split-plot design was used with four light treatments—white, red, and blue LEDs (90 μmol m-2 s-1, 16-hour photoperiod) and natural light—as main plots and cutting types (apical and basal) as subplots. After nine weeks, red LED light induced the highest rooting percentage (82%) and root development. Basal cuttings produced the longest roots (13.65 cm) and the highest number of roots per cutting (7.87). Shoot growth was also enhanced by LED lighting compared to natural light, particularly under red and blue light, with basal cuttings showing the most vigorous development. These results demonstrate that LED lighting, especially red and blue spectra, significantly improves adventitious rooting and the quality of plantlets obtained from stem cuttings of E. leucocephala.