In vitro culture of Aloe arborescens shoots using light-emitting diodes

Aloe arborescens is a plant that is very appreciated for both ornamental purposes and the nutraceutical properties of its extract. For these reasons, it is multiplicated through in vitro micropropagation. In the present study, we have investigated the influence of LED (Light Emitting Diodes) systems as a primary light source on the growth of A. arborescens. In vitro-cultivated shoots of A. arborescens were submitted to different light treatments provided by LED: red light (R), blue light (B), white light (W), a combination of 75% red light and 25% blue light (RB), and green (G). The traditional fluorescent light tubes (FL) were used as control. Our results show that plants cultivated under R and RB treatments display a greater number of shoots and tend to be taller, with a higher total fresh weight. The amount of total organic nitrogen was significantly higher after the R, B and W light regimes. The quality of tissues was further evaluated by measuring the total phenols, antioxidative power (Ferric Reducing-Antioxidant Power, FRAP), flavonoids, chlorophylls and carotenoids. The highest values of FRAP and total phenols were detected in RB and B, whereas the amounts of photosynthetic pigments and flavonoids did not significantly differ between the six tests, except for the slightly higher amount of chlorophyll b in shoots cultivated under red light. Overall, our data shows a differential response of A. arborescens growth and metabolite production depending on LED light quality.