Successive media to improve the in vitro rhizogenesis of Nothofagus nervosa (Phil.) Dim. et Mil.

In vitro rooting constitutes a difficult step during the micropropagation process of forest species. The successive media culture technique represents one way to overcome this barrier and includes modifying physical (e.g. photoperiod) and chemical (e.g. flavonoids) factors during the rooting phases. The aim of this study was to obtain a successive media protocol based on the incorporation of flavonoids during the in vitro rooting of Nothofagus nervosa. The factors evaluated were the type, concentration, and combination of flavonoids in relation to the rooting phases, the presence of IBA in the culture medium, the photoperiod, and the effect of flavonoids on total tissue peroxidase activity. The photoperiod used included a darkness period during the rooting induction stage and the presence of 0.61 µMIBA in the culture medium. The results showed that flavonoid incorporation at a concentration of 20 µM accelerated the appearance of roots and improved the quality of the already formed ones. Each type and concentration of flavonoid produced different responses, with (±)naringenin giving the best results. The latter caused a peak in the peroxidase activity that was absent in the control treatments. This work allowed identifying an optimized rooting protocol through a successive media culture technique that improved the speed of appearance, as well as the quantity and quality of roots for a single N. nervosa clone.