Influence of auxins on in vitro rooting of microshoots of Nothofagus glauca (Phil.) Krasser

Nothofagus glauca forms essential associations with problematic species such as Nothofagus alessandrii, Beilschmiedia berteroana and Nothofagus leonii. By enhancing its native environment, N. glauca increases its ecological and scenic value. It is considered a keystone species in certain habitats, and its continued decline or loss may directly affect other species. Ex situ conservation is a priority for the recover), of the species; therefore, tissue culture is, among others, one of the alternative mechanisms for effective propagation and conservation of N. glauca. The aim of this study was to evaluate the independent effect of two auxins, 1-naphthalene acetic acid (NAA) and indole 3-butyric acid (IBA) in vitro rooting of microshoots of N. glauca from successive subcultures on MS medium. Six treatments were established containing 1 mgl(-1), 3 mgl(-1), and 5 mgl(-1) of NAA and IBA. Experimental design included a hormone-free control and four replicates of each treatment. We evaluated the survival and rooting of the microshoots, the root length (mm), and the number of roots formed per explant. Survival of microshoots was recorded at 100% when 3 mgl(-1) IBA was added to the culture medium. Furthermore, significant differences existed between the control treatment and the microshoots subjected to hormone immersion. 87.5% adventitious root formation was observed with 1 mgl(-1) IBA, and 75.0% was observed with 3 mgl(-1) of NAA. The results indicate that the presence of auxin in the culture medium is essential for in vitro root formation and provides the ability to maintain the rhizogenic potential of the species in ex vitro conditions.