In vitro propagation of Opuntia ellisiana Griff. and acclimatization to field conditions.

The genus Opuntia is a valuable forage resource in arid and semiarid lands during periods of drought and shortage of herbaceous plants. However, absolute minimum temperatures in the plains of Mendoza represent a limiting factor to cultivate several species. Opuntia ellisiana is a cold hardy species, so the goals of this study were to massively propagate is using in vitro culture techniques, and then to acclimatize plantlets obtained to field conditions. Different sterilization protocols were tested. Areoles were isolated in laminar airflow cabinet, and cultured on Murashige-Skoog medium, supplemented with sucrose and different BAP and IBA combinations. Explants were grown at 27 +/- 2 degrees C, under a 16-h photoperiod. The shoots produced were used in the rooting assay using different auxin combinations. In the most efficient growth treatment, plantlets reached 100% shooting after 35 days of culture, and a mean length of 10.2 mm after 49 days of culture. A 100% rooted plantlets was obtained on a medium containing 5 mg L-1 IBA, after 12 days of culture. Acclimatization was achieved under greenhouse conditions, showing 100% plantlet survival. This study suggests that O. ellisiana can be successfully micropropagated by areoles, and easily acclimatizated to field conditions.