Acclimatization of the endangered Mexican epiphytic orchid, Laelia speciosa (H.B.K.) Schltr

In vitro propagation could be an alternative for the conservation of the endemic and endangered Mexican epiphytic orchid Laelia speciosa (H.B.K.) Schltr. The goal of this study was to develop a protocol that would enhance acclimatization of in vitro – derived L. speciosa plantlets – a critical stage in propagation and subsequent conservation. Observations of stomata opening during ex vitro acclimatization, and the time of in vitro culture (0, 5, 10, 15, 20, 25, 30 days) in greenhouse conditions (pre-acclimatization), on the survival and development of seedlings during the ex vitro acclimatization were carried out. In addition, the effect of different levels of nutrients (100%, 75%, 50%, 25% and 0%-strength salts) and sucrose (0, 10, 20, 30, 40 g l−1) in the Murashige and Skoog medium (MS) on the same parameters were measured. Plantlets incubated 20 days in greenhouse conditions before ex vitro acclimatization also displayed the best growth with a survival rate of 97.5%, related with high stomata opening. Plantlets on MS containing 100%-strength salts (with 20 days of pre-acclimatization, 40 g l−1 sucrose) had the highest rate (97.5–100%) of survival and vigor when acclimatized. By improving micropropagation through acclimatization, the sustainable management of L. speciosa now more likely, benefitting the conservation of this endangered species.