In vitro propagation and conservation of Cattleya tigrina A. Rich

ABSTRACT: Cattleya tigrina A. Rich has been suffering heavy losses in its natural habitat and it is now included in the list of plants that are vulnerable to extinction. The development of in vitro propagation and conservation methodologies, as well as acclimatization, are considered important for species at the risk of extinction, as they promote the multiplication and conservation of the species, hence avoiding the loss of their genetic variability. The present study established the protocol of micropropagation and the in vitro conservation of C. tigrina. For the in vitro propagation, the study tested two volumes of the MS medium and two medium consistencies (stationary liquid and semi-solid). For acclimatization, the substrate mixtures containing pine bark, charcoal, vermiculite, and coconut coir were analyzed. For the in vitro conservation, different concentrations of the salts were tested in the MS medium, together with the osmotic regulators (sucrose, mannitol, and sorbitol), and at two temperatures (18 and 25 °C). The results obtained inferred that the semi-solid medium was superior to the stationary liquid medium in the variables of survival and the presence of roots, while the liquid medium was superior to the semi-solid medium in the number of shoots. For acclimatization, pine bark was the substrate where the plants developed an improved height, with sprouting, and rooting. The conservation was satisfactory and the plants remained viable for a period of 730 days, with the MS medium with 25% of the salts, and at temperatures of 18 oC or 25 oC. The plants were propagated in the stationary liquid MS medium (10 mL) and the semi-solid medium (25 mL), while they were acclimatized in pine bark and preserved in the MS medium with 25% of the salts (18 oC or 25 oC).