Micropropagation of the ornamental vulnerable bromeliads Aechmea blanchetiana and Aechmea distichantha

Abstract

Aechmea blanchetiana and Aechmea distichantha are Brazilian native bromeliads with great ornamental value, although none of the species are produced commercially. Therefore, market demands are met through nature predatory exploitation. This study intended to (1) evaluate the in vitro seed germination of A. blanchetiana and A. distichantha and (2) establish micropropagation protocols for both species, aiming at producing plantlets for the market, as well as to germplasm in vitro conservation. Germination experiments were carried out in completely randomized designs with two treatments (presence and absence of light) and seven and eight replications respectively for A. blanchetiana and A. distichantha. In vitro seedlings, produced under light conditions, were used as explants in the multiplication experiment (MS medium). The experimental design was again completely randomized, with treatments in factorial 2 (NAA concentrations; 0.05 and 0.5 μM) x 2 (cytokines: BAP and KIN) x 2 (cytokine levels: 2.2 and 4.4 μM) + 1 (control with basal MS, without growth regulators), with ten replications per treatment. We evaluated fungal and bacterial contamination, total and cumulative seed germination and number of shoots per treatment in each subculture. We observed only fungal contamination and only in A. blanchetiana (14.0%). Light favored in vitro seed germination in both species (99 and 62% respectively for A. blanchetiana and A. distichantha). MS medium + 0.5 μM NAA + 2.2 μM BAP resulted in the highest multiplication rate for both species, with significant contrasts between this treatment and the control in both species (105.62 more shoots in A. blanchetiana; 223.80 in A. distichantha). BAP promoted the formation of rootless shoots, while kinetin favored the formation of roots rather than shoots. A. blanchetiana and A. distichantha showed 90 and 97% of survival respectively in plantlet acclimatization.