Enhanced germination of seeds native to Brazil: A comparative analysis between free and nanoencapsulated gibberellic acid in Dyckia sp. (Bromeliaceae)

Brazil is home to a great diversity of species of the genus Dyckia. However, many of these species are threatened due to habitat destruction and predatory exploitation. An alternative to conserving these plants is sexual propagation using plant regulators to stimulate germination. Gibberellic acid (GA₃) is an effective regulator in this process, but its instability and ease of degradation pose challenges. Therefore, nanoencapsulation of GA₃ could be used to protect the molecule and allow controlled release. In this study, the effects of different doses of GA₃ were evaluated on the germination of four species: D. cabrerae, D. dusenii, D. pottiorum and D. walteriana. The first stage consisted of soaking the seeds in different concentrations of GA₃, in which the species D. dusenii and D. walteriana showed significant responses to GA₃, with an increase from 35% to more than 60% germination. However, the species D. cabrerae and D. pottiorum responded positively to GA₃ only in vegetative growth parameters. In the second stage, the use of nanoparticles of alginate/chitosan (NP ALG/CS) and chitosan/tripolyphosphate (NP CS/TPP) containing GA₃ was compared with free GA₃ and with NPs without GA₃. It was verified that the use of nanoencapsulated GA₃ resulted in a more efficient germination response in D. walteriana seeds, using smaller doses of the regulator (between 0.75 mg · L⁻¹ and 1.0 mg · L⁻¹), mainly with the ALG/ CS NPs. Therefore, the use of GA₃ is recommended for D. dusenii and D. walteriana, and for the latter, nanoparticles containing ALG/CS-GA₃ allow a reduction in the required dose.