Looking for the conservation and sustainable use of Cyathea corcovadensis (Raddi) Domin (Cyatheaceae): the influence of environmental factors on gametophytes

Abstract

Cyathea corcovadensis (Raddi) Domin, Cyatheaceae, is a tree fern that grows in hygrophilous and gallery forests, riparian vegetation, and seasonal forests in the northeast, southeast, and south of Brazil. In Rio Grande do Sul (RS), the species is only recorded on the northern coast and is included in the list of the State’s endangered flora. The effect of pH, temperature, and photoperiod on spore germination and gametophyte development of C. corcovadensis was assessed. Three experiments were performed: (1) pH values 4, 5, 6, and 7; (2) at temperatures of 20, 23, 26, 29, and 32 °C; and (3) for photoperiods of 8, 12, 16, and 24 h of light and in the dark. Higher percentages of germination were observed when spores were cultured at pH values from 4 to 6, at 23, 26, and 29 °C, and exposed to 8, 12, and 16 h of light. No germination occurred in the dark. Gametophyte development accelerated in pH values 4 and 5, at 23 and 26 °C, during 8, 12, and 16 h of exposure to light. The three abiotic conditions in which higher germination percentages occurred and gametophytes in more advanced developmental stages were found coincided with the characteristics of the native forest environment of this species. The results contribute to the knowledge of abiotic requirements and tolerances of the species and provide data for the cultivation of the species in botanic gardens or horticultural institutions, using spore germination as a strategy for ex situ propagation and conservation.