In vitro study of effects of growth hormones on sporophyte development of Cyathea spinulosa

Cyathea spinulosa Wall. ex Hook. is a type genus of Cyatheaceae family. It is listed in endangered category of IUCN Red Data Book and also placed in Convention on International Trade of Endangered Species of Flora and Fauna (CITES) Appendix II. The spore germination, gametophyte morphogenesis and sporophyte rooting of Cyathea in response to 2.0% sucrose and three major growth hormones: Indole–3 acetic acid (IAA), indole–3 butyric acid (IBA) and naphthalene acetic acid (NAA) was studied. The study was carried out at the tissue culture laboratory of Central Department of Botany, Tribhuvan University, Nepal. The spore of Cyathea was reared on Knop’s Basal Medium (KBM) with 2.0% sucrose after surface sterilization. The sporophyte was sub-cultured on medium with growth hormones IAA, IBA and NAA, each containing 1, 2 and 3 ppm concentrations. The study suggested that Cyathea exhibited bipolar germination and the gametophyte development was Adiantum type. The mature gametophyte was observed as heart shaped. Sex organs were not observed up to 24 weeks which indicates the development of apogamous sporophyte. The growth hormones affect the development of leaves and roots. The sporophyte containing three leaves and two roots was the best result obtained in KBM containing 1 ppm IAA.   Key words: Cyatheaceae, Cyathea spinulosa, morphogenesis, Knop’s medium, growth hormones, apogamous sporogophyte.