Effect of Storage Temperature on Seed Viability and In Vitro Germination of Nobile Dendrobium Hybrids

Abstract

Nowadays, seed storage plays an important role for long-term conservation for plant genetic resources including orchids. Besides, asymbiotic germination provides an essential tool for commercial propagation and conservation purpose. Nobile-type Dendrobium hybrids are in high demand as decorative pot plants due in part to their showy flowers. In this study the effect of storage temperatures on seed viability and subsequent germination capability of nobile Dendrobium hybrids was evaluated. Mature seeds from ripe capsules were collected from three cross combinations of nobile Dendrobium hybrids; D. Spring Dream ‘Apollon’ x D. Hamana Lake ‘Dream’, D. Golden Tower x D. 012-3, and D. 184-1 x D. 140-1 and air-drieD. The dried seeds were stored at either room temperature (25+2 °C) or -20 °C for twenty four months. In vitro seed germination and viability test by TTC stain were investigated. The germinability and viability varied on storage temperature as well as hybrid combinations and duration of seed storage. The viability of seed stored at -20 °C was higher than at room temperature as revealed by their germination percentage. Stainability percentage of seed stored at room temperature was severely low after 9 months of storage, while seed stored at -20 °C could maintain viability longer than at room temperature. Seed germination decreased rapidly after 6 months at room temperature, whereas seeds stored at -20 °C the germination decreased after 20 months. Also, the seeds rarely developed to advance seedling stages (stage 5 and 6) after 20 months of storage at -20 °C.