Surface sterilization and moist storage conditions for recalcitrant seeds of three Asian tree species

ABSTRACT: Ex situ storage of recalcitrant seeds is challenging, due to seed-desiccation sensitivity. Various moist storage techniques have been used to store seeds, but moist conditions also promote fungal infection. This study determined suitable sterilizing agents for surface cleaning and suitable moist storage conditions for three tree species: Heynea trijuga Roxb. ex Sims, Neocinnamomum caudatum (Nees) Merr. and Phoebe lanceolata (Nees) Nees. We used a factorial design with three factors: sterilizing agents, storage temperature and storage media. There were four surface-sterilization treatments – i) no sterilization (control), ii) 70% ethanol, iii) 3% NaOCl, and iv) 25% metalaxyl. Seeds were stored with two storage media (moist sand and moist filter paper) and at two storage temperatures (room temperature and 4 °C). Percentage fungal infection and seed germination were recorded. For H. trijuga and P. lanceolata, 3% NaOCl (five-minute soaking) was the best sterilizing agent, whilst N. caudatum had no optimal sterilizing agent. We recommend storing seeds with moist storage media at 4 °C. The best storage media for H. trijuga was moist filter paper, while for P. lanceolata either moist sand or filter paper was suitable. However, N. caudatum seeds should be sown immediately after collection as storage was not successfull. Our findings emphasize the importance of testing individual species, to determine optimal techniques for surface sterilization and storage.