Seed Storage Behavior of Sapium discolor Muell.-Arg.and Bischofia javanica Blume

The storage behavior and germination characteristics of seeds of Taiwan tallow tree (Sapium discolor) and Javanese bishopwood (Bischofia javanica) were investigated in the present study. The germination percentage of freshly collected mature seeds of S. discolor from Duona, Kaohsiung County in 1997 was 59% over 16 weeks under alternating temperatures of 30/20℃ with 8 h of light. With cold stratification of freshly collected seeds for 2 mo, the germination percentage reached as high as 85.3%. Therefore, about 30% of seeds showed deep dormancy. The mean germination time was reduced from 54 d for freshly collected mature seeds to 41 d after 1 mo of stratification. Seed germinability of S. discolor could be maintained at -20~15℃, for at least 24 mo at MCs (moisture contents) of between 1.8 and 7.9% (on a fresh-weight basis). These results confirm that S. discolor seeds exhibit orthodox seed storage behavior.
The germination percentage of freshly collected mature seeds of B. javanica from Sansia, Taipei County in 1997 was 78% over 8 weeks under alternating temperatures of 30/20℃ with 8 h of light, and the mean germination times were between 10 and 18 d. Most freshly mature seeds survived when they were desiccated to 5.3~12.5% MCs; however, the viability of those seeds with 3.7~12.5% MCs dropped significantly at -20℃ after 24 mo of hermetic storage. The optimum seed moisture contents of B. javanica were 8, 5~13, and 5~8% for -20, 4, and 15℃ storage, respectively. The temperature effect on seed longevity revealed that the longevity of seeds stored at 4℃was better than those at -20 and 15℃. We estimated that the optimum seed storage conditions for B. javanica are provided by combining a temperature of 4℃ with about an 8% MC. These results confirm that B. javanica seeds exhibit intermediate storage behavior that is characterized as being tolerant to desiccation but sensitive to freezing temperatures.