Multiple Shoot Proliferation and Plantlet Establishment in Shoot Tip and Nodal Culture of Taiwan Sassafras (Sassafras randaiense (Hay.) Rehd.)

Cold-stratified and H2O2-pretreated seeds of Sassafras randaiense were used. After detaching the seed coat and cotyledon, germination of the embryo axis on MS medium increased to 58.3% at constant 25℃. In vitro multiple shoot proliferation of shoot tip culture was optimal on woody plant medium (WPM) containing 1mg/L BA, which achieved 100% proliferation and 3.7 shoots per explant. With the addition of 50-100mg/L L-glutamine, the shoot number per explant increased to 4.2, but the percentage of multiple shoot formation dropped. If adenine was supplemented, multiple shoot formation and shoot number per explant decreased as compared to those using 1mg/L BA. When nodal explants were cultured, the formation of multiple shoots was poor, but the sprouting of axillary buds was distinct. In the first subculture, 4.7 shoots per explant proliferated, and a stable multiplication rate of 1:3.6 was maintained from 1 subculture to the next. Root induction of microcutting was optimal on MS medium containing 1mg/L IBA, which obtained 80% rooting and 3.3 roots per microcutting. In vitro plantlets were successfully transplanted to plug plates placed in a culture room. The survival rate was 100% for all plantlets grown on 3 combinations of different growth media. During the process of hardening in the greenhouse, mortality of plantlets was less than 20%. Both acclimated plantlets and seedlings were out-planted with the same field conditions. Tissue-cultured trees main tamed better growth vigor than did sexually derived trees by the third year in the test plantation, although no statistical differences were found in survival, tree height, or diameter at breast height (DBH) between the 2 groups of trees.