Studies on the Original Plants identification, Mass Propagation and the Free Radical Scavenging Capacity of Three Taiwanese Dendrobium Species

• Main Authors: Shu-Fung Lo, 羅淑芳
• Other Authors: Hsin-Sheng Tsay
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/84509468243106269169

博士 === 國立中興大學 === 農藝學系 === 92 === Studies on the Morphology, Mass Propagation and the Free Radical Scavenging Capacity of Three Taiwanese Dendrobium Species Summary To understand the characteristics of native medicinal herb plants of Taiwanese Dendrobium, including D. linawianum, D. moniliforme and D. tosaense, field collection was conducted between 1999 and 2000. The collected plant materials were subjected to morphological studies by external observation and microscopic examination. Tissue culture experiments on seed germination were carried out followed by the screening of culture matrix of the transplanted seedlings. Chemical analysis of mineral concentrations and evaluation of anti-oxidizing ability of the 6-month old transplanted plants were then conducted to provide basic information related to their medicinal utilization. The results are abstracted as follows. 1. There were significant differences in external morphology among the three Dendrobium species. The mid-upper stem of D. linawianum is flat column in shape with elongated leaves containing 5 major veins per leaf. Its flower has light purple front ends on white petals and violet front end on lip petal. D. moniliforme has cylindrical stem and needle-shaped leaves with 3 major veins per leaf. The flower has white petals without any colored mark and a lip petal with a brown strip. D. tosaense has cylinder stem and shield-like leaves with 5-6 major veins per leaf. It has light green petals and a white lip petal with a red strip. 2. D. linawianum had the thickest leaf sheath and the widest vascular bundles than the other two species. Needle-shaped crystals were commonly observed in the leaf sheath cells of D. linawianum while only particle-shaped crystals were found sporadically in D. moniliforme. Tracheids of scalar form and net form existed in the three species, but those of spiral form were also observed in D. tosaense. Plants of D. linawianum had thicker cuticlular layer and slight lignification on stem surface. Lignification was not observed in the other two species. The stem cells of D. linawianum and D. moniliforme contained single-particle crystals but not for D. tosaense. Tracheids of net form and porous form were common in the stem of D. tosaense, and those of net form and scalar form were generally existed in the other two species. 3. Pollination experiments were conducted among different flowers within an individual species. Pollinating pollens collected 1-2 days after flowering for D. moniliforme and 1-4 days after flowering for D. tosaense to stigmas of the same age gave the highest fruiting rates (83% and 100%, respectively). The fruiting percentage was jointly affected by the vigor of pollen and stigma, as expressed (in days after flowering) by the pollen age and time of pollination. The capsules attained the maximum length at 6-7 weeks after pollination. 4. Examination by scanning electron microscopy revealed that the megaspore developmental staged occurred at 5-8 weeks after pollination for D. moniliforme and 3-6 weeks after D. tosaense. The seed coat was fully developed and the seed was separated from the placenta at 9 and 7 weeks after pollination for D. moniliforme and D. tosaense, respectively. The seed coat started to dry and showed wrinkled appearance thereafter.. 5. Seeds of D. moniliforme and D. tosaense were germinated in vitro at 12 weeks after pollination. The culture medium containing 1/2 MS basic salt supplemented with 3% sucrose and 0.9% Difco agar showed the best results of germination rates. The young seedlings were then subcultured and the medium of MS basic salt with 1.5% sucrose, 8% each of banana homogenate, potato juice and coconut milk, and 0.9% Difco agar was superior in promoting plant growth to other medium treatments. When the seedlings were transplanted to the greenhouse, the best culture matrixes were sphagnum moss and the mixture of sphagnum moss and tree fern, judged by the performances of survival rates. 6. After 6-month culture in greenhouse, the plants were grounded and extracted with methanol. The extracts showed DPPH radical scavenging activities similar to that of α-tocopherol. Further tests on the partially purified extracts indicated that quercetin and alkyl ferulates were the major components of anti-oxidizing ability for D. tosaense and D. moniliforme, respectively. 7. The N, P and K concentrations in the in vitro cultured seedlings were high for both D. moniliforme and D. tosaense. After 1 year of culture in greenhouse, N, P, and K concentrations of the transplanted plants decreased significantly, and were similar to those of the field-collected plants in some cases. The transplanted plants had the highest concentrations of Ca and Mg. In addition, the in vitro cultured seedlings of D. tosaense tended to have higher concentrations of Fe, Mn, Cu, Zn, and B.