出雲山苗圃土肉桂種子苗物候及葉片化學成分的季節變化

Seasonal Changes in Phenology and Leaf Chemical Composition of Cinnamomum osmophloeum Seedlings in Chuyunshan Nursery

土肉桂（Cinnamomum osmophloeum Kaneh.）為臺灣樟科原生植物，因含有肉桂醛（Cinnamaldehyde）成分，以往臺灣民間曾以土肉桂作為肉桂的代用品。另外所含的香豆素（Coumarin）可能造成肝損傷，我國法規已限定天然香料造成之殘留含量須在2.0 mg/kg以下。
林業暨自然保育署臺中分署出雲山苗圃自2005-2006年於中部採種培育臺灣原生種土肉桂，並於2019年12月採收上述母樹之飽滿種子進行培育，培育2年後選擇較健壯苗木250株種植於苗圃林地裡。本研究連續四季進行該250株種子苗葉片六種主要化學成分的分析，包括肉桂醛、丁香酚（Eugenol）、伽羅木醇（Linalool）、乙酸肉桂酯（Cinnamyl acetate）、肉桂醇（Cinnamyl alcohol）、香豆素等，並搭配葉片物候觀察，除了可了解個體間差異，也可了解其季節變化。
各次調查葉片之物候皆以葉成熟期為主。由於該區為種子苗，因此呈現基因多樣性，分析結果發現葉片各種主要化學成分呈現單株間差別大，250株種子苗中95%以上為肉桂醛型，與母樹的化學表現型相符，但是單株間肉桂醛濃度差異很大（92-19,300 mg/kg）。經過連續四季之觀察，以10月時肉桂醛濃度整體最高，1月次之，然無法單純從葉片物候決定採收季節，最佳採收期應根據栽植之品系特性而調整。其中有17株至少有一季期間因葉片化學成分組成比例的改變，因此所屬的化學表現型也改變了。單株間香豆素濃度差異亦大，其中有3株的香豆素濃度很高，建議移除。

Cinnamomum osmophloeum Kaneh. is an endemic plant of the Lauraceae family in Taiwan. Because it contains cinnamaldehyde, Taiwanese use it as a substitute for cinnamon. However, the coumarin it contains may cause liver damage. In Taiwan, regulations limit the residual content of this natural flavoring to less than 2.0 mg/kg.
From 2005 to 2006, C. osmophloeum collected in the central region were cultivated in Taichung Branch, Forestry and Nature Conservation Agency Chuyunshan nursery. In December 2019, the seeds of these C. osmophloeum mother trees were collected and germinated. After 2 years of cultivation, 250 healthy seedlings were selected and planted in the ground of nursery. This project mainly analyzes six main chemical components (cinnamaldehyde, eugenol, linalool, cinnamyl acetate, cinnamyl alcohol, and coumarin) of the leaves as well as observes leaf phenology of these 250 seedlings for four consecutive seasons.
The leaf phenology observation results show that most individuals were at the stage of the leaf maturity at all four seasons. Since these seedlings have genetic diversity, the various chemical components of the leaves vary greatly among individual plants. It was found that over 95% of the 250 seedlings were classified as cinnamaldehyde type. This is consistent with the chemotype of the mother trees. However, the cinnamaldehyde concentration varied greatly among individuals (92-19,300 mg/kg). Among seasons, the overall cinnamaldehyde concentration was the highest in October, followed by January. However, it is unable to determine the harvest season simply based on leaf phenology. The optimal harvest period should be adjusted according to the characteristics of the planted variety. Among them, 17 plants had great changes in the leave chemical composition during at least one season, and therefore changed their chemotype. The coumarin concentration varied greatly among individual plants. Three seedlings have very high coumarin concentrations and are recommended to be removed.