氮鉀肥不同施用量對萬能薯生長及機能性成分含量之影響

Abstract

萬能薯 (Cynanchum taiwanianum Yamazaki) 為臺灣原生種藥用植物，主要分布於中部中海拔山區，全株植物皆可入藥及食用，使其具有相當好的經濟價值。早期萬能薯主要用來治療毒蛇咬傷，近二十年來民間常用來治療胃潰瘍、青春痘、肝病、以及高膽固醇等疾病。研究發現萬能薯的主要活性成分為'cynandione A '，其具有免疫調節、抗發炎、抗腫瘤、保肝和神經保護等功效。目前由於缺乏有關萬能薯及其栽培技術的生長基礎資料，使其藥用食材來源不足及品質不穩。本研究目的為利用盆栽及田間試驗進行探討氮肥及鉀肥對萬能薯的生長、多酚類化合物與cynandione A的生合成影響。盆栽試驗使用二種量之氮肥 (100及150 kg N ha-1) 及三種量之鉀肥 (100、150及200 kg K2O ha-1) 組合成六種處理，分別為N1K1、N1K2、N1K3、N2K1、N2K2及N2K3。田間試驗分為氮肥處理組及鉀肥處理組，氮肥處理組共有三種量之氮肥處理 (100、150及200 kg N ha-1)，分別為N100、N150及N200；鉀肥處理組共有三種量之鉀肥處理 (100、150及200 kg K2O ha-1)，分別為K100、K150及K200。每種處理皆會與未施肥的對照組做比較。結果顯示，盆栽及田間試驗中，施肥後萬能薯地上部與根部之乾重皆高於對照組，但肥料處理組之間並無顯著差異。不同量的氮肥及鉀肥處理組間之地上部與根部之總酚類及總黃酮類濃度無顯著差異，而盆栽試驗之對照組地上部總黃酮類濃度顯著高於其他處理組。地上部阿魏酸的濃度在N1K3處理組顯著最高，其餘多酚類化合物濃度在地上部或是根部的不同處理組之間皆無顯著差異。萬能薯的主要活性成cynandione A只在根部測得。不同量的氮肥及鉀肥處理組間之cynandione A濃度無顯著差異。本研究說明氮肥及鉀肥皆為萬能薯根部發育的重要養分，本試驗之肥料施用量的不同對於萬能薯中機能性成分濃度的影響並無顯著差異，但當氮肥施用量為150 kg N ha-1搭配鉀肥的施用於N : K2O比值小於1時能夠獲得較佳的根部生質量，以及較高的機能性成分含量。

Cynanchum taiwanianum is an indigenous medicinal plants in Taiwan, its whole plant can be harvested for use as medicine and food. Traditionally, C. taiwanianum is used to treat snake bites, however, in recent years it is also popularly used for treating stomach ulcers, acne, liver disease, cholesterol and other diseases. Studies have shown that cynandione A is the main bioactive compound of C. taiwanianum. This compound had been demonstrated to have anti-inflammatory, anti-tumor, hepatoprotective, and neuroprotective. To date, due to the lack of basic information on its growth, and without good cultivation techniques, this has resulted in poor harvest, instable supply and poor quality of this medicinal ingredient. The main aim of this study was to investigate the effects of nitrogen and potassium fertilizers on the growth and the biosynthesis of main bioactive compound (cynandione A) and polyphenolic compounds in pot and field cultivated C. taiwanianum. Pot experiment consisted of two nitrogen rates (100 and 150 kg N ha-1) and three different rates of potassium (100,150 and 200 kg K2O ha-1) to form six different treatments, namely N1K1, N1K2, N1K3, N2K1, N2K2 and N2K3. Field experiment comprised of nitrogen and potassium treatments; nitrogen treatment contained three application rates, including 100, 150 and 200 kg N ha-1, and was named N100, N150 and N200, respectively, whereas potassium treatment contained three application rates, including 100,150 and 200 kg K2O ha-1, and was named K100, K150 and K200, respectively. The results showed that after fertilization treatments, although both shoot and root biomass were higher than the Control, there was no significant difference between fertilization treatments. The total phenolic and total flavonoid concentrations in the shoots and roots of fertilization treatments were not significantly different from each other. The total flavonoid concentrations in the shoot of the Control were significant higher than the fertilization treatments in the pot experiment. In the shoots, the concentration of ferulic acid was the highest in the N1K3 treatment. In the roots, the concentrations of polyphenolic compounds were not significantly different between treatments. Cynandione A was only detected in the roots and was found to have no significant difference between treatments. This study concludes that both nitrogen and potassium fertilizers are important elements for the development of C. taiwanianum roots. The different fertilization treatments showed no obvious effects on the concentrations of functional compounds. However, the combination of 150 kg N ha-1 nitrogen fertilizer and potassium fertilizer in a ratio lower than 1 were shown to be the best condition for the production of root biomass and the contents of functional compounds.