有機質肥料施用量對萬年薯的生長及機能性成分含量之影響

Abstract

萬年薯 (Cynanchum taiwanianum )為一種台灣原生種藥用植物，主要生長在中高海拔草生地上，早期主要用於治療毒蛇咬傷，然而近年來民間常用來治療胃潰瘍、紅斑狼瘡、青春痘、痔瘡、疝氣、肝病、黑斑、便秘及降膽固醇等疾病。研究發現萬年薯含有多種活性成分，其中以cynandiones A及B、cynanchone A及C21-steroidal glycoside最被重視；這些成分已被證明具有抗發炎、抗腫瘤、殺菌及保肝等功效，此說明其具有作為藥品開發的潛力。目前對於萬年薯肥培管理的研究稀少，因此本研究目的是探討三種有機質肥料施用量對於萬年薯生長、多酚類化合物及cynandione A等活性成分含量的生合成影響，藉此研究成果建立優質萬年薯生產的最適施肥條件。本研究以盆栽試驗進行，採完全隨機設計 (CRD)，處理組分為控制組、化學肥料 (150 kg N ha-1)、一倍有機質肥料 (150 kg N ha-1)、兩倍有機質肥料 (300 kg N ha-1) 及三倍有機質肥料 (450 kg N ha-1)處理，於種植180天後採收萬年薯全株，並分析土壤及植體樣品。結果顯示，施肥後萬年薯地上部生質量高出控制組20%，但施肥處理間無顯著差異；根部生質量在化學肥料處理最低，其他處理組間則無顯著差異。化學肥料及三種不同量的有機質肥料處理之地上部總酚類及總黃酮類濃度與控制組無顯著差異；根部總酚類及總黃酮類濃度則在兩倍有機質肥料處理低於其他處理組。Cynandione A只於根部測得，且不受到有機質肥料施用的影響。地上部的沒食子酸及阿魏酸的濃度在化學肥料處理組顯著最高；根部綠原酸、表兒茶素、肉桂酸香草酸的濃度則是在兩倍有機質肥料處理下較低；此外，兒茶素及阿魏酸主要是累積在根部，沒食子酸及表兒茶素則是累積於地上部。抗氧化活性結果顯示，地上部DPPH (2,2-diphenyl-1-picrylhydrazyl)自由基清除力及鐵離子還原抗氧化力 (Ferric reducing antioxidant power; FRAP) 不受到肥料施用的影響；根部的DPPH自由基清除力及FRAP活性在兩倍化學肥料處理最低，其他處理間無顯著差異。相關性分析結果發現根部的總酚類及總黃酮類濃度與FRAP活性及DPPH自由基清除力有顯著的相關，而cynandione A的濃度也與總酚類及總黃酮類的濃度有相關性。本研究說明，施用肥料後萬年薯地上部生質量顯著的增加，而化學肥料處理則會降低根部生質量，肥料的施用不會影響總酚類及總黃酮類的濃度，cynandione A只於根部測得，且濃度不會受到肥料施用影響。本研究所使用的土壤肥沃且富含有機質，雖然不同處理間萬年薯的生長及機能性成分的含量沒有明顯的差異，然而不施肥或施用150 kg N ha-1的有機質肥料的結果為最佳，此條件下根部生質量及機能性成分的含量較高。

Cynanchum taiwanianum is an indigenous medicinal plant in Taiwan. In the early time, C. taiwanianum was used to treat poisonous snake bite. However, currently it is popularly used to treat stomach ulcers, lupus erythematosus, acne, hemorrhoids, hernias, liver disease, constipation, cholesterol and other diseases. Studies have shown that C. taiwanianum had many bioactive compounds like cynandiones A and B, cynanchone A and C21-steroidal glycoside; these compounds have been demonstrated to have anti-inflammatory, anti-tumor, liver protective, anti-bacterial and antioxidant activities. At present, information on the cultivation of C. taiwanianum remains limited. Therefore, the objectives of this study were to evaluate the effects of organic fertilization rates on the growth and contents of polyphenolic compounds and cynandione A in C. taiwanianum. This study was conducted on pots comprising of five treatments namely no fertilizer (BK; 0 kg N ha-1), chemical fertilizer (CF; 150 kg N ha-1), organic fertilizer (OF1; 150 kg N ha-1), two times organic fertilizer (OF2; 300 kg N ha-1) and three times organic fertilizer (OF3; 450 kg N ha-1). At 180 days after cultivation, soil samples and the whole plants were collected for chemical analysis. The results showed that after fertilization treatments, although the shoot biomass increased about 20%, there was no significant difference between fertilization treatments. The CF group had the lowest root biomass, whereas there was no significant difference between treatments. The total phenolic and total flavonoid concentrations in the shoots of chemical and organic treatments were not significantly different from that of the control. The total phenolic and total flavonoid concentrations in roots were noted to decrease in the OF2 treatment. Cynandione A was only detected in the roots and was found to have no significant difference between treatments. In the shoots, the concentrations of gallic acid and ferulic acid were the highest in CF treatments. In the roots, the concentration of chlorogenic acid, cinnamic acid and epicatechin were found to decrease in the OF2 treatment. In addition, catechin and ferulic acid were mainly accumulated in the roots, whereas gallic acid and epocatechin were mainly accumulated in the shoots. Results on antioxidant activity showed that in the shoots, there was on difference in the DPPH radical scavenging and FRAP activities between treatments. However, a decrease in the DPPH radical scavenging and FRAP activities were noted in the roots of the OF2 treatment. The correlation analysis showed that the total phenolic and total flavonoid contents were highly correlate with the DPPH radical scavenging and FRAP activities in the roots. Besides, the content of cynandione A also had good correlation with the total phenolic and total flavonoid contents in the roots. This study indicate that fertilization treatments increased the shoot biomass of C. taiwanianum but not the root biomass. The total phenolic and total flavonoid concentrations were not effect by the fertilization treatments. This study demonstrated that the cynandione A was only detected in the root of C. taiwanianum and its content was influenced by the different fertilization treatments. The soil used in this study was fertile and rich in organic matters. Although there was no difference in the growth of C. taiwanianum and content of functional compounds, application of no fertilization and 150 kg N ha-1 organic fertilizer were shown to be the best condition for the production of root biomass and functional compounds.