植物工場水耕苦苣及其倍半萜內酯類含量之研究

Abstract

苦苣(Cichorium endivia L.)之營養價值高，含有山萵苣素(lactucin)、脫氧山萵苣素(8-deoxylactucin)及山萵苣苦素(lactucopicrin)等倍半萜內酯類(sesquiterpene lactones)，是西歐國家廣泛栽培的蔬菜，但臺灣僅零星栽培。苦苣在長日環境下趨向生殖生長，產量降低，且不同季節栽培品質不一。本研究以苦苣‘綠精靈’ (‘Green Curled Ruffec’)為試驗材料，探討適合於植物工場周年生產安全無毒且品質良好苦苣的環境條件。育苗以日/夜溫25℃/25℃及山崎氏萵苣水耕養液電導度1.2 dS˙m-1較佳。育成期則以23℃/20℃及光暗週期16 hr/8 hr栽培者產量最高，而因栽培期縮短為49天，植株皆維持營養生長狀態，並未受長日影響而抽苔。倍半萜內酯類含量以20℃/17℃栽培者較高，但不受日長影響。分別調整山崎氏萵苣水耕養液至磷32 mg˙L-1、硫32 mg˙L-1、鎂24 mg˙L-1、氮135 mg˙L-1、硝銨比25:75或電導度1.2 dS˙m-1栽培苦苣時，產量較高且硝酸鹽含量低。而分別以磷8 mg˙L-1、硫32 mg˙L-1或鎂24 mg˙L-1栽培苦苣時，其倍半萜內酯類含量提升。苦苣定植於臺北溫網室28天，以春季較適合，當春作延至56天，則自由態脫氧山萵苣素增加、總倍半萜內酯類含量提升。於夏季栽培，植株趨向生殖生長，自由態脫氧山萵苣素與總倍半萜內酯類含量亦增高。營養生長期苦苣之總倍半萜內酯類含量主要受自由態山萵苣苦素的影響。

Endive (Cichorium endivia L.) has high nutritional value. It contains sesquiterpene lactones incliding lactucin, 8-deoxylactucin, and lactucopicrin. Endive has been widely cultivated in Western Europe, but is not common in Taiwan. Under long day, endive switches to reproductive growth with reduced yield. The quality also differs in different seasons. This research aimed on the suitable environmental conditions for producing safe endive with good quality all year round using ‘Green Curled Ruffec’ as materials. Day/night temperatures 25℃/25℃ and electrical conductivity 1.2 dS˙m-1 in Yamazaki nutrient solution for lettuce were suitable for hydroponically grown endive ‘Green Curled Ruffec’ seedlings. After transplanting, the yield of endive grown under 23℃/20℃ and photoperiod 16 hr/8 hr was the highest. Because of the shorter cultivation period in this experiment, endive maintained vegetative growth without bolting caused by long day. The content of sesquiterpene lactones was higher at 20℃/17℃, but there was no difference among photoperiod treatments. Endive showed high fresh weight and low nitrate content in modified Yamazaki nutrient solution for lettuce with phosphorous 32 mg˙L-1, sulfur 32 mg˙L-1, magnesium 24 mg˙L-1, nitrogen 135 mg˙L-1, nitrogen-form ratio 25:75, or electrical conductivity 1.2 dS˙m-1, respectively. The contents of sesquiterpene lactones in endive were increased in modified Yamazaki nutrient solution for lettuce with phosphorous 8 mg˙L-1, sulfur 32 mg˙L-1 or magnesium 24 mg˙L-1, respectively. Among 4 seasons, spring was suitable for endive growth of 28 days in the Plastic/screen house in Taipei. The contents of free 8-deoxylactucin and total sesquiterpene lactones were increased if the cultivation extended to 56 days in spring. Endive grown in summer switched to reproductive growth, and the contents of free 8-deoxylactucin and total sesquiterpene lactones were also increased. The content of total sesquiterpene lactones was affected by free lactucopicrin in vegetative-growing endive.