植物工場水耕綠葉紫蘇及其酚類含量之研究

Abstract

紫蘇(Perilla frutescens L.)為富含酚類之香草作物，具有抗氧化、抗過敏、消炎及抗菌等作用，可作為鮮食、藥用、萃取精油及保健食品。綠葉紫蘇之鮮葉常用於日本料理，但其進口價格高，且有農藥殘留疑慮。於植物工場內能調控環境條件，且可不使用農藥，穩定生產安全衛生的作物。本研究旨在探討植物工場栽培綠葉紫蘇的環境條件及其酚類含量，期有助於生產高品質之綠葉紫蘇鮮葉。綠葉紫蘇以白光發光二極體(light-emitting diode, LED)育苗需20~21天，於育苗後期12天分別以電導度0.6或1.2 dS∙m-1之Kim養液栽培，或以電導度0.6 dS∙m-1之Kim養液栽培6天後，再改以電導度1.2 dS∙m-1之Kim養液栽培6天；結果以電導度1.2 dS∙m-1處理之21天齡苗莖徑、地上部乾重及壯苗指數0.032較大，定植後25天之株高、莖徑、地上部鮮重22.6 g與乾重以及地下部乾重亦皆顯著較高。綠葉紫蘇育成期以電導度1.2、1.5及1.8 dS∙m-1之Kim養液栽培，當養液電導度為1.8 dS∙m-1時，其葉片葉綠素與類胡蘿蔔素含量顯著較低；三種電導度處理之產量與葉片之迷迭香酸、木犀草素、芹菜素、咖啡酸、總類黃酮含量、抗氧化力及硝酸鹽含量間皆無顯著差異，故以電導度1.2 dS∙m-1為後續試驗之Kim養液濃度。綠葉紫蘇育成期以光強度89、123、165、204及250 μmol∙m-2∙s-1之T5螢光燈栽培，於光強度204 μmol∙m-2∙s-1下，其株高、莖徑、地上部鮮重20 g與乾重、葉片葉綠素與類胡蘿蔔素之含量皆較高，葉片迷迭香酸含量6492 μg•g-1 DW、木犀草素含量7.6 μg•g-1 DW、總類黃酮含量318.5 μg•g-1 DW與抗氧化力5638 μg GAE∙g-1 DW亦皆較高。綠葉紫蘇育成期以紅綠藍光比值為R44G3B53、R55G2B43、R63G3B34、R65G8B27、R67G2B31之五種LED以及色溫6500K之T5螢光燈栽培；T5螢光燈處理之株高、莖徑、地上部鮮重與乾重皆顯著較五種LED高；但六種光源下葉片迷迭香酸、芹菜素、總類黃酮、維生素C含量、抗氧化力以及硝酸鹽、葉綠素與類胡蘿蔔素含量間皆無顯著差異。綠葉紫蘇連續採收葉寬7~10 cm之可售葉時，同時摘除側芽則葉片鮮重與品質較穩定，單株可採收四次共9片葉，單葉鮮重為0.96~1.04 g。綜之，建議於綠葉紫蘇育苗後期12天以電導度1.2 dS∙m-1之Kim養液栽培，育成期及採收期則以上述養液與光強度204 μmol∙m-2∙s-1、色溫6500K之T5螢光燈栽培，連續採收可售葉應同時摘除側芽。

Perilla (Perilla frutescens L.) is an herbal plant rich of phenolic compounds with anti-oxidant, anti-allergic and anti-inflammatory effects. Perilla can be used as fresh spices, traditional Chinese medicine, essential oil or functional foods. Leaves of green perilla are often used in Japanese cuisine. However, the price of imported leaves is high, and there is pesticide residues problem. Crop production could be stable in the controlled environment of plant factory without pesticides application. In order to produce clean and high quality green perilla leaves, this study aimed at the suitable environmental conditions in plant factory for cultivating green perilla, and the accumulation of antioxidant phenolics. The seedling stage of green perilla lasted for 20~21 days. Green perilla seedlings were cultivated under three electric conductivities (EC) of Kim nutrient solution in the last 12 days of seedling stage. In nutrient solution with EC 1.2 dS∙m-1, green perilla had higher plant height, stem diameter, shoot dry weight, and seedling index 0.032. On 25 days after transplanting, plant height, stem diameter, shoot fresh weight 22.6 g and plant dry weight of green perilla were also higher. After transplanting, green perilla was cultivated in nutrient solution with EC 1.2, 1.5, or 1.8 dS∙m-1 after transplanting. The contents of chlorophylls and carotenoids were lower in the 1.8 dS∙m-1 treatment. No difference existed among three EC in nutrient solution on plant growth, contents of nitrate, rosmarinic acid, luteolin, apigenin, caffeic acid and total flavonoids, and antioxidant capacity in leaves. Thus, EC 1.2 dS∙m-1 was selected and used in the following experiments. After transplanting, green perilla was cultivated under 89, 123, 165, 204, and 250 μmol∙m-2∙s-1 of T5 fluorescent lamp. Under 204 μmol∙m-2∙s-1, the plant height, stem diameter, shoot fresh weight 20 g, plant dry weight of green perilla and contents of chlorophylls and carotenoids in leaves were higher on 24 days after transplanting. The contents of rosmarinic acid, luteolin, and total flavonoids, and antioxidant capacity in leaves were also higher under 204 μmol∙m-2∙s-1, which were 6492 μg•g-1 DW, 7.6 μg•g-1 DW, 318.5 μg•g-1 DW, and 5638 μg GAE∙g-1 DW, respectively. After transplanting, green perilla was cultivated under five light-emitting diode R44G3B53, R55G2B43, R63G3B34, R65G8B27, and R67G2B31, and T5 fluorescent lamp (6500K). Plant height, stem diameter, and shoot fresh and dry weight of green perilla were higher under T5 fluorescent lamp (6500K). There was no difference among 6 light sources on contents of rosmarinic acid, apigenin, total flavonoids, vitamin C, nitrate, chlorophylls, and carotenoids, and antioxidant capacity in leaves. When leaves were harvested successively, the fresh weight and quality of marketable leaves were more stable if removing lateral buds at the same time. The accumulated harvested leaves per plant was nine with fresh weight 0.96~1.04 g per leaf. In conclusion, it is recommended to cultivate green perilla in Kim nutrient solution with EC 1.2 dS∙m-1 during last 12 days of seedling stage. After transplanting, Kim nutrient solution with EC 1.2 dS∙m-1 and 204 μmol∙m-2∙s-1 of T5 fluorescent lamp (6500K) are suggested. When harvesting marketable leaves successively, the lateral buds should be removed.