短期缺水對芥藍菜(Brassica oleracea)硝酸鹽、草酸鹽含量與抗氧化能力的影響

Effect of Short-Term Water Deficit on Nitrate and Oxalate Content and Antioxidant Capacity in Chinese Kale (Brassica oleracea)

麥德琳(Mitylene A. Bailey)

指導教授 ： 蔡秀隆 博士 ； 方中宜 博士

國立屏東科技大學/農學院/熱帶農業暨國際合作系所/碩士(2011年)

https://doi.org/10.6346/NPUST.2011.00246

摘要

芥藍菜（Brassica oleracea）在亞洲是廣泛地作為菜餚的十字花科葉用蔬菜，於萌芽後約45天即可採收其葉片與莖部食用。本研究目的在於探討植物遭受缺水逆境導致硝酸鹽、草酸鹽含量的變化與硝酸鹽還原作用偶聯草酸鹽的生合成作用的可能性。藉由六個芥藍菜品種（V1:大莖黃花、V2:綠葉、V3:臺南黑芥蘭、V4:圓葉白花、V5:高莖黑芥蘭、V6:蕙津）初步缺水逆境試驗的結果，選取兩個品種（V1與V4）作為進一步研究的材料。受試植物生長至四葉期時，進行七天的斷水處理，之後，恢復澆水使植株恢復生長。於斷水前、缺水期與恢復期，取樣植株以HPLC分析硝酸鹽、草酸鹽含量的變化。結果顯示缺水處理植株(DS)的葉片硝酸鹽濃度增加，比對照處理植株(CK)高300 µg/g。莖部與全株硝酸鹽濃度亦比對照處理植株(CK)高，尤其在V1品種，約高了500µg/g。缺水處理植株(DS)的葉片可溶性草酸鹽濃度則減少，V1品種比對照處理植株(CK)減少30 mg/g，V4品種比對照處理植株(CK)約減少 85mg/g。同樣地，缺水處理植株(DS)的莖部可溶性草酸鹽濃度亦比對照處
濃度均隨著生長而提高。缺水處理植株(DS)的葉片、莖部與全株總草酸鹽濃度亦比對照處理植株(CK)低。V4品種全株總草酸鹽濃度比對照處理植株(CK)低99 mg/g，V1品種比對照處理植株(CK)約減少61 mg/g。由試驗結果得知，V1 品種遭受短期缺水後，恢復能力較好。此品種進一步被採用以進行抗氧化能力的檢測，以螢光分光光度計分別測定抗過氧化游離基、抗氫氧游離基與抗過渡元素等氧游離基吸附能力(ORAC)。試驗結果發現植株抗氧化能力隨著生長而提高，但是當植物遭受缺水逆境時，植株抗氧化能力明顯降低。

關鍵字

抗氧化能力 ； 芥藍菜 ； 缺水逆境 ； HPLC ； 硝酸鹽 ； 草酸鹽

並列摘要

Chinese kale, Brassica oleracea, is a leafy vegetable from the Brassicacea family and is widely consumed in Asian cuisine. The edible portions of the plant include the leaves and some parts of the stem at maturity, 45 days after emergence (DAE). Concerns about nitrate and oxalate levels in plants that have experienced drought stress caused by water deficit and probable coupling of nitrate (NO3-) reduction and oxalate biosynthesis incited this study. Six varieties were surveyed in order to select two varieties for more detailed study. These varieties were Big Stem Yellow (V1), Green Leaf (V2), Tainan Black (V3), Round Leaf White (V4), Tall Black (V5) and Veg-Gin (V6). Two varieties of Chinese kale, Big Stem Yellow (V1) a locally grown variety and Round Leaf White (V4), a cultivated variety
for commercial purposes were chosen to study in more detail to determine the stress response of different varieties of the same species. They were subjected to a carefully monitored period of water deficit that lasted for seven days; thereafter they were irrigated and allowed to recover. High Performance Liquid Chromatography (HPLC) analysis was conducted during vegetative stage, water deficit stage and recovery stages. It was found that there was an increase in nitrate concentration only in the leaves of drought stressed plants (DS) for both varieties and differed from the control (CK) more than 300µg/g, the bigger difference seen in the V1 variety. There was also increase nitrate concentration in the stems and whole plants higher than 500 µg/g when compared to the control in the V1 variety. There was a decrease in soluble oxalate concentration in the leaves by as much as 30 mg/g for the V1 variety when compared to the control during the stress stage. There was approximately 85 mg/g difference however for the V4 variety. Also, the concentration in the stem was comparable to the control for both varieties. Soluble and insoluble oxalate concentrations increased throughout the stages for both varieties. The total oxalate concentrations for the DS treatment for leaves and stems and whole plants were significantly lower than its CK counterpart for both varieties; whole plant concentrations were significantly lower than CK treatment. Concentrations were also lower in the CK treatment by as much as 99 mg/g for soluble oxalate in the V4 variety. Meanwhile, the DS for the V1 variety was much as 61mg/g for soluble oxalate concentration. These findings were compared to that of spinach bought from the market. It was determined that V1 had better recovery from short term drought stress. This variety was further examined for its antioxidant capacity against peroxyl radicals, hydroxyl radicals and transition metals. The assay was conducted and the data was obtained by using flourescence spectrophotometry for detecting oxygen radical absorbance capacity (ORAC). It was found that there was a general increase in trend of antioxidant capacity for the control but during the stress stage there was a marked decrease in antioxidant capacity which caused a significant reduction in the total score when compared to the control.

並列關鍵字

Antioxidant capacity ； Chinese kale ； drought stress ； HPLC ； nitrate ； oxalate

參考文獻

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