Please use this identifier to cite or link to this item:
Hydroponic Cultivation of Spinach with Low Oxalate, Low Potassium, and High Iron Contents
nutrient solution,nitrate,oxalate,potassium,chronic kidney disease,
|Publication Year :||2016|
|Abstract:||菠菜(Spinacia oleracea L.)是富含維生素及礦物質之世界性蔬菜作物，但其有草酸鹽與硝酸鹽含量高的問題，而慢性腎臟病患食用含鉀量高的蔬菜可能引起高血鉀症。臺灣菠菜生產期為秋冬季，於環控條件下栽培應可週年生產。本研究於設定光暗週期11 h/13 h與日夜溫度20℃/15℃之生長箱內進行。於菠菜‘美和’、‘西螺大葉’及‘綠菠菜’之種子酸蝕發芽試驗中，‘美和’以18 N濃硫酸蝕傷其外果皮0.5 h，以清水沖洗後，再置於玻璃培養皿中，於15℃下靜置發芽7日，發芽率為85.8%，較‘西螺大葉’穩定；再綜合品種草酸鹽比較試驗，‘美和’亦較‘綠菠菜’有更高的發芽率、發芽整齊度、生長勢及產量，草酸鹽含量亦較低。‘美和’及‘西螺大葉’適用養液試驗，陳養液之產量與品質較小川養液佳。故選擇‘美和’為後續試驗材料，並以陳養液栽培為對照組。以上述方式酸蝕‘美和’種子後播種，7日後將幼苗放入一吋立方海棉塊中，以清水育苗。育苗養液試驗中，於播種後2週，以花寶2號1000倍稀釋液為養液，育苗11日壯苗指數1%時即可定植；若改以1/2陳養液育苗，第11日壯苗指數達1.22%，應可提早於第9日定植，縮短育苗時間。根據養液濃度與採收期試驗以及養液酸鹼值試驗，‘美和’適合定植在電導度2.0 dS∙m-1、pH 6.5之陳養液(EC 2.0)，於定植後3日及每週以6 N NaOH或4 N H2SO4校正pH值，並補充養液維持養液體積；在採收前3日僅以清水補充養液，可食部位之硝酸鹽含量可降低為261 mg∙100 g-1 FW，且於定植後30日之產量較高。提高莖葉鐵含量試驗之結果顯示，葉施螯合鐵或硫酸亞鐵者，雖然地上部含鐵量提高為3.77及8.18 mg∙100 g-1 FW但有葉燒情形，外觀不良且產量降低；於養液添加硫酸亞鐵雖使根部含鐵量增加為對照組的2.3倍，但地上部含量0.94 mg∙100 g-1 FW與對照組無差異；於養液添加螯合鐵，地上部含鐵量僅有1.04 mg∙100 g-1 FW，故葉施及養液添加皆不適合做為提高菠菜含鐵量之方式。以生產低鉀菠菜為目標，進行調整養液降低莖葉鉀含量試驗、採收前限鉀降低莖葉鉀含量試驗以及降低莖葉鉀含量綜合試驗；將陳(EC 2.0)養液之硝酸鉀濃度降為1/6，並以硝酸銨補足氮源，水耕菠菜可食部位之草酸鹽、硝酸鹽及鉀含量分別為277、163及476 mg∙100 g-1 FW，比對照組分別下降了35.7%、37.6%及50.9%，且鈉含量僅有4.77 mg∙100 g-1 FW，改善了前人低鉀菠菜鈉含量大幅上升的問題，；而葉片抗壞血酸及可溶性固形物含量亦分別提高為686 mg∙100 g-1 FW及8.3。Brix，故為栽培低鉀菠菜之最佳方式；但若供慢性腎臟病患食用，建議透過水煮、川燙等烹調方式，減少可溶性草酸鹽及鉀離子，並須注意當日飲食之總鉀量。|
Spinach (Spinacia oleracea L.), rich in vitamins and minerals, is a world popular vegetable. However, spinach is also rich in oxalate and nitrate. Dietary potassium restriction is recommended for chronic kidney disease patients to prevent hyperkalemia. In Taiwan, spinach is produced during autumn and winter. Year-round production could be achieved through hydroponics in controlled environment. This study was executed in the growth chambers set with light 11 h/dark 13 h, and day 20℃/night 15℃. Seeds were scarified with 18 N sulfuric acid for 0.5 h and then placed in glass dishes at 15℃ for 7 days. The germination rate of ‘Mei-he’ was 85.8% and more stable than that of ‘Xiluo-da-ye’. According to experiment of oxalate contents in spinach cultivars, ‘Mei-he’ was higher than ‘Green Spinach’ in germination rate, uniformity, plant growth and yield, and oxalate content in shoot was also lower. Combining the result of cultivars and nutrient solution experiment, Chen (EC 2.0) nutrient solution showed better yield and quality than Ogawa nutrient solution. Hence, ‘Mei-he’ was used as the material for other experiments and Chen (2.0) nutrient as the control solution. ‘Mei-he’ seeds were scarified by the method mentioned abrove. Seven days after sowing, seedlings were put in one-inch cubic sponge for hydroponies. Seedlings were planted in seedling nutrient solution for 11 days with seedling index 1% and ready for transplanting. In seedling nutrient solution experiment, seedling index was 1% and 1.22% in 1/2 Chen nutrient solution. Earlier transplanting for 2 days cuuld achieved by using 1/2 Chen solution (EC 1.1). According to nutrient solution concentration and harvest time experiment and nutrient solution pH experiment, spinach was suitable to be cultivated in nutrient solutoin with Chen (EC 2.0) and pH 6.5. One the 3rd day after transplanting and in each week, 6 N NaOH or 4 N H2SO4 were used to adjust pH. Fresh nutrient solution was added to maintain the solution volume. Three days before harvest, only water was supplemented to reduce plant nitrate content to 261 mg∙100 g-1 FW. The prodution was highest on 30 days after transplanting. In the experiment of enhancing iron content in spinach shoot, foliar fertilization showed promoting effect, while nutrient addition not. The iron contents of EDTA-Fe and FeSO4 foliar fertilization were 3.77 and 8.18 mg∙100 g-1 FW, respectively. However, foliar fertilization caused leaves sunburn so affected the appearance and yield. Although nutrient addition of FeSO4 might enhance iron content to 2.3 fold in root, iron contents in shoot, 0.94 mg∙100 g-1 FW, were as much as control. Nutrient addition of EDTA-Fe didn’t raise iron content in shoot, either, which were 1.04 mg∙100 g-1 FW. It is suggested that nether foliar fertilization nor nutrient addition was effective way to enhance iron contents in shoot. To archive the production of low-potassium spinach, reduced potassium concentration in nutrient solution or replacement of nutrient by water before harvest were two possible strategies. In the experiement of reducing potassium nitrate amount to 1/6 and supplementing N in nutrient by ammonium nitrate, the contents of oxalate, nitrate and potassium in shoot were the lowest, 277, 163 and 476 mg∙100 g-1 FW, respectively; sodium content of 4.77 mg∙100 g-1 FW which was lower than that in the previous low-potassium spinach; and ascorbate and total soluble solids contents in blade 686 mg∙100 g-1 FW and 8.3。Brix. However, when chronic kidney disease patients eat low potassium spinach, soluble oxalates in edible parts of spinach should be removed through boiling or other cooking methods. Besides, overall consumption of potassium in one day should be calculated.
|Appears in Collections:||園藝暨景觀學系|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.