高鹽分養液中鉀濃度對番茄植株生長之影響

Effect of Potassium Level in High Sodium Nutrient Solution on Plant Growth of Tomato

番茄‘桃佳’品種在NFT系統下栽培，對照組養液EC值為2.5dS•m^(-1)，處理組EC值分別以NaCl及KCl調整為6.0、8.0、10、12 dS•m^(-1)等。EC6.0、8.0、10和12 dS•m^(-1)處理的葉面積分別為35.8、28.2、27.7及25.3平方公尺／plant，顯著較對照組的46.0平方公尺／plant為低，而植株基部到頂部之莖徑和乾重，亦以處理組較對照組為低。植株以EC6.0、8.0、10和12 dS•m^(-1)處理30天後，其葉片水分潛勢分別為-1.39、-1.50、-1.62和-1.73 Mpa，顯著較對照組-1.19 Mpa低，葉片水分潛勢與養液EC值呈現負相關，而葉片氣孔導度和密度，亦以處理組較對照組為低。顯示高NaCl養液添加KCl至EC值8 dS•m^(-1)，對植株生長之抑制尚不明顯，10及12dS•m^(-1)則影響植株正常生長。另考量緩和Na+及Cl-離子對植株之傷害，以KNO3作為K+和NO3-離子之來源，對改善番茄植株生長之效果應較KCl為佳。 Tomato plants cv. Taoga were grown with the nutrient film technology (NFT) in National Chiayi University to study the effect of potassium level in high sodium nutrient solution on growth of plants. The basic nutrient solution with EC 2.5 dS•m^(-1) was prepared as check, and high sodium nutrient solutions were made up with the basic nutrient solutions adding NaCl up to EC 6 dS•m^(-1), and then KCl was added up to EC 8, 10, and 12 dS•m^(-1) as the treatments. The leaf area of treatments and check were 35.8, 28.2, 27.7, 25.3 and 46.0 M^2/plant, and leaf water potential were -1.39, -1.50, -1.62, -1.73 and -1.19Mpa, respectively. In addition, stomatal density, stomatal conductance, plant height and stem fresh weight of treatments were lower than those of check. However, the difference between EC 6, 8 dS•m^(-1) treatments and check was not significant. It was deduced that proper potassium salt might compensate the inhibition of plant growth in high sodium nutrient solution. Potassium level of EC 8 dS•m^(-1) can be recommended to tomato growers for good plant growth and fruit quality.