葉柄抽出液を利用したブドウ'デラウェア'におけるカリウム欠乏症の診断(土壌管理・施肥・灌水)  [in Japanese] Diagnosis of Potassium Deficiency by Using Petiole Extract in 'Delaware' Grape(Soil Management, Fertilization & Irrigation)  [in Japanese]

葉柄抽出液を利用した加温栽培'デラウェア'におけるカリウム欠乏症の診断法を検討した.小型反射式光度計で測定した葉柄抽出液中カリウム濃度と葉中カリウム含有率との間には正の高い相関があり,カリウム欠乏症診断に活用できると考えられた.また,開花期に小型反射式光度計で測定した葉柄抽出液中カリウム濃度が2,400ppm以下では,この時に肉眼的な症状が認められなくても,カリウム欠乏症が発生する可能性が高いと考えられた.しかし,この時カリウムを供給することにより欠乏症の発生を回避できることが示唆された.

This experiment aimed to establish a method for diagnosing potassium deficiency in 'Delaware' grape using petiole extract. It is considered that potassium concentration in petiole extract could be used for diagnosis of potassium deficiency in 'Delaware' grape, because there was a significant positive correlation between potassium concentration in the petiole extract and potassium content in leaves. When potassium concentration in the petiole extract which was measured by a simple reflection photometer system at the flowering stage was found to be lower than 2,400ppm, potassium deficiency would definitely occur at a later stage, even if none of the symptoms were observed at that time. However, it is suggested that potassium deficiency could be avoided by the application of potassium after diagnosis.