ブドウ'マスカット・オブ・アレキサンドリア'における葉柄搾汁液のカリウム濃度と葉焼け障害および果実品質との関係(土壌管理・施肥・灌水)  [in Japanese] Relationship between Potassium Level in Petiole Sap and the Leaf Scald and Fruit Quality of the 'Muscat of Alexandria' Grape(Soil Management, Fertilization & Irrigation)  [in Japanese]

ブドウ'マスカット・オブ・アレキサンドリア'におけるカリウムのリアルタイム栄養診断法を確立するため,養液栽培した樹について,葉柄搾汁液のカリウムの濃度と葉の葉焼け発生率および果実品質との関係を検討した.果粒軟化期における葉柄搾汁液中のカリウム濃度と葉焼け発生率との間に有意な相関関係が認められ,カリウム濃度が500mg・L^<-1>以下では,濃度が低いほど葉焼けの発生か多い傾向か認められた.果粒軟化期におけるカリウム濃度と果粒重との間にも,相関関係が認められ,カリウム濃度が1,000mg・L^<-1>以下では,濃度が低いほど果粒重か小さい傾向が認められた.カリウム濃度と成熟果実の糖度との間には負の相関関係が認められたが,4,000mg・L<-1>までは栽培上問題となるほどの糖度低下は観察されなかった.幼果期における葉柄搾汁液中のカリウム濃度と葉焼け発生率および果実品質との関係は,果粒軟化期に比べると,明瞭でなかった.

This study investigated the real-time diagnosis of potassium concentration in 'Muscat of Alexandria' grapes grown in a soilless culture system using perlite medium. Potassium concentration in the squeezed sap of the petiole was investigated at different growth stages. Its relations to the severity of leaf injury attributable to potassium deficiency at stage III of fruit growth and fruit quality were assessed. Potassium concentration lower than 500 mg ・ L^<-1> in sap at veraison engenders a higher correlation between the potassium level and leaf scald severity. These signs are more severe in plants with lower potassium concentrations. There were no such signs when potassium concentrations in the sap greater than 500 mg・L^<-1>. At 1000 mg・L^<-1> or lower potassium concentration in the sap at veraison, a positive relationship was also observed between the potassium level and berry size. Berry size was smaller when the potassium level in the sap was less than 1000 mg・L^<-1>. Even when the potassium concentration was 4000 mg・L^<-1>, an extremely low sugar content, implying a lower commercial value, was not observed. Relationships between potassium concentrations in the sap at the berry set stage and leaf scald or fruit quality were not clearer than those at the veraison stage.