PROBLEM TO BE SOLVED: To provide a water management method in fruit cultivation, by which watering is managed in accordance with a water stress measurement value so as to make fruits each have an objective sugar content/acid degree even if affected by rain fall/fine weather so that high-quality fruits are surely produced.SOLUTION: The water management method in fruit cultivation includes the following process: preparing a cultivation model having water potential until a harvest date from 60 days to 190 days after flowering of a mandarin orange fruit tree to have the objective sugar content (&ge13°) and the objective acid content [ (1.0-1.13)g/100 ml] actually measuring the water potential at 10 days intervals from the 60th day to obtain an integration value per day of actually measured water potential per day from the 60th day to the 90th day and an integration value of model water potential of a cultivation model, and the difference &DeltaS of the water potential integration value per day which is obtained by subtracting the model value from the actually measured value modifying the model water potential of the cultivation model so as to compensate the difference &DeltaS by 100 days from the 90th day to the 190th day when the model cultivation is finished and watering so as to be close to the modified model water potential value thereafter.COPYRIGHT: (C)2008,JPO&INPIT【課題】 降雨・天候の影響を受けても、果実の糖度・酸度を目標のものにできるように灌水を水分ストレスの計測値を用いて制御して、高品質の果実を確実に生産できるようにする。【解決手段】 目標の糖度(13度以上)と酸度の酸含量(1.0~1.13g/100ml)となるためのミカンの果樹の開花後から60日目から190日目の収穫日までの水ポテンシャルの栽培モデルを作製し、60日目から10日間隔で水ポテンシャル値を実測し、60日目から90日目までの実測の水ポテンシャルの日積算値と、栽培モデルのモデル水ポテンシャルの日積算値とを求め、実測からモデルを差し引いた水ポテンシャル日積算値の差分△Sを求め、この差分△Sを90日目からモデル終了の190日目までの100日間で補償するように栽培モデルのモデル水ポテンシャルを修正し、以後この修正モデル水ポテンシャル値に近づくように、灌水する。【選択図】図5
