スイカの裾換気型トンネル栽培における密閉および固定管理が生育, 収量および果実品質向上に及ぼす影響(栽培管理・作型)  [in Japanese] The Improvement of the Growth, Fruit Quality and Yield of Watermelon by Revised Method of Managing Non-Perforated Low Tunnels(Crop Production & Cropping Type)  [in Japanese]

スイカ'祭ばやし777'を用い, 北海道における4月下旬定植の裾換気型トンネル栽培において, 生育初期の換気方法と親づる摘心の有無が生育, 収量および果実品質に及ぼす影響について検討した.定植後約4週間トンネルを密閉したところ, トンネル内の日最高気温は最高で約50℃に達したが, 開閉による換気を行った慣行区と比べ, 葉焼け程度に有意差は認められなかった.生育は密閉区でやや優る傾向が認められた.着果節位は慣行区で平均14節前後であったのに対し, 密閉区で18節前後と上昇した.糖度および良果収量は密閉区で高くなった.親づる摘心については, 処理間で一定の傾向は認められなかった.密閉処理終了後の約2週間について, 裾部をわずかに開けた状態で固定した場合に, 慣行に比べ若干生育が促進される傾向が認められ, 糖度も高くなった.個体当たりの総葉身重と果実重および糖度との間には正の相関が認められた.本技術により, スイカの裾換気型トンネル栽培における定植から着果期までのトンネル換気作業の大半が不要となり, 全作業時間のうち約10%が削減可能と試算された.

The effects of ventilation methods on the growth, fruit quality and yield of watermelon in non-perforated low tunnels were examined. The non-perforated low tunnels are usually ventilated by raising and lowering the edges of the plastic cover. In order to save the daily labor needed to ventilate the tunnels, we tested a treatment method that does not require ventilation for approximately 6 weeks after planting until the fruit set stage. During the initial 4 weeks of this period, the edges of the tunnel were buried with soil (buried) and kept closed. During the latter 2 weeks of this period we left one tunnel slightly open. The control was ventilated as usual. The maximal temperature inside the buried tunnel increased to approximately 50℃, but there was no significant difference in the degree of leaf burn. The growth of watermelon plants in the buried-open tunnel excelled slightly, with heavier fruit weight, higher soluble solid content and yield. The bigger difference in day and night temperature of the buried-open tunnel seemed to be one of the factors contributing to this result. This study demonstrated that it is possible to save most of the labor spent ventilating non-perforated low tunnels for watermelon, and 10% of all the working hours can be reduced. Furthermore, it is expected that growth and productivity will improve when the plants are exposed to high temperatures through the use of this method.