大玉トマトの防根給水ひも栽培における生育途中の根域拡張と「ひも」適用が果実生産に及ぼす影響

This study was conducted to investigate the possibility to use capillary wick system in large-fruited tomato production. The first experiment in the autumn-winter season of 2006 was carried out to investigate the effects of the amount of substrate on growth and yield of tomato. Treatments involved growing large-fruited tomato in one box (2.8ℓ/plant) continuously, or adding substrate at flowering of the 7th truss in a 2nd box (5.6ℓ/plant). Fruit yield was higher when the root-zone was extended with double the substrate volume. The second experiment in spring-summer season of 2007 was aimed at improving growth and yield of tomato by extension of root-zone and addition of wick. Tomato plants were either grown in one box with one wick continuously, or with addition of substrate in a 2nd box at flowering of the 4th truss. Additionally, one more wick was inserted into 50% of the 2nd boxes. Half of the plants were grown in two boxes with one wick, and the other half with two wicks. Higher yield was obtained from the plants grown in two boxes with two wicks, suggesting that fruit yield was increased by increasing water transport through wick addition coupled with root-zone extension. Plant growth and fruit yield of large-fruited tomato was stable without blossom-end rot when root-zone was extended and half strength of Ohtsuka-A nutrient solution supplied through the capillary wick system. There was, however, a slight sign of physiological disorder at the leaf margins similar to potassium deficiency.

「防根給水ひも」を利用した底面給水法が大玉トマト生産に適用可能かどうかを検討した．2006年秋ﾝ冬季の実験では，培地量がトマトの生育と収量に及ぼす影響について調査した．大玉トマトを終始1stBox（＝2.8ℓ･plant－1）で栽培する処理区と７段花房開花時に2ndBox（＝2.8ℓ）に培地を追加し，最終的に１stBox + 2ndBox（＝5.6ℓ･plant－1）で栽培する処理区を比較した結果，培地量を２倍にし，根域を拡張した処理区の収量が高くなった．2007年春ﾝ夏季の実験では根域拡張および「ひも」適用本数の増加によりトマトの生育収量を改善出来るかを検討するため，終始 1stBox，「ひも」1本で栽培する区，4段花房開花時に培地を追加し最終的に1stBox + 2ndBoxで栽培するが，そこには「ひも」は配さない区，培地を加えると同時に「ひも」を配する区の3区でトマトを栽培した．その結果，1stBox + 2ndBox，「ひも」2本で栽培したトマトが最も収量が高かった．培地追加時に「ひも」を配することで水輸送量が増大した事が収量増加に繋がったものと考えられた．以上の結果より，生育途中で培地量を増やすと同時に，もう1本の「ひも」を配置して大塚A処方1/2濃度で終始管理すれば，生育中期にK欠乏と思しき葉縁の黄変が見られるものの，尻腐れ果実のほとんど発生しない安定したトマト生産が可能であるといえる．