促成トマトの養液土耕栽培における窒素施用量と

かん水量の違いが収量，品質に及ぼす影響

　

荒木雅登・林田達也・井手治・満田幸恵・山本富三・柴戸靖志

（土壌・環境部）

　

　促成トマト「ハウス桃太郎」の養液土耕栽培における窒素施用量とかん水量の違いが収量，品質，窒素収支に及ぼす影響を明らかにするとともに，養水分管理のための栽培期間中の土壌中硝酸態窒素含量の診断指標値を検討した。

１　定植時の土壌中無機態窒素量は45kg/10aで，栽培期間中経時的に無機化する窒素 量は4kg/10a程度と推定された。

２　点滴チューブを用いる養液土耕栽培では散水チューブを用いる慣行栽培と比較して，かん水を同量とした場合，窒素施用量は50％削減しても果実収量は97％と　同水準で，品質も同等であった。また，このときの栽培期間中の窒素吸収量は32kg/10aであった。

３　高品質安定生産のためには，12月〜5月において株当たりの1日のかん水量は100〜500mL，窒素施用量は10〜45mgで管理するのが適する。

４　土壌中の硝酸態窒素含量の診断指標値は5〜10mg/100gである。　

［キーワード：窒素栄養診断，窒素収支，点滴かん水，トマト，養液土耕栽培］

　

Effects of Irrigation and Nitrogen Fertilizing on Yield and Quality of Tomatoes Cultured in a Forcing House by Drip Fertigation. ARAKI Masato, Tatsuya HAYASHIDA, Osamu IDE, Yukie MIZDA, Tomizou YAMAMOTO and Yasushi SHIBATO (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent. 24:16-22 (2005)

  This study was conducted to clarify the dynamics of nitrogen and the effect of irrigation and nitrogen fertilization on the yield and quality of forcing ‘HAUSUMOMOTARO' tomatoes by drip fertigation. At the same time, the indexes of nutritional diagnoses for controling fertigation were obtained. The results were as follows. (1) The amount of inorganic nitrogen in the plowed soil of the field at the time of planting was 45kg per 10a. The mineralized nitrogen while culturing the tomatoes was estimated at only 4kg per 10a. (2) When the amount of nitrogen applied by drip fertigation was reduced by 50% and the amount of irrigation was equal to a conventional culture, the yield and quality of the tomatoes were similar. Also, the amount of nitrogen uptake by the tomatoes by drip fertigation was 32kg per 10a. (3) While forcing tomato was cultured by drip fertigation from December to May, the amount of irrigation in the range of 100 to 500mL plant^-1 day^-1 and applied nitrogen in the range of 10 to 45mg plant^-1 day^-1 were appropriate. (4) The index of the nitrate nitrogen content for diagnosing the soil was 5 to 10mg per 100g.　

[Key words: drip fertigation, drip irrigation, nitrogen balance, nutritional diagnosis of nitrogen, tomato ]