福岡県農業総合試験場研究報告22(2003) pp 69 - 74
促成ナスの養液土耕栽培における施肥およびかん水方法
井上惠子・山本富三・柴戸靖志・石坂 晃
（園芸研究所）
促成ナスにおいて養液土耕栽培技術を確立するために，かん水，施肥管理方法および好適な土壌の硝酸態窒素濃度について明らかにした。
１ 作殿前窒素濃度が0.13%，全炭素濃度が1.54%で，25℃で230日間培養後の無機体窒素量が22.3mg/100gの砂壌土の圃場では，促成ナス‘筑陽’は， 養液土耕栽培により慣行栽培の施肥量（70kg/10a）を50%程度まで削減できた。その場合の1日当たりの施肥量は時期別収量に応じて調整し， 10月〜2月の窒素施用量が130mg/株，3〜4月が190mg/株，5〜6月が250mg/株であった。
２ 養液土耕栽培における土壌の硝酸態窒素濃度は畝中央部で高く，点滴かん水チュ−ブ下で最も低くなり，畝中央部とかん水チューブの中間点において平均的な値を示すため，この中間地点が，リアルタイム土壌診断を行う場合の採土位置として適する。
３ 慣行栽培の施肥量を50%程度削減させた場合の土壌の硝酸態窒素濃度（畝中央部とかん水チューブの中間点）は，概ね10〜15mg/100gである。
４ 点滴かん水チューブ（吐水口20cm間隔）を株を挟んで30cmの位置に1畝に2本設置すると散水チューブ（1畝2本）を用いた慣行栽培と同等の収量， 品質が得られる。
[キ−ワ−ド：促成ナス，養液土耕，点滴かん水チューブ，硝酸態窒素濃度]
Methods of Irrigation and Fertilization for Forcing Culture of Eggplant by Drip Fertilizing Culture. INOUE Keiko, Akira ISHIZAKA, Tomizou YAMAMOTO and Yasushi SHIBATO(Fukuoka Agric. Res. Cent., Chikusino, Fukuoka 818-8549, Japan)Bull. Fukuoka Agric. Res. Cent., 22: 69 - 74(2003)
The authors investigated on irrigation and fertilization of eggplant of forcing culture and appropriate concentration of nitrate in the soil cultivating the eggplant to diagnose nutrient condition of the soil in real time during the growing in order to establish the methods of drip fertilizing culture.
1. The topsoil of test field was sandy loam, the concentration of T-N was 0.13% and the concentration of T-C was 1.54%. The amount of inorganic nitrogen in the topsoil after 230 days cultivation at 25℃ was 22.3 mg/100g. On forcing culture of ‘Chikuyou' eggplant, the amount of fertilizer was reduced to 50% of the usual practice amount (N:70 kg/10a) by the drip fertilizing culture. The amount of nitrogen application per day (mg/day･plant) was changed according to the yield of each term, that is 130 mg from October through February, 190 mg from March through April and 250 mg from May through June.
2. The concentration of nitrate nitrogen in the soil of the ride was the high at the center of the ride, and low under drip irrigation tube during the drip fertilizing culture. The average value was shown at the mean point between the above two points. Therefore, the mean point was appropriate to extract the soil for diagnosing nutrient concentration in the soil in real time during its growing period.
3. The nitrate nitrogen concentration of the soil was about 10~15 mg/100g when about 50% of the practical amount of fertilizer was applied by the drip fertilizing culture.
4. When two irrigation tubes were placed 30 cm apart from a plant to both sides on a ride, the yield and quality of the eggplant were equal to that of the practice culture using 2 sprinkler tubes for a ridge.
[Keyword: eggplant of forcing culture, drip fertilizing culture, drip irrigation tube, nitrate nitrogen]