福岡県農業総合試験場研究報告

ハイドランジアの底面給水栽培における用土pH、用土資材と施肥濃度

［摘要］ハイドランジアの底面給水栽培において生育に好適な用土のpHについて明らかにするとともに，混合する用土資材と花色の発現および鮮明な花色を得るための促成期の時期別施肥濃度について，窒素，リン酸，カリを等量とした肥料を用いて検討した。
　ハイドランジアは，青系品種，赤系品種ともにピートモス単用の用土では，炭酸苦土石灰を 1L当たり 2～ 4ｇ混入し，pHを4.5～5.5に調整した用土で良好に生育した。
青系品種では，炭酸苦土石灰を 1L当たり 3ｇ混入してpH調整したピートモスを基本用土として，赤玉土，赤土，鹿沼土を容量で25％混合すると青色に，フヨウライト，パーライト，ヤシガラ，杉皮を混合すると，鮮明な桃色に発色した。また，ピートモスと赤玉土の混合用土を用い，促成期における液肥の濃度を生育段階ごとに50－100－25ppm（前期－中期－後期）とすると生育が優れ，花色は青色となった。
　赤系品種は，ピートモスとフヨウライト，ヤシガラの混合用土を用いると，促成期に施用する液肥の濃度にかかわらず鮮明な赤色となった。

［キ－ワ－ド：ハイドランジア、花色、pH、用土資材、施肥濃度］

　Effect of Compost pH, Compost Material and Fertilization Concentration in Subirrigation Culture of　Hydrangea on Growth and Sepal Color.　KUNITAKE Toshihiro, Takahiro TANIGAWA and Naohiko KUROYANAGI. (Fukuoka Agric. Res Cent, Chikushino, Fukuoka　818-8549, Japan) Bull. Fukuoka Agric. Res. Cent., 21: 30 - 34(2002)

　Suitable compost pH for the growth of hydrangea in a subirrigation culture was clarified. Also, the　relation between compost material and sepal color was examined by applying varying densities of liquid fertilizer composed of equal amounts of nitrogen, phosphorus and potassium according to the stages of growth during forcing stage.

　Hydrangeas of both blue and red cultivars grew well in sphagnum peat alone whose pH was adjusted　to the range of 4.5 to 5.5, by mixing 2 to 4g of calcium dolomite per liter of peat.

　When a blue cultivar was grown in compost composed of 75% sphagnum peat and 25% red ball loam, red loam and Kanuma soil, the flowers turned out blue. On the other hand, when the same cultivar was grown in compost composed of 75% sphagnum peat and 25% fuyolite, perlite, coconut husk and cedar bark, the flowers turned out clear pink. Also, a test conducted using sphagnum peat and mixing compost of the red ball loam, and the administration of liquid fertilizer in the forcing stage at 50 - 100 - 25ppm (the prophase-metaphase-later stage), the growth was good for the concentration of every period and resulted in blue sepal color. In the case of a red cultivar, the color turned out clear red when it was cultivated in mixed compost of sphagnum peat and fuyolite and coconut husk, regardless of liquid fertilizer concentration in the forcing stage.