フキの1年生株を用いた伏せ込み促成栽培による花穂および葉柄の生産(栽培管理・作型)  [in Japanese] Production of Spikes and Petioles in Forcing Culture of Japanese Butterbur (Petasites japonicus Fr. Schmidt) Using One-year-old Rootstocks(Crop Production & Cropping Type)  [in Japanese]

フキ栽培種の在来'水ブキ'(雌株)および`春いぶき'の1年生株を用いて,積雪期でも花穂を安定生産でき,さらに3月に葉柄を生産できる「伏せ込み促成栽培法」について検討した.春に種株を植え付けて根株養成を行い,降雪前の12月に根株を掘り取り,冷蔵し,これを翌年1,2,3月にガラス室内の温床に伏せ込んだ.冷蔵庫から出庫直後の根株から収穫した花穂は,両品種ともに苞の緑色が淡く商品性が劣ったが,伏せ込み6日後に収穫した花穂は,日光を浴びることにより,苞の緑色が濃くなり商品性が向上した.しかし,3月まで冷蔵した根株を伏せ込んだ場合,両品種ともに苞がほとんど開き,花穂のしまりが悪かった.両品種とも1月に根株を伏せ込むことによって,3月にS級品(葉柄の長さ40cm以上50cm未満)の葉柄の収穫が可能であった.'春いぶき'は,花穂および葉柄収量ともに在来'水ブキ'(雌株)よりも優れ,伏せ込み促成栽培に適する品種であると考えられた.

A study was carried out to develop a forcing culture of Japanese butterbur using one-year-old rootstocks 'Haruibuki' and 'Mizubuki' (the latter a native cultivar of Gunma pref.) with the objective of harvesting spikes between January and February and petioles in March. In the initial phase of this experiment, rootstocks with spikes were dug out in December, and kept in cold storage, then rootstocks with spikes were planted in a hotbed after removing them from the refrigerator in January, February and March. When rootstocks were immediately taken from the refrigerator, the color of bracts was too light for the spikes to be marketed. The color of bracts became deep green and the quality was improved by exposure to sunlight for six days after planting rootstocks in a greenhouse hotbed. When rootstocks were planted in March, spikes were loose since bracts were opened. When rootstocks were planted in a hotbed in January, it was possible to harvest S-size petioles (length : 40〜50cm) in March after harvesting spikes in January. It was thought that 'Haruibuki' was more suitable than 'Mizubuki' for forcing culture using one-year-old rootstocks, judging from the total spike and petiole yield.