ヤマアジサイにおける着花特性に基づく栽培管理方法の確立(繁殖・育苗)  [in Japanese] Establishment of Cultivation System Based on Flowering Characteristics in Hydrangea serrata (Thunb.) Ser.(Propagation & Transplant Production)  [in Japanese]

ヤマアジサイの鉢物生産技術を確立するため,ヤマアジサイの着花特性を解析し,さらに挿し木時期と摘心が花房の着生に及ぼす影響を調査した.ヤマアジサイ16品種の着花特性を調査した結果,ほとんどのヤマアジサイは腋芽にも花房を着生する頂腋芽着花型品種であった.また,ほとんどのヤマアジサイの花芽分化は,10月下旬に始まり,11月下旬にはがく片形成期から花弁形成期となった.しかし,'白扇'と'マイコアジサイ'のがく片形成期は12月下旬であった.頂腋芽着花型である'七変化'および'シチダンカ'を6月上,中および下旬に挿し木し,鉢上げ5週間,6週間後に摘心した.'七変化'の花房の着生数は挿し木時期が遅いほど減少した.また,摘心によって側枝数は増加したが,花房の着生数は無摘心に比べて減少した.以上のことから,頂腋芽着花型のヤマアジサイに関しては,6月上旬に挿し木し,その後摘心を行わずに管理することにより,十分な花房数を確保できると考えられた.

Flowering characteristics and effects of timing the cutting and pinching of flowers in Hydrangea serrata (Thunb.) Ser. were investigated in order to establish a pot plant cultivation system. Sixteen varieties most of which were the lateral branch-flowering types were used. In most of the cuttings, flower bud differentiation started in late-October and differentiated sepals developed in late-November. Sepals of 'Hakusen' and 'Maiko Ajisai' differentiated in late-December. Cuttings of 'Shichihenge' and 'Shichidanka' were planted in early-, middle- and late-June and the shoots were pinched 5 and 6 weeks after planting. The number of flower clusters of 'Shichihenge' gradually decreased with delay in the planting date of cuttings. Pinching promoted the emergence of lateral branches but decreased the number of flower clusters. These results indicate that a sufficient number of flower clusters develop in the lateral branch-flowering type of H. serrata when cuttings are planted in early-June and cultivated without pinching.