キク'精興の誠'の黄斑発生を助長する温度条件(栽培管理・作型)  [in Japanese] Temperature Inducing Yellow-Leaf-Spot of 'Seikou-no-makoto' Chrysanthemum : Chrysanthemum morifolium Ramat(Crop Production & Cropping Type)  [in Japanese]

キク'精興の誠'における黄斑の発生原因を明らかにするため,温度が黄班発生に及ぼす影響を検討した.プラスチックハウスで電照栽培した株を,自然日長の温度勾配型温室に搬入し,外気温の変動に追随して推移する温度条件下で生育させた.温室搬入前の株の育成場所における温度条件と同様の温度条件で生育させた場合の発生程度は小さかった.一方,温室搬入前の温度条件との温度較差が大きかった低温および高温条件で生育させた株では発生が著しかった.次に,生育温度の変動が黄斑に及ぼす影響を調べるため,温度勾配型温室内の低温,中屋および高温条件で10日間株を生育させた後,それまで栽培した温度条件とは異なる2つの温度条件あるいは引き続き同じ温度条件で栽培した.はじめに低温あるいは中温条件で栽培した株では,その後いずれの温度下においても発生は少なかった.一方,はじめに高温条件で栽培した株では発生は助長され,特に高温条件から低温条件に移した株で発生は増大した.以上より,'精興の誠'の黄斑発生は高温条件によって誘導され,その後の温度低下の程度が大きいほど症状の進行が促進されるものと考えられた.

The effect of temperature on the occurrence of yellow-leaf-spot, a physiological disorder of cut chrysanthemum, was investigated in 'Seikou-no-makoto' chrysanthemum. After long day treatment, plants were grown under natural day length in a temperature gradient chamber (TGC), in which air temperature followed the fluctuation of outside ambient temperature. Slight yellow-leaf-spot occurred in plants grown at intermediate temperature in TGC. This temperature regime was similar to the temperature regime before transfer to TGC. However, yellow-leaf-spot occurred remarkably higher in low or high temperature regimes. To investigate the effect of fluctuation of temperature on the occurrence of yellow-leaf-spot, plants were grown in low, intermediate and high temperature regimes in TGC, and after 10 days, plants were transferred to other temperature regimes or grown under the same temperature. The occurrence of yellow-leaf-spot was slight in low or intermediate temperature regimes 10 days after the start of treatment, but severe in high temperature regime. The occurrence of yellow-leaf-spot remarkably increased in plants transferred from high temperature regime to low temperature regime. In conclusion, the occurrence of yellow-leaf-spot in 'Seikou-no-makoto' was promoted by high temperature, and further increased by a drop in temperature after exposure to a high temperature.