気温および地温がキク‘精興の誠’の黄斑発生に及ぼす影響

Leaf-yellow-spot, a physiological abnormality occurring in leaves of several chrysanthemum (Chrysanthemum x morifolium) cultivars is a very serious production problem in Japan. High temperature or high irradiation are possible physiological factors, which may lead to leaf-yellow-spot. In the present study, effects of air or medium temperature on the occurrence of leaf-yellow-spot in 'Seikou-nomakoto' were investigated. The nodal position with spotted leaves and rate of leaf-yellow-spot increased with increasing day/night temperature. The nodal position with spotted leaves and rate of leaf-yellow-spot of plants grown on 30°C night air temperature were smaller than those grown on 25°C or ambient night air temperature. The days to first occurrence of leaf-yellow-spot showed no differences among medium temperatures. As occurrence of leaf-yellow-spot was not affected by root zone temperature, we recognized that occurrence of leaf-yellow-spot was promoted by high temperature or solar radiation on shoot, especially leaf. Occurrence of leaf-yellow-spot was reduced by long period high temperature and/or high solar radiation as plant growth reduced. Therefore, we thought that occurrence of leaf-yellow-spot was promoted by environmental condition as plant growth would promote.

キク（Chrysanthemum × morifolium）‘精興の誠’の葉身で発生する黄斑に及ぼす気温および培地温度の影響を調査した．昼夜温を40/30℃，35/25℃，なりゆきの3区で栽培した場合，昼夜温が高いほど生育は抑制され，黄斑の発生は早くなったが，黄斑発生度は40/30℃区と比較してなりゆき区で高くなる傾向がみられた．夜温を30℃，25℃となりゆき区で栽培した場合，黄斑発生度は30℃区と比較してなりゆき区で有意な差がみられた．生育が抑制されるほどの長期間の強光や高温は黄斑発生を抑制させたことから，生育が旺盛な環境条件における外的要因により黄斑発生は助長されると考えられた．地下部の温度は黄斑発生に影響しなかったことから黄斑発生は地上部，特に葉身部位の高温により助長されることが明らかになった．

原著論文 (Original paper)