岡山大学農学部 Acta Medica Okayama 0474-0254　 96 1 2007 Effect of Nutrient Levels and Mineral Composition on the Occurrence of Yellow-leaf-spot in Chrysanthemum 43 48 EN Akinori Oki Tanjuro Goto Kaori Nagasuga Atsushi Yamasaki 　Yellow-leaf-spot, a physiological abnormality occurring in leaves of several chrysanthemum (Chrysanthemum ×morifolium) cultivars harvested from September to October, is a very serious problem in Japan, of which causes have not been well established. Water stress, high temperature, high irradiation or nutrient stresses are possible physiological factors which may lead to yellow-leaf-spot. In the present study, effects of nutrient levels and mineral composition on the occurrence of yellow-leaf-spot were investigated. ‘Seikou-no-makoto’ and ‘Seikou-no-masaru’ plants were grown in 5 nutrient solutions (N 0, 60, 120, 180, 240 ppm based on Enshi-shoho). In ‘Seikou-no-masaru’ no yellow-leaf-spot occurred. However, in ‘Seikou-no-makoto’, the nodal position with spotted leaves and rate of yellow-leaf-spot increased as nutrient levels increased. ‘Seikou-no-makoto’ plants were supplied with 6 different nutrient solutions containing 3 times N, P, K, Ca, Mg or Fe in 1/3 concentration of Enshi-shoho solution for 3 or 14 days. The nodal position with spotted leaves and rate of yellow-leaf-spot was not affected by mineral composition. The nodal position with spotted leaves and rate of yellow-leaf-spot increased with increasing days of application. Both cultivare were supplied with 7 different nutrient solutions with lacked N, P, K, Ca, Mg, Fe or only microelement (no mineral) in 1/2 Enshi-shoho solution for 10 days. In ‘Seikou-no-masaru’, no yellow-leaf-spot occurred. It occurred only in ‘Seikou-nomakoto’. yellow-leaf-spot occurred in control, P, K, Ca, Mg, Fe deficiency and no mineral, but only slightly in all cases. These results suggest that the occurrence of yellow-leaf-spot was dependent on genotype, and that excessive or deficiency specific elemental mineral stress had no significant effect. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 94 1 2005 培地および定植期がキク‘精興の誠’の黄斑発生に及ぼす影響 15 18 EN Tanjuro Goto Akinori Oki Yoshihiro Kageyama Effects of medium and planting data on the occurrence of leaf-yellow-spot in chrysanthemum 'Seikounomakoto' Dendranthema grandiflora Kitamura were investigated. Long duration was required until occurrence of leaf yellow-spot. Moreover, advance of leaf-yellow-spot was slow. The occurrence of leaf-yellow-spot was remarkably increased by sandy loam soil, but decreased by peatmoss and sand medium. Regardless of medium, pattern of occurrence of leaf-yellow-spot was similar. The occurrence of leaf-yellow-spot was attected by planting date, and was remarkably increased by high temperature and irradiation, but decreased by low temperature affected the occurence of leaf-yellow-spot No potential conflict of interest relevant to this article was reported.