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Effect of Ethephon on Leaf Primordium and Involucre Formation in Summer-to-Autumn-Flowering Chrysanthemum
Hiroyuki SUGIURA and Masayoshi FUJITA
J. Pestic. Sci.
28, 331-337 (2003)
The effect of three-stage spraying of 200 mg/l ethephon in the flower bud stage with leaf primordium and involucre was studied for chemical control of growth and flowering in summer-to-autumn-flowering chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura) cultivars under open field conditions. Leaf primordium and young leaf numbers of 'Iwanohakusen', 'Madobe', 'Seiun' and 'Summer-yellow' with and without ethephon spraying were 17.3-18.2 in the early growing stage, and maximum leaf primordium and young leaf numbers were 19.8-22.8 in the starting involucre formation stage, and decreased after that. The development of leaf primordium and young leaf numbers under ethephon spraying was inhibited by 15-30 days compared to without ethephon. Leaf primordium development and young leaf numbers of 'Summer-yellow' with ethephon were more inhibited than other cultivars. The budding was also markedly inhibited and the leaf numbers were increased. As a result, the transformation from leaf primordium to involucre was inhibited by ethephon application in summer-to-autumn-flowering chrysanthemum.
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