| Co-Investigator(Kenkyū-buntansha) |
YANAGI Tomohiro Kagawa University, Faculty of Agriculture, Professor, 農学部, 教授 (70221645)
TAKAMURA Takejiro Kagawa University, Faculty of Agriculture, Assistant Professor, 農学部, 助教授 (40253257)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
The relationship between the degree of flower colour and changes in contents of the main anthocyanins under various controlled temperatures was examined so as to clarify the effects of high temperature on flower colouration in six pink flower genotypes of greenhouse chrysanthemum. Poor colouration of flowers was observed at 30℃ in all genotypes except 'Chatoo'. This genotype showed little difference in flower colour between different temperature treatments. The degree of change in flower colour differed depending on the genotype, whereas no clear differences in flower colouring were observed between Summer-to-Autumn flowering and Autumn flowering genotypes. All genotypes showed lower contents of the two anthocyanins tested (cyanidin 3-O-(6''-O-monomalonyl-glucopyranoside and cyanidin 3-O-(3'',6''-O-dimalonyl-θ-glucopyranoside) at higher temperatures. Therefore, flower colour changes were attributable to changes in these two main anthocyanins. Differences in colouration between genotype
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s and temperature conditions were also detectable in values that were measured using a colorimeter. Changed parameters that were visually verifiable were the a^* value, representing the degree of red colour, and the C^* value, representing chroma. For 'Sei-Monako', which showed visually great differences by eye between temperature treatments, the a^* and C^* values were low under high temperature conditions. On the other hand, in 'Chatoo', the differences detected by eye and those in a* and C^* values between temperature treatments were small. In addition, the present results indicate that mean temperature is more important than either day or night temperature in determining the degree of flower colouration.
Delayed flowering of chrysanthemum under high temperature conditions is a serious obstacle for all year round cut chrysanthemum flower production in southern temperate and sub-tropical zones. To clarify the causes of flowering delay in spray chrysanthemum, two different genotypes of spray chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitam. syn. Chrysanthemum morifolium) were grown under high-temperature conditions : summer-to-autumn flowering type (SA type, high temperature tolerant) and autumn flowering type (A type, high temperature sensitive). Their flower-bud initiation and development were subsequently compared. Results clarify that two independent events caused by high temperatures occur in the shoot apex of spray chrysanthemum under short-day conditions. First, high temperatures slowed floral development in inflorescence, thereby increasing the number of florets in both SA and A chrysanthemum genotypes. Secondly, high temperatures slowed the developmental speed of inflorescence after the budding stage, and the time to reach the break bud stage was prolonged, thereby delaying flowering, especially in A chrysanthemum genotypes. Less
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