2020 Volume 32 Issue 1 Pages 29-36
Solid ray floret of dahlia (Dahlia variabilis) cultivar ‘Nessho’ frequently exhibit color fading from autumn to spring. We have been maintaining the plants that produced an original red-colored capitulum in February 2012 as relatively low sensitive (RL) to low temperature plants and two plants that showed color-fading in June 2012 as relatively high sensitive (RH) to low temperature plants. Using cuttings obtained from three RL (RL1-, RL2-, and RL3-line) and two RH (RH1- and RH2-line) plants, color-fading occurrence in capitula was evaluated. From mid-October 2012 to mid-January 2013, the RL2-line plants exhibited a significantly lower extent of color fading index and a significantly higher number of completely red capitula than all RH-line plants when the minimum temperature was below 10°C. It was suggested that the RH-line plants had greater low temperature sensitivity and that they would decrease productivity of red-colored ‘Nessho’ capitulum. Any parasites would not contribute for the color fading occurrence in ‘Nessho’. From June to July 2017, a RL2-line plant produced color-faded capitula, and these plants would have RH characteristic. In conclusion, elimination of RH plants would be needed for suppressing the color fading occurrence of ‘Nessho’.
