2016 Volume 15 Issue 4 Pages 417-424
Night break (NB) is an effective method to depress flower induction in short-day plants. It has been suggested that red (R) light is more effective than light containing R and far-red (FR) light on the depression of flower induction. This study revealed the effect of the NB duration with R and FR light on the depression of flower induction using two genotype of chrysanthemum (summer-to-autumn flowering type ‘Iwano-Hakusen’, and autumn-flowering type ‘Jimba’). When the duration of NB was short, R light was more effective than R+FR light, and a reversible response to R-FR light was also observed. On the other hand, R+FR was more effective when more than 2-hour NB was applied for ‘Iwano-Hakusen’, and more than 45-min NB with R or R+FR showed the same effect in ‘Jimba’. The results indicate that the effect of NB was affected by both the duration and light quality of NB. Ten-hour NB with R or R+FR was given to 92 genotypes of chrysanthemum. Only a few genotypes showed a stronger depression of flower induction by R+FR NB, suggesting that R light NB should be recommended for commercial cut chrysanthemum production.
