We investigated the relationship of temperature with the flowering period of Prunus lannesiana Wils. ‘Kawazu-zakura’ cherry blossom trees planted in the Minamiizu-cho Aono river embankment. We also studied the acceleration of flowering owing to the effect of hydrogen cyanamide (H₂CN₂) spraying for improvement of ornamental value, promotion of tourism, and production of cut flowers. In 2011, 20, 50, and 100 % blooming was reported by February 16, February 21, and March 2, respectively. In 2012, 20, 50, and 100 % blooming was reported by February 23, February 26, and March 9, respectively. There was a difference of 5-7 days in the flowering date between 2011 and 2012. The cumulative temperature with the number of days between “green tip” and “full bloom” in the floral bud development process was within 234-259 degree days, and it remained fairly constant over all years evaluated. However, the average temperature from early November to mid-November, before the start of flower bud development, was 2.6-3.8 ℃ higher in 2012 than in 2011. It was suggested that the temperature after flower bud development initiation, in addition to the temperature during endodormancy termination, greatly affects the flowering period of ‘Kawazu-zakura’. After spraying of H₂CN₂, the branches were cut and transferred to a thermostatic chamber, where flower bud development started earlier by 35, 32, and 19 days at 5, 10, and 15 ℃, respectively, than in the untreated plot. However, there was no difference in flower bud developmental rate. Thus, flowering was accelerated by this treatment, mainly due to early development of flower buds. No effects of H₂CN₂ spraying on floral diameter and petal color were observed.

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We investigated the effects of CO₂ enrichment and application of 5-aminolevulinic acid (ALA)-based fertilizer during raising seedling under environmental control on the early growth of Limonium sinuatum (L.) Mill. ‘Souun’. Seedlings were grown in 7.5-cm polyethylene pots in two growth chambers with a day/night temperature regime of 20 ℃/15 ℃ and a 12-h light/12-h dark photoperiod (PPFD 74 μmol m^-2 s^-1). Four treatments were applied to the potted plants: general liquid fertilizer applied once per week (control group); ALA-based fertilizer and general liquid fertilizer (ALA group); CO₂ concentration increased to 1200 μmol mol^-1 for 5 hours of the light period (CO₂ group); and ALA-based fertilizer combined with CO₂ enrichment (CO₂+ALA group). After 5 weeks of these treatments, there was no significant difference in any of the measured parameters between the CO₂ group and the control group. The leaf area, fresh weight of aerial parts, and fresh weight of underground parts were significantly higher in the ALA group than in the control group. The number of leaves, SPAD value, leaf area, fresh and dry weight of aerial parts, dry weight of underground parts, and percentage of underground part dry matter were significantly higher in the CO₂+ALA group than in the control group. After 3 months of these treatments, there was no significant difference in cut flower yield and quality among the treatment groups. These findings clarified that application of ALA-based fertilizer under CO₂ enrichment conditions promotes the early growth of L. sinuatum under weak light environmental control.

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