We have investigated to clarify the effects of shading and daylength treatments during summer on the growth and development of flower buds and cut-flower quality of forced tree paeony.
A few sepals were observed at the start of treatments. Shading treatment decreased solar light intensity and lowered growing temperature, and consequently, accelerated flower-bud differentiation. The number of petals for shading plot (S) was larger than that of control one (C) at the end of treatments. Difference in petal number was also observed for daylength treatments. The growth of plants in SD (25 ℃, short daylength (8 hours, 10,000 lx)) plot was more advanced than that in LD (25 ℃, long daylength (16 hours, 10,000 lx)) plot.
The number of days from emergence to flowering was 31 days in all plots. Flowering percentages were 90% for LD plot and 78% for the C and S plots.
Cut-flower quality at anthesis for LD plot was excellent. Flower weight and cut-flower weight for C and S plots were inferior to those for LD and SD plots. The number of petals for C plot was the least. No close relation was observed between flower diameter and petal number or flower weight.
Flower buds for plants produced in Daisen tended to be more advanced than those produced in Matsue. The petal number of cut flower with prechilling (C, S, LD and SD plots) was less than that without prechilling (plants produced in Daisen), though leaf area of cut flower was larger for the former than that for the latter.