Effects of Pre-chilling and Pre- and Post-budbreak Temperature on the Subsequent Growth and Cut-flower Quality of Forced Tree Peony.

Abstract

This study was undertaken to clarify the effects of pre-chilling and temperatures immediately after planting and after bud-break (growing season) on vegetative growth and cut-flower quality of tree peony 'Hanakisoi', forced early, and 'Hanakisoi' and 'Yachiyotsubaki', forced mid-season. 1. Sprouting and flower dates were advanced by pre-chilling treatment. When initial growth temperature was kept low, flowering percentage was relatively high whether the plants were pre-chilled or not. Although flowers from pre-chilled plants had fewer petals per bloom at anthesis, the expansion of leaves in these plants were good so that the cut flower form was superior to that obtained from non-pre-chilled plants. 2. When the average daily temperature during the growth period after sprouting was kept at about 17-degrees-C for 'Hanakisoi' and 'Yachiyotsubaki', the number of days from sprouting to flowering was 30 days or less. When the average temperature was reduced to about 13-degrees-C, the flowering time was delayed by 15 days, but the cut-flower quality was greatly improved in comparison with that kept at 17-degrees-C. These results indicate that when initial growth temperataure after planting was kept low, the flowering percentage became higher; when the growing temperataure was kept low, cut-flower form was improved, but anthesis was delayed. Therefore, growing temperature should be regulated according to the turnover rate of crops, cropping system, and demand for cut flowers.