Abstract
Roses were grown under conditions of high-temperature (30/25oC) and low-temperature (20/15oC). The nitrogen content is greater and photosynthetic activity is higher in the low temperature grown leaves (L-leaves) than in the high temperature grown leaves (H-leaves). Since photosynthetic activity was low in H-leaves, excess-light-energy was considered to be relatively larger. Therefore, characteristics of excess-light-energy dissipation system were investigated. When photosynthesis was measured at 25oC, electron flow rate of water-water cycle (WWC) is larger and 1-Fv' /Fm' remained at higher levels in H-leaves. On the contrary, when photosynthesis was measured at 15oC, electron flow rate of WWC in L-leaves increased with increasing of light intensity, but it did not increase in H-leaves. Nevertheless, 1-Fv' /Fm' was higher in H-leaves than in L-leaves. In H-leaves, heat dissipation remained at higher level and WWC was driven around growth temperature, WWC was not driven at low-temperature.
