Short communication Photosynthetic response of Japanese rose species Rosa bracteata and Rosa rugosa to temperature and light

The photosynthetic leaf characteristics of two rose species native to Japan were measured. The optimum temperature range for photosynthesis of Rosa bracteata was higher than that of Rosa rugosa. The photosynthetic response to temperature of R. bracteata was slower than that of R. rugosa. Maximum photosynthetic rates were reached at an irradiance of higher than 750 m mol mÿ2 sÿ1 in both species. At saturating irradiances, the net photosynthetic rate of R. bracteata was 18.7 m mol mÿ2 sÿ1, higher than that of R. rugosa (16.8 m mol mÿ2 sÿ1). At low irradiances, the net photosynthetic rate of R. rugosa was higher than that of R. bracteata. The light compensation point of R. rugosa was lower than that of R. bracteata. Thus, these rose species may be showing adaptations that allow them to photosynthesize ef®ciently under their native environmental conditions. # 2000 Elsevier Science B.V. All rights reserved.