Response of Dahlia Photosynthesis and Transpiration to High-Temperature Stress

The high temperature may cause difficult growth or bloom in the summer, which is key problem limiting cultivation and application of dahlia. photosynthetic physiological mechanisms dahlia under stress were studied to provide a theoretical basis for expanding range annual production. Two varieties, ‘Tampico’ ‘Hypnotica Tropical Breeze’, used as test materials treated 1 d 2 at temperatures 35/30 °C 40/35 (day/night: 14 h/10 h) then recovered 25/20 7 d. A treatment was control. results are follows: (1) High-temperature resulted chlorophyll (Chl) content, Fv/Fm, transpiration rate (Tr), net (Pn), water potential decreasing significantly, Chl Tr, stomatal density higher than those Breeze’ during same period. (2) After two varieties with high-temperature d, plant morphology various indices gradually returned normal, better condition Breeze’. (3) Both could not withstand days.