Photosynthetic characteristics of three varieties of Lilium “Oriental Hybrids” in the central areas of Yunnan Province, China

To understand the ecophysiological adapta-tion of Lilium "Oriental Hybrids", which are grown for their commercial bulbs, the gas exchange, leaf N and chlorophyll content of the three varieties were investigated in the central areas of the Yunnan Province. Among the three varieties, light-saturated photosynthetic rate at ambient CO2 (Amax) of Tiber was the highest, while that of Siberia was the lowest. The difference in the Amax was related to the carboxylation efficiency (CE), leaf mass per unit area and leaf N content per mass, which indicated that their photosynthetic capacity was influenced by the activity and/or the quantity of Rubisco. The three vari-eties had lower photosynthetic saturation points and pho-tosynthetic compensation points, but the photosynthetic rates were not decreased up to 2000 μmol.m-2s-1 of the light intensity. This indicates that the three varieties had broad adaptability to light intensity. There were signifi-cant differences in the photosynthetic optimum temper-ature among the three varieties. Siberia had the highest photosynthetic optimum temperature (25.5℃-34.9℃), and is likely to grow well in warm areas. Sorbonne had the lowest photosynthetic optimum temperature (19.3℃-25.6℃), and its growth is favored in cool areas. Tiber can maintain a high photosynthetic rate within a wide range of temperature. Therefore, Tiber is the most suitable variety for the climate in the central areas of the Yunnan Province, China.