Ecophysiological Characteristics of Herbaceous Peony(Paeoniaceae) 'Da Fugui'

The diurnal changes in photosynthetic characteristics of herbaceous poeny(Paeonia lactiflora Pall.,Paeoniaceae) 'Da Fugui' were studied by the portable photosynthesis system (LI-6400). The relationship between the net photosynthesis rate(Pn) & transpiration rate(Tr) and environmental & physiological factors were studied. The result showed that Pn fit the quadratic equation curve with photosynthetically active radiation(PAR), air temperature(Ta), leaf temperature(TI)and relative humidity (RH), respectively, otherwise, the relationship between Tr and PAR, Ta, TI as well as RH respectively was linear. Multiple regression analysis showed that the most important factors which affected Pn & Tr were PAR together with RH. The light saturation point(LSP) of 'Da Fugui' is about 1300 mu mol.md(-2).s(-1), and feasible temperature for this cultivar is below 28 degrees C.Pn would reach the max of the day when RH round about 60%. Quadratic equation can be fitted between Pn and stomatal conductance (Gs), and Linear equation can be fitted among Pn and intercellular CO(2) concentration(Ci), Tr and Gs, Tr and Ci, respectively.