Abstract:

The results showed that the critical points of light compensation and saturation in Ginkgo seedlings were about 78μmol m^-2S^-1 and 1050μmol m^-2S^-1 respectively,which meant that Ginkgo was a light-demanding Plant.CO₂ compensation point was 100μl 1^-1.It was found that the suitable leaf tem perature for photosynthesis was about 26℃.Under normal cultivation conditions the diurnal change of photosynthetic rate showed a double peak curve and a obvious midday depression.Stomatal limitatiion was main factor causing midday depression of photosynthesis, but sometimes nonstomatal limitation was noted.Ecological factors causing stomatal limitation were mainly low air relative humidity and high vapor pressure difference between the leaves and air.However,high leaf temperature was main factor other than stomatal limitation.The measures to alleviate or to decrease the midday depression of photosynthesis were also discussed

Key words: Ginkgo biloba L., Characteristics of photosynthesis, Midday depression of photosynthesis