Daily variation of photosynthetic physio-ecological characteristics of different citrus cultivars.

The results from determining photosynthetic rate and correlation physio-ecological factors of three citrus cultivars(Unshiu,Bendizao and Kumquat) by LI-6400 Portable Photosyntometer under the natural condition showed that there was obviously difference in photosynthetic rate between three citrus cultivars and the order of photosynthetic rate was Unshiu Bendizao Kumqua,the daily variation of;photosynthetic rate of Unshiu and Bendizao showed double peaks with the phenomenon of midday rest and the daily variation of photosynthetic rate of Kumquat showed single peak.There were significant positive correlations between photosynthetic rate and photosynthetic active radiation(PAR),stomatal conductance(Cond),transpiration rate(Tr) in three citrus cultivars.There was a positive correlation between photosynthetic rate and temperature in three citrus cultivars and there were negative correlations between photosynthetic rate and air relative humidity(RH),air CO2 concentration(Ca),intercellular CO2 concentration(Ci) in three citrus cultivars.The daily variation of water use efficiency(WUE) of three citrus cultivars showed a decline trend and there was no significant difference between different cultivars.