Elementary Study on Diurnal Viration of Photosynthesis and Its Correlation to Environmental Factors in Xanthoceras sorbifolia Bunge

CIRAS-2 portable photosynthesis system was adopted to studied the diurnal variations of net photosynthetic rate,transpiration rate,stomata conductance,intercellular CO2 concentration in Xanthoceras sorbifolia Bunge,photosynthetically active radiation,air tempreture and air CO2 concentration.The results showed that net photosynthetic rate and transpiration rate of Xanthoceras sorbifolia Bunge presented a double-peak curve.There appeared a phenomenon of photosynthesis "midday depression".There were significant positive relationships between net photosynthetic rate and transpiration rate,photosynthetically active radiation,air tempreture.There was negative relationship between net photosynthetic rate and intercellular CO2 concentration.The air CO2 concentration showed significant positive relationship with intercellular CO2 concentration.There were significant negative relationships between photosynthetically active radiation,air tempreture and intercellular CO2 concentration;Stomata conductance showed significant negative relationships with air tempreture and leaf tempreture.There were significant positive relationships between air tempreture,photosynthetically active radiation and leaf tempreture.