Physiological responses of the photosynthetic carbon assimilation of one-Year-old seedlings of three sandy plant species to environmental factors were studied. The results showed that ( 1 ) the variation in photosynthetic characteristics among the sandy plant species was larger in high light and high CO2 concentration than those in low light (0 -400 μmol·m -2·s -1) and CO2concentration (0 -200 μmol·mol -1). The response curves of photosynthetic rate of Atraphaxis bracteata to light intensity,CO2 concentration,temperature,and relative humidity were all located in the upper position to Morus alba and Apoceynum venetum in both July and September. ( 2 ) Photosynthetic parameters were significantly different between July and September in each species,with A. bracteata and M. alba having stronger photosynthetic capacity in July whereas A. venetum having stronger photosynthetic capacity in September. ( 3 ) A. bracteata was adapted to higher light intensity,CO2 concentrations and temperature,showing to some degree characteristics of sun plants. M. alba was sensitive to temperature and was adapted to shade environments. A. venetum had weak ability to adapt to high light and low CO2 assimilation,but had a longer duration of CO2 assimilation during growing seasons.
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