ABSTRACT
<p><b>OBJECTIVE</b>To study the relationship between photosynthetic characteristics and environmental factors in leaves of P. lobata.</p><p><b>METHOD</b>Photosynthetic characteristics and environmental factors were measured by using CIRAS-2 portable photosynthesis system.</p><p><b>RESULT</b>The apparent quantum yield in leaves was 0.0173 micromol CO2 x micromol(-1) photon. The dark respiration rate was 2.9333 micromol x m(-2) x s(-1). The light compensation point of photosynthesis was 180 micromol x m(-2) x s(-1). The light saturation point was 1600 micromol x m(-2) x s(-1). The carboxylation efficiency was 0.0338 micromol x m(-2) x s(-1). The light respiration rate was 2.5 micromol x m(-2) x s(-1). The CO2 compensation point was 100 micromol x mol(-1), The CO2 saturation point was 1 600 micromol x mol(-1).</p><p><b>CONCLUSION</b>Photo flux density and air temperature are major environmental factors influencing diumal changes of net photosynthetic rate.</p>