Abstract: The effect on photosynthesis-light response curve and CO₂ response curve of the seedlings of four pepper cultivars treated under the different low light intensitieswere investigated using a LI-6400 portable photosynthesis system. The results showed that under shading conditions, light compensation point (LCP) ,light saturation point (LSP) , CO₂ compensation point (CCP) , CO₂ saturation point (CSP) , photosynthetic rate at light saturation point, dark respiration rate (Rd) , carboxylation efficiency (CE) , RuBPCase activity,and maximum RuBP regeneration rate decreased, but apparent quantum yield (AQY) increased. The decrease of net photosynthetic rate under low light intensity was considered as a result of RuBP carboxylation restriction and regeneration restriction. In addition, as the light intensity decreased, the chlorophyll contents
(Chl. ) increased, but the chlorophyll a /b ratio (Chl.a /b) and specific leaf mass ( SLM) declined. Cultivars relatively lower LCP and Rd, higher AQY and CE under low light intensitywith may possess potential low light-tolerance.

Key words: Pepper, Low light intensity, Photosynthetic characteristics, RuBP carboxylase