Abstract:Photosynthetic characteristics of three sweet cherry cultivars Sato Nishiki, Stella and Napoleon Bigarreau were studied comparativelywith the CIRAS-2 photosynthetic instrument. The results showed that diurnal change in net photosynthetic rate ( Pn) of mature cherry leaves was a typical bimodal curve determinately regulated by stomatal conductance. The responsive curves of photosynthesis in mature cherry leaves to the change of photosynthetic active radiation, CO2 concentration and air temperature can be described with quadratic equations. The light compensation point (LCP) of different cherry cultivars was 10 - 82 μmol·m- 2 ·s- 1 , light saturation point (LSP) was 970 - 1 040 μmol·m- 2 · s- 1. Stella had the lowest LCP among the three cultivars, while Sato Nishiki had the highest LSP. The CO2 compensation point (CCP) was 90 - 116μmol·mol- 1 , and the CO2 saturation point (CSP) was 1 030 - 1233 μmol·mol- 1. The CCP of Sato Nishiki was lower but with higher CSP, and its carboxylation efficiency (CE) and maximal Pn ( Pm) preponderated over the other ones are obviously. The suitable temperature scope of sweet cherry photosynthesis changed from 11℃ to 36℃, and the most suitable temperature was between 23℃and 25℃, in which Pn of Sato Nishiki exceeded the other two cultivars significantly.