Abstract: The LI-6400 Portable Photosynthesis System of LI-COR was used to study the photosynthetic characteristics of strawberry and its response to the rising CO₂ concentration at the full2fruit stage in the solar greenhouse. The results showed that the daily variation of net photosynthetic rate in leaves presented a bimodal curve and an obvious‘midday depression’phenomenon occurred. The first peak value was the highest , which occurred
at about 10 : 00 am , the net photosynthetic rate was CO₂ 13. 1μmol·m^-2·s^-1, the second peak value occurred at 16 : 00 pm , the net photosynthetic rate was CO₂ 9. 5μmol ·m^-2·s^-1. The main reason for the midday
depression was stomatal factors.At midday ,light intensity was the largest ,vapor pressure deficit between leaves and air as well as stomatal limiting value reached maximum but air relative humidity , stomatal conductance and intercellular CO₂ concentration reached minimum and hence occurred photosynthetic midday depression. When light intensity reached 1 000μmol ·m^-2·s^-1 and CO₂ concentration was lower than 600μmol ·mol^-1, its net photosynthetic rate was higher than that of the much higher light intensity.At such light intensity the CO₂ saturation point was 943. 3μmol·mol ^-1 and CO₂ compensation point was 91. 7μmol·mol^-1.

Key words: Strawberry, Photosynthetic characteristics, CO₂ concentration, Solar greenhouse