Effects of prolonging ventilation time and enriching CO₂ in greenhouse on the ecologic factors and photosynthetic rate of cucumber

The effects of prolonging ventilation time and enriching CO₂ in greenhouse on the photosynthetic rate of cucumber were studied．The results show that prolonging ventilation time increases the CO₂ concentration by 43．80uL／L，decreases the temperature，humidity and the leaf dew duration by 2．40℃ ，350Pa，and 2．50h／d，respectively．Prolonging ventilation time and enriching CO₂ increase the average of photosynthetic rate by 1．63>umol／m²·S and 3．33umol／m²·S，respectively and increase the accumulation of the photosynthetic product．