INCREASE IN PHOTOSYNTHETIC RATE OF VEGETABLE CROPS WITH CO₂-ENRICHMENT

The CO₂ concentrations inside the closed greenhouses are low at daytime when plants are cultivated.
At low CO₂ concentrations, the photosynthetic rates of vegetable crops decrease obviously.
At 100ppm, they drop to 15–40% compare with those of 300ppm.
On the other hand, they increase the value with the rising of CO₂ concentration.

The photorespiration rates of vegetable crops have high values in higher temperatures and lower CO₂ concentrations.
Thus, it is expected that CO₂-enrichment is an efficient means for increasing photosynthesis, because of the improved partial-pressure gradient for CO₂ into the leaf, and because of the inhibition of photorespiration, in the practical greenhouse culture.

The cultivation experiments were carried out, to ascertain the effects of CO₂-enrichment on glasshouse grown tomatoes in winter seasons.
The yields were increased and the number of puffy fruit was decreased with CO₂-enrichment.

Symposium on More Profitable Use of Energy in Protected Cultivation

K. Takahashi

https://doi.org/10.17660/ActaHortic.1978.76.17