Greenhouse CO2 Enrichment

What is carbon dioxide enrichment and how does it help maximize yields?

Greenhouse carbon dioxide (CO2) enrichment is a growing technique used to increase plant productivity. More than 90% of the dry matter of a plant is created from the photosynthetic conversion of atmospheric CO2. By manipulating greenhouse CO2 levels, plant growth can be accelerated. Why is that? Well, it is simple math! The primary energy source for a plant is photosynthesis, which follows the following chemistry equation:

6CO2 + 6H20 + (energy) → C6H12O6 + 6O2
Carbon Dioxide + Water + Energy from light = Glucose and Oxygen

So by giving plants more carbon dioxide, they can produce more plant matter. Doubling CO2 concentration has been experimentally shown to increase total crop yield up to 30% in greenhouse and growth chamber conditions. There is a catch though! Photosynthetic uptake of CO2 and production of plant biomass are temperature and light-dependent, with ~25°C being ideal. So in addition to the plant's potential capacity for CO2, the greenhouse environment can create limiting conditions.

Greenhouse Carbon Dioxide Enrichment

Throughout the day plants use up the CO2 available inside the greenhouse. The air directly around the leaves becomes depleted and needs to be replaced with fresh air. Greenhouse CO2 enrichment systems are sometimes used to increase plant productivity. With good horizontal airflow, less CO2 enrichment is needed (1000 to 1200 ppm). CO2 injectors, CO2 generator, or combustion heaters can be used to increase CO2 levels inside the greenhouse.

Greenhouse CO2 Enrichment Supplies

Titan Controls CO2 Regulator

carbin dioxide regulator for greenhouse

Compatible with Titan Controls CO2 Controllers or other 120 Volt controllers and timers
Precision accuracy flow meter- 0.5 to 15 SCF/hour
Heavy-duty solenoid valve
High-quality oilless pressure gauge
Includes two plastic tank washers and 12 ft of CO2 dispensing line
Brass construction for long-lasting dependability and durability
Requires 1 Amp/120 V/ 60 Hz power
Optional CO2 inline heater sold separately

Science Spotlight: Greenhouse Gas Exchange

CO2 is consumed by plants throughout the day as they conduct photosynthesis. The air directly around the leaves becomes depleted of CO2 and needs to be replaced with fresh air (or have CO2 levels added with an enrichment system). Proper greenhouse ventilation ensures that the depleted air around the plant will be replenished. If CO2 is not replenished, photosynthesis rates in the plant decrease and result in overall decreased plant productivity.

In photosynthesis, the carbon from CO2 is used to create sugars and starches that the plant can store. The oxygen from CO2 is a waste product that must be released at night when pores open in the plant’s leaves. Greenhouse exhaust fans and shutters help release the spent air from the building and replenish it with fresh air.