Why measure CO2 in greenhouses?
It is essential to monitor the CO₂ value in greenhouses at all times, since different plants have different needs. For example, C3 plants cannot store and transpire CO₂ at the same time, because their stomata are permanently open. On the other hand, C4 plants can store CO₂ in their environment, so they do not need to keep their stomata open. A third type of plant, the CAM-plant, can only absorb CO₂ at night, since their stomata are closed during the day.
In order to utilize CO₂ to maximum effect without risking damage, it is important to have effective control of the ventilation when growing plants. Generally, the best effect is to distribute CO₂ to young plants and parent plants regularly, and to all plants for a short period during spring. If the plant is sensitive, it is extremely important to have pure CO₂ to prevent damage.
A good level of CO₂ is estimated to be up to 1,000 ppm. If the levels of CO₂ are too high in the greenhouse, plants can be damaged because they close their stomata more than normal. This can result in damage to the plant during warm periods.
The concentration of CO₂ varies considerably over the course of 24 hours. The reason for levels as high as 500 to 1,000 ppm is due to plant respiration, which is usually higher during the night, regardless of the type of plant.
How does it work?
If all plants grow in the same conditions (including the CO₂ level), it increases the likelihood that they can be harvested at the same time with similar results. The annual consumption of CO₂ in a greenhouse is about 5 - 10 kg/m2, and only in exceptional cases is this exceeded.
The positive effects of CO₂ can vary considerably. For example, tomatoes and cucumbers can obtain a 8-10% higher return.
In a study done by Crookshanks, Taylor, and Dolan (1998), results showed that CO₂ enriched plants produced more biomass than other plants. These fortified plants put their new biomass into the root, to be able to develop faster, become stronger specimens, and contribute to the plant’s reproduction.
- Higher profits
- Less damage on the plants
- Shorter growing period