Plates 3e. Flue gas distribution in greenhouse.
The Greenhouse Effect & Photosynthesis | Sciencing
It is important to have an adequate distribution system. The distribution of CO2 depends mainly on air movement within the greenhouse(s), as CO2 does not travel very far through diffusion. For instance, when a single source of CO2 is used for a large surface area or several connecting greenhouses, a distribution system must be installed. This system must be designed to evenly distribute the CO2 in the greenhouse especially when flue gas CO2 or liquid CO2 is used. Air circulation using horizontal airflow fans or fan-jet system provides uniform distribution by moving large volumes of air within the greenhouse when top vents are closed or exhaust fans are not operational. Today, growers supplementing with liquid CO2 or flue gas CO2 have a central header with small individual tubes (with evenly spaced holes) placed low in the crop canopy or in the case of bench crops, under the bench. The potential for low CO2 levels inside a dense crop canopy (chrysanthemums) makes it beneficial to supplement within the canopy. Air movement around the plants will also improve the CO2 uptake because the boundary layer around the individual leaf is lessened bringing the CO2 molecules closer to the leaf.
The greenhouse effect occurs naturally
Do not allow excessive CO2 levels in greenhouses. Levels of 5,000 ppm can cause dizziness or lack of co-ordination to humans. Higher than recommended levels can cause necrosis of old tomato and cucumber leaves. African violet leaves become very hard and brittle, show a very dark greenish-grey colour and often malformed flower petals, which do not fully expand. A similar symptom with freesia flowers has been observed where the CO2 burner was used to provide the majority of the heat requirements of the greenhouse, and thereby generating excessive amounts of CO2. Except in emergencies, do not use CO2 burners as the prime heating system.
Green | Greenhouse | Photosynthesis
High-volume sprayers are popular and have been used for years in greenhouses. They can accommodate a wide range of pesticide types and offer flexibility in their operation. However, high-volume sprayers require a great deal of labor, are time consuming to use, and are considered to be low in application efficiency. It has been estimated that less than 10% of the active ingredient reaches the actual target when using high-volume systems. However, most insecticides and miticides are labeled for high-volume application. As previously discussed, most greenhouse insects and mites are found on the underside of the leaves, making it difficult for the spray to reach the pest.