Plate 1. Carbon dioxide generator.

Liquid carbon dioxide has become popular for many growers even though it is usually more expensive. The main advantages of using liquid CO2 include purity of product, no concerns about crop damage, nor heat or moisture production, better control of CO2 levels and the flexibility to introduce the CO2 within the plant canopy at any time. Pure CO2 is delivered in bulk by truck to the greenhouse. Special storage tanks rented from the supplier are required at every site (). The compressed CO2 is in a liquid state and must be vaporised through vaporiser units (). The distribution system for liquid CO2 in the greenhouse is simpler to design and install. Most growers use 18 mm black flexible polyvinyl chloride (PVC) tubing with holes punched at an appropriate spacing (). For a small operation the CO2 may be supplied in cylinders.

Carbon dioxide available in the atmosphere is absorbed by plants through their leaves i.e.

At night, plants resort to respiration, wherein they use oxygen to convert sugar into energy.


In case of photosynthesis, carbon dioxide and water react in the presence of light energy derived from sunlight to produce sugar and oxygen.


Carbon dioxide in photosynthesis

While carbon dioxide is absorbed by leaves, water enters the plant through its roots.

Ambient CO2 level in outside air is about 340 ppm by volume. All plants grow well at this level but as CO2 levels are raised by 1,000 ppm photosynthesis increases proportionately resulting in more sugars and carbohydrates available for plant growth. Any actively growing crop in a tightly clad greenhouse with little or no ventilation can readily reduce the CO2 level during the day to as low as 200 ppm. The decrease in photosynthesis when CO2 level drops from 340 ppm to 200 ppm is similar to the increase when the CO2 levels are raised from 340 to about 1,300 ppm (). As a rule of thumb, a drop in carbon dioxide levels below ambient has a stronger effect than supplementation above ambient.


Plants during photosynthesis use carbon dioxide

C4 plants almost never saturate with light and under hot, dry conditions much outperform . They use a two-stage process were CO2 is fixed in thin-walled mesophyll cells to form a 4-carbon intermediate, typically malate (malic acid). The reaction involves phosphoenol pyruvate () which fixes CO2 in a reaction catalyzed by PEP-carboxylate. It forms oxaloacetic acid (OAA) which is quickly converted to malic acid. The 4-carbon acid is actively pumped across the cell membrane into a thick-walled bundle sheath cell where it is split to CO2 and a 3-carbon compound.

"Carbon dioxide is a crucial take into account photosynthesis

While hydrogen is combined with carbon dioxide and used by the plant to produce its food, oxygen―being a by-product of the entire process―is released into the atmosphere through the stomata.

dioxide used by plants for photosynthesis

Carbon dioxide + Water + Light energy → Glucose + Oxygen)
In this equation, carbon dioxide, water and sunlight are the reactants which are present at the start of the reaction, while glucose and oxygen are the products of this process.

Carbon Dioxide is necessary for Photosynthesis in …

Allphotosynthetic organisms--with the exception of a minor group ofbacteria, the halobacteria--contain the light-absorbing pigmentchlorophyll, which plays a key role in the transfer of energy fromlight to chemical compounds.Photosynthesis is the fundamental process that maintains life onEarth.