The importance of limiting factors

• Plants make their own food using photosynthesis, which is important not only for the plants themselves, but for the other organisms that feed on the plants.
• Limiting factors of photosynthesis reduce yields of crops and other economically-important plants.
• Conditions can be set up in greenhouses and outside tunnels to reduce the effects of limiting factors.
• Increasing the light intensity in greenhouses will increase the growth of crop or horticultural plants.
• Greenhouses can be constructed from glass or alternative materials that enable maximum transmission of light.
• Plants can be positioned for maximum light absorption.
• Artificial lighting systems can be used with increased light intensities that provide optimum wavelengths of light.
• The length of a single wave, measured from one wave peak to the next, is known as the wavelength of light for photosynthesis.
• Heat is often used in greenhouses and makes plant growth possible when the weather is cold outside.
• Temperature regulation is important in greenhouses, as cooling may also be required.
• Crop irrigation involves growers finding a balance as high humidity will promote the growth of pathogenic fungi.
• The amount of water vapour in the atmosphere measured as a percentage is known as humidity.
• Irrigation systems are also used outdoors.
• Above one per cent, carbon dioxide changes cell pH, making it more acidic.
• In greenhouses at higher temperatures, photosynthetic production declines, and carbon dioxide supplements have no effect.
• Mineral ions are necessary for both plant and animal health and are given to plants.
• Plants in greenhouses are often sprayed with water to keep the humidity high.
• Normal yield for tomatoes is 4.4 kg and enriched yield is 6.4 kg.
• To increase the carbon dioxide concentration in a growing area, plant growers can use paraffin heaters on a small scale, carbon dioxide wastes from industrial processes that has been cleaned up before use, or liquid carbon dioxide, applied through pipes, though this can be expensive.
• Mineral ions are required to synthesise other essential molecules from the glucose produced during photosynthesis.
• Normal yield is 0.9 kg and enriched yield is 1.1 kg for lettuce.
• The network of hyphae produced by a fungus is known as mycelium.
• Increased temperatures in greenhouses increase the rate of photosynthesis.
• Hydroponics involves growing plants in a porous material (other than soil) and allowing water containing nutrients to filter through it.
• Fungi can be grown in bags around the greenhouse, adding carbon dioxide through their respiration.
• Plants are sometimes grown in liquid systems called hydroponics.
• A large group of eukaryotic organisms that contain single-celled yeasts, moulds and mushrooms, grown as a mycelium, are known as fungi.
• Irrigation systems in greenhouses help to increase yields.
• The concentration of carbon dioxide in greenhouses is often kept at around 0.1 per cent.
• Having a pH lower than 7 makes it more acidic, and it becomes toxic at higher levels.