Factors affecting photosynthesis

• Limiting factor is the factor which is closest to its minimum in a metabolic pathway
• Compensation point is when the rate of respiration is equal to the rate of photosynthesis so there is no net gas exchange
• If light intensity is low, ATP and reduced NADP production will slow and so slows the rate of the Calvin cycle
• Light intensity is rarely the limiting factor except at night
• Wavelength of the light can also affect rate of photosynthesis

  • green is slow
  • red + blue fastest
• Low carbon dioxide concentration results in slower rate of glycerate 3-phosphate formation which slows the Calvin cycle
• Atmospheric carbon dioxide is low so it is often the limiting factor
• Low temperature means less kinetic energy and so fewer collisions between enzymes and substrates
• High temperatures denature rubisco and ATP synthase
• Overcoming effects of limiting factors

  • fields -> reduce shade and competition
  • greenhouses -> heaters for carbon dioxide, artificial lighting
  • irrigation
  • fertilisers