limiting factors - higher

• What do limiting factors of photosynthesis affect?

  Yields of crops and economically-important plants
• How can conditions be set up to reduce limiting factors?

  Using greenhouses and outside tunnels
• What happens when light intensity is increased in greenhouses?

  Growth of crop or horticultural plants increases
• What methods can plant growers use to maximize light absorption?

  • Use glass or alternative materials for greenhouses
  • Position plants for maximum light exposure
  • Implement artificial lighting systems
• What are the benefits of artificial lighting systems in greenhouses?

  They provide optimum wavelengths and increase light intensity
• What is the effect of carbon dioxide on plant growth?

  Many plants can use additional carbon dioxide
• What was the yield difference for lettuce in normal vs. carbon dioxide-enriched greenhouses?

  0.2 kg increase from 0.9 kg to 1.1 kg
• What was the yield difference for tomatoes in normal vs. carbon dioxide-enriched greenhouses?

  2.0 kg increase from 4.4 kg to 6.4 kg
• How can growers increase carbon dioxide concentration in greenhouses?

  Using paraffin heaters or carbon dioxide wastes
• What is one method of applying liquid carbon dioxide in greenhouses?

  Through pipes, though it can be expensive
• What role do fungi play in carbon dioxide enrichment?

  They add carbon dioxide through respiration
• What is the typical carbon dioxide concentration in greenhouses?

  About 0.1 percent
• What happens to carbon dioxide levels above 1 percent?

  It changes cell pH and becomes toxic
• How does temperature affect photosynthesis in greenhouses?

  Higher temperatures increase photosynthetic production
• What is the purpose of irrigation systems in greenhouses?

  To increase yields and maintain humidity
• What is a potential downside of high humidity in greenhouses?

  It promotes the growth of pathogenic fungi
• What is hydroponics?

  Growing plants in liquid systems
• What is the benefit of hydroponics for growers?

  It optimizes mineral ions for plants
• What is the role of mineral ions in plants?

  They are required to synthesize essential molecules
• Why is temperature regulation important in greenhouses?

  To ensure optimal rates of photosynthesis
• What are the main factors that limit photosynthesis?

  • Light intensity
  • Carbon dioxide concentration
  • Water availability
  • Temperature