Lecture 26: Factors Affecting Transpiration

Introduction

• Transpiration is the process of water movement through a plant and its evaporation from aerial parts, like leaves.
• It's crucial for nutrient uptake, cooling the plant, and maintaining flow of water from roots to leaves.

Key Factors Affecting Transpiration

1. Environmental Factors

• Light:
  • Increases the rate of transpiration.
  • Stomata open in the light to allow gas exchange for photosynthesis.
• Temperature:
  • Higher temperatures increase transpiration as water evaporates more quickly.
• Humidity:
  • Low humidity increases transpiration rate.
  • High humidity decreases the transpiration rate due to reduced concentration gradient.
• Wind:
  • Wind removes the water vapor surrounding the plant, increasing transpiration.
  • Stagnant air decreases transpiration.

2. Internal Factors

• Leaf Surface Area:
  • Larger surface areas increase transpiration.
• Cuticle:
  • Thick cuticles can reduce water loss.
• Stomatal Density and Distribution:
  • More stomata can increase transpiration rate.
  • Stomata location (e.g., underside of leaves) can influence transpiration.

Adaptations to Reduce Transpiration

• Some plants adapt to reduce transpiration, such as having fewer stomata, possessing thicker cuticles, or rolling leaves to reduce surface area.

Conclusion

• Transpiration is essential for plant health and affected by both external and internal factors.
• Understanding these factors can help in managing plant growth and managing resources effectively.

This lecture covers the significant factors influencing transpiration and provides insights into how plants adapt to control water loss, crucial for their survival and productivity.