Page 1: Environmental Factors Affecting Transpiration

This page details the four main environmental factors that affect the rate of transpiration in plants: light intensity, temperature, humidity, and air flow. Each factor is explained in detail with its specific impact on the transpiration process.

Definition: Transpiration is the process of water movement through plants and its evaporation from aerial parts, especially leaves.

Light Intensity:

• Brighter light conditions increase photosynthesis rates, leading to more open stomata
• More open stomata allow greater water evaporation, increasing transpiration
• During darkness, stomata close and transpiration reduces significantly

Highlight: The relationship between light intensity and transpiration is directly proportional - more light typically means higher transpiration rates.

Temperature:

• Higher temperatures increase water particle energy
• Enhanced particle energy leads to more rapid evaporation and diffusion through stomata

Example: Just as warm air helps clothes dry faster on a clothesline, warmer temperatures accelerate water evaporation from leaves.

Humidity:

• Higher humidity decreases transpiration rates due to reduced concentration gradients
• Lower humidity promotes faster transpiration through steeper concentration gradients

Vocabulary: Concentration gradient refers to the difference in water vapor concentration between the inside and outside of the leaf.

Air Flow:

• Wind removes water vapor from leaf surfaces
• Increased air movement maintains steep concentration gradients
• Higher wind speeds generally result in increased transpiration rates

Quote: "Water molecules that leave the leaf are quickly blown away" in windy conditions, maintaining a high concentration gradient.