Transpiration
Transpiration is a vital process in plant physiology involving the loss of water vapor from the aerial parts, primarily through leaves. It occurs mainly through structures called stomata, but also through the cuticle and lenticels. This process not only helps in cooling the plant but also plays a crucial role in water absorption and the upward movement of water, commonly referred to as the transpiration pull. This section further discusses various types of transpiration, significance, and factors affecting the transpiration rate, highlighting its importance in maintaining plant health.
Types of Transpiration
- Stomatal Transpiration: The primary and most significant form of transpiration, occurring through stomata, which are small openings on leaves.
- Cuticular Transpiration: Water loss through the cuticle, a waxy layer covering leaves.
- Lenticular Transpiration: Water vapor loss through lenticels, which are small openings found on the stems of woody plants.
Significance of Transpiration
- Cooling Effect: Transpiration helps in reducing leaf temperature and preventing overheating.
- Water Transport: It generates a negative pressure that facilitates water upward movement from roots to leaves.
- Mineral Transport: Essential for the transportation of nutrients dissolved in water.
Factors Affecting Transpiration
- Light: Increased light enhances transpiration rates due to opening of stomata.
- Temperature: Higher temperatures increase the evaporation rate, leading to increased transpiration.
- Humidity: Low atmospheric humidity elevates transpiration as the moisture gradient between the leaf and air increases.
- Wind: Wind can remove moisture from around the leaf, promoting greater transpiration.
Example
Consider a hot, dry day. On such days, the transpiration rate typically increases significantly due to a combination of high temperatures and low humidity levels.