Transpiration

• Transpiration is the process by which water leaves the body of a living plant and reaches the atmosphere as water vapor.
• The water is taken up by the plant-root system and escape through the leaves.
• It can be stomatal, cuticular or lenticular. Most of the stomatal transpiration takes place through plant leaves.

Phytometer method of measuring transpiration

• It is laboratory method. It is a large vessel filled with soil in which one or more plants are rooted. The soil surface is sealed to prevent evaporation. The escape of moisture is only by transpiration which can be determined by weighing the plant and container at desired intervals.

T=(W1+W)-W2

Where; T= transpiration (ml)

W1=Initial weight of instrument

W2= Final weight of instrument

W=Total wt of water added during full growth of plant.

Factors affecting transpiration

I. Percentage of sunshine (90% of daily transpiration occurs during day)

II. Wind speed

III. Mean monthly temperature: Plant growth normally ceases when temperature fall down to 40C & hence transpiration occurs in small quantity.

IV. Humidify

V. Types of crops/growth stage of crops

VI. Moisture level on soil

VII. Rainfall intercepted by vegetation