The objects are:

Definition of transpiration

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Understanding the process of transpiration

Learning types of transpiration

Advantages of transpiration to plant

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Definition of fruit

• Transpiration or water cycle: is theprocess of water movement througha plant and its evaporation from aerialparts especially from leaves but alsofrom stems and flowers.

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Transpiration

Types of transpiration

1. Cuticular Transpiration:the loss of water in theform of water vapour through the cuticle is knownas cuticular transpiration.

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Transpiration through cuticle

2. Lenticular transpiration: Loss of water in the form ofwater vapour taking place through the lenticels presentin woody stem and fruits is called as lenticulartranspiration. It amounts 1-5 percent of the total waterloss by the plant.

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Types of transpiration

3. Stomatal transpiration: Stomata are minute poresconfined to epidermis of green shoot and leaves. Openingand closing of stomata are controlled by guard cells.Maximum loss (80-90 percent of the total water loss) ofwater from the plant tissues takes place through the

stomatal openings.

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Types of transpiration

Cross section of leaf

How much water do plants transpire?

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During a growing season, a leaf will transpire many timesmore water than its own weight. An acre of corn gives off about3,000-4,000 gallons (11,400-15,100 liters) of water each day, anda large oak tree can transpire 40,000 gallons (151,000 liters) peryear.

Evaporation and transpiration Evaporation: occurs when water becomes vaporfrom bodies of water

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Evapotranspiration: is the sum ofboth evaporation and transpiration - the waywater moves from the liquid state to the gaseousstate.

Transpiration: occurs when water leaves a plant as vapor

Internal factors affecting on transpiration

1. Number of leaves: More leaves (or spines, or otherphotosynthesizing organs) means a bigger surface area and morestomata for gaseous exchange. This will result in greater waterloss.

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2. Number of stomata: more stomata will provide more pores fortranspiration.

3. Size of the leaf: A leaf with a bigger surface area will transpirefaster than a leaf with a smaller surface area.

4. Presence of plant cuticle: A waxy cuticle is relatively impermeableto water and water vapour and reduces evaporation from theplant surface except via the stomata.

External factors affecting transpiration

Temperature: Transpiration rates go up as thetemperature goes up, especially during thegrowing season, related to open and closed thestomata.

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Relative humidity: As the relative humidity ofthe air surrounding the plant rises thetranspiration rate falls. It is easier for water toevaporate into dryer air than into moresaturated air.

Wind and air movement: Increased movement of theair around a plant will result in a higher transpirationrate. This is somewhat related to the relative humidityof the air.

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External factors affecting transpiration

Type of plant: Plants transpire water at different rates.Some plants which grow in arid regions, such as cacti andsucculents, conserve precious water by transpiring lesswater than other plants.

Soil-moisture availability: When moisture is lacking,plants can begin to senesce (premature ageing, which canresult in leaf loss) and transpire less water.

Antitranspirant• Antitranspirants :are compounds applied to the leaves of plants to

reduce transpiration. They are used on Christmas trees, oncut flowers, on newly transplanted shrubs, and in other applicationsto preserve and protect plants from drying out too quickly. Theyhave also been used to protect leaves from salt burn and fungaldiseases.

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