Potassium ion concentration and water potential control the opening and closing of stomata : Potassium ion concentration and water potential control the opening and closing of stomata
Slide 2 :
Significance of Transpiration : Significance of Transpiration Much amount of water must be made available to a plant in order to support transpiration and the plant survival.
Transpiration often results in water loss, especially in high temperature and low humidity.
Slide 4 : This raises an interesting and often controversial question: Is there any positive advantage in transpiration to be gained by the plant?
It has been argued that transpiration is required to bring about the ascent of sap, that it increases nutrient absorption and that it assists in the cooling of leaves.
It has also been argued that transpiration is little more than a necessary evil as suggested by Curtis (1926).
Advantages of Transpiration : Advantages of Transpiration 1. Absorption of water
Transpiration increases the rate of water by the roots.
Transpiration causes a pull in the xylem tubes which helps in the suction of water by the root from the soil.
Slide 6 : 2. Absorption and translocation of mineral salts
More rapid rate of transpiration results in increase in the rate of absorption of mineral salts and their upward movement.
3. Cooling effect : 3. Cooling effect The leaves absorb quantities of the radiant energy which raises their temperature. Transpiration plays an important role in controlling the temperature of the plants.
Rapid evaporation of water from the aerial parts of the plant through transpiration brings down their temperature and prevents them from excessive heating.
4. Exchange of gases : 4. Exchange of gases Stomata is the passage through which CO2 is absorbed for photosynthesis and oxygen is released out.
Similarly during respiration O2 is taken in and CO2 comes out
Disadvantages of Transpiration : Disadvantages of Transpiration 1. Loss of bulk of water
Transpiration sends out 95% of the water
absorbed by plants.
2. Internal water deficit
When the rate of transpiration is high and there is scarcity of water in the soil, an internal water deficit is created in the plants.
This leads to wilting and eventually may cause the death of the plants.
GUTTATION or EXUDATION : GUTTATION or EXUDATION Water loss from the tips or margins of leaves
In form of liquid drops
Slide 11 : The water drops come out through specialized pores called hydathodes or water stomata.
Slide 12 :
Slide 13 : Many grasses,
Nasturtium spp.,
Lycopersicum esculentum (tomato),
Colocasia esculenta ,
Vitis vinifera,
Impatiens balsamea,
Canna spp. and
Chrysanthemum spp.,
Rose and
Strawberry
Slide 14 : Root pressure helps in guttation Strawberry leaves