1. Temperature : Rate of transpiration is directly proportional to the temperature. Transpiration rate increases with increase in temperature.
2. Light : More light closes the stomata.
3. Relative humidity : Rate of transpiration is inversely proportional to the relative humidity.
4. Velocity of the wind : The rate of transpiration is directly proportional to the velocity of wind. However, the wind of 40-50 km/hr brings closing of stomata and thus decreases the rate of transpiration.
5. Atmospheric pressure : Rate of transpiration is inversely proportional to the atmospheric pressure.
The water moves through the apoplast pathway in a passive way. The direction of the movement of water is according to the concentration gradient and hence no energy is required for the same. The water is absorbed in the following way -:
1. Root hairs have low water potential as compared to the soil. Thus, root hairs absorb water from the soil.
2. The water from soil enters into root hairs due to osmosis.
3. The cortical cells just adjoining to epidermal cells with root hair have much more osmotic pressure than root hair cells. Thus, water from epidermal cells diffuses into cortical cells adjoining them. The water diffuses passively through the cortical cells until they reach the casparian stripe which are suberized.
2. Providing mechanical support to the non-woody stems.
3. Keeping the leaves erect and fully expanded.
4. It helps in cell enlargement.
5. It is responsible for absorption of water as it creates a negative water potential.
1. Water molecules diffuse from the soil into root hair by osmosis.
2. Cell to cell movement of water occurs by osmosis.
3. Opening and closing of stomata are due to osmotic changes in guard cells.
4. The flowers remain fully stretched due to osmosis.
5. The plant movements like nyctinasty, seismonasty etc. occur due to the changes in the osmotic pressure.
6. The cells remain fully turgid due to osmosis.
1. The cell walls of plant cells remain moist due to diffusion of water molecules from one cell to the other.
2. The ions in the cells get uniformly distributed due to diffusion.
3. Transpiration is also due to diffusion of water vapour from intercellular space of spongy parenchyma into the atmosphere through stomata or cuticle.
4. The exchange of gases occurs through stomata due to diffusion.
5. The aroma or fragrance of flowers spreads due to the diffusion and insects are attracted for pollination.
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