DENDROLOGY

Detailed explanation-1: -As the relative humidity of the air surrounding the plant rises the transpiration rate decreases. It is easier for water to evaporate into dryer air than into more saturated air. Increased movement of the air around a plant will result in a higher transpiration rate.

Detailed explanation-2: -At high atmospheric humidity, transpiration is low. This is because the rate of transpiration is directly proportional to the saturation deficit. It is dependent on the gradient of vapor pressure. Thus, the higher the humidity, the lower the rate of transpiration.

Detailed explanation-3: -The rate of transpiration depends on the relative humidity of the air. The more the humidity of air, the less the rate of transpiration.

Detailed explanation-4: -Light, high temperatures, and wind increase transpiration rate while humidity reduces it. Light stimulates stomatal opening (see Stomatal Opening and Closure), allowing water vapor to easily leave the leaf.

Detailed explanation-5: -Transpiration is reduced if the air outside is humid. High humidity in the air reduces the rate of outward diffusion of the internal water vapour across stomata, thereby reducing the rate of transpiration.