DENDROLOGY

Detailed explanation-1: -During daytime in the sunlight, the rate of transpiration is faster. This is because the stomata remains open to allow the inward diffusion of carbon dioxide for photosynthesis. During dark, the stomata are closed, and hence transpiration hardly occurs at night.

Detailed explanation-2: -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.

Detailed explanation-3: -Since stomata are closed at night, it is generally believed that transpiration only happens during the day. Stomata, however, can be open at night and closed during the day in some succulent plants. But the rate of transpiration is lower at night.

Detailed explanation-4: -Transpiration is the evaporation of water from plants. So the photosynthesizing leaf loses more amount of water by evaporation. so sunlight speeds up transpiration by warming the leaf.