Question

Which one of the following will reduce the rate of transpiration?

• A. Increase in wind velocity
• B. Rise in temperature
• C. Increase in water uptake by plants
• D. Decrease in light intensity

Answer 1

Answer: (D)

Decrease in light intensity

Stomatal pore size is regulated by guard cells. Guard cells are known to have chloroplast, which are involved in photosynthesis. The photosynthetic synthesis of sugars in guard cells increase solute potential and allows these cells to take up water due to reduced water potential. When water enters the guard cells, they swell and stomata open. When light intensity is low, the photosynthetic synthesis of sugars in guard cells will be low and guard cells will not gain enough turgor for opening of stomata.