Stimulation of transpiration by nitrogenous materials

Abstract

After a temporary decrease in transpiration on the day of treatment, the addition of urea or of potassium nitrate to the soil of potted plants of tomato (Lycopersicon esculentum Mill) increased the rate of transpiration from 10 to 40%. This increase was proportional to the amount of nitrogen applied and lasted for several days. The temporary decrease on the day of addition was a salt effect similar to the depression caused by sodium chloride or mannitol. Unlike potassium nitrate, neither potassium phosphate nor sodium chloride increased transpiration, indicating that the stimulation was a nitrogen effect. The increase in transpiration is thought to be linked to an increased nitrogen metabolism in the plants.