Evolution of Corn Transpiration and Leaf Water Potential during Sprinkler Irrigation

Corn (Zea mays L.) transpiration during daytime solid-set sprinkler irrigation was analyzed on two neighbouring subplots to determine the effect of the transpiration reduction on water application efficiency. During each irrigation event, one subplot was irrigated (moist treatment) while the other was not (dry treatment). Transpiration rates were determined at each subplot by the heat balance method (Dynamax Flow4 System) before, during and after the irrigations. During irrigations, there was a significant decrease in transpiration (60%) for the moist treatment. Within the first hour after irrigation, transpiration rates were also smaller for the moist treatment, but the reduction was lower (17%). It was found a significant correlation between the transpiration reduction and the decrease of water vapor deficit during, and after the irrigation event. Leaf water potential during the irrigation increased (about 61%) for the moist treatment, which suggests that the reduction of transpiration was not due to stomata closure but to smaller water vapor gradient between the plant and the surrounding atmosphere.