Seasonal near-continuous patterns of leaf-to-air vapor pressure deficits in differentially irrigated cotton: potential importance in assessing water demand.

摘要

The application of water to crops, in the needed amount, at the right moment in time, is important. The water status of the crop is often used to determine the need for irrigation. Since the water status of a crop can be difficult to measure directlyit is often inferred from the environment. Measurement of the above ground environment can be automated and the data can used used in models to predict irrigation amount and timing. The vapor pressure deficit (VPD) of the air is a good indicator of the potential water need. VPD is calculated with the assumption that the temperature of the canopy is similar to air temperature. Canopy temperature of cotton was monitored across irrigation regimes and was used to calculate leaf-to-airVPD. Leaf-to-airVPD declined with increasing irrigation amounts. The value of leaf-to-airVPD in the prediction of potential ET for the crops was assessed.