Crop water stress index and non-stressed baseline of corn grown in the state of Wyoming, US

In semi-arid and arid regions drought can be devastating for agriculture. Irrigation may avoid water deficit due to lack of rainfall as long as supplies are certain. However, short periods of drought during critical growth stages may result in low yields. From the different approaches that exist to determine drought stress in plants, the Crop Water Stress Index (CWSI) has been gaining attention. However, site- and crop-specific determinations of the non-stressed baseline (NSB) might be needed. The objective of this study was to assess the performance of a locally derived NSB for the determination of drought stress in corn. A corn experiment was conducted at the University of Wyoming Research & Extension Center located in Powell, WY. The experiment, planted on May 16^th, 2011 on a sub-surface drip irrigated field, consisted on three irrigation regimes, including 1.0ET_c; 0.7ET_c, and; 0.5ET_c. Canopy temperature, measured with infrared thermometers installed at each replicate as well as environmental variables were recorded continuously during most of the growing season using a system consisting of a data logger and radio transmitter/receiver to a dedicated computer. A NSB, derived from the 1ET_c irrigation treatment was estimated. CWSI results using the NSB as recommended by literature and those from the locally derived NSB were compared. It was observed that the locally derived NSB yielded considerably lower CWSI values. The locally derived NSB improved the determination of water stress. Our results evidenced the potential use of the CWSI as a tool for irrigation scheduling in corn.