Assessing the impact of measurement errors in the calculation of CWSI for characterizing the water status of several crop species

Abstract Canopy temperature is generally accepted as an indirect but rapid, accurate, and large-scale indicator of crop water status is, therefore, proposed to monitor irrigation needs. Crop Water Stress Index (CWSI) the most widely used among existing thermal-based indicators, its links with stress have been demonstrated. When calculating CWSI using empirical approach, differential between canopy air normalized by two thresholds, also known baselines. The Non-water baseline (NWSB) in approach calculated relationship T c – a (°C) vapor pressured deficit (VPD, kPa) for well-irrigated crops. baselines display different slopes depending on species, which significant impact computed CWSI. This study analyzed resulting errors due measurement critical inputs needed calculation. Six species were selected according their NWSB that range from − 0.5 3 °C·kPa −1 this analysis, assuming ranging 0.2–1 °C , 0.25–2 5–10% relative humidity (RH). It was concluded effects observed are heavily dependent slope therefore vary across species. calculation very sensitive bias temperature. These maximal less steep. VPD ranged 2 6.6 kPa, error 1 measuring affected 28 83% orange, displaying minimum (− kPa ). On contrary, crops steeper such squash ) showed 8% same interval. differences considered may be related contrasting coupling atmosphere, determines influence pressure transpiration rate. highlights importance reliable climatic data need accurate calibrated thermal sensors calculate accurately.