Site-Specific Evaluation of Canopy Resistance Models for Estimating Evapotranspiration over a Drip-Irrigated Potato Crop in Southern Chile under Water-Limited Conditions

Abstract

The evapotranspiration () process is an essential component in many agricultural water management systems, and its estimation is even more determinant when crops are grown under water-limited environments. The traditional canopy resistance () approaches were evaluated to simulate potato evapotranspiration () using the original Penman–Monteith equation under different irrigation levels. A field study was carried out on a drip-irrigated potato crop (var. Puyehue INIA) located in the Research Center Carillanca (INIA), La Araucanía Region, Chile (38°41′ S, 72°24′ W, 188 m above sea level) during the 2018/2019 and 2019/2020 growing seasons. The different irrigation levels were full irrigation (), 75% of (), and 60% of (). The soil water content, morphological, physiological, meteorological, and micrometeorological variables were measured to calculate the different approaches and estimate ET for both growing evaluated seasons. The final values of estimated were compared to the soil water balance method (). The use of amphistomatous (LA) and hypostomatous (LH) approaches are the best alternative to estimate the on potato crops. The best estimation of ET was found for with an overestimation of 0.6% for , 7.0% for , and 13.0% for , while for with underestimations of 12.0, 11.0 and 31.0% for , , and , respectively. The lowest average values of root mean square error (RMSE), mean absolute error (MAE), and index of agreement (d) were observed for in both and conditions, with values of 4.4 and 3.2 mm, 3.2 and 2.5 mm, and 0.82 and 0.87, respectively. More investigation is necessary on the plasticity of the morphological features of potato leaves and canopy geometry, as the stomatal water vapor flowing on the canopy surface could be affected, which is a key factor in the canopy resistance model for accurate estimation under soil-water-limited conditions.

Responses in the Coupling of Carbon and Water Vapor Exchanges of Irrigated and Rainfed Andean Potato (<i>Solanum Tuberosum</i> Subsp. Andigenum) Agroecosystems

“…Regarding diurnal patterns, the tendency of the estimated half-hourly Rc had a similar magnitude, along the growth stages. Averaged midday Rc values around 15 s m −1 were similar to those reported for potato by Amer & Hatfield (2004) and López-Olivari et al (2022) and lower than values reported by Kjelgaard & Stockle (2001) (midday Rc values close equal to 40 s m −1 ). As seen for daily data, diurnal aerodynamic resistance generally was higher than canopy resistance.…”

“…This expected low canopy resistance under wellwatered conditions has been reported by other researchers (Aires et al, 2008;Kumagai et al, 2008;Paulino Junior and Silva von Randow, 2017;Souza et al, 2012). Unlike with López-Olivari et al (2022), we observed a larger aerodynamic resistance (generally higher than Rc) indicating more importance of Ra in total resistance to water vapor transport. Regarding diurnal patterns, the tendency of the estimated half-hourly Rc had a similar magnitude, along the growth stages.…”

Carbon and water vapor exchanges coupling in irrigated and rainfed Andean potato (Solanum tuberosum subsp. andigenum) agroecosystems

“…At the diurnal half-hourly scale in the well-watered conditions FI site, we observed higher ET, GPP, and sink activity (more negative NEE) during the lowest Rc, which evidence an intense carbon-water exchange under a low bulk resistance to mass transfer (Amer and Hatfield 2004;Aires et al 2008;Kumagai et al 2008;Souza et al 2012; Paulino Junior and Silva von Randow 2017; Wehr and Saleska 2021) that supports a higher CO2 sequestration activity. Our midday Rc values around 15 s m −1 were like those reported for potato by Amer and Hatfield (2004) and López-Olivari et al (2022) and lower than values reported by Kjelgaard and Stockle (2001) (40 s m−1). In the DI site, ET continues at a high rate while there is a high restriction in the GPP and NEE fluxes.…”

Novel Approaches for the Empirical Assessment of Evapotranspiration over the Mediterranean Region

“…The second approach, known as the micrometeorological method, uses a scientific understanding of the physics of evapotranspiration. Mathematical relationships have been developed to describe these processes through two fundamental climatological components: energy balance and mass transport [10,[17][18][19]. The third method centers on developing empirical relationships that are often site-specific and based on regional climatological conditions and often used in regression analysis.…”