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Variation in water content (h) in the soil profile during the 2008-2009 (above) and 2009-2010 (below) seasons. Dashed lines indicate field capacity (FC) and watering threshold (70% AW).
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Crop evapotranspiration (ETc) is essential for irrigation scheduling. The amount of water consumed can be estimated by multiplying the reference evapotranspiration (ET0) by a crop coefficient (Kc); the value of Kc is usually obtained from FAO Paper nr 56. In table grapes (Vitis vinifera L.), Kc are obtained from experiments in vines trained on trel...
Citations
... Data were collected from April 29th to August 22nd, on clear-sky days, at intervals of approximately 10 days. ISR was obtained by measuring, at solar zenith, the flux density of the photosynthetically active radiation (PAR, 400-700 nm, µmol photons m −2 s −1 ) available over the canopy (3 readings/replicate) and under the canopy (6 readings/replicate), using a solar bar (AccuPAR model LP-80 PAR/LAI, Decagon Devices, Pullman, WA, USA) [37]. Mean values and the corresponding ISR percentages were computed according to Equation (2) [37]: ...
... ISR was obtained by measuring, at solar zenith, the flux density of the photosynthetically active radiation (PAR, 400-700 nm, µmol photons m −2 s −1 ) available over the canopy (3 readings/replicate) and under the canopy (6 readings/replicate), using a solar bar (AccuPAR model LP-80 PAR/LAI, Decagon Devices, Pullman, WA, USA) [37]. Mean values and the corresponding ISR percentages were computed according to Equation (2) [37]: ...
... This work investigated the challenges posed by plastic film coverings in vineyards, and demonstrated that, despite interference, accurate estimation of crucial ground parameters was achieved; these included (i) ISR, which is strictly related to leaf area [72] and crop coefficients [37,84,85], and (ii) Ψstem, which is a reliable indicator of plant water status. ...
In the framework of precision viticulture, satellite data have been demonstrated to significantly support many tasks. Specifically, they enable the rapid, large-scale estimation of some viticultural parameters like vine stem water potential (Ψstem) and intercepted solar radiation (ISR) that traditionally require time-consuming ground surveys. The practice of covering table grape vineyards with plastic films introduces an additional challenge for estimation, potentially affecting vine spectral responses and, consequently, the accuracy of estimations from satellites. This study aimed to address these challenges with a special focus on the exploitation of Sentinel-2 Level 2A and meteorological data to monitor a plastic-covered vineyard in Southern Italy. Estimates of Ψstem and ISR were obtained using different algorithms, namely, Ordinary Least Square (OLS), Multivariate Linear Regression (MLR), and machine learning (ML) techniques, which rely on Random Forest Regression, Support Vector Regression, and Partial Least Squares. The results proved that, despite the potential spectral interference from the plastic coverings, ISR and Ψstem can be locally estimated with a satisfying accuracy. In particular, (i) the OLS regression-based approach showed a good performance in providing accurate ISR estimates using the near-infrared spectral bands (RMSE < 8%), and (ii) the MLR and ML algorithms could estimate both the ISR and vine water status with a higher accuracy (RMSE < 7 for ISR and RMSE < 0.14 MPa for Ψstem). These results encourage the adoption of medium–high resolution multispectral satellite imagery for deriving satisfying estimates of key crop parameters even in anomalous situations like the ones where plastic films cover the monitored vineyard, thus marking a significant advancement in precision viticulture.
... In relation to actual evapotranspiration (ETa), which is directly linked to AKcb values, three important results stand out; a) Simulated maximum daily ET rates under optimal conditions showed similar values (5 mm d − 1 ) than those reported in studies using lysimeters in the same valley but for Crimson and 'Thompson Seedless cultivars (Ferreyra et al., 2006;Villagra et al., 2014;Zúñiga-Espinoza et al., 2015). Simulations of ETa have also been reported for HYDRUS-1D under rainfed vineyards in southern France when comparing against Eddy covariance measurements . ...
Table grape production requires large amount of water, which can be problematic in semi-arid Mediterranean regions, where climate change projections anticipated reductions in water availability associated to decreases in precipitation and increases in temperature. In this context, this study aims to evaluate the effect of contrasting irrigation strategies and climate change scenarios on key water balance variables using a Chilean Table grape crop as case study. A standard and an improved irrigation management treatments were implemented in situ during the observed growing seasons, respectively. Then, the HYDRUS-1D water transfer model was run to simulate the three observed growing seasons and 27 near future growing seasons (2019/2020-2044/2015) under climate change conditions. Satisfactory calibration and validation results against soil moisture and water storage measurements were obtained within the first and the second observed growing seasons respectively (RRMSE values below 5%). Results during the observed seasons showed that by changing the standard irrigation by the improved irrigation management, the water use efficiency (WUE i) increases from 49.5% to 55.7%. For the near future, the calibrated model shows that under all the tested climate change scenarios, irrigation strategies based on supplying 80% and 50% of the crop evapo-transpiration (ETc) (deficit irrigation scenarios) have larger efficiencies compared to the standard irrigation management (presenting a higher actual basal crop coefficient and lower percolation). Similar results were obtained under future extreme climate change years, defined as the ratio between model-based projections of reference evapotranspiration (ET0) and precipitation, with the deficit irrigation scenarios having larger effi-ciencies than the standard irrigation management. Based on these results, it is concluded that by mid-century, the irrigation management has more relevance than climate change impacts for tables grapes growing under a Mediterranean climate in central Chile.
... Four works applied EC systems to measure actual, ET c act (Villagra et al., 2011;Carrasco-Benavides et al., 2012;Er-Raki et al., 2013;Marras et al., 2016). Villagra et al. (2014) combined the use of EC with the SWB. The EC technique was associated with sap flow measurements for the determination of crop transpiration in the studies by Poblete-Echeverría et al. (2012) and Poblete-Echeverría and Ortega-Farias (2013). ...
The present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (Kc) and basal (Kcb) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman–Monteith ETo equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard Kc and Kcb data. Preference was given to studies reporting on the fraction of ground cover (fc), crop height (h), planting density, crop age and adopted training systems. The Kc and Kcb values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly fc, h and training systems. The ranges of reported Kc and Kcb values were grouped according to crop density, particularly fc and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated Kc and Kcb values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard Kc and Kcb values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vines.
... Thus, irrigation requirements of kiwifruit vines trained on a pergola trellis have been estimated to be about 20% higher (>10.000 m 3 ha − 1 season − 1 ) (Holzapfel et al., 2000) than those of table grapevines using the same trellis system (±8000 and 9000 m 3 ha − 1 season − 1 ) (Villagra et al., 2014). ...
Kiwifruit is widely recognized as a fruit crop sensitive to water stress due to low stomatal regulation. Unfortunately, many of the most important kiwifruit producing areas have been affected by increasing water scarcity due to climate change. Protected cultivation may be used in kiwifruit vines not only to mitigate water stress and potential reductions in fruit quality but also to increase intrinsic water use efficiency. At the beginning of fruit maturation, two environmental conditions (uncovered and covered with a transparent plastic covering) were assessed in mature kiwifruit plants (Actinidia deliciosa Chev. cv. Hayward) subjected to conventional and deficit irrigation regimes in San Nicolás, Chile, for two consecutive seasons. The results showed that covered plants under deficit irrigation required twice the time to exhibit severe water stress levels (~−1.3 MPa) than plants under open-field conditions. Despite changes in solar radiation quantity and quality due to the transparent plastic covering, differences in rates of water stress occurrence between cover treatments in deficit-irrigated vines were not explained by differences in soil desiccation or stomatal conductance. The delay in severe water stress onset led to considerable water savings and caused no reductions in either yield or fruit quality, which increased water productivity between 21% and 71%. Fruit from covered plants subjected to deficit irrigation exhibited higher firmness at greater maturity (>7.0 Brix). The increase in water productivity in severely water-stressed kiwifruit vines, when using late-season plastic canopy cover, confirms that protected cultivation can be an excellent tool to reduce the impact of limited irrigation in many kiwifruit producing areas affected by water scarcity.
... However, it is important to emphasize that the estimation of kc using VI may vary in space and time, especially due to variations in the cropping system and agroclimatic characteristics of each region, so the values estimated for a crop in a given region may not be applicable for other growing regions (VANINO et al., 2015;VILLAGRA et al., 2014), which makes it necessary to analyze and develop local methods that are functional for each region. Despite this geospatial limitation, the use of RS techniques to assist in irrigation programming may be more accurate than fixed values in the literature (VANINO et al., 2015), such as those pre-established by FAO-56. ...
Technological evolution is essential to make irrigated agriculture more efficient in the use of water. Thus, this review article aims to contextualize irrigation in the age of agriculture 4.0 in order to address how these new technologies are impacting the rational use of water. With regard to the automation of irrigated systems, irrigation efficiency with moisture sensors, applications using smartphone, controllers and fertilizer injectors, as well as how their operation can promote irrigation, was addressed. Regarding irrigation management, the use of remote sensing as an option to determine crop evapotranspiration was contextualized, listing the types of spectral bands and sensors used to collect images (orbital, aerial and terrestrial), in the monitoring of crop water status. The importance of data collection in the delineations of management zones for precision irrigation and what possible advances can still be achieved with regard to obtaining and analyzing data were also discussed. Finally, it is concluded that, despite the high efficiency of automated irrigation systems, information of soil, climate and plant attributes obtained through the range of data provided by sensors will be responsible for mitigating the global impacts caused by irrigated agriculture in the near future, since this information can enhance irrigation, with maximum efficiency, thus reducing water consumption by agriculture.
... Lysimeters are used to define water movement across a soil boundary for agronomic and environmental studies (Christiane 2004;Aboukhaled 1982). Lysimeters are used in the determination of CWR through crop development (Paulina et al., 2013;Evett, et al., 2006,). They are either weighing or non-weighing. ...
... Thus, the practice of picking Kc values as recommended from FAO 56 (Allen et al., 1998) needs to be re-evaluated in the light of possible actual water requirement of newly developed crop varieties. (Paulina et al., 2013). ...
Accurate irrigation planning requires basic information about the soil, environment and the water requirements of the crop to be cultivated. With new variety of a crop comes the physiological characteristics that may be somewhat different from known varieties. Crop Water Requirement (CWR) and Crop Coefficient (Kc) are major factors required in irrigation planning and they vary with crop developmental stages. Four non-weighing Lysimeters (Diameter, 60cm and Depth, 50cm) were used to determine CWR, Kc as well as crop performances under specific conditions. The CWR and Kc of Maize variety (SUWAN-1-SR) were determined across the four developmental stages (Initial, Development, Mid and Late) using the lysimeter system. The CWR were 58.8, 176.8, 206.0, 59.6 mm and Kc were 1.0, 1.6, 1.4, 0.7 for the respective stages. In comparison with FAO 56 maize Kc and CWR values, SUWAN-1-SR requires more water across the developmental stages and a sum of 501.2mm for the crop cycle. The average yield was 14.1t/ha, while average Water Use Efficiency (WUE) in the Lysimeter plots was 2.68±0.44 kg/m 3 at a planting spacing of 40cm x 40cm, The WUE is high confirming the yielding potential of SUWAN-1-SRif given necessary nutrient inputs, and water requirement met. The developed lysimeter can be used to efficiently determine CWR.
... The platform makes use of the modified FAO Penman-Monteith model [8,9,10,13,19,24,25] to define actual daily crop water use, as the product of site-specific atmospheric evaporative demand maximum value, assuming: (1) unlimited moisture availability and ambient atmospheric conditions, or potential evapotranspiration (ETp) [26] and (2) actual crop leaf area index, expressed as a crop coefficient function (Kc) [27][28][29]. ...
... The Kc = (t) function can be represented by a double sigmoid curve (Figure 2) for the initial three crop phenology stages (budbreak, flowering, and veraison) [36,37]; a constant maximal value from veraison to harvest, and a linear decline for the postharvest irrigation stage, reaching a Kc final = Kc initial [37]. The maximal Kc max value has been widely reported for most irrigated crops [27]; at flowering [Kc flower = (Kc max /Kc initial )/2] [26,38]. ...
... Crop evapotranspiration (ET c ) was determined daily from the product of ET o and the crop coefficient (k c ). Values of k c for this study were obtained from previously developed coefficients for field-grown, overheadpergola-trained Thompson Seedless in the Valparaiso Region, Chile (Villagra et al. 2014). Phenological stages during the season were recorded when 50% of vines showed the typical features of the stage based on the modified Eichhorn-Lorenz system (Coombe 1995). ...
Crimson Seedless is one of the most important table grape cultivars in the world, but often exhibits uneven berry color when grown in warm climates. Deficit irrigation is used extensively by growers during the ripening phase to advance fruit maturity and color, but there is a lack of information about the relationship between irrigation practices and fruit ripening variability. We imposed deficit irrigation in a commercial Crimson Seedless vineyard in the Maipo Valley, Chile, from veraison to harvest in two consecutive seasons. The fruit was tested for uniformity of Brix, firmness, and the color parameters “L”, “a”, “b”, and the Color Index of Red Grapes using analysis of variance on absolute residuals (Levene’s test). Postveraison water stress increased water productivity, Brix, and slightly improved berry coloration, but did not affect berry weight, size, or firmness. Moderate levels of water stress
improved color uniformity at harvest, as lower values of leaf water potential were associated with a lower percentage of green berries that never matured. These results confirmed the role of deficit irrigation in the table grape ripening process. In contrast, extending the fruit ripening period by delaying harvest beyond 18 Brix did not increase color accumulation, but did increase berry shatter.
... This variation coincides with the plant development of the crop and the subsequent process of senescence of the plants. Similar variation patterns of Kc were observed in different annual crops Villagra et al, 2014;Guimaraes et al, 2015). Figura 3. Tasa diaria de evapotranspiración medida con el método de la covarianza eddy (ETa) y la obtenida con el método FAO Penman Monteith modificado por la relación de cobertura el factor de cobertura (ETraj). ...
... Esta variación coincide con el desarrollo vegetativo del cultivo y el proceso posterior de senescencia de las plantas. Patrones similares de variación del Kc se observaron en diferentes cultivos de ciclo anual Villagra et al., 2014;de Guimaraes et al., 2015). La tasa diaria de ETa medida con el método de la covarianza eddy y la ETa estimada a partir de la ET de referencia (método FAO Penman-Monteith) fue muy similar en los meses del ciclo de producción del viñedo (Figura 4). ...
Timely and adequate irrigation scheduling in agriculture requires information corresponding to the daily rate of crops ET established or to be established in different agricultural regions. Therefore, the objective of this study was to determine the daily rate of current ET (ETa) of the vine cultivation, from the reference ET (ETr) obtained with the FAO Penman Monteith method and its comparison with the crop ETa obtained with an eddy covariance system. We conducted the study in a vineyard of Vinícola San Lorenzo, Parras, Coahuila, during the production cycle of the vine (Vitis vinifera cv Shiraz) from April to September 2014. Within the vineyard we delimited two sections of 5.2 ha, and on each we installed eddy system sensors to obtain the daily rate of crop ET (ETa). Simultaneously, we continuously measured the total incident solar radiation, temperature and relative humidity and wind speed. With this information, we obtained the daily reference ET rate (ETr). The daily rate (ETa) of one of the sections of the vineyard was compared to the ETr to obtain the monthly adjustment coefficients of crop development (Kc). The study results showed that based on the Wilcoxon test for paired populations (p≤0.01), the daily rate of ETa measured in the vineyard (with the eddy covariance method) was equal to the Eta rate obtained from the ETr (with the FAO Penman Monteith procedure) corrected by the plant coverage ratio factor and the monthly coefficients (Kc) of crop development.
... This variation coincides with the plant development of the crop and the subsequent process of senescence of the plants. Similar variation patterns of Kc were observed in different annual crops Villagra et al, 2014;Guimaraes et al, 2015). Figura 3. Tasa diaria de evapotranspiración medida con el método de la covarianza eddy (ETa) y la obtenida con el método FAO Penman Monteith modificado por la relación de cobertura el factor de cobertura (ETraj). ...
... Esta variación coincide con el desarrollo vegetativo del cultivo y el proceso posterior de senescencia de las plantas. Patrones similares de variación del Kc se observaron en diferentes cultivos de ciclo anual Villagra et al., 2014;de Guimaraes et al., 2015). La tasa diaria de ETa medida con el método de la covarianza eddy y la ETa estimada a partir de la ET de referencia (método FAO Penman-Monteith) fue muy similar en los meses del ciclo de producción del viñedo (Figura 4). ...
Timely and adequate irrigation scheduling in agriculture requires information corresponding to the daily rate of crops ET established or to be established in different agricultural regions. Therefore, the objective of this study was to determine the daily rate of current ET (ETa) of the vine cultivation, from the reference ET (ETr) obtained with the FAO Penman Monteith method and its comparison with the crop ETa obtained with an eddy covariance system. We conducted the study in a vineyard of Vinicola San Lorenzo, Parras, Coahuila, during the production cycle of the vine (Vitis vinifera cv Shiraz) from April to September 2014. Within the vineyard we delimited two sections of 5.2 ha, and on each we installed eddy system sensors to obtain the daily rate of crop ET (ETa). Simultaneously, we continuously measured the total incident solar radiation, temperature and relative humidity and wind speed. With this information, we obtained the daily reference ET rate (ETr). The daily rate (ETa) of one of the sections of the vineyard was compared to the ETr to obtain the monthly adjustment coefficients of crop development (Kc). The study results showed that based on the Wilcoxon test for paired populations (p <= 0.01), the daily rate of ETa measured in the vineyard (with the eddy covariance method) was equal to the Eta rate obtained from the ETr (with the FAO Penman Monteith procedure) corrected by the plant coverage ratio factor and the monthly coefficients (Kc) of crop development.
