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Information on actual consumptive water use and water productivity of wine grape vineyards grown with high-wire cordon (HWC) and vertical shoot position (VSP) trellis systems is limited, but it is critical to inform the selection of resource-efficient grapevine training systems and irrigation water management practices. This article describes an applied-research study conducted in the Central Valley of Chile to determine the actual evapotranspiration (ETa), actual crop coefficients (Ka), water productivity (WP), and water footprint (WFP) of microirrigated wine grape vineyards operated for commercial production with HWC and VSP trellis systems. ETa and Ka were determined using the residual of the energy balance (REB) method from micrometeorological measurements collected at the study vineyards with a combination of surface renewal and eddy covariance equipment. Field measurements of other biophysical parameters were also collected at each study site to characterize the soil water status in multiple locations across the vineyards at various soil depths using moisture tension–monitoring units, vine water status using midday stem water potential (ΨSTEM) , and fraction of photosynthetically active radiation (fPAR) intercepted by the vine canopy at different times during the growing season. Finally, the fruit yield was determined from grape samples collected at the HWC and VSP vineyard blocks during commercial harvest operations. The study was conducted over the course of two consecutive growing seasons (2019–2020 and 2020–2021). A reduction of 37% in the available water supply occurred during the 2019–2020 season with respect to the average water supply. Findings from the research study showed that when the water supply was less limited, the HWC trellis had 12% higher seasonal cumulative ETa than the VSP trellis, whereas the HWC system appeared more affected by water stress than the VSP trellis during the water-limited season. The analysis of the data sets also showed that the HWC enabled wine grape growers to achieve significantly higher fruit yield and water productivity, and lower water footprint per unit of wine grapes produced during the water-limited season. [ABSTRACT FROM AUTHOR]

Recent prolonged droughts in California have emphasized the urgent need to implement more efficient water management practices for high value tree crops. Accurate estimation of evapotranspiration (ET), a main component of consumptive water use, is critical for improving management of micro-irrigated pistachio orchards grown in the San Joaquin Valley of California. We estimated ET of three mature commercial pistachio orchards on non-saline and increasingly saline soils in 2015 and 2016, using the Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) method and Landsat 8 satellite observations. Based on a comparison with field observations at 8 sites, we modified the parameterizations of the momentum roughness length and net radiation for pistachio tree crops and reduced the uncertainty of daily ET estimates. When compared with field data, the recalibrated METRIC ET estimates had an R 2 of 0.59, a mean absolute error of 1.1 mm/day, and a RMSE of 1.4 mm/day during Landsat overpass dates (n = 72). The METRIC ET map captured the temporal dynamics and spatial heterogeneity both within and among the orchards. The mean annual crop season estimated ET (mid-March to mid-October in 2016) with remote sensing decreased by 32% from 1064 ± 99 mm in the non-salt affected control orchard to 725 ± 82 mm in the orchard with the highest level of soil-water salinity. The ET reduction was consistent with canopy volume differences among the study orchards, as shown by summer Normalized Difference Vegetation Index (NDVI) from Landsat observations, e.g., 0.72 ± 0.06 in the control vs. 0.52 ± 0.06 in the most saline orchard. The available energy was controlled mostly by canopy features and explained 64% of daily ET variation among all Landsat pixels and satellite overpass days. The normalized differenced water index (NDWI) could be considered as an important parameter to capture the partitioning of available energy for ET (R 2  = 0.38), suggesting that the lower soil osmotic potential in saline orchards further reduced crop ET. [ABSTRACT FROM AUTHOR]