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Andrew G. Reynolds, Amal Ehtaiwesh and Christiane de Savigny

water. Meteorological equations such as the modified Food and Agriculture Organization of the United Nations (FAO) Penman-Monteith equation ( Allen et al., 1998 ) are used to schedule irrigation needs by calculating reference evapotranspiration from

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Harold McCutchan and K.A. Shackel

Abbreviations: ET, evapotranspiration; ψ, water potential; VPD, vapor pressure deficit. 1 UC Cooperative Extension, 733 County Center III Court, Modesto, CA 95355. This work supported in part by a grant from the California Prune Board. The cost of

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Amir M. González-Delgado, Manoj K. Shukla and Brian Schutte

had the highest cumulative volume of effluent compared with the C, PF, and ST treatments. However, no significant differences in leachate volumes were seen among the treatments. Fig. 1. Cumulative volume of effluent ( A ) and evapotranspiration ( B

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Albert Sutherland*, Mike Schnelle and Derek Arndt

The American Horticulture Society (AHS) Heat Zone categories have been developed to categorize ornamental plant adaptability to different air temperature climates. These zones, like the Plant Hardiness map showing plant cold hardiness zones within the United States, are primarily north to south zones. Within the Great Plains region of the United States, the AHS Heat Zone categories provide a basic level of plant adaptability to air temperature, but do not account for plant reaction to variations in wind, relative humidity or sunlight. Daily reference evapotranspiration provides a single number that responds to variations in air temperature, wind, relative humidity and sunlight. In Oklahoma, the Oklahoma Mesonet provides a uniform statewide network of weather monitor towers that can be used to accurately calculate both short and tall American Society of Civil Engineers (ASCE) reference evapotranspiration (ref ET) across the entire state. Accumulated daily ref ET values can be used to provide further refinement in categorizing ornamental plant adaptability.

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D.C. Bowman and L. Macaulay

Comparative evapotranspiration (ET) rates of 20 cultivars of tall fescue (Festuca arundinacea Schreb.) were measured over 7 days in a greenhouse study. Small but significant differences in ET rates existed between the cultivars grown under nonlimiting water and nutrient conditions on day 1 following mowing. Greater differences had developed after 7 days of growth, with ET ranging from a low of 10.0 mm·day-1 for `Shortstop' to a high of 13.5 mm·day-1 for `Alta'. Day 7 ET was positively correlated (r = 0.82) with clipping dry weight. Six of the tall fescue cultivars were selected for a subsequent experiment to determine the stability of relative rankings for ET over time. Although average ET varied by up to a factor of two among five dates, the rankings were nearly identical for the five dates and were consistent with the rankings in the first experiment.

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D. Michael Glenn, C. Feldhake, F. Takeda and D.L. Peterson

The objectives of this lysimeter study were to 1) evaluate the amount of dewfall, 2) determine the contribution of dew to daily evapotranspiration (ET) in fall-grown strawberries (Fragaria ×ananassa Duch.), and 3) determine the relationship between actual and potential ET (PET) of strawberry. Dewfall amounts averaged 0.8 mm·day–1 and accounted for 33% of the daily ET during the 27 Sept. to 6 Nov. period. Daily ET was linearly related to PET calculated from the Penman–Monteith equation, with an accuracy of ±3 mm based on lysimeter ET. Daily ET for 2- to 4-day periods was estimated with an accuracy of ±1 mm using the Penman–Monteith. We conclude that dewfall cannot be ignored in the ET of fall-grown strawberries in the mid-Atlantic section of the United States.

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R.L. Green, S.I. Sifers, C.E. Atkins and J.B. Beard

We compared evapotranspiration (ET) rates for 11 Zoysia genotypes, encompassing two species and their hybrid, maintained at nonlimiting soil moisture under field conditions and in an environmental chamber of high evaporative potential. ET rate relationships to leaf area [leaf extension rate (LER)], canopy resistance [shoot density (SHD)], and internal resistance [abaxial (AB) and adaxial (AD) leaf blade stomatal densities] characteristics were determined. Three-year ET rate means were not significantly different among genotypes in the field study, but ET rates among genotypes differed significantly under the higher evaporative potential of an environmental-chamber study. ET rate was not significantly correlated with LER for either the data from the field or the chamber. ET rates of both types of tests also were not significantly correlated with SHD or AB or AD leaf blade stomatal density. Data from field and environmental-chamber research suggest that differences of individual morphological traits among the 11 zoysiagrasses do not influence the ET rate when measured from minilysimeters maintained at nonlimiting soil moisture.

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Preston K. Andrews, David J. Chalmers and Mapasaka Moremong

Abbreviations: A, alfalfa; CWSI, crop water stress index; CTV, canopy-temperature-variability; D, drainage; ET, evapotranspiration; FI, full irrigation; H, herbicide strip; I, irrigation, IR, infrared P, black plastic mulch; R n , net radiation; SDD

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Xuewen Gong, Shunsheng Wang, Cundong Xu, Hao Zhang and Jiankun Ge

, which was measured by water balance approach in 2015 and weighing lysimeter in 2016. The plant transpiration data were collected every 15 min by a CR-1000 data logger (Campbell Scientific Inc.). Evapotranspiration. The ET c was measured from March to

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Richard C. Beeson Jr

time clock systems (Beeson, personal communication). Most irrigation managers are unaware of day-to-day changes in reference evapotranspiration (ETo), a value that quantifies evaporation potential of the immediate microclimate, and corresponding changes