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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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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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Abstract

Small weighing lysimeters were used to determine potential evapotranspiration (ET) (i.e., ET when soil water is not limiting) rates of turf weeds and ground-covers. When ET was monitored during two consecutive summers, white clover (Trifolium repens L.) had the highest mean water use rate (7.4 mm·day-1). Dichondra (Dichondra repens J.R. Forst. and G. Forst.), a low-growing C4 dicot, and barnyardgrass [Echinochloa crusgalli (L.) Beauv.], a C4 monocot, used the least water (3.9 and 4.1 mm·day-1, respectively). ‘Merion’ Kentucky bluegrass (Poa pratensis L.), a C3 species, and yellow foxtail [Setaria glauca (L.) Beauv.] and smooth crabgrass [Digitaria ischaemum (Schreb.) Muhl.], C4 species, exhibited intermediate ET rates. Water use rates of these ground-covers should be considered when using them in landscapes. Eradication of some weeds, such as white clover, in well-watered turf areas may be an effective means of reducing ET.

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Abstract

Potential evapotranspiration (ET) (i.e., ET when soil water is not limiting) rates of creeping bentgrass (Agrostis palustris Huds.) and annual bluegrass (Poa annua L.) were determined during two consecutive summers using weighing lysimeters in the field. When evaluated under putting green conditions, significant species differences in ET were observed during several weeks in 1985 and 1986. Differences were small, however, and irrigation requirements should not vary much between these species. Both species exhibited lower water use rates in 1986 when cut at 6 mm (4.6 mm·day-1) than at 12 mm (4.9 mm·day-1). These small differences should not greatly affect water requirements of putting green turf maintained at variable cutting heights. Variability of ET throughout the study periods suggests that water savings could result if ET is monitored, and irrigation adjusted accordingly.

Open Access

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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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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, 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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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

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.22″) located less than 5 km from the research site. Total precipitation was measured, and growing degree days (base of 10 °C, 1 Apr. to 31 Oct.) and grass reference evapotranspiration (ET o ) were calculated. The accumulated growing degree days (GDD) increased

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.08 mm, respectively (54% ET reduction). Overall, average ET reduction under LT in all three trials was 60%. Fig. 1. Daily evapotranspiration at canopy levels in brussels sprouts grown under low tunnel (LT) and open field (Open). Air temperatures, solar

Open Access