Day Versus Night Irrigation Loss From Sprinkler Irrigation of Urban Crops

Nighttime irrigation is a widespread strategy to conserve water, as it reduces wind drift and evaporation loss (WDEL). However, daytime sprinkler irrigation may also conserve water by lowering the temperature and increasing the humidity of crop microclimates, thereby reducing evapotranspiration (ET). Therefore, the objectives of this study include: 1) quantify whether a water savings exists between day and night irrigation with a water balance approach, 2) analyze the microclimate effects by irrigation timing to determine any changes to WDEL and evaporative demand, and 3) assess the quality and yield response of two urban crops. In 2019-21, we established 12 field plots in Logan, UT (41.77°N, -111.81°W) to test two irrigation timings (night, 2:00-4:00 am, and day, 2:00-4:00 pm) with two urban crops (turfgrass and zinnia cut flowers) with a sprinkler system in triplicate. Field instrumentations include a central weather station, flow meters on sprinkler sets, soil moisture sensors at 8 cm and 18 cm depths, canopy air temperature and humidity sensors, surface temperature sensors, and catch cups. WDEL was 10% greater for daytime irrigation than nighttime in both 2019 and 2020. The total ET of turf was 533.5 mm (± 16.49) per season with daytime irrigation and 540.3 mm (± 11.96) with night. For zinnia, ET was 517.5 mm (±14.87) and 529.8 mm (±13.53) per season with day and night irrigation, respectively. There were no significant differences in the yield of turf or the marketable yield of zinnia in 2019 or 2020. The quality of the turf as average percentage cover was 96% with daytime irrigation and 93% with nighttime irrigation, and there were no significant differences with the dark green color index (DGCI). Our results across crop indicate that daytime irrigation increases WDEL, but reduces ET when applied during maximum daytime temperatures, compared to nighttime irrigation. A final field season will be conducted in 2021 and the study will be used by water managers for policy decisions that weigh public demand, system capacity of districts, and irrigation efficiency. Presentation Time: Thursday, 12-1 p.m. Zoom link: https://usu-edu.zoom.us/j/83738417563?pwd=SHlRcGdaaTdmVzVUOENqTnVHQ3UzZz0

Daytime Versus Nighttime Sprinkler Irrigation of Two Urban Crops in a Semi-Arid Climate at High-Elevation

Nighttime irrigation scheduling is a longstanding water conservation approach to reduce evaporative losses in Utah\u27s semi-arid, urban landscapes. However, residential demand now exceeds system capacity, and the efficiency of the practice has come under question. Therefore, the objectives of this study include: 1) quantify whether a water savings exists between day and night irrigation with a water balance and energy balance approach, and 2) analyze microclimate and crop quality effects to determine any changes to evaporative demand or plant stress by irrigation timing. In 2019, we established 12 field plots in North Logan, UT (41.77° N, -111.81° W, 1380 m elevation) to test two irrigation timings (2:00 - 4:00 am and 2:00 - 4:00 pm) with two urban crops (turfgrass and zinnia cut flowers) on a sprinkler system in triplicate. Field instrumentation included a central weather station, flow meters on sprinkler sets, soil moisture sensors at 0.08 m and 0.18 m depths, canopy air temperature and vapor pressure, surface temperature, and catch cups for wind drift and canopy interception calculations. Daytime irrigation resulted in greater wind drift and evaporative losses (WDEL) by 7% compared to nighttime in both crops. A decrease in canopy and surface temperature, as well as the vapor pressure deficit was greater with daytime irrigation than nighttime, decreasing the evaporative demand at maximum air temperature (Tmax). Turf and zinnia yield and quality were not affected by irrigation timing, though the percentage cover of turf was significantly greater with daytime irrigation compared to nighttime. Thus, landscape irrigation scheduling should avoid hours with peak wind speed to reduce the WDEL and irrigate the field at or after Tmax to reduce the evaporative or heat stress to the crop

Leaf morphological and anatomical variations of paper birch populations along environmental gradients across Canada

Leaf morphology and anatomy have been found to vary considerably among tree species, and leaf characteristics have widely been used for analyzing plant growth and resource use strategies because of their structural adaptation to withstand environments. Considering the changing climate projections, early-successional, broad niched species like paper birch (Betula papyrifera Marsh.) are expected to increase dominance due to a zonal shift of natural vegetation and/or open gaps within the current vegetation zones. Hence, it is important to understand factors such as leaf characteristics that enable these pioneer species to inhabit a wide geographic range and their increasing dominance. Paper birch is a pioneer tree species in North America that inhabits wide climatic and geographic gradients; in addition, the species has developed different leaf morphology and anatomy that have allowed paper birch to adapt to diverse habitats. This study examines how the leaf characteristics of paper birch vary under uniform and stressed environments. The major objectives were (a) to investigate leaf characteristics variations in paper birch populations grown in uniform environmental conditions as in a greenhouse and a common garden; (b) to correlate between leaf characteristics and paper birch’s environment of origins; (c) to investigate leaf characteristic variations in paper birch populations grown under different carbon dioxide concentrations [CO2] and soil water levels to determine the relationship between leaf characteristics and individual or interacting effects of [CO2], water levels and populations; and (d) to analyze the relationship within and between leaf morphology and anatomy of the birch populations. The study found significant differences among paper birch populations in leaf morphological characteristics under a uniform environment at the greenhouse and the common garden. The leaf characteristic variations in the uniform environment may be related to the different genotypes of the birch inhabiting a wide environmental gradient. In paper birch populations grown in the common garden, significant differences in stomatal density, stomatal area, pore area and guard cell width were identified. As expected, the birch populations in greenhouse and common garden environments showed significant correlations of leaf characteristics, namely specific leaf area (SLA), leaf maximum width index and petiole area to latitude, longitude, elevation, temperature, precipitation and aridity index of origin. Correlation between leaf characteristics of paper birch in the greenhouse showed that populations originated in limited precipitation (during growing season) had low hair density on leaf adaxial surface, with larger leaf width and petiole area. Birch populations grown in the common garden revealed that populations originated in higher mean annual precipitation had less hair density on leaf adaxial surface with smaller leaf area and higher stomatal density. Relationships within the leaf characteristics revealed significant correlations within and between leaf morphology and anatomy as populations with larger leaf area had larger petiole area and less adaxial hair density in greenhouse. The larger petiole in larger leaf reflects the need for mechanical strengthening to support, whereas inverse relationship between leaf area and hair density possibly showed a strategy of the birch to balance water loss. In common garden, the birch populations with larger leaf area had larger specific leaf area and higher adaxial hair density but low stomatal density. All these features in paper birch populations provide a structural basis for reducing water loss through leaves and increasing water use efficiency. There was no consistency in leaf characteristics when the paper birch populations were grown in uniform environments as in the greenhouse and the common garden. Analysis of the leaf characteristics in the birch showed significant differences due to the interaction and/or main effects of [CO2], water levels and populations. Paper birch had decreased leaf area and increased stomatal density under elevated [CO2] which might have reduced stomatal conductance and increased water-use efficiency. Under low soil water level, paper birch populations studied had smaller stomatal area, pore area and guard cell width. Contrasting with the expectation neither stomatal area was larger nor stomatal density increased under low water level. A trade-off between stomatal area and density in this study showed that stomatal area per unit leaf area remained the same. Hence, smaller stomatal area and guard cell width under low water level must have improved [CO2 ] diffusion and decreased water loss compared to larger stomatal area and guard cell width. The results of this study confirmed significant genotypic difference in leaf characteristics of paper birch populations irrespective of a uniform growing environment. The characteristics, namely leaf area, maximum width, SLA, stomatal density and stomatal area, appear related to the environment of origin; however, these relationships were not consistent in the birch populations grown in the greenhouse and common garden. Paper birch populations acclimated to the uniform environments; differences in leaf area, stomatal density and stomatal area in paper birch populations under different [CO2] and soil water levels prove the birch’s ability to acclimate to environmental changes. Lastly, integration of leaf morphology and anatomy enhanced paper birch’s ability to balance between [CO2] gain and water loss

Fundamental Analysis of Triple Layer Area Decoupled Photovoltaic Modules

Masteroppgave fornybar energi- Universitetet i Agder, 2015The main objective of this work is to analyse the area decoupled triple layer photovoltaic module, by application of voltage matching under AM 1.5 light spectrum. This includes, calculation of detailed balance efficiency, calculation of optimal numbers of cells in each layer to achieve voltage matching comparisons with independently operated triple layer stack. Performance change under various different scenario is also observed. We have used MatLab programing software for all our analysis i.e., plots and calculations. At first we investigated the optimal efficiency of independently operated cells of triple layer stack. Then applying area decoupling technique in a triple layer voltage matched module, we analysed the performance of such module under AM 1.5 spectrum. Upon comparisons the voltage matched module performed similarly to the independent stacks with only slight optimal efficiency difference, which occurred due to calculation round-off. If perfect area decoupling is achieved then it should be exact. Different sets of available semiconductor materials which are non-toxic are tried out in the analysis to find the best possible combination which gives optimal result. Lastly the performance of such optimized voltage matched area decoupled photovoltaic modules under other different spectra is studied. Which showed our area decoupled voltage matched module performed similarly to the independently operated stacks of cells under other different spectra too with no or only slight variation in efficiency. The methods adapted to get the results are described in this report. The results show that the voltage matched tandem module, which is area decoupled gives detailed balance efficiency of 51.2 under numbers of cells in each stack at 32, 60 and 118, for top, middle and bottom layer respectively, with 60 silicon cells layer at middle layer. This tandem module performs similarly as the independently operated stacks under same condition. But change in spectrum affects its optimal performance due to spectral mismatch. If the area de-coupled module is optimized for the AM1.5 spectrum, it will be a little less efficient than an independently operated stack when the spectrum changes