|Mateos Remigio, Vilma - IOWA STATE UNIVERSITY|
|Asbjornsen, Heidi - IOWA STATE UNIVERSITY|
Submitted to: International Workshop on Sap Flow
Publication Type: Abstract Only
Publication Acceptance Date: April 25, 2008
Publication Date: October 21, 2008
Citation: Mateos Remigio, V., Asbjornsen, H., Tarara, J.M., Sauer, T.J. 2008. Evaluating transpiration in an annual crop and perennial prairie species using the heat balance method in central Iowa, U.S.A.. International Workshop on Sap Flow. Confernece Booklet. p. Technical Abstract: The incorporation of native perennial plants into landscapes dominated by annual cropping systems in the Midwestern United States may enhance water quality and promote stable provision of water supply by regulating water flows in the soil-plant-atmosphere continuum. Design of mixed annual-perennial agroecosystems should be based on sound understanding of different species’ hydrologic functioning to maximize complementarity in time and space. However, most previous approaches to quantifying plant water use in the agricultural Midwest have measured evapotranspiration on broad landscape scales and have not distinguished between water use patterns of individual plant species or communities. The objectives of this research were to quantify and compare patterns of seasonal water use for a dominant prairie species (Ratibida pinnata (Vent.) Barnh; “coneflower”) and an annual crop species (Zea mays L.; “corn”) in Central Iowa. Additionally, this research determined the relationship between sapflow and environmental variables (e.g., Net Radiation, Rn, and Vapor Pressure Deficit, VPD) for each species and assessed the potential for scaling individual plant transpiration data to the stand level based on allometric relationships with plant structural characteristics (leaf area, stem diameter, biomass), verified against stand-level Bowen ratio estimates of evapotranspiration. Heat balance sensors were used to measure sapflow for R. pinnata and Z. mays on stems ranging in diameter from 5 mm to 19 mm. Sensors were installed on five individuals of each species and rotated to new individuals every week. Sampled plants were harvested at the end of the sampling period for determination of total leaf area and biomass in the laboratory. Measurements were taken over a 27-day period during the peak growing season, from July 17 to August. 12. Minimum and maximum sapflow values were 0.035 kg day-1 and 0.079 kg day-1 for R. pinnata, and 0.273 kg day-1 and 0.552 kg day-1 for Z. mays, respectively. Whole plant sapflow over the sampling period was 1.320 kg for R. pinnata and 10.928 kg for Z. mays.