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Partitioning Of Evapotranspiration And Its Relation To Carbon Dioxide Exchange In A Chihuahuan Desert Shrubland, Russell L. Scott, Travis E. Huxman, William L. Cable, William E. Emmerich Jan 2006

Partitioning Of Evapotranspiration And Its Relation To Carbon Dioxide Exchange In A Chihuahuan Desert Shrubland, Russell L. Scott, Travis E. Huxman, William L. Cable, William E. Emmerich

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Key to evaluating the consequences of woody plant encroachment on water and carbon cycling in semiarid ecosystems is a mechanistic understanding of how biological and non-biological processes influence water loss to the atmosphere. To better understand how precipitation is partitioned into the components of evapotranspiration (bare-soil evaporation and plant transpiration) and their relationship to plant uptake of carbon dioxide (CO2) as well as ecosystem respiratory efflux, we measured whole plant transpiration, evapotranspiration, and CO2 fluxes over the course of a growing season at a semiarid Chihuahuan Desert shrubland site in south-eastern Arizona. Whole plant transpiration was measured …


Use Of A Crop Water Stress Index For Scheduling The Irrigation Of Sunflower (Helianthus Annuus L.), Tolga Erdem, Yeşi̇m Erdem, A. Hali̇m Orta, Hakan Okursoy Jan 2006

Use Of A Crop Water Stress Index For Scheduling The Irrigation Of Sunflower (Helianthus Annuus L.), Tolga Erdem, Yeşi̇m Erdem, A. Hali̇m Orta, Hakan Okursoy

Turkish Journal of Agriculture and Forestry

This study was designed to evaluate different threshold crop water stress index (CWSI) values to schedule irrigation for sunflower (Helianthus annuus L.) grown under furrow irrigation. Irrigations were started when CWSI values reached 0.2, 0.4, 0.6, 0.8 and 1.0 (non-irrigation). The CWSI values were computed from measurements of canopy temperature, air temperature and atmospheric vapor pressure deficit. Total irrigation water amounts of 679, 584, 470 and 227 mm were applied to the T_{0.2}, T_{0.4}, T_{0.6} and T_{0.8} treatments, respectively. The maximum seasonal evapotranspiration (ET), 809 mm was measured from the T_{0.2} treatment. Irrigation levels significantly affected seed yield. Although the …


Determination Of Crop Water Stress Index For Irrigation Scheduling Of Bean (Phaseolus Vulgaris L.), Yeşi̇m Erdem, Sezen Şehi̇rali̇, Tolga Erdem, Di̇nçer Kenar Jan 2006

Determination Of Crop Water Stress Index For Irrigation Scheduling Of Bean (Phaseolus Vulgaris L.), Yeşi̇m Erdem, Sezen Şehi̇rali̇, Tolga Erdem, Di̇nçer Kenar

Turkish Journal of Agriculture and Forestry

This study was conducted to determine the relationship between the canopy-air temperature differential and the vapor pressure deficit (VPD), which can be used to quantify the crop water stress index (CWSI) under fully irrigated (100%) and maximum water stress (0%) conditions of trickle irrigated bean. The effects of 5 irrigation levels (100%, 75%, 50%, 25%, and 0% replenishment of soil water depleted when 50% of available soil moisture was consumed in the 0.60 m soil profile depth of fully irrigated treatment) on seed yields and resulting CWSIs calculated using the empirical approach were also investigated. The highest yield and water …