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Leaf water potential will increase as water is withheld from the plant and plant <br />water stress increases. Water status measurements required removing one fully <br />matured leaf randomly selected from trees in each treatment and measured for water <br />holding capacity using a Plant Water Status Console. The leaf was removed from the <br />plant and immediately placed in a sealed chamber with the petiole extending through a <br />sealing hole in the chamber. A fresh slightly angled cut was made and nitrogen gas was <br />delivered to the leaf under slowly increasing pressure until water exudes from the <br />petiole surface. The pressure necessary for this to occur is an indication of the leaf <br />water potential or water holding capacity of the leaf, an indication of the water stress <br />and thus physiological stress of the plant. Different plants from each treatment were <br />selected at each testing to minimize leaf loss from sampling. From 2-3 total <br />measurements were made from each treatment each day of measurement. Number of <br />measurements depended on the time necessary for each measurement, so that all <br />measurements fall within the dawn-time window. Each day of measurements included <br />the full cycle of irrigation treatments. Size of sampled leaf was recorded as length from <br />tip to petiole (mm), and maximum width (mm). An empirical equation was developed to <br />relate width and length to actual leaf area. <br />Quality assurance/quality control procedures: <br />Measurements were made and recorded periodically throughout the growing <br />season. Field staff that conducted growth and pressure measurements were trained on <br />correct measuring protocols by R. Musselman, using instrumentation and measurement <br />tools provided by the project. Field staff were instructed to contact R. Musselman by <br />phone should questions arise regarding sampling measurements or protocols. Data <br />collected in 2005 were recorded by hand on data sheets and transferred to excel files <br />for analysis. Data were keyed directly into a field data processor in 2006 for transfer to <br />excel files and analysis. Backups of field data sheets and original data files were <br />archived. A field notebook documented events as they occurred throughout the season. <br />11 <br />