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Roger Kjelgren, Lixue Wang, and Daryl Joyce

moved indoors for measurement. Leaf water potential was measured in a custom Scholander-type pressure chamber ( Ritchie and Hinckley, 1975 ) constructed at the University of Queensland and fitted with a digital readout. Osmotic adjustment in terms of

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Amos Naor, Isaac Klein, and Israel Doron

The sensitivity of leaf (ψleaf) and stem (ψstem) water potential and stomatal conductance (gs) to soil moisture availability in apple (Malus domestics Borkh.) trees and their correlation with yield components were studied in a field experiment. Two drip irrigation treatments, 440 mm (H) and 210 mm (L), were applied to a `Golden Delicious' apple orchard during cell enlargement stage (55-173 days after full bloom). Data collected included ψstem, y leaf, gs, and soil water potential at 25 (ψsoil-25) and 50 cm (ψsoil-50). No differences in midday ψleaf's were found between irrigation treatments. Stem water potential was higher in the H treatment than in the L treatment in diurnal measurements, and at midday throughout the season. Stomatal conductance of the H treatment was higher than the L treatment throughout the day. Stomatal conductance between 0930 and 1530 hr were highly correlated with ψstem. The H treatment increased the percentage of fruit >65 mm, and increased the proportion of earlier harvested fruit reaching marketable size compared to the L treatment. Fruit size in the first harvest and the total yield were highly correlated with ψstem. The degree of correlation between plant water stress indicators and yield component decreased in the following order: ψstemsoil-25,soil-50leaf. The data suggest that midday ψstem may serve as a preferable plant water stress indicator with respect to fruit size.

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Xiaoya Cai, Terri Starman, Genhua Niu, Charles Hall, and Leonardo Lombardini

transpiration rate and leaf area ( Lazaridou and Koutroubas, 2004 ). In our study, high leaf WUE under drought stress was observed in all four cultivars ( Fig. 3 ). Leaf water potential. During the dry down, midday ψ at SMC between 20% and 35% was similar among

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Nauja Lisa Jensen, Christian R. Jensen, Fulai Liu, and Karen K. Petersen

μL·L −1 . Plant–water relations. Midday leaf water potential and crown water potential were measured 0, 2, 4, 5, 6, 7, 9, 11, 13, and 15 d after start of treatments. Measurements of ψ leaf were carried out using a pressure chamber (Soil

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Michael J. Costello

that nodding needlegrass exhibited a low summer cuticular transpiration rate, suggesting a drought tolerance mechanism. This study evaluated summer soil moisture and vine leaf water potential patterns with nodding needlegrass as a cover crop compared

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Dario Mantovani, Adolfo Rosati, and Domenico Perrone

both the gravimetric soil water content (θ) of each pot and the predawn leaf water potential (Ψ L ) on days 0, 2, 4, 5, and 6 of the drought cycle. At the beginning of the experiment, the plants were overwatered, drained overnight, and pot weight was

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Kuo-Tan Li, Jacqueline K. Burns, and James P. Syvertsen

middle section of the canopy. Leaf and fruit retention was measured in all ‘Hamlin’ orange field trials. Leaf water content, leaf dry weight, midday leaf water potential, and leaf chlorophyll fluorescence and chlorophyll content were measured as described

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Genhua Niu, Denise S. Rodriguez, and Wayne Mackay

decreased ( Björkman et al., 1980 ). However, no relationship was found between leaf water potential and leaf stomatal conductance ( g S ) for oleander ( Gollan et al., 1985 ). Two representative commercial cultivars, Hardy Pink and Hardy Red, and two

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Mindy L. Bumgarner, K. Francis Salifu, Michael V. Mickelbart, and Douglass F. Jacobs

Technologies, Inc., Plainfield, IL) and the Accumet 950 pH/ion Meter (Fisher Scientific, Pittsburgh, PA), respectively. Seedlings were sampled on a different five dates (21 June, 7 July, 29 July, 14 Aug., and 10 Sept. 2007) for predawn leaf water potential

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Xiaoya Cai, Terri Starman, Genhua Niu, and Charles Hall

constant SMCs (9%, 15%, 22%, and 32%), Nemali and van Iersel (2008) found that gas exchange, chlorophyll fluorescence, and leaf water potential were similar between 32% and 22% SMC for impatiens ( Impatiens wallerana Hook.) and salvia ( Salvia splendens