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Suejin Park, Sarah A. Mills, Youyoun Moon, and Nicole L. Waterland

poor postproduction conditions are estimated to result in 5% to 20% of unsalable crops ( Healy, 2009 ), and water stress is one of the major causes of diminished aesthetic quality and salability of plants. Therefore, it is highly desired to minimize

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Katrina J.M. Hodgson-Kratky, Olivier M. Stoffyn, and David J. Wolyn

not be economical for commercial production. Consequently, breeding to improve germination under water stress could result in increased germination and establishment on bare soils in the field and facilitate the domestication of this species. Studies

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D. Joseph Eakes, Robert D. Wright, and John R. Seiler

Abbreviations: EC, electrical conductivity; MSC, moisture stress conditioning; P L , leaf turgor potential; PV, pressure-volume; RWC, relative leaf water content; SWC, symplastic water content; ψ L , leaf water potential; π 100 , π 0 osmotic

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Carolyn F. Scagel, Guihong Bi, Leslie H. Fuchigami, and Richard P. Regan

, or increased water stress ( Cabrera, 2004 ). Fertilizer application rates commonly used for container-grown crops are based on optimal water availability, a condition that rarely exists in commercial production systems. Fertilizer management effects

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Jinhong Yuan, Man Xu, Wei Duan, Peige Fan, and Shaohua Li

Water is a limited resource worldwide. Water deficits often result in a decrease of P n , which can influence vegetative growth, yield, and fruit quality in fruit trees. The response of photosynthesis to water stress is correlated with stress

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Rajeev Arora, Dharmalingam S. Pitchay, and Bradford C. Bearce

This study evaluated the effect of reversible water stress on heat stress tolerance (HST) in greenhouse-grown geraniums. Water stress was imposed by withholding irrigation until pots reached ≈30% (by weight) of well-watered (control) plant pots, and maintaining this weight for 7 days. Control plants were watered to just below field capacity, every other day. Leaf xylem water potential (LXWP, MPa), leaf-relative water content (LRWC,%), media water content (MWC, % fresh weight), and heat stress tolerance (HST, LT50) were determined for control and stressed plants. HST (LT50), defined as temperature causing half-maximal percent injury, was based on electrolyte leakage from leaf disks subjected to 25 to 60C. Control-watering was restored in stressed plants and above measurements made after 7 days of recovery. Data indicate: 1) LXWP, LRWC, and MWC in control and stressed plants were –0.378 and –0.804 MPa, 92.31% and 78.69% and 82.86% and 15.5%, respectively; 2) HST increased significantly in stressed as compared to control plants (LT50 of 55C vs. 51C); 3) control plants were near maximally injured by 53C treatment and sustained more than 3-fold greater injury than stressed plants at 53C. In recovered plants, LXWP and RWC reversed back to control levels, paralleled by loss of higher HST.

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Preston K. Andrews, David J. Chalmers, and Mapasaka Moremong

Abbreviations: A, alfalfa; CWSI, crop water stress index; CTV, canopy-temperature-variability; D, drainage; ET, evapotranspiration; FI, full irrigation; H, herbicide strip; I, irrigation, IR, infrared P, black plastic mulch; R n , net radiation; SDD

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Kelly T. Morgan, Smita Barkataky, Davie Kadyampakeni, Robert Ebel, and Fritz Roka

. To evaluate the effect of short- and long-term water drought stress on mechanical harvesting, a 3-year field study was conducted to test the hypothesis that no significant injury by mechanical harvesting occurs to healthy, well-watered citrus trees

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Daniel Drost and Darlene Wilcox-Lee

Asparagus is considered a relatively drought tolerant plant, but few studies are available on the gas exchange response to soil moisture stress. Seedlings were grown in the greenhouse for six months before initiation of the water stress treatments. Soils were allowed to dry to matric potentials of -0.05, -0.3 and -0.5 MPa before rewatering to pot capacity. Gas exchange and fern water potentials were measured diurnally on asparagus plants when soil matric potentials reached their minima. Decreasing soil matric potentials decreased net carbon dioxide assimilation, stomatal conductance and fern water potential. Assimilation rates (6 am) were between 3 and 5 umols m-2 s-1 for all soil moisture treatments. Carbon assimilation rates of 10, 8, and 7 umols m-2 s-1 were recorded at 10 am for the -0.05, -0.3 and -0.5 MPa soil matric potentials, respectively. Assimilation rates decreased sharply over the remainder of the day. The diurnal pattern for conductance were similar to the assimilation rates. Fern water potentials were greater in the -0.05 MPa than in the -0.5 MPa treatment for all measurement periods with an intermediate response for soil matric potentials of -0.3 MPa. Fern water potentials were highest at 6 am (-0.2 to -0.6 MPa) before declining to their minima (-1.5 to -1.8 MPa) at 10 am. Water potentials remained at these low levels throughout the day before recovering slightly at 6 pm.

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Daniel Drost and Darlene Wilcox-Lee

Asparagus is considered a relatively drought tolerant plant, but few studies are available on the gas exchange response to soil moisture stress. Seedlings were grown in the greenhouse for six months before initiation of the water stress treatments. Soils were allowed to dry to matric potentials of -0.05, -0.3 and -0.5 MPa before rewatering to pot capacity. Gas exchange and fern water potentials were measured diurnally on asparagus plants when soil matric potentials reached their minima. Decreasing soil matric potentials decreased net carbon dioxide assimilation, stomatal conductance and fern water potential. Assimilation rates (6 am) were between 3 and 5 umols m-2 s-1 for all soil moisture treatments. Carbon assimilation rates of 10, 8, and 7 umols m-2 s-1 were recorded at 10 am for the -0.05, -0.3 and -0.5 MPa soil matric potentials, respectively. Assimilation rates decreased sharply over the remainder of the day. The diurnal pattern for conductance were similar to the assimilation rates. Fern water potentials were greater in the -0.05 MPa than in the -0.5 MPa treatment for all measurement periods with an intermediate response for soil matric potentials of -0.3 MPa. Fern water potentials were highest at 6 am (-0.2 to -0.6 MPa) before declining to their minima (-1.5 to -1.8 MPa) at 10 am. Water potentials remained at these low levels throughout the day before recovering slightly at 6 pm.