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D.C. Ferree and J.G. Streeter

Container-grown `Chambourcin' grapevines were exposed to soil compaction created by changing soil bulk density to determine the effect of levels of compaction, rootstocks and moisture stress on mineral nutrition, leaf gas exchange and foliar carbohydrate levels. Shoot growth, leaf area, number of inflorescences and leaf dry weight decreased linearly as soil bulk density increased with the effects being significant above 1.4 g·cm-3. The early season leaf area was reduced 40% in the second season, but later leaves were unaffected by a soil bulk density of 1.5 g·cm-3. Net photosynthesis (Pn) and transpiration (E) increased linearly with increasing soil bulk density the first year, but the second year a nonlinear pattern was observed with highest rates at 1.3 and 1.4 g·cm-3. Soil bulk density of 1.5 g·cm-3 reduced number of leaves, leaf area and shoot length and advanced bloom 16 days on `Chambourcin' vines on six rootstocks with no interaction of rootstock and soil compaction. Withholding water for 8 days reduced Pn and E in all treatments, with no effect on shoot length, leaf, stem and total dry weights. Moisture stress in the noncompacted soil caused a reduction in leaf concentration of fructose, glucose and myo-inositol, but moisture stress had no effect in the compacted soil. Moisture stress caused a reduction in sucrose in both compacted and noncompacted soil. Compacting soil to a bulk density of 1.5 g·cm-3 was associated with an increase in leaf N, Ca, Mg, Al, Fe, Mn, Na, and Zn and a decrease in P, K, B, and Mo.

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Lucas O’Meara, Matthew R. Chappell, and Marc W. van Iersel

by progressively closing their stomates to reduce transpiration and prevent dehydration ( Sperry et al., 2002 ; Tezara et al., 1999 ), although the severity of the drought response is species-specific ( Niu et al., 2006 ). Some of the more drought

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Eric W. Kerschen, Caleb Garten, Kimberly A. Williams, and Melanie M. Derby

occupants and the desire to reduce building energy consumption, passive or low-energy humidification approaches are of increasing interest. Plants can influence the humidity of an interior environment through transpiration (water movement through a plant and

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William L. Bauerle, Dennis J. Timlin, Yakov A. Pachepsky, and Shruthi Anantharamu

Application of process-based models beyond the research community has been limited, in part because they do not operate in a user-friendly Windows environment. We describe the procedure of adapting a spatially explicit biological-process model, MAESTRA, to run in a standard graphical user interface (GUI). The methods used to adapt the MAESTRA model are generally applicable to other process-based models and therefore simplify other coupling attempts. We discuss recommendations based on our experiences for model input structure and interface design, two components that will allow various models to work with a generic interface. MAESTRA uses modified versions of the Ball-Berry stomatal conductance (gs) and Farquhar photosynthesis(Anet) models to estimate transpiration and photosynthesis on a leaf area basis and scale the sunlit and shaded fractions to the whole tree. We present MAESTRA estimates within a standardized graphical user interface for crop simulators (GUICS) windows environment and furthermore, we provide dialog boxes and graphical displays of the MAESTRA model input and whole tree output for red maple trees. In so doing, we present a technology transfer via the GUICS that prevents any watering down of the science behind the MAESTRA model, yet allows an accurate decision support tool to reach a wide audience.

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Nihal C. Rajapakse, David Wm. Reed, and John W. Kelly

Experiments were conducted to evaluate Dendranthema × grandiflorum (Ramat.) Kitamura cv. Bright Golden Anne quality and post-storage growth following storage in the range of 5 to 35C, initial soil water levels (60%, 80%, 100%), and durations (0 to 8 days). Transpiration rate showed a quadratic relationship with storage temperature. Initial soil water content had little effect on transpiration rate in dark storage environments. The lowest transpiration rate was observed in plants stored at 15 or 20C. Amino acid (AA) leakage and post-storage growth were well-correlated. Plants stored at or above 25C became etiolated during storage, while storage at 15C or below did not cause etiolation. Temperatures at or below 15C did not affect subsequent growth rate of chrysanthemum plants. Storage at 20C and above caused a reduction in post-storage growth rate following 2 days of storage.

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Michio Kanechi, Masakatsu Ochi, Michiko Abe, Noboru Inagaki, and Susumu Maekawa

The effects of natural ventilation and CO2 enrichment during the rooting stage on the growth and the rates of photosynthesis and transpiration of in vitro cauliflower (Brassica oleracea L.) plantlets were investigated. In vitro plantlets were established in airtight or ventilated vessels with or without CO2 supplied (≈1200 μg·L-1) through gas permeable films attached to the vessel's cap for 15 days before transplanting ex vitro. Leaves generated in vitro in ventilated vessels had a higher photosynthetic rate than those produced in airtight vessels, which lead to greater leaf expansion and shoot and root dry matter accumulation during in vitro culture and acclimatization. Enhanced photosynthesis in leaves of ventilated plantlets was positively correlated with chlorophyll content. Increasing photosynthetically active radiation from 70 to 200 μmol·m-2·s-1 enhanced the growth of in vitro plantlets under ventilated conditions but it depressed photosynthesis of the leaves grown photomixotrophically with sugar and CO2 enrichment which might be due to the feedback inhibition caused by marked accumulations of sucrose and starch. Higher CO2 levels during in vitro culture enhanced photosynthesis under photoautotrophic conditions, but inhibited it under photomixotrophic conditions. Fifteen days after transplanting ex vitro, high photosynthetic ability and stomatal resistance to transpiratory water loss of ventilated plantlets in vitro had important contributions to rooting and acclimatization. Our findings show that the ventilated culture is effective for accelerating photoautotrophic growth of plantlets by increasing photosynthesis, suggesting that, especially for plantlets growing in vitro without sugar, CO2 enrichment may be necessary to enhance photosynthetic ability.

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C.P. Sharma and Sandhya Singh

When grown in refined sand with one-twentieth normal K supply, cauliflower (Brassica oleracea L. var. botrytis L. cv. Pusi) had lower dry matter and tissue concentration of K than the controls and developed visible symptoms characteristic of K deficiency. In K-deficient plants, the specific leaf weight, diffusive resistance, and proline concentration in leaves were significantly higher and relative water content (RWC), leaf water otential (ψ), stomatal aperture, stomatal density, and transpiration rate were significantly lower than in control plants. When K-deficient plants were supplied additional Na to the extent K was deficient, Na concentration in the plants increased and the plants recovered from the K deficiency effect on free proline concentration, RWC, leaf water potential, stomatal aperture, stomatal density, specific leaf weight, diffusive resistance, and transpiration.

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Richard J. Campbell and Richard P. Marini

The interaction of N fertilization and European red mite (ERM) [Panonychus ulmi (Koch)] feeding on the physiology of greenhouse-grown `Imperial Delicious' apple (Malus domestica Borkh.) leaves was evaluated. Visual damage was noticeable with 75 mite days (MD) and was consistently greatest on the low-N leaves. Net photosynthesis (Pn) was decreased by mite feeding in all N treatments. However, with equal MD, the high-N treatment retained higher Pn than the low- or medium-N treatments. Transpiration, dark respiration, leaf N, and total chlorophyll increased with N and were reduced by mite feeding. Mite feeding increased dark transpiration at all N levels. Relative water content was unaffected by N and was reduced by mite feeding. Specific leaf weight increased with N and MD.

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Avinoam Nerd and Park S. Nobel

Water relations and fruit development were studied for up to 100 days after anthesis for potted plants of Opuntia ficus-indica (L.) Mill. (a prickly pear) that were either well-watered or water-stressed, each plant consisting of a medium-sized cladode bearing two or three fruit. Even though cladodes of water-stressed plants lost up to 50% of their thickness, their fruit continued to gain water and to develop; at ripening such fruit had only 16% less water than fruit of watered plants. Maturation indicated by the decrease in fractional peel content and increases in pulp weight and in pulp soluble sugar content was hastened by water stress, leading to ripening ≈88 days after anthesis for water-stressed plants, which was 10 days earlier than for watered plants. Fruit had a lower stomatal frequency than the cladodes but both exhibited Crassulacean acid metabolism behavior. Transpiration occurred mainly at night, and the daily amount of water transpired per unit fruit surface area decreased with time, especially for fruit of water-stressed plants. This decrease was related to fruit expansion (leading to decreased stomatal frequency) for watered plants and to both fruit expansion and water stress for water-stressed plants. At 75 days after anthesis, daily diameter changes of fruit were correlated with transpiration, contraction occurring at night and expansion during the daytime, and changes were greater for watered plants for which daily transpiration was higher.

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Juan Carlos Melgar, Arnold W. Schumann, and James P. Syvertsen

of the treatments using fully expanded single leaves from the middle of the shoot of five replicate plants per treatment. Net assimilation of CO 2 (A CO2 ), stomatal conductance, leaf transpiration (E lf ), and instantaneous water use efficiency (WUE