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A. Matar, W.L. Berry, C.L. Mackowiak, G.W. Stutte, R.M. Wheeler, and J.C. Sager

Tissue nutrient (element) content profiles were determined for wheat and potato plants grown hydroponically (NFT) in NASA's Biomass Production Chamber (20 m2) using a complete nutrient solution with electrical conductivity maintained at 0.12 S·m–1. Profiles were compared to patterns of nutrient accumulation during vegetative stages reported for highly productive wheat and potatoes grown in the field under a wide range of conditions. Among the essential elements, differences between the hydroponically and field-grown crops were observed only for Ca, Mg, and Mn in the recently mature leaves, and these differences were related to changes in growth phase and/or consistency of nutrient supply during plant growth. Nutrient profiles for both hydroponically and field-grown crops were also compared to deficiency and toxicity critical levels compiled by various workers. As expected for high-yielding crops, the profiles for both crops were well within the sufficiency ranges for all evaluated nutrients.

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Nicole Burkhard, Derek Lynch, David Percival, and Mehdi Sharifi

A 2-year study in Nova Scotia examined the effectiveness of thickly applied organic mulches as a method of weed control in highbush blueberries (Vaccinium corymbosum L.), and assessed weed and mulch impact on crop growth, leaf nutrient concentration, yield, and quality under organic production management. Mulches, applied in-row at 20-cm depth, included pine needles (PN), manure–sawdust compost (MC), and seafood waste compost (SC). Competition from weeds negatively affected crop growth and productivity, reducing canopy volume (16% to 38%), leaf nitrogen concentration and berry yields (up to 92%), number (up to 91%), and specific weight (up to 21%). Among mulches, PN proved to be the most effective in suppressing weed growth with 55% less and 73% less aboveground weed biomass compared with the control in 2005 and 2006, respectively, although PN productivity effects were much more modest. One year after application, PN lost some efficacy at suppressing weeds but was still superior to both composts. Distribution of weed species was substantially altered by mulch treatment. Both composts prevented some weed emergence (i.e., sheep sorrel), but weed seeds germinating in composts, especially SC, experienced prolific growth likely as a result of available nutrients in composts. No detrimental effects on short-term plant productivity were noted despite high C:N ratios of PN and MC (72:1 and 48:1, respectively). Plant vigor and yield were typically higher for compost mulch treatments, especially in weed-free subplots, and composts provided more complete fertilization reflected in increased leaf tissue elemental (NPK) composition. Fruit soluble solid (sugar) content was found to be significantly lower in PN and MC compared with SC, whereas total phenolic content was unaffected by mulches. Mulch application can improve organic highbush blueberry productivity by improving soil properties, nutrient availability, and weed suppression; however, precautions should be taken to avoid excess nutrient loading and weed seed contamination of mulches.

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James P. Mattheis

Ripening and development of physiological disorders and decay were assessed in ‘d’Anjou’ pear fruit after 1-methylcyclopropene (1-MCP) treatment and cold storage in air or controlled atmosphere (CA). Fruit were exposed after harvest to 0 or 12.6 μmol·L−1 1-MCP and then stored at 0.5 °C in air or 1, 3, or 5 kPa O2 with 0.5 kPa CO2. Pears were held poststorage at 20 °C for 7 days before analysis. 1-MCP fruit usually had higher hue compared with controls. Softening after removal from storage was delayed in 1-MCP fruit regardless of storage atmosphere; however, control fruit stored in air or CA ripened to below 23 N, a minimum value for consumer acceptance, after all storage durations. 1-MCP fruit stored in air, 3, or 5 kPa O2 softened in the outer cortex (fruit surface to 8 mm into the cortex) to below 23 N only after 9 m, however, only fruit stored in air softened to less than 23 N in the inner cortex (8 mm to coreline). 1-MCP treatment also delayed deformation in cortex tissue tensile strength (TTS); after six or more months, 1-MCP fruit TTS was lower compared with those for control fruit. After 9 m, 1-MCP fruit stored in air had TTS values similar to those of controls whereas values for fruit stored in CA increased with CA O2 concentration. Titratable acidity was higher in 1-MCP-treated fruit stored in air (6 m only) or 3 or 5 kPa O2 compared with controls. Superficial scald developed after 6 m on control fruit stored in air or 5 kPa O2 and on control CA fruit regardless of O2 concentration after 9 m. No 1-MCP fruit developed scald. The results indicate ‘d’Anjou’ pear ripening in response to 1-MCP is influenced by storage pO2 as well as storage duration, and at the 1-MCP treatment concentration used, softening to a consumer standard for firmness occurred only in fruit cold stored in air for 9 months plus a 7-day poststorage ripening period. These fruit had peel hue less than 100, and the yellow peel color may not be consistent with current market expectations.

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Thomas E. Marler and Mark A. Lander

101 WORKSHOP 13 (Abstr. 669–674) Long-term Recovery Dynamics of Perennial Species Following Tropical Cyclone Damage

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Alan L. Wright, Tony L. Provin, Frank M. Hons, David A. Zuberer, and Richard H. White

nutrient dynamics. Problems commonly associated with land compost application include nutrient accumulation in soil, leaching, and runoff. The long-term cycling of nutrients in compost-amended soils is dependent on compost quantity and quality in addition

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M. Lenny Wells

may result in overapplication of fertilizer. In addition, proper timing of N applications based on soil N dynamics and plant demand can play a large role in the efficient use of fertilizer N. The in situ soil core technique can be helpful in evaluating

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Rhuanito Soranz Ferrarezi, Marc W. van Iersel, and Roberto Testezlaf

dynamics and plant growth in a sensor-controlled subirrigation system. Our objectives were: 1) to automate a subirrigation system using capacitance-type soil moisture sensors to monitor and control substrate θ; 2) to evaluate short-term substrate θ dynamics

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Quanen Guo, Tianwen Guo, Zhongming Ma, Zongxian Che, Lili Nan, Yiquan Wang, Jairo A. Palta, and Youcai Xiong

secondary substances accumulated. Fruit trees are perennials and there is no disturbance in the growing soil. The distribution characteristics of their root system are different from that of cereals crops. In studying the temporal and spatial dynamics of

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Lisa E. Richardson-Calfee, J. Roger Harris, Robert H. Jones, and Jody K. Fanelli

. The rapid regeneration of a new root system is essential for the survival of a newly transplanted tree. Thus, basic information concerning the dynamics of how root systems develop after transplanting will improve our understanding of how trees

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Carolyn F. Scagel, Richard P. Regan, and Guihong Bi

accounted for the variation associated with urea treatment. Results and discussion Nitrogen rate effects on 2005 carbon and nitrogen dynamics. Total biomass and N uptake between Mar. 2005 and Nov. 2005 increased, while N use efficiency decreased with