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Lesley A. Judd, Brian E. Jackson, and William C. Fonteno

top of the rhizometer to allow for complete substrate saturation. ( D ) Water inside the rhizometers is allowed to drain and captured to measure air space. Fig. 2. ( A ) Design of rhizometer illustrating the clear-sided Plexiglas ® allowing for root

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Pei-Wen Kan, Yu-Ching Cheng, and Der-Ming Yeh

is currently available. Four mechanisms of foliar variegation have been identified by Hara (1957) , namely, chlorophyll type, pigment type, air space type, and epidermis type. Most foliar variegation can be characterized into two basic categories

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Eugene K. Blythe and Donald J. Merhaut

The physical properties of container-growing substrates, particularly air space, container capacity, and bulk density, have a significant impact on plant growth, and knowledge of these properties is essential in properly managing nursery

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Magdalena Zazirska Gabriel, James E. Altland, and James S. Owen Jr

porosity (TP), air space (AS), and container capacity (CC). The most common substrate components use in the Oregon nursery industry is douglas fir [ Pseudotsuga menziesii Mirb. (Franco)] bark (DFB), sphagnum peatmoss, and pumice. Each of these individual

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James S. Owen Jr and James E. Altland

increasing substrate moisture from the top to the bottom of a container. This substrate moisture gradient results in an inverse relationship between air space (AS) and container capacity (CC) where AS decreases and CC increases from the top to the bottom of a

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James E. Altland, James S. Owen Jr., and Magdalena Z. Gabriel

, AS decreased, CC and TP increased, and D b changed very little over time. The presence of a plant in the core tended to exacerbate the decrease in AS and the increase in CC. Shrinkage was affected by the presence of a plant, but only minimally. Air

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John M. Ruter and Hendrik van de Werken

The effect of container design on physical parameters of media with different bulk densities was evaluated. A significant interaction between container design and media for water-holding capacity and air space was found. A container with a polyester fabric bottom had the largest media air space and the smallest water-holding capacity after 24 h of drainage when placed on a column of sand to allow for free drainage from the container medium. For the media tested, a blend of composted pine bark and hardwood bark (PB:HB) appeared to have good physical characteristics for a container medium in the container designs that were evaluated. Container design should be considered when selecting a container medium because physical parameters of a given medium will be influenced.

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Shohei Yamaki and Migifumi Ino

A study was conducted to determine the distribution of sugars in vacuoles, cytoplasm, and free space in apples (Malus domestica Bork) picked at the immature and mature stage of maturity. The volumes of free space and air space were 13.4% and 14.5%, respectively, in immature fruit, and 14.6% and 25.6%, respectively, in mature fruit. The inner cellular volume (vacuole + cytoplasm) was 72% and 60% for immature and mature fruit, respectively. About 90% of each sugar (glucose, fructose, sucrose, and sorbitol) was found in the vacuole. The concentration of total sugar in the inner cell or free space was 326 or 128 mm each in immature fruit and 937 or 406 mm each in mature fruit. Permeability to sugars across the plasma membrane and tonoplast also increased with fruit maturation, 7- to 30-fold for the tonoplast and 4- to 5-fold for the plasma membrane in mature compared to immature fruit. Cells in immature fruit apparently enlarge through higher turgor pressure from sequestering of sugars into vacuoles, and cease to enlarge in mature fruit as the amount of sugar unloading into the fruit is reduced due to the accumulation of sugar in the free space or cytoplasm.

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F. Roger Harker, Christopher B. Watkins, Paul L. Brookfield, Mellisa J. Miller, Suzanne Reid, Phillippa J. Jackson, Roderick L. Bieleski, and Tim Bartley

Preharvest development and postharvest disappearance of watercore in `Fuji' apples (Malus ×domestica Borkh.) from a northern (Hawke's Bay, latitude 39° south) and southern (Otago, latitude 45° south) region of New Zealand were compared. A new method for quantifying watercore was developed. A photocopy was taken of the symptoms after each fruit was cut in half through the equator, and then the area of affected flesh (photocopies black) was measured using morphometric methods and compared to the area of unaffected flesh (photocopies white). Watercore was more severe and developed earlier in the season in Otago than in Hawke's Bay. In Otago, a block-type watercore predominated, disorder symptoms initially appearing in the tissues located at the junction of two carpels, while in Hawke's Bay a radial-type of watercore predominated, initially appearing in the tissues surrounding the coreline vascular bundles. Regression analysis identified that orchard and harvest date accounted for most of the differences in watercore symptoms and that the initial appearance of low levels of watercore was the best predictor that fruit would start to develop commercially significant levels of watercore. Incorporation of background color, internal ethylene concentration, starch pattern index, and firmness only slightly improved the regression coefficient. Watercore disappeared from the flesh during storage of fruit from both regions. Fruit from early harvests had the least severe symptoms, and the highest rates of watercore disappearance during storage. In fruit with more severe symptoms at harvest, its disappearance during storage was associated with an increase in fruit volume and air space, which occurred despite continuing mass loss. We suggest that during storage, the extracellular fluid associated with watercore symptoms is absorbed into the cells, and thus drives the increase in fruit volume.

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James E. Altland, James S. Owen Jr., Brian E. Jackson, and Jeb S. Fields

.0.1, SAS Institute; Cary, NC) or SAS (SAS Institute), respectively, and means separated where appropriate using Tukey’s honestly significant difference (α = 0.05). Results and Discussion Expt. 1. Air space, CC, and TP were affected by pine bark age ( Table