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  • Author or Editor: H. Harris x
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Root and shoot phenology were observed, and root length within rootballs were calculated for Fraxinus pennsylvanica Marsh. (green ash), Quecus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees established in a rhizotron. Easy-to-transplant species (green ash and tree lilac) had more root length within rootballs than difficult-to-transplant species (Turkish hazelnut and scarlet oak). Shoot growth began before root growth on all species except scarlet oak, which began root and shoot growth simultaneously. Fall root growth ceased for all species just after leaf drop. Implications for tree transplanting are discussed.

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Four each of landscape-sized Fraxinus Pennsylvania Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut) and Syringa reticulata Hara `Ivory Silk' (tree lilac) were established on a rhizotron in Ithaca, New York, and root and shoot growth characteristics were observed throughout 1992. Root growth did not begin on any species before bud break. Green ash, scarlet oak and Turkish hazelnut exhibited recurrent shoot growth. Most root growth occurred during periods of bud rest, although no marked antagonism between shoot and root growth was evident. Green ash root growth was synchronous with shoot growth. The root harvest zone of green ash and tree lilac contained higher root length densities, and roots contained within appeared less suberized than that of Turkish hazelnut or scarlet oak. Root spread: crown spread ratio was greatest for Turkish hazelnut. Little root growth occurred on any species after fall leaf drop or when soil temperatures were below 5C. Implications for transplanting are discussed.

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Abstract

Bighart, an improved Pimiento pepper (Capsicum annuum L.) variety (Fig. 1), was developed at the Agricultural Experiment Station, Auburn University, Auburn, Alabama, and released to the Associated Pimiento Canners in February 1969. Bighart averaged 74% more yield than the commercial Truhart variety in 2 years’ trials at the North Alabama Horticulture Substation, Cullman, Alabama. Bighart fruits were 37% heavier, had 13% thicker walls and gave a 10% higher recovery of canned product than those of Truhart. In addition, the concentrated fruit set and fruit maturity of Bighart promises suitability for machine harvest.

Open Access

Abstract

Thermal blast peeling yielded products of comparable quality to freeze–heat-peeled tomatoes (Lycopersicon esculentum Mill.). Both methods resulted in higher peeled yields and firmer fruit than did caustic, steam-peeling, or peeling by scalding. Thermal blast peeling may thus be a practical alternative to traditional methods.

Open Access

Vegetable variety trials are of interest to the entire vegetable industry from breeders, seed companies, growers, consultants, researchers, to Extension personnel. The Auburn Univ. vegetable variety trial results have been made more accessible and user-friendly by becoming available online at http://www.ag.auburn.edu/dept/hf/faculty/esimonne. Users can point and click through a completely searchable database by selecting one of the following categories: 1) explanation of rating system and database, 2) list of vegetable crops, 3) description of variety types of crops, 4) contacting seed companies and web sites, 5) vegetable variety trial team members. For additional information about vegetable variety production, a link to horticulture extension publications has been included. The database gives each vegetable crop tested by Auburn Univ. a rating and allows a search for varieties. For each crop, the five options available to search the database are “rating,” “variety name,” “variety type,” “seed company,” and “type.” The Web page is primarily intended to be a quick, practical reference guide to growers and horticulture professionals in Alabama. Variety performances presented are based on small-scale research plots and test results may vary by location. It is always recommended to perform an on-farm trial of several varieties before making a large planting of a single variety.

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Three experiments were conducted to determine the feasibility of using Biobarrier, a landscape fabric with trifluralin herbicide-impregnated nodules, of various sizes to prevent root escape of trees from the drainage holes of 56-liter containers in below-ground pot-in-pot (P&P) and above-ground Keeper Upper (KU) nursery production systems. In addition, side holes or slits were cut in some container walls to test the effect of Biobarrier on the prevention of circling roots. In Expt. 1 (P&P), Betula nigra L. `Heritage' (river birch) trees with no Biobarrier had root ratings for roots escaped through drainage holes that indicated a 5-fold increase in numbers of roots than for treatments containing Biobarrier. All Biobarrier treatments reduced root escape and resulted in commercially acceptable control. In Expt. 2 (KU), control and the Biobarrier treatment river birch trees (30 nodules) had commercially unacceptable root escape. In Expt. 3 (P&P), control and 10-nodule treatment Prunus × yedoensis Matsum. (Yoshino cherry) trees had commercially unacceptable root escape, but treatments containing 20 and 40 nodules resulted in commercially acceptable control. Biobarrier did not limit shoot growth in any of the experiments. The results of these experiments indicate that Biobarrier did not prevent circling roots, but sheets containing at least 8 or 20 nodules of trifluralin acceptably prevented root escape from drainage holes in the pot-in-pot production of 56-liter container river birch trees and Yoshino cherry trees, respectively.

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Root and shoot growth periodicity were determined for Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh.,Corylus colurna L. (Turkish hazehut) and Syriaga reticulara (Blume) Hara `Ivory Silk' (tree lilac) trees. Two methods for determining root growth periodicity using a rhizotron were evaluated. One method measured the extension rate of individual roots, and the second method measured change in root length density. A third method, using periodic counts of new roots present on minirhizotrons, was also evaluated. The root extension method showed the least variability among individual trees. Shoot growth began before or simultaneously with the beginning of root growth for all species with all root growth measurement methods. Species with similar shoot phenologies had similar root phenologies when root growth was measured by the root extension method, but not when root growth was measured by the other methods. All species had concurrent shoot and root growth, and no distinct alternating growth patterns were evident when root growth was measured with the root extension method. Alternating root and shoot growth was evident, however, when root growth was measured by the other methods.

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Root system regeneration after transplanting of large trees is key to successful establishment, yet the influences of different production systems and transplant timing on root growth remain poorly understood. Patterns of new root production and mortality were therefore measured for 1 year after transplanting landscape-sized Acer saccharum Marsh. (sugar maple). Trees were transplanted into root observation chambers (rhizotrons) from two production systems, balled-and-burlapped (B&B) and pot-in-pot (PIP), in November, December, March, April, and July and compared with non-transplanted trees. Although root production stopped in midwinter in all transplants and non-transplanted field-grown trees, slight wintertime root production was observed in non-transplanted PIP trees. Root mortality occurred year-round in all treatments with highest mortality in winter in the transplanted trees and spring and summer in the non-transplanted trees. Non-transplanted PIP trees had significantly greater standing root length, annual production, and mortality than non-transplanted field and transplanted PIP trees. For B&B trees, greatest standing length, production, and mortality occurred in the April transplant treatment. Production and mortality were roughly equal for non-transplanted trees, but production dominated early dynamics of transplanted trees. Overall, increases in root length occurred in all treatments, but the magnitude and timing of root activity were influenced by both production system and timing of transplant.

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Thirty-one partial bermudagrass (Cynodon spp.) disease-resistance gene analogs (BRGA) were cloned and sequenced from diploid, triploid, tetraploid, and hexaploid bermudagrass using degenerate primers to target the nucleotide binding site (NBS) of the NBS–leucine-rich repeat (LRR) resistance gene family. Alignment of deduced amino acid sequences revealed that the conserved motifs of the NBS are present and all sequences have non-Drosophila melanogaster Toll and mammalian interleukin-1 receptor (TIR) motifs. Using a neighbor-joining algorithm, a dendrogram was created and nine groups of deduced amino acid sequences from bermudagrass could be identified from those sequences that span the NBS. Four BRGA markers and 15 bermudagrass expressed sequence tags (ESTs) with similarity to resistance genes or resistance gene analogs were placed on a bermudagrass genetic map. Multiple BRGA and EST markers mapped on T89 linkage groups 1a and 5a and clusters were seen on T89 19 and two linkage groups previously unidentified. In addition, three primers made from BRGA groups and ESTs with similarity to NBS-LRR resistance genes amplify NBS-LRR analogs in zoysiagrass (Zoysia japonica or Z. matrella) or seashore paspalum (Paspalum vaginatum). This gives evidence of conservation of NBS-LRR analogs among the subfamilies Chloridoideae and Panicoideae. Once disease resistance genes are identified, these BRGA and EST markers may be useful in marker-assisted selection for the improvement of disease resistance in bermudagrass.

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The objectives of this study were to determine root and shoot growth periodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees and to evaluate three methods of root growth periodicity measurement. Two methods were evaluated using a rhizotron. One method measured the extension rate (RE) ofindividual roots, and the second method measured change in root length (RL) against an observation grid. A third method, using periodic counts of new roots present on minirhizotrons (MR), was also evaluated. RE showed the least variability among individual trees. Shoot growth began before or simultaneously with the beginning of root growth for all species with all root growth measurement methods. All species had concurrent shoot and root growth, and no distinct alternating growth patterns were evident when root growth was measured by RE. Alternating root and shoot growth was evident, however, when root growth was measured by RL and MR. RE measured extension rate of larger diameter lateral roots, RL measured increase in root length of all diameter lateral roots and MR measured new root count of all sizes of lateral and vertical roots. Root growth periodicity patterns differed with the measurement method and the types of roots measured.

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