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Ricardo Goenaga, Tomas Ayala, and Adolfo Quiles

limited by high soil alkalinity of calcareous soils. Materials and methods This study was conducted at the USDA-ARS, Germplasm Introduction and Research Unit in St. Croix, U.S. Virgin Islands (coarse-loamy, carbonatic, isohyperthermic Typic Calciustolls

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Willard T. Witte, Scott Schlarbaum, Roger Sauve, and Phillip C. Flanagan

Efforts have been underway since 1988 to establish a nursery research station in McMinnville, TN. Approximately 80 acres of farm property has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining funding via the Capacity Building Grants Program to initiate a plant evaluation and introduction program at the new station. Initial trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, and Ulmus. Herbaceous genera are Echinacea, Hemerocallis, and Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Complementary grant proposals have been recently submitted. Design, funding and support of all Tennessee introduction and evaluation programs will be discussed.

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Claude E. Thomas, Amnon Levi, and Ellis Caniglia

Two hundred sixty-six Citrullus lanatus (Thumb.) Matsum. & Nakai accessions (Plant Introductions and named cultivars) were tested against a race 2 Sphaerotheca fuliginea (Schlechtend.: Fr.) Pollacci isolate to evaluate for resistance to powdery mildew disease. Growth room-grown seedlings were artificially inoculated with conidia from watermelon host leaves at 2-day intervals from the appearance of the first true leaf until test results data were taken, when the second true leaf was fully expanded. Plants were evaluated on a 1 to 9 scale of increasing disease severity. Disease indices (DIs) were calculated as weighted averages for each entry. All genotypes with resistant plants (powdery mildew rating 1 to 3) were reevaluated in a replicated test of 3 replications of 10 plants each. Disease indices were again calculated. Twenty-two plant introductions (PIs) and one named variety displayed intermediate resistance to powdery mildew in the replicated test with DIs ranging from 5.0 to 6.0.

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Jia Xiangyun and Zhang Deshun

Tobira Pittosporum (Pittosporum tobira) is an evergreen and broadleaf shrub with fragrant flowers. The introduction began in 1978. The plants blossomed and bore fruits in 1981. The seedlings grew up from seeding in 1982, then the freeze resistances of seedling were experimented with the Spartan Training System according to follow proper sequence and make steading progress rule. Some excellent plants were sifted out progressively. In order to enrich the afforestation materials in Jinan, it offers a new species.

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Michael A. Creller and Dennis J. Werner

Surface morphology of peach [Prunus persica (L.) Batsch] Plant Introduction 133984 (`Marina') differs from standard peach and nectarine clones. Scanning electron microscopic examination of `Marina', a standard peach (`Contender'), and a nectarine (`Sunglo') was conducted. At anthesis, `Marina' ovaries were glabrous, similar to `sunglo' nectarine. Fruit of `Contender' were fully pubescent at anthesis. Examination of `Marina' fruit two weeks after anthesis revealed the presence of both pubescent and glabrous sectors on the fruit surface. At fruit maturity, most of the fruit surface of `Marina' was covered with pubescence, but trichome density was considerably less than `Contender' peach. Trichome morphology of `Marina' differed from that of `Contender'.

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Dale E. Herman and Lawrence J. Chaput

Woody plant improvement research has been an active program at North Dakota State Univ. (NDSU) for many years. Eighteen cultivars have been introduced since 1986, and ≈10 additional releases are anticipated over the next 6 years. These superior, winterhardy cultivars have increased the inventory of adapted woody plants for landscape use in the northern plains, particularly USDA hardiness zones 3 and 4. Emphasis will be placed on recent introductions and promising plants for potential future release. An extensive, statewide cooperative evaluation program is conducted at seven sites throughout North Dakota and also at the NDSU Research Arboretum near Absaraka.

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Robert E. Lyons

An historic feature of the JC Raulston Arboretum (JCRA) is to identify new and unusual ornamental plant materials for landscape use through an active program of observing landscape performance at the JCRA in Raleigh. Introduction of plant materials into commerce occurs primarily through programs conducted in concert with the North Carolina Association of Nurserymen and through a unique policy of “open access” for nurserymen. One program, The JC Raulston Selections Program, returns revenues to the general operations and maintenance functions of the JCRA; others are not revenue generating, and are provided as a service to the industry. To a lesser extent, the general public may participate in receiving new plants via a special program offered through JCRA membership. The JCRA is also an official trial garden site for the All America Selections program and seed companies. Elements of these introduction and evaluation programs will be discussed within the context of the past, present, and plans for the future for program maintenance and possible changes.

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Paul G. Thompson, Boyett Graves, and John C. Schneider

The sweetpotato weevil is the most-destructive worldwide pest of sweetpotato and only low to moderate levels of resistance to the insect are available in acceptable cultivars. No sources of high resistance levels have been identified; consequently, there is a need to identify additional sources of resistance genes to develop high resistance levels. To begin a search for sources of resistance, plant introductions were evaluated for injury levels. In 1993, 100 plant introductions were evaluated for sweetpotato weevil injury and 62 of the least injured were tested again in 1994. In 1995, 36 of the least injured in 1993 and 1994, plus 24 additional PIs were evaluated. Control cultivars included `Regal', moderately resistant; `Jewel', intermediate; and `Beauregard' and `Centennial', susceptible. Measurements of injury were percentage of roots injured, and, stem and root injury scores based on a 0–5 scale, with 0 being no injury. First year results indicated that a low level of resistance to stem injury is available in the PIs tested. Stem injury was more severe in the following year and no differences were found. Lower weevil populations will be required to screen for low levels of stem injury resistance. Percentage injured roots and root injury scores were lower over the 3 years for five PIs than for `Regal'.

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Willard T. Witte, Scott Schlarbaum, Roger Sauve, and Phillip C. Flanagan

Since 1988, efforts have been underway to establish a nursery research station in McMinnville, Warren County, Tennessee. Approximately 80 acres of farm property adjacent to the Collins scenic river has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining grant funds via the Capacity Building Grants Program to initiate a plant evaluation and introduction program. Replicated trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, Ulmus. Herbaceous genera are Echinacea, Hemerocallis, Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Additional grant proposals have been recently submitted.

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Richard M. Hannan, Charles J. Simon, and Raymond L. Clark

The Horticulture Program at the Western Regional Plant Introduction Station is responsible for the maintenance and distribution of germplasm collections of ten crop genera. These ten genera include over 28,000 accessions of 267 species of germplasm with either food or ornamental potential. The largest collection is beans (Phaseolus, > 11,500 accessions) which includes 32 species. Large collections of the cool season food legumes include Cicer, Pisum and Lens. Smaller legume collections include Lupinus, Lathyrus, Trigonella and Vicia. Although there are fewer than 3300 accessions within these four genera, there are 134 species represented. Although smaller in number of accessions, the Allium and Lactuca collections are extensively utilized for food and ornamental development programs. Associated with the curation and seed maintenance of these crops is a seed-borne virus eradication program, the development of core collections, and expansion of the evaluation data and other documentation into the Germplasm Resources Information Network.