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Grants are awarded to research projects that yield practical benefits for growing or enjoying rhododendrons or yield new insights into the biology, geographical distribution or history of species or hybrid rhododendrons. |
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2008 Awards |
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Nonanoic Acid and Trichoderma
Isolates for Management It has been discovered that some microorganisms have antibiotic control of fungal pathogens. The research involves isolation of specific compounds from specific kinds of bacteria and testing their effect on two kinds of fungal disease under controlled greenhouse conditions. The anticipated benefits to rhododendron growers are a potential biofungicide that will be cheaper than currently registered conventional fungicides and which is environmentally friendly. |
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Identification and Classification of Rhododendron Powdery Mildew in the
Pacific Northwest Powdery mildew is a serious disease of susceptible rhododendron cultivars and species causing leaf spotting, defoliation, and reduced growth. This is more of a problem in different regions of the country, but particularly in the Pacific Northwest. The taxonomy of powdery mildew is very complex involving many different species. This project will characterize the morphology of powdery mildew fungi on Rhododendron species using light and scanning electron microscopy and will assess relationships among these fungi using nucleic acid sequences. The objective is to use this classification information to determine the correct names of the North American powdery mildews on Rhododendron species. This research will enable plant pathologists and rhododendron breeders to target more effectively their efforts in controlling powdery mildew. |
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Genome Sizes in Rhododendron ssp. The numbers of chromosomes, also known as ploidy levels, are of interest for plant breeders as polyploidy (extra sets of chromosomes) can influence characteristics of growth vigor or in the case of ornamentals, the ornamental value. The analysis of the DNA content can give more information than just the ploidy level. Although a lot of information is available about the number of chromosomes among certain genotypes of rhododendrons, little information is available about the genome size. Genome size is important from a phylogenetic point of view and also important for plant breeding. |
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Are There Toxins in Rhododendron Nectar? The plant tissues of rhododendrons are know to contain toxins that affect nerve and muscle cells when ingested by animals. There are also accounts of "mad honey" consumed by humans reported back to ancient history. The question arises as to why rhododendrons have toxin in the nectar they offer to pollinators. The research will try to determine how widespread toxins are throughout a large number of different Rhododendron species. This proposal describes nectar as the "currency" between pollinators and plants and it is the nectar that attracts many insects. The objective of this research is to determine whether the presence of rhododendron-specific toxins (grayanotoxins) in nectar correlates with pollinator type predicted on the basis of rhododendron floral traits. |
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2007 Awards |
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Improving Fertilizer and Water
Use Efficiency of Container-Grown Rhododendron The objective of this multi-year study is to characterize the seasonal dynamics of nitrogen uptake and internal cycling in evergreen and deciduous rhododendron cultivars. The effects of liquid and controlled release fertilizer on plant growth and nitrogen uptake will be compared and the influence of nitrogen on water use and photosynthetic performance will be assessed. It is hypothesized that excess nitrogen during nursery production decreases the efficiency of water use and the quality of container grown rhododendrons. This has important environmental as well as economic implications. Avoiding excess fertilizer run-off and increasing fertilizer efficiency is a hopeful expected outcome this research. |
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Rhododendron Decline of the
Southern Appalachian Mountains: Holistic Study of Biotic and Abiotic Factors
Compared Between Healthy and Declining Stands Dieback or decline of Rhododendron maximum has been reported in an increasing number of areas in the southern Appalachians and the Great Smokey Mountains National Park. Because of the uncertainty of causal factors, a holistic approach will be taken in an effort to identify abiotic or biotic factors that might cause wild Rhododendron maximums to decline at more than 10 sites. Specifically, the holistic approach proposed will compare site factors responsible for increased plant stress, occurrence and importance of fungal pathogens, and changes or loss of mycorrhizal associates compared between healthy and declining stands of rhododendrons. In addition to helping manage rhododendron decline, the data collected may also help aid in the increased understanding of forest decline and the factors involved. |
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Breeding Polyploid
Rhododendrons and Azaleas Polyploids are organisms that have more than two complete sets of chromosomes. Polyploidy will be induced chemically in rhododendrons resulting in triploid and tetraploid sets of chromosomes. The objective is to determine ploidy level and genome size of a diverse range of species, hybrids and cultivars of rhododendrons using a combination of flow cytometry and light microscopy. |
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2006 Awards |
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Mechanisms for Winter Photoprotection in Rhododendron
subsection pontica: a physio-genetic analysis Temperature-leaf leaf movement, termed thermonasty, possibly functions in evergreen Rhododendron species by reducing oxidative stress in leaves caused by winter sunlight. Thermonasty varies among Rhododendron species and appears to be positively correlated with cold hardiness. This proposal explores that relationship and asks whether thermonasty is a necessary condition for winter hardiness. The hybridization of R. catawbiense (exhibits thermonasty) and R. ponticum (does not exhibit thermonsaty but has phototolerance to winter sun) in the Waterer hybrids created the "ironclad rhododendrons" resulting in greatsuccess in growing under a wide range of conditions. This research proposes to test the hypothesis that more than just thermonasty, possibly a biochemical response, is responsible for cold hardiness and that there may be an additive effect by relying on different mechanisms for photoprotection from winter sun. |
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Understanding the Mechanism of
Cold Hardening in
Rhododendrons: The overall objective of this project is to study the roll of a specific Rhododendron catawbiense gene, RcDhn5, in protecting plants from freeze injury. This gene encodes a "cold stress-responsive" protein called dehydrin. The goal is to obtain enough purified 25 kDa dehydrin protein, the product of the RcDhn5 gene, to conduct biochemical assays for its stress-protective properties. Bioassay tests will be performed by adding the protein to a known cold sensitive enzyme, such as LDH and/or MDH, to see if this protein has a freeze-protection and/or dehydration-stress protection properties. The significance of the research would be in the identification of genes responsible for conferring freezing tolerance and possibly in the future use genetic engineering to develop new selections of plants with ornamentally superior traits. |
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Mapping the Dstribution of Rhododendron arboreum ssp. nilagiricum
(Zenker) Taag, Rhododendron is an important genus occurring in the high altitudes of the Himalayan region, having ecological significance and economic importance in addition to its graceful flowers. India records 72 Rhododendron species, 20 subspecies and 19 varieties. Precise information on a species including distribution and ecology is important in developing management and conservation strategies. The project objectives are to prepare distribution maps of the Western Ghats region for Rhododendron arboreum ssp. nilagiricum, identify ecological limiting factors for distribution, analyze management practices in locations not under conservation, assess the threat status for this species, and identify possible areas for reintroduction or range extension. The significance of the research will be to prepare a conservation action plan for the management of the habitat and Rhododendron arboreum ssp. nilagiricum species for sustainable biodiversity conservation. |
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2005 Awards |
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Rhododendron Database Project –
Hybrid Phase The goal of this project is to develop a not-for-profit electronic Internet and computer-searchable Rhododendron Database containing multiple characteristics of rhododendron species and hybrids. The database resource will be accessible to rhododendron experts, hybridizers, nursery professionals, American Rhododendron Society members and the general public. The database will be utilized to identify, contrast, and compare the characteristics of various rhododendrons. Each plant record will have 40-50 different identification features and plant characteristics. The database will provide a comprehensive analytical tool for those studying and developing rhododendrons. |
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Ploidy Manipulation and DNA
Quantification for the Genetic Improvement of Rhododendron Significant past improvements have been made to the cultural and ornamental characteristics of rhododendrons, however, continuing technological advancements provide researchers with an increasing ability to utilize the incredible diversity within the genus to achieve further progress. This research project will utilize flow cytometry (a method for quantifying DNA content in individual cells), ploidy manipulation (changing chromosome number from diploid to tetraploid and even to triploid and interspecific hybrids (hybridizing between different rhododendron species). The overall strategy is to develop Rhododendron varieties that are improved in bloom quality, fragrance and climatic adaptability. A rare Japanese native, R. uwaense, will be used as a breeding parent because it possess highly fragrant flowers and substantial heat tolerance. Flow cytometry will also help identify the phylogenetic relationship of R. uwaense with other subgenera. Hybrid seedlings from R. uwaense and crosses of tetrapoid R. catawbiense with diploid ponticum spp. will hopefully result in triploid progeny. Triploid plants in previously studied genera including Vaccinum, Betula and Viburnum have resulted in new desirable traits. Hybrid seedlings from this research project will also be tested for zone 3 winter hardiness. |
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2004 Awards |
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Identifying Taliense
Rhododendrons Using Leaf Waxes The subsection Taliensia includes several species such as R. aganniphum, R. alutaceum, R. phaeochrysum and R. roxieanum, which are highly prized for their flowers and foliage. Taxonomy is difficult due to natural hybrid swarms and one of the primary goals of this research is to use the chemistry of leaf waxes as markers for species characterization and identification. A study of leaf waxes is much less expensive than DNA analysis. The significance of the work will be to see if species in the Taliensia subsection can be characterized and then confirm if species can be differentiated from hybrids. This will help growers and botanists with implications for both conservation and horticulture. |
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Utilizing Allopolyploid Azaleodendrons for Breeding Superior Hybrid sterility is often a problem encountered when chromosomes do not match up between two parents during plant hybridizing. Induction of polyploidy (syn. allepolyploidy), which is artificially increasing the number of chromosomes, can often restore fertility. The putative azaleadendron called 'Fragrant Affinity' will be the cultivar analyzed in this study. Effort will be made to identify the parentage, possibly R. catawbiense x R. viscosum or R. ponticum x R. viscosum, of 'Fragrant Affinity'. One goal of the research is to develop documented fertile allepolypoids of 'Fragrant Affinity' with implications for further successful hybridizing. |
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2003 Awards |
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Development of a USDA Zone 4A Rhododendron Cold Hardiness
Trial/Display Garden The primary goals will be to develop a wider range of flower colors and more reliably bud-hardy rhododendrons for Zone 3/4 landscapes. The proposed trial/display garden will be on the grounds of the Minnesota Landscape Arboretum in Chanhassen, Minnesota and will be open to the public. For many visitors, viewing the proposed display garden would be a rare encounter with evergreen rhododendrons. A local architect has donated the landscape design and funds will be used to properly prepare planting areas. |
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The Effect of Phosphorus in Different Formulations on the Flower Bud
Formation of Rhododendrons The purpose of the research is to show the effect of phosphorus, in different formulations, on the flower and vegetative bud set of elepidote rhododendrons ('Roseum Pink', 'Catawbiense Alba', and 'Wyandanch Pink'). Plant age and light conditions have an effect on flower bud set, but there has long been a debate about the importance of adding phosphorus as well as other nutrients to stimulate more flowering. Controlled nursery conditions over a three-year period will test the effects of di-ammonium phosphate, super-phosphate and starter fertilizer (9:46:15) on the ratio of flower buds and vegetative buds. If positive results are found, then a recommendation on how to increase flowering will significantly benefit all growers of rhododendrons. |
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Collection of Winter Hardy Rhododendrons at the Central Siberian Botanical
Garden in Novosibirsk, Russia The goal is to find winter hardy genotypes of rhododendron species that will grow well under the conditions of Novosibirsk. Russian botanists recognize 12-15 species native to Western and Eastern Siberia and the Russian Far East Region. Species of greatest interest are R. ledebourii, R. dahuricum, R. mucronulatum and R. sichotense. These species exhibit tremendous variations in size and flower color. Micropropagation techniques will be applied to selected clones and seed will be sent to the ARS. |
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2002 Awards |
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Ecology of Vireya Species in their Natural Habitat A new giant cell type with unusual cellular morphology has been identified as being unique to vireya rhododendrons. The goal of this study was to validate this observation in natural populations of vireyas in New Guinea, take tissue samples for later DNA and microscopic laboratory analysis, and do field experimentation measuring photosynthesis in response to various light and carbon dioxide conditions. Outcomes will provide a greater understanding of the ecology of vireyas and the function of the newly discovered cell type. |
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Physiological Study of Deacclimation in Rhododendron The specific objectives of the study are to characterize the timing and speed of deacclimation, which is the opposite of fall acclimation for winter, through a time-course study of five Rhododendron species that vary in their freezing tolerance (R. maximum, R. ponticum, R. carolinianum, R. dichroanthum and R. arboretum). The study will also identify and quantify proteins (dehydrins) whose relative abundance appears to be affected by a winter thaw treatment. Possible results include an understanding of how plants acclimate to winter temperature and maintain deacclimation. This will be useful for evaluation of plants in the landscape and breeding programs. |
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An Evaluation of Powdery Mildew Disease on Deciduous
Azaleas Cultivars The researchers will evaluate over a two-year period, 50 deciduous azalea cultivars and species in two separate locations (Minnesota and Ohio) for resistance to powdery mildew. A second phase includes a survey of additional numbers of cultivars and species in eastern North American public gardens, significantly broadening the study. While plant pathology is not the primary focus, attention will be given to identifying the fungal species involved. An expected outcome is not only a "good doer list" of species and cultivars, but ratings will assist breeders for further plant introductions. |
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2001 Awards |
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Cold Acclimation and Freezing Tolerance in Rhododendron
maximum Techniques of protein extraction and analysis by two-dimensional gel electrophoresis will be refined and key leaf and thylakoid membrane proteins will be identified during a yearly developmental cycle. A through understanding of the molecular aspects of cold acclimation and freeze tolerance could be of great significance in efforts to improve varieties and extend the growth range of rhododendron species into colder climatic zones. |
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Nursery Production and Landscape Performance of Azaleas The overall objective of this project is to identify and promote superior azalea selections. A wide range of cultivars will be evaluated during nursery production (propagation and container production through flowering) for two years and for at least five years in the landscape. |
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Collection of Rhododendron sect. Vireya in Sulawesi,
Indonesia for Studies The objective of the project is to obtain herbarium and live material, for both DNA and morphological studies, of a group of species that is not well known. Material for propagation will be collected when possible. Cutting material will be sent to the Rhododendron Species Foundation after establishment in Australia. Wild-collected seed will be sent to the Vireya seed exchange. |
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American Rhododendron Society |