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  • Author or Editor: Mark P. Widrlechner x
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In 1991, the USDA–ARS North Central Regional Plant Introduction Station made available for distribution 129 accessions of germplasm representing 31 genera of herbaceous ornamentals. This number increased to 329 accessions of 42 genera by 1995. During 1991–95, more than 500 seed packets were distributed to fulfill requests for these plants received from a diverse array of public and private researchers. An analysis of this demand together with expert advice from Crop Germplasm Committees and technical considerations, such as ease of culture and seed production, can help set priorities to plan germplasm regeneration to meet future demand. A recent analysis of demand at U.S. National Plant Germplasm System active sites indicated that demand ranging between 0.23 and 0.97 distributions per available accession per year was typical. Of the 42 ornamental genera analyzed in this study, 9 were demanded more frequently than was typical, 10 were demanded less frequently, with the remainder in the typical range. In order of increasing frequency, the nine genera with the highest distribution rates were Verbena, Gypsophila, Echinacea, Lapeirousia, Delphinium, Cerastium, Baptisia, Lilium, and Tanacetum. Six of these genera are represented only by a single available accession. Notably, Echinacea and Tanacetum are of research interest both as ornamentals and as medicinal/industrial crops. This poster gives a brief overview of the economic value of these genera, display the results of the demand analysis, discuss the results relative to recommendations from Crop Germplasm Committees and requestors, and consider how demand can shape management plans for the acquisition and regeneration of ornamental germplasm.

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Prunella vulgaris (Lamiaceae), commonly known as selfheal, is a perennial herb with a long history of use in traditional medicine. Recent studies have found that P. vulgaris possesses anti-inflammatory, antiviral, and antibacterial properties, and it is likely that this will lead to increased commercial demand for this species. To date, research publications on P. vulgaris cultivation and genetics are scarce. Using accessions originally collected from different geographical regions, we investigated the breeding system of this species by observing variation in floral morphology, time of pollen release, and selfed-seed set in bagged flowers and isolated plants. Two types of floral morphology, one with exerted styles, extending past open corollas when viewed from above, and the other with shorter, inserted styles, were found among 30 accessions. Two accessions originally collected from Asia uniformly displayed exerted styles, and 27 accessions had inserted styles. One accession from Oregon displayed variation in this trait among individual plants. Microscopic observation of seven accessions, including ones with both exerted and inserted styles, revealed that they all release pollen to some degree before the flowers open. Using bagged flowers, we found that selfed-seed set varied widely among eight accessions, ranging from 6% to 94%. However, bagging may underestimate seed set for some accessions. The two accessions with the lowest rates when using bagged flowers increased in seed set by 350% and 158%, respectively, when we evaluated single, unbagged plants in isolation cages. The accession with 6% selfed-seed set when bagged also had exerted styles. These findings suggest that mating systems in P. vulgaris may be in the process of evolutionary change and that understanding breeding-system variation should be useful in developing efficient seed-regeneration protocols and breeding and selection strategies for this species.

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This study was conducted to determine the inheritance of anthocyanin production and of malate dehydrogenase banding patterns in Agastache rugosa. Results of the study support the hypothesis that anthocyanin production is controlled by a single dominant gene, designated as A, for anthocyanin production. The Mdh-3 banding patterns are controlled by two alleles, each of which associated with a two-banded phenotype. A monomeric quaternary structure of MDH, which is rather atypical among plant species, can be inferred from the results. No linkage was found between the loci governing anthocyanin production and Mdh-3 banding patterns. This is the first report of heritable variability in A. rugosa.

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The relationship between in vivo pollen germination and vital staining was tested for 7 genotypes of deciduous azalea (Rhododendron sp.) differing in fertility. Fluorescein diacetate, 3-amino-9-ethylcarbazole (AEC), and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) all showed significant correlations between staining and germination. AEC produced the highest significant correlation (r = 0.96). AEC and MTT were the most suitable vital stains for azalea pollen.

Open Access

Seed germination patterns were studied in Echinacea purpurea (L.) Moench grouped by seed source, one group of seven lots from commercially cultivated populations and a second group of nine lots regenerated from ex situ conserved wild populations. Germination tests were conducted in a growth chamber in light (40 μmol·m–2·s–1) or darkness at 25 °C for 20 days after soaking the seeds in water for 10 minutes. Except for two seed lots from wild populations, better germination was observed for commercially cultivated populations in light (90% mean among seed lots, ranging from 82% to 95%) and in darkness (88% mean among seed lots, ranging from 82% to 97%) than for wild populations in light (56% mean among seed lots, ranging from 9% to 92%) or in darkness (37% mean among seed lots, ranging from 4% to 78%). No germination difference was measured between treatments in light and darkness in the commercially cultivated populations, but significant differences were noted for treatments among wild populations. These results suggest that repeated cycles of sowing seeds during cultivation without treatments for dormancy release resulted in reduced seed dormancy in E. purpurea.

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