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Janine R. Conklin and James C. Sellmer

species and their cultivars, less active and threatening cultivars may be defined and could be recommended for landscape use ( Wheeler and Starrett, 2001 ). The purpose of this research was to determine germination and seed viability of norway maple

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Carlos De la Cuadra, Alexis K. Vidal, Patricia Peñaloza, Leví Mansur, and Carlos Huenchuleo

should also remain viable in dry storage for more than 1 year. Based on the previous text, the objective of the present study is to determine the optimum temperature for germination, while also assessing the effect of storage time on the seed viability of

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Sandra B. Wilson and Gary W. Knox

Japanese silver grass (Miscanthus sinensis) and 14 cultivars were transplanted in northern and southern Florida and evaluated for landscape performance, flowering, growth, and seed viability. All plants survived the 84-week study at both locations with the exception of `Morning Light', where 22% to 33% of the plants died. In northern and southern Florida, `Arabesque', `Adagio', `Cosmopolitan', and `Gracillimus' received the highest visual quality ratings on average throughout the entire study, yet other cultivars such as `Central Park' and `Silberfeder' performed well but had much narrower windows of peak performance. Cultivars such as `Little Kitten' and `Sarabande' performed far better in southern Florida than in northern Florida. Regardless of location, `Morning Light' and `Puenktchen' generally did not perform as well as other cultivars. In northern Florida, four consecutive months of very good to excellent flowering (75% to 100% canopy coverage) were observed for `Adagio', `Arabesque', `Cosmopolitan', `Gracillimus', `Little Kitten', `Sarabande', `Silberfeder', and `Zebrinus'. However, in southern Florida, peak flowering periods for these cultivars were delayed and generally only lasted for 1 to 2 months. On average, plants in northern Florida were larger and produced 2.8 times more flowers than plants in southern Florida. All cultivars produced viable seed with germination of viable seed ranging from 53.6% (`Cabaret') to 100% (`Gracillimus') in southern Florida, and from 49.8% (`Arabesque') to 100% (`Adagio', `Little Kitten', `Sarabande', and `Variegatus') in northern Florida.

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Terry A. Bacon and David H. Byrne

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Courtney L. Tchida and Mary H. Meyer

Miscanthus is one of the most popular ornamental grasses. Reports of self-seeding however, have occurred in the Central Atlantic states, making it a possible weed threat. Ascertaining whether Miscanthus self-seeds or not may determine its continued use as an ornamental, decorative plant. With more than 50 named cultivars of Miscanthus sinensis and several other Miscanthus species available in the trade, wide morphological variation appears to exist within this genus. Because Miscanthus is a warm-season grass requiring a relatively long growing season, self-seeding may vary depending on the USDA Hardiness Zone in which the plant is grown. Mature inflorescences from 35 different cultivars or species of Miscanthus were collected or acquired from nurseries or arboreta in USDA Zones 4, 5, 6, and 7 in the fall or early winter of 1996. Inflorescences were examined for seed set by hand cleaning. The percentage of viability seed and seed germination was determined by germination in laboratory conditions. Results varied by cultivar or species and as well as by source. A comparison of results will presented and the implications of Miscanthus self-seeding or becoming a potential weed threat will be discussed.

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Sandra B. Wilson, Carlee Steppe, Zhanao Deng, Keri Druffel, Gary W. Knox, and Edzard van Santen

independent seed testing facility (U.S. Forest Service National Tree Seed Laboratory, Dry Branch, GA) to determine initial seed viability and germination. Seed viability was examined on a subsample of 100 seeds using a tetrazolium (TZ) staining test adapted

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Scott B. Lukas, Joseph DeFrank, Orville C. Baldos, and Ruijun Qin

, seeds were air dried and stored in sealed containers at 5 °C. Both seed batches showed higher than 90% seed viability before experimental evaluation using a 1% tetrazolium chloride (TZ) solution following standardized methods outlined by the

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Barbara M. Reed, Sara Schwanke, and Rebecca Shala

Cryopreservation in liquid nitrogen (LN) is relatively routine for many small, desiccation-tolerant (orthodox) seeds. Seeds of Pyrus species are considered orthodox but have not been evaluated for LN storage. Seeds of freshly collected P. communis L. (`Bosc') were evaluated for germinability and by TZ staining after exposure to four LN treatments: 1) direct immersion and direct removal; 2) direct immersion and 1 minute in LN vapor phase before removal; 3) 2 minutes in vapor phase before immersion and direct removal; and 4) 2 minutes in vapor phase before immersion and 1 minute in vapor phase before removal. Fresh `Bosc' seed viability evaluated by TZ and greenhouse germination tests remained high (83% to 100%) following four types of LN treatments, compared to the controls (77% to 87%). Differences in `Bosc' seed viability were small and TZ results showed no significant differences among the LN treatments. Direct LN immersion and removal resulted in significantly more greenhouse-germinated `Bosc' seeds than the other treatments and fewer control seeds germinated than any LN treated seeds. Fresh `Bosc' seed cryopreserved at 7.9% moisture exhibited high germinability by both TZ and germination tests. LN exposure caused no physical damage to the seeds. Chemical name used: 2,3,5-triphenyltetrazolium chloride (TZ).

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Kent J. Bradford

In 1981, R.H. Ellis and E.H. Roberts published a classic paper on the quantification of aging and survival in seeds (Seed Sci. & Technol. 9:373). This paper and subsequent refinements described a model of seed aging in storage that was based on the fact that to a good approximation, deaths over time in a seed population are normally distributed. The model provides a quantitative description of seed longevity across a wide range of storage temperatures and moisture contents. Despite its theoretical importance and practical success, the Ellis–Roberts approach has not been widely adopted by the seed industry to assess seed quality and predict longevity in storage. This may be due, in part, to the rather unfamiliar statistics (probit analysis) used in the model and the apparent complexity of the equations. It will be the argument of this presentation, however, that the precise quantification of seed longevity that this model affords is less significant than the insight that it provides into the nature of seed populations and how to think about them. The objective of this presentation will be to demystify the Ellis–Roberts model and illustrate with concrete examples how the application of population-based thinking is advantageous in many aspects of seed storage and quality assessment.

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Jian Fang and E.E. Roos

Achieving the optimum moisture content for long-term seed storage usually requires that seeds be dried after receipt at a genebank. Soybean (Glycine max L.) seeds were dried using four procedures: over concentrated H2S O4, over silica gel, at 15% relative humidity (RH), or in an oven at temperatures of 30, 35 and 40C. Following dying seeds were stored at 40C for 10 days and at 5C for one yr. Seeds were evaluated for germination and vigor (root length, dehydrogenase, and leachate conductivity). Initial moisture content (mc) was reduced from 8.3% to between 6.6% (24 hr at 30C) and 4.6% (H2S O4, 30 days). Germination and vigor of seeds was essentially unchanged immediately following the drying treatments. Storage for 10 days at 40C reduced germination by up to 12% while storage for one yr at 5C had a similar effect (14% maximum loss) for most treatments. The treatments having the lowest drop in germination after one yr of storage treatment were the silica gel and the 30C oven treatments, which dropped only 3% in germination. Drying at 15% RH, also resulted in a lower loss in germination. In all three tests, vigor of seeds after storage at 40C was higher than controls for the the silica gel and 15% RH treatments as well as for the 30C and 35C oven treatments. Storage at 5C gave similar results for all three vigor assessments.