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Michael W. Olszewski, Courtney A. Young and Joel B. Sheffield

). Latting (1961) determined that mechanical scarification of Illinois bundleflower seed resulted in higher final germination percentage (FGP) compared with sulfuric acid scarification, alternate freezing and thawing, hot water, or control treatments. Mean

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

physical treatments were tested to break dormancy in seeds of this species ( Baskin et al., 2004 ). One treatment involved mechanically scarifying seeds, after 2 weeks of incubation; seeds that were mechanically scarified had germinated to 96% to 100% in

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Ai-Rong Li, Kai-Yun Guan and Robin J. Probert

and complete darkness) and three artificial treatments were used in our experiments. For the treatment in darkness, the dishes were put into a paper box wrapped with aluminum foil. For artificial treatments, seeds were either scarified by rubbing

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J. Ryan Stewart and Irene McGary

and thus only require scarification to germinate ( Quick, 1935 ; Quick and Quick, 1961 ). Keeley (1991) did not consider seeds of ceanothus species to be sensitive to light for induction of germination. We hypothesized the germination response of

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Stanta Cotner, John R. Clark and Eric T. Stafne

A study was conducted in the Winter–Spring 2004 to evaluate the effects of seed (pyrene) scarification period on blackberry (Rubus L. subgenus Rubus) genotypes that had a range of seed weights. The study was done in an attempt to identify optimum scarification period for variable seed weights for the purpose of increasing germination of blackberry seeds produced from hybridizations in the Arkansas blackberry breeding program. Scarification treatments of 1, 2, or 3 hours were used on 14 genotypes. Seeds were then stratified for 3.5 months and sowed on a commercial potting medium in a heated greenhouse. Germinating seedlings were counted over a 15-week period and total germination determined. Data analysis indicated significant genotype effect on germination but no scarification treatment nor genotype × scarification treatment interaction significance. The results indicated that scarification period did not affect germination and varying this period predicated on seed weight was not beneficial based on the genotypes used in the study.

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John M. Ruter and Dewayne L. Ingram

Seeds of Sophora secundiflora (Ort.) Lag ex. DC. (mescal bean) were scarified with hot water or concentrated sulfuric acid to determine an optimal pretreatment for successful germination. Scanning electron micrographs indicated that the acid scarification treatment removed the seed cuticle. One-year-old seeds were successfully stored and germinated ≈2 days sooner than from the current year if both were given an acid pretreatment. Germination rate increased as acid pretreatment time increased from 30 to 120 minutes. Soaking seeds in water at room temperature or in hot water (initially 93C) for 24 hours had no effect on germination.

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Dale T. Lindgren

Penstemon, a U.S. native plant/wildflower, is increasing in use as a landscape plant. Penstemon species are commonly propagated by seeds. However, species vary greatly in percent seed germination,

Seeds from eight sources of Penstemon germplasm were given cold moist stratification periods of either 0, 2, 4, 6, 8 or 10 weeks. One-half of the seed for each treatment was scarified with sandpaper. The study was repeated twice, once in 1989 and once in 1990.

Seed germination varied with species, and with the length of stratification. Greatest germination occurred at the 6, 8 and 10 week periods and the lowest germination occurred with no stratification. There were also differences between species in percent germination, Average percent germination was highest for P. gracilis and lowest for P. haydenii There was a significant species × stratification interaction, Seed scarification did not influence germination as much as seed stratification in these studies

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John R. Duval and D. Scott NeSmith

Production of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] transplants is hindered by poor, inconsistent emergence, and frequent seed coat adherence to cotyledons. Seed coat adherence leads to weakened and slow growing plants. High seed costs, coupled with stand establishment problems, discourages transplant producers from growing this crop. Improvement of triploid watermelon emergence will lessen financial risks to growers and transplant producers and will provide a more reliable production system. Mechanical scarification was evaluated as a means to overcome inconsistent emergence and seed coat adherence. Seeds of `Genesis' triploid watermelon were placed in a cylinder with 100 g of very coarse sand (1.0 to 2.0 mm diameter) and rotated at 60 rpm for 0, 6, 12, 24, and 48 hours in a series of experiments. Number of emerged seed was recorded daily, to obtain emergence dynamics. No significant differences were observed in seed coat adherence among treatments. The longest duration of scarification However, enhanced emergence as compared to the control in three of four experiments. These data support earlier suggestions that a thick or hard seed coat is a factor contributing to poor germination and emergence of triploid watermelons.

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Janine G. Haynes, Wallace G. Pill and Thomas A. Evans

Switchgrass (Panicum virgatum L.) is one of the perennial, native, warm-season grasses recommended as a component of wildflower meadows. Seed treatments to alleviate low seed vigor and seed dormancy of switchgrass would enhance establishment of either plug transplants or seedlings after direct sowing into the meadow. “Heavy” seeds (45.5 mg/50 seeds) of open-pollinated switchgrass stored under cool and dry conditions (average 13 °C, 30% relative humidity) for 24 months had higher germination percentage than “light” seeds (26.0 mg per 50 seeds). In factorial combination, the heavy seeds were subjected to acid scarification (8 M H2SO4 for 5 min), sodium hypochlorite treatment (5.25% NaOCl for 15 min), and moist chilling (prechilling in 0.2% KNO3, for 14 days). Acid scarification followed by NaOCl treatment additively increased germination, a response that was associated with marked corrosion of the lemma margin in the distal region of the caryopsis, as observed by scanning electron microscopy. Prechilling the seeds following acid scarification and NaOCl further increased germination. All three treatments combined (acid scarification, NaOCl, and prechilling) almost doubled the final emergence and greatly increased seedling shoot dry mass in both a warm and cool postsowing environment. However, the effectiveness of these seed treatments was lost after 32 months of dry storage.

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S. Grange, D.I. Leskovar, L. Pike and G. Cobb

Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the U.S. However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of the H2O or H2O2; both nicking and H2O2 increased germination, but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (CV = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seedcoat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.