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Donita L. Bryan, Michael A. Arnold, R. Daniel Lineberger and W. Todd Watson

Three spineless phenotypes of Acacia wrightii G. Bentham ex A. Gray were identified with aesthetic landscape potential. Experiments in seed, cutting, grafting, and tissue culture propagation were undertaken to perpetuate this desired spineless phenotype. Germination percentages for mechanically scarified seeds ranged from 33% to 94%, however yield of spineless seedlings was low (0% to 34%). Sulfuric acid scarification for 10, 20, 30, or 60 minutes hastened and unified germination compared to nontreated seeds by 7 to 8 days. Vegetative propagation was successful for softwood cuttings. Rooting measures increased with auxin (2:1 indole butyric acid to naphthalene acetic acid) concentrations from 0 to 15000 mg·L–1, with maximum rooting percentage (70%), root number (9.2), and root length (12.4 cm) per softwood cutting at 15000 mg·L–1 auxin 8 weeks after treatment. Rooting was not successful for semi-hardwood or hardwood cuttings. Whip-and-tongue or T-bud grafting was not successful. Tissue culture of shoots from in vitro germinated seedlings indicated that shoot proliferation was greatest in Murashige and Skoog (MS) medium with 15 μm zeatin. The number of shoots that rooted in vitro increased with increasing concentrations of indole-3-butyric acid from 0 to 25 μm.

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Thomas H. Boyle and Kristen Hladun

A series of experiments was performed to examine the germination responses of Baptisia australis (L.) R. Br. seeds. Germination tests were conducted at 23 °C and numbers of germinated seed were counted daily for 21 days. Seeds were separated into two size fractions using standard sieves. Seeds in the large-seeded fraction were heavier than those in the small-seeded fraction, but seed size/weight did not affect the germination percentage at 21 days (G21), the number of days to 50% of final germination (T50), or the number of days between 10% and 90% germination (T90 – T10). Seeds were classified into two groups based on testa color. Light-brown seeds (17% of total) were heavier and had lower G21 and higher T50 and T90 – T10 values than medium- to dark-brown seeds (83% of total). Seeds scarified mechanically germinated nearly 100% and had lower T50 and T90 – T10 values than untreated seeds. Untreated seeds had a higher T50 value than seeds soaked overnight in 20°C water, but the G21 and T90-T10 values were similar for the two treatments. Mechanical scarification followed by overnight soaking in 20 °C water yielded a G21 value of only 12%, and the low germination percentage was attributed to imbibition damage. When seeds were scarified in concentrated H2SO4 for 0, 1, 5, 20, 40, or 80 min, G21 values increased quadratically while T50 and T90 – T10 values decreased quadratically as the immersion time increased. To test the effects of moist heat on germination responses, seeds were immersed for 0, 0.5, 1, 2, 4, or 8 minutes in 85 °C water. G21 values increased linearly as the immersion period increased from 0 to 2 min but remained similar when the immersion time exceeded 2 min. The duration of immersion in hot water did not affect the T50 values whereas T90 – T10 values decreased linearly as the immersion period increased. We conclude that physical dormancy is responsible for temporal variation in germination of B. australis seeds. Scarifying seed in concentrated H2SO4 for 20 to 80 minutes may be the most practical means of treating bulk lots of B. australis seeds to obtain rapid and uniform (≥85%) germination.

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Jyotsna Sharma and William R. Graves

Attributes of Leitneria floridana Chapman have been recognized, but this North American shrub remains rare in commerce, and little information on propagation is available. We studied germination of seeds collected from several disjunct populations of L. floridana in 2002 and 2003. In 2002, ≤5% germination occurred when ripe drupes from Missouri and Florida were sown soon after collection. Effects of GA3 (750 mg·L-1 for 24 hours) were assessed on stored drupes leached with water and on seeds excised from stored drupes. Germination percentages were 21 and 32 for leached drupes and excised seeds from Florida, respectively, but ≤5% germination occurred among germplasm from Missouri and among untreated drupes from both provenances. Viability of ungerminated seeds among treatments ranged from 0% to 7%. In 2003, fleshy, apparently unripe drupes from Texas, which were scarified with H2SO4 and then treated with 1000 mg·L-1 GA3 showed 48% germination (germination value = 3.9). Up to 29% germination (germination value = 2.7) occurred when seeds were excised from unripe drupes from Arkansas and Missouri and then were treated for 24 hours with 750 or 1000 mg·L-1 GA3. We conclude that provenance, developmental stage of drupes when collected, storage, and pregermination treatments influence viability and germination of seeds of L. floridana. Barriers to germination may be avoided by collecting drupes when they are green and fleshy.

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Y.C. Sun, Y.J. Zhang, K. Wang and X.J. Qiu

Iris lactea seed is characterized mainly by physiological dormancy. Two experiments were conducted to investigate the effect of NaOH treatment and stratification on Iris seed germination. In Experiment 1, seeds were treated with 14.38 m NaOH for 0 to 28 hours. In Experiment 2, NaOH treated and nontreated seeds were stratified under 7 °C and moistened condition for 0 to 40 days. As results, NaOH treatment for 20 hours effectively removed seedcoat and improved germination percentage from 0% to 56% compared to control (0 hours). However, germination percentage started to decrease after 20 hours. Stratification for 40 days further improved germination percentage of NaOH treated seeds to >80%, but did not affected seeds without NaOH treatment. Results demonstrate that combination of NaOH treatment and stratification is an effective practice to break Iris seed dormancy and improve germination percentage.

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Joseph J. King and Mark P. Bridgen

Presowing treatments and temperature regimes were tested to improve germination of Alstroemeria hybrids 3 to 12 months following harvest. In addition, seeds from 20 intraspecific F1 hybrids of five selections were also tested 3 to 7 or 8 to 12 weeks following harvest. Seeds were pretreated by chipping the seedcoat above the embryo, general abrasion of the entire seedcoat, or soaking 12 hours in distilled water, GA, (0.029, 0.29, 2.9 mm), or KNO3 (0.5 and 1.0 m). Pretreatments were evaluated under three environmental regimes: 8 weeks at a constant 18-25C (warm), 4 weeks at 18-25C followed by 4 weeks at 7C (warm-cold), or 4 weeks at 7C followed by 4 weeks at 18-25C (cold-warm). There was an interaction between pretreatment and environmental regime for percent germination. Germination percentages for the water soak and GA, at 0.29 or 2.9 mm were significantly higher than for the other pretreatments, but were not significantly different from one another. The warm-cold environment yielded higher germination percentages than the other environments. The time to germination was longest for the cold-warm regime. This response depended on the genotype and the age of the seed. Chemical name used: gibberellic acid (GA3).

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Robert L. Geneve

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Olga A. Kildisheva, R. Kasten Dumroese and Anthony S. Davis

benefit from scarification, the cause of dormancy has not been examined directly ( Page et al., 1966 ; Roth et al., 1987 ; Sabo et al., 1979 ; Smith and Kratsch, 2009 ). In these species, imbibition (critical for germination) is regulated by a water gap

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Elise B. Benhase and John G. Jelesko

invasive plant, there is rather limited knowledge about T. radicans germination patterns. Two prior studies suggest that T. radicans drupes require scarification to initiate seedling germination. One study focused on T. radicans seed dispersal by

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Cameron Northcutt, Daniel Davies, Ron Gagliardo, Kylie Bucalo, Ron O. Determann, Jennifer M. Cruse-Sanders and Gerald S. Pullman

., Pawling, NY). The fabric tended to minimize seed damage, especially after scarification procedures that weakened the seedcoat. Media and culture conditions Prior experiments by ABG staff showed excellent Sarracenia species growth and vigor without signs

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Dilinuer Shalimu, Ke Li, Carol C. Baskin, Jerry M. Baskin and Yujun Liu

storage at room temperature and at 4 °C, sulfuric acid scarification, treatment with gibberellic acid (GA 3 ), cold (moist) stratification, acid scarification plus cold stratification, and warm stratification followed by cold stratification on breaking