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N. Wartidiningsih and Robert L. Geneve

Germination was evaluated in six seed lots of purple coneflower purchased from four different seed companies. Standard germination percent ranged from 28% to 90% depending on the seed lot. For seed collected in 1989, seed size and stage of development of the seed at harvest could not account for the wide variability in seed germination observed in the purchased seed lots. preconditioning the seed with either cold stratification (10°C for 10 days) or osmotic priming (PEG or salt solution at -5 bars for 5 days) increased the rate of germination and the overall percent germination for all seed lots and dramatically improved germination in the poor germinating seed lots. Preconditioning appears to overcome either a shallow physiological dormancy or compensates for seeds with poor vigor or quality. In either case, seed preconditioning drastically improved seed germination (rate and percent) in greenhouse and field tests for purple coneflower.

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Robert G. Anderson and Robert L. Geneve

Different planting dates, plant densities and pinching practices were used to determine the production practices that produced the best quality cut stems from field grown godetia under Kentucky conditions. Godetia `Grace Salmon' transplants were planted at a plant density of 40 plants m-2 on Mar 23, Apr 8 and Apr 23, 1991 in ground beds with black plastic mulch. All plants flowered in early to mid June, but plants from the Mar 23 planting date had the highest yields of commercial quality stems (387 stems m-2) and over 80% of the stems were longer than 55 cm. In a separate experiment, transplants of `Grace Red' and `Grace Rose Pink' were planted on April 5 at plant densities of 4.5 m-2 (unpinched), 10 m-2 (soft pinch on May 1) and 23 m-2 (hard pinch on May 1). Pinching treatments were used to increase the number of secondary and tertiary branches on each plant. Although the pinching treatments produced more branches, a low percentage of the branches were commercial quality cut stems.

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Jenny Heringer Vires, Robert Geneve, and Robert Anderson

Purple coneflower, Echinacea sp. (Asteraceae), is a herbaceous perennial native to North America. Within the past decade, extensive research has been conducted to confirm echinacea's immunostimulatory, antiviral, and antibacterial benefits to humans. E. angustifolia, E. purpurea, and E. pallida are the primary species grown and studied for the herbal industry. However, there are other species and cultivars that may produce higher yields in biomass and chemical quality. The objective for this study is to evaluate the differences in biomass and phenolic content of five cultivars of E. purpurea and five species of Echinacea under Kentucky growing conditions. Differences in biomass (dry weight) of Echinacea species and cultivars harvested after the first year of growth was determined. There was a significant difference in total dry weight between E. purpurea cultivars. E. purpurea `Bright Star' and `Clio' produced significantly greater total dry weight compared to all other cultivars. There was no significant difference in root or flower biomass between cultivars. Biomass production differed between Echinacea species for root, vegetative, and flower parts. The total biomass of E. purpurea and E. tennesseensis was significantly higher compared to other species. E. pallida and E. paradoxa were not significantly different from E. purpurea in root biomass, even though both species produced less above-ground growth. E. tennesseensis produced 45% to 105% more flowers compared to other species. Differences in phenolic content between species and cultivars will also be presented.

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Jenny Heringer Vires, Robert Anderson, and Robert Geneve

Purple Coneflower [Echinacea sp. (Asteracea)] is of great value to the horticultural, pharmaceutical, and herbal industry. More research is needed to determine cultural practices that will produce a plant high in biomass and phenolic content, the chemical used for testing the quality of the harvested plant on a percent basis of roots, flowers and vegetative parts. The objective of this experiment is to determine if biomass and phenolic content of Echinacea purpurea and E. purpurea `Magnus' is influenced by fertilization after flower bud removal and vegetative pruning. The second objective of this study is to form an evaluation of the differences in biomass and phenolic content of five cultivars of E. purpurea and five species of Echinacea. Biomass and phenolic content will be evaluated to determine if exposing these plants to various treatments increases the quality of the plant over 1 and 2 years of growth. Differences in dry weights of Echinacea species and cultivars harvested after the first year of growth was determined. There was a significant difference in total dry weight between E. purpurea cultivars. Echinacea purpurea `Bright Star' and `Clio' significantly produced the most total dry weight compared to all other cultivars. There was no significant difference in root or flower biomass between cultivars. Biomass of Echinacea species was significantly different in root, vegetaive and flower parts. The total biomass of E. purpurea and E. tennesseensis was significantly higher compared to other species. Echinacea pallida and E. paradoxa were not significantly different from E. purpurea in root biomass, even though both species were small in above ground growth. Echinacea tennesseensis significantly produced 45% to 105% more flowers compared to other species. Differences in phenolic content between species and cultivars will also be presented.

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Tina Wilson, Robert Geneve, and Brent Rowell

Membrane damage associated with rapid influx of water during imbibition can play a role in the poor emergence and seedling vigor associated with sweet corn germination. Film-coating as a seed treatment has been used to improve germination and vigor in sweet corn and this improvement may not be associated with changes in imbibition rate. Two seed lots of shrunken-2 variety sweet corn, low-vigor `Even Sweeter' and high-vigor `Sugar Bowl', were treated with a hydrophilic polymer film-coating and evaluated for differences in emergence and water uptake. Both cultivars were grown at 19, 21, and 26 °C with no effect on emergence due to film-coating. Imbibition curves were established for untreated and hydrophilic film-coated seeds. Film-coated seeds showed an 18% increase in fresh weight compared to untreated seeds for both cultivars during a 6-h period. Bulk conductivity tests resulted in no significant mean difference between untreated and hydrophilic-treated seeds after 24 h. These seed lots have been treated with a hydrophobic polymer and are currently being evaluated for cold temperature emergence and imbibition rates. Water entry during imbibition will also be compared for untreated sugary (su) and shrunken-2 (sh2) seeds using the fluorescent compound trisodium salt, 8-hydroxypyrene-1, 3,6-trisulfonic acid (HPTS).

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Jennifer Marohnic, Robert Geneve, and Jack W. Buxton

Capillary mats were used to vary the water content in oasis blocks during mist propagation of chrysanthemum cuttings. Mats placed on the surface of the propagation bench extended over the edge of the bench and downward a distance of either 0 or 20 cm. Oasis blocks with chrysanthemum cuttings `Boaloi' and `Salmon Charm' were placed on mats under intermittent mist (10 seconds every 5 minutes) between 5 am and 8 pm. Relative water content, mL of water/gram oasis, and leaf water potential were measured at noon every 5 days. After 26 days number of roots per cutting was evaluated. Water content in the oasis block was reduced by 49% (450 to 219 mL/g dry weight of oasis) by hanging the capillary mat 20 cm over the edge of the bench compared to 0 cm treatment. Cuttings showed an increase in leaf relative water content from 49% and 51% at day 1 to 65% and 71% by day 11 for `Boaloi' and `Salmon Charm', respectively. Following initial root formation, leaf relative water content increased to 85%. Over the course of the experiment `Boaloi' and `Salmon Charm' showed an average reduction in leaf water potential of 0.14 and 0.08 MPA, respectively. `Boaloi' showed overall higher root numbers than `Salmon Charm'; however, no difference in rooting between mat treatments was observed.

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Gisele G. Martins, Robert Geneve, and Sharon Kester

Quercus falcata acorns were cold-stratified for 120 days and then sown in vermiculite under greenhouse conditions. When radicles were 7 cm long, the root tip was either removed (physically pruned) or dipped in a copper hydroxide solution (copper-treated). Intact root systems were used as control. Seedlings were then moved to a root box to observe root system architectures. The box was built of clear plexiglass 2.5 mm thick, and each face was 25.7 × 35.7 cm. Styrofoam spacers were used to separate faces, and nuts and bolts were placed along edges to hold the root box together. To permit observation of the entire root system, plants were grown in a plane between the plexiglass surface and a nylon sheet that separated roots from the medium (MetroMix 510). At 7, 9, and 11 days after treatment, the entire root system was traced on an acetate sheet, and number of internal and external links and number of secondary and tertiary roots were recorded. Total length, internal and external root links length, were obtained using digital analysis (MacRhizo). Dry weight of roots and shoots was collected at the end of this experiment (day 11). Treatment effects were evident 11 days after treatment. Copper-treated plants had statistically more secondary roots and larger internal link length than control or physically pruned plants. Also, copper-treated plants had smaller mean external link length, showing a more branched root system. Root biomass was similar for all treatments; however, copper-treated plants had smaller root: shoot ratio. This suggests that copper was acting as more than a pruning agent because copper-treated plants showed a different root system architecture compared to physically pruned plants.

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Rodney O. Jones and Robert L. Geneve

The seedcoat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud (Cercis canadensis L.). A discontinuous area was observed between macrosclereid cells in the palisade layer of the seedcoat which formed a hilar slit. A cap was formed during germination as the seedcoat separated along the hilar slit and was hinged by the macrosclereids in the area of the seedcoat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seedcoat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seedcoat between dormant and nondormant imbibed seeds. However, the thickened mesophyll of the seedcoat in this region and the capacity of the endosperm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.

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Tina Wilson, Robert Geneve, and Brent Rowell

One possible influence film-coating may have on seeds is modifying water uptake and electrolyte leaking during imibibition. Film-coating is a seed treatment that can improve sweet corn germination, especially under cold soil conditions. Two shrunken-2 sweet corn varieties (`Even Sweeter' and `Sugar Bowl') were treated with a polymer film-coating and evaluated for water uptake patterns during imibibition. `Even Sweeter' is a low-vigor sweet corn, while `Sugar Bowl' is a high-vigor variety. Standard germination tests were performed according to AOSA rules and suggest film-coated seeds germinated at a slower rate than untreated seeds. After 4 days of imibibition, `Sugar Bowl' film-coated seeds had 5% germination, while untreated seeds had ≈20% germination. However, after 7 days, film-coated seeds had 94% germination with untreated seeds at 80% germination. Results were similar for `Even Sweeter'. Bulk electrical conductivity readings were taken over 24 h to determine the amount of electrolyte leakage during imibibition. Low-vigor `Even Sweeter' had 92% higher overall leakage than high-vigor `Sugar Bowl'. Additional conductivity readings were taken for both seed lots every 2 h for 12 h. Film-treated seeds leaked 15% less than untreated seeds for `Sugar Bowl'. However, `Even Sweeter' film-coated seeds actually leaked 17% more than the untreated seeds. In both cases, 70% of electrolyte leakage occurred within the first 12 h of imibibition. An imibibition curve was established for the two seed lots comparing untreated and film-coated seeds. During the first 6 h of water uptake, film-treated seeds weighed ≈50% more than the untreated seeds for both `Even Sweeter' and `Sugar Bowl'. Pathways for water uptake as influenced by film-coating shrunken-2 seeds will also be presented.

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Rodney O. Jones and Robert L. Geneve

Seed coat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud. A discontinuous area was observed between macrosclereid cells in the palisade layer of the seed coat which formed a hilar slit. A symmetrical cap was formed during germination as the seed coat separated along the hilar slit and was hinged by the macrosclereids in the area of the seed coat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seed coat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seed coat between dormant and non-dormant imbibed seeds. However, the thickened layer of mesophyll cells of the seed coat in this region and the capacity of the endospetm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.