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Gary R. Bachman and Ted Whitwell

Demand for commercially grown Uniola paniculata L. (southern seaoats) is increasing for use in restoring beaches damaged by tropical storms. Fresh seeds harvested from the Jekyll Island, Ga area (with permission of the Jekyll Island Authority), were planted in 50 peat: 50 perlite and treated with 100 or 500 ppm GA4 for 24 h. Germination was higher for 100 compared to 500 ppm GA4. Liners grown from seed and planted with the crowns even with the surface of the pine bark-sand media, compared to deep planting to simulate burial conditions of beach planting, had the highest shoot and root weights after 100 days. Uniola paniculata liners with the crowns buried had reduced weights due to higher moisture conditions in the bottom of the containers. Uniola paniculata grown without supplemental fertilization had shoot weights similar to those of plants receiving 1.5 lb N/yd3 (0.89 kg N/m3) from both quick or slow release fertilizers. Increasing N to 3 lb/yd3 (1.78 kg N/m3) and/or supplying micronutrients only, reduced shoot weight. Nursery production of Uniola paniculata in pine bark-sand is one way to increase the supply of this important dune plant.

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Gary R. Bachman and Ted Whitwell

Southern seaoats (Uniola particulata) are difficult to propagate from seed due to low seed numbers produced and cold dormancy effects. To efficiently produce southern seaoats in the nursery industry the dormancy must be effectively broken to assure quick and even germination. 24 hr soaks in gibberillic acid (100 and 500 ppm) or scarification of the seed coat combined with GA soaks were compared. Seeds were planted in 50/50 peat/perlite medium 2.5 cm deep. 21 DAT both the 100 and 500 ppm GA soaks had higher germination rates. The 100 ppm GA was determined to he most effective (56% germination) with the seedlings being 3 cm in length. The 500 ppm treated seeds were 6 cm in length hut twisted from the GA causing excessive cell elongation.

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Gary R. Bachman and Ted Whitwell

Bittercress (Cardamine hirsuta) is a nuisance weed in the ornamental nursery industry. Seed formation and dispersal during propagation production at an ornamental nursery were studied. There is much variability in silique number and seed per silique with the means being 77 and 29. respectively after five weeks. Average number of seed produced was 2233 per plant. The seeds arc forcefully expelled with a mean distance of 61 cm. Germination of these freshly released seeds was 90% after 13 days with a generation time of nine weeks. Seed source in the nursery was from either the gravel floor or reuse of the propagation containers. Comparing germination of bittercress seedlings in dirty or cleaned containers, use of dirty containers resulted in significantly higher numbers of bittercress seedlings than the cleaned.

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Gary R. Bachman and Margaret J. McMahon

It is theorized that photomorphogenic reductions in stem elongation are similar to thermomorphogenic plant response, i.e. increased red:far-red light response is similar to –DIF (day temperature < night temperature). The long hypocotyl (hy) mutants of Arabidopsis thaliana Landsberg are phytochrome mutants that are less responsive to light quality than wild type. These include mutants of phytochrome chromophore biosynthesis (hy 1, hy2, hy6), phytochrome B (hy3), blue-light receptor (hy4), and signal transduction (hy5). These mutants were grown in growth chambers with temperatures of 18C day/24C night (–DIF) and 24°C day/18°C night with a 14-h photoperiod. Lighting consisted of both incandescent and fluorescent lamps. Growth measurements of five of the mutants were consistent with reported effects of DIF. The height of these plants were significantly greater in the +DIF regime when compared to –DIF. The hy5 mutant showed little difference in the height measurements of plants grown in either -DIF or +DIF. This mutant has a phytochrome signal transduction deficiency. This result indicates that a functional photoreceptor is required, even in reduced quantities as in the phytochrome chromophore biosynthesis mutants, to signal perception of DIF temperature conditions.

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Gary R. Bachman and James D. Metzger

Interest in using alternative materials for potting substrate is increasing in response to availability and rising costs of peat and other conventional materials. Vermicompost (VC) is one such material. It is important to understand physical and chemical changes in potting substrate when amended with VC produced from different waste sources, pig (PVC) and beef cattle (BVC) manure in this study. Distribution of particles greater than 2 mm decreased, particles 0.5 to 1 mm increased, and particles less than 0.5 mm remained unchanged as PVC and BVC amendment increased. Dry bulk density and water-holding capacity increased with increasing PVC and BVC amendment. Porosity and air volume were inversely related to VC amendment, decreasing with increasing VC amendment. Saturated substrate extract sampling revealed nitrate nitrogen, phosphorus, calcium, magnesium, zinc, copper, iron content as well as electrical conductivity increased with increasing PVC and BVC amendment.

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Gary R. Bachman and Mary C. Halbrooks

The role of Fe DTPA (Diethylenetriaminepentaacetic acid) in the occurrence of a specific physiological disorder affecting the leaves of cutting geranium was investigated. Industry reports indicate that affected leaves have excessively high concentrations of Fe and sometimes Mn. Symptoms of the disorder first affect maturing leaves, and may in severe cases affect immature leaves. Symptoms progress from marginal/interveinal chlorosis and necrosis, to affect whole leaf necrosis. Rooted cuttings were grown in a soil-less peat based media, with Fe DTPA concentrations of 1, 5, 15, and 20 ppm. Iron and manganese leaf concentrations were significantly higher in symptom than in non-symptom tissue and increased as Fe DTPA treatment level increased. As Fe DTPA treatment level increased there was a significant increase in dry weight of symptom tissue and a decrease in non-symptom tissue dry weight. Plants grown in media amended with dolomite (pH> 5.8) had similar degrees of symptom occurrence compared to plants grown in unamended media (pH ≈ 5.4).

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Sara Michele Wills and Gary R. Bachman

Vermicompost or worm-worked wastes have been reported to enhance seedling germination and growth during plug production. The objective of this project was to examine the effects of vermicompost on germination of a herbaceous perennial having varying viability in coir-based container media. Seeds of Echinacea purpurea (Purple Coneflower) collected from field-grown plants in 1998 and 1999 were considered low- and medium-viability seeds, respectively. A third group of seeds was purchased from a major seed company and was considered to have high viability due to optimal storage conditions. “Ragdoll” germination tests resulted in the following viability ratings: low (1%), 1998; medium (67%), 1999; and high (79%), purchased seed. The three sources of seed were planted into coir-based media. Vermicompost was incorporated into the media at 10% by volume. The control media did not have vermicompost added. Twelve days after project initiation seeds sown into media containing vermicompost had 73% and 90% greater germination than control media for the 1999 and purchased seed. At the project conclusion, 24 days after initiation, seeds sown into media containing vermicompost had 23% and 42% greater germination than the controls for the 1999 and purchased seed. The 1998 seed had 5% germination after 24 days compared to 1% for the control. The addition of vermicompost could be used as a method to increase germination rate and percentage of seeds having lower viability.

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Gary R. Bachman and Margaret J. McMahon

Using spectral filters to reduce the amount of far-red (FR) light perceived by plants has been shown to effectively reduce internode elongation of many floriculture crops. It is theorized that gibberellin (GA) function is inhibited in some way by the increase in the red: far-red light ratio. Sex expression of flowers are effected by exogenous applications of gibberellin and cause a shift in flower sex expression towards maleness. The use of growth regulators (GA inhibitors) have demonstrated a shift towards femaleness. Flowering of spinach, a dioecious species, and cucumber (staminate and pistillate lines), a monoecious species, were surveyed for shifts in flower sex expression, indicating a suppression of GA. Male: female flower ratio decreased from 7.6:1 to 4.06:1 when comparing the controls and –FR for the staminate cucumber line and 1:13 to 1:40 for the gynecious cucumber line. The decrease in male flowers on plants grown in a –FR environment are an indication that the function of GA is inhibited. There was no significant effect on the male: female flower ratios of the spinach.

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Gary R. Bachman and Margaret J. McMahon

`Celebrity White' hybrid petunia plants (Petunia ×hybrida Hort. Vilm-Andr.) were grown either in chambers constructed of CuSO4-filled panels acting as spectral filters removing the far-red light (-FR) or in environmental control chambers under temperature treatments of 24 °C day/18 °C night (+DIF) or 18 °C day/24 °C night (-DIF). Growth responses for plants grown under CuSO4 filter (-FR) or -DIF temperatures were similar in that both treatments resulted in decreased internode length, increased stem diameter, and decreased cell length and cell diameter in epidermal, cortical, and pith tissues. Reduced cortical cell length contributed the largest percentage to internode length reductions compared to epidermal and pith tissue for the -FR treatment while reductions in cell length of all three tissues contributed to internode reduction of -DIF-treated plants. Chlorophyll a increased for plants grown under -FR, but decreased for plants grown in -DIF when compared to the appropriate controls.

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Sandra M. Reed, Gary R. Bachman and W. Edgar Davis