temperature conditions ( Garner and Björkman, 1996 ). Nevertheless, during ornamental plant production, the application of plant growth regulators (PGRs) is still the most commonly used tool for achieving an effective reduction in plant height ( Latimer, 1992
Commercial nurseries utilize large amounts of water and nutrients during the production cycle of container-grown plants. Excess water contaminated with N and P can impact the quality of surface water and groundwater. Earlier work by the authors found that constructed wetlands are highly efficient for removing N at water temperatures above 15 °C. However, PO4 removal was highly variable with uptake coinciding with periods of active plant growth and net export occurring during all other periods. Ornamental plants that remediate nutrients, especially phosphorus, would be very useful in designing constructed wetlands for commercial nurseries and greenhouses, rain gardens, and homeowner buffer strips. A greenhouse study was initiated in 2003 at Clemson Univ.'s Biosystems Research Complex to screen commercially available ornamental plants for their phytoremediation potential. Among others, these included the woody ornamental plants Cornus amomum, Myrica cerifera `Emperor', and Salix integra `Hakura Nishiki' and the semiaquatic herbaceous ornamental plants Canna `Bengal Tiger' and `King Humbert', Colocasia esculenta `Illustris', Rhynchospora colorata, Iris virginica `Full Eclipse, Pontederia cordata `Singapore Pink', and Thalia geniculata `Red Stem'. Plants were grown in pea gravel media kept saturated with one of five concentrations of Hoagland's Solution. Herbaceous and woody ornamental plants were harvested after 8 and 13 weeks, respectively. Water usage and biomass production were measured and nitrogen and phosphorus uptake was assessed. Experiments were replicated twice for each cultivar. Results indicate several species have the potential to be used in phytoremediation systems.
Due to increasing consumption of water in landscapes and concern over conservation of water resources, this study was conducted to determine the effect of fertilizer source on water consumption of turf and ornamentals and to compare total water use (WU) of st. augustinegrass and ornamentals. The experiment was performed in a climate-controlled greenhouse at the G.C. Horn Turfgrass Field Laboratory at the University of Florida in Gainesville. `Floratam' st. augustinegrass (Stenotaphrum secundatum Walt. Kuntze) was compared to a mix of common Florida ornamentals including canna (Canna generalis L.H. Bailey), nandina (Nandina domestica Thunb.), ligustrum (Ligustrum japonicum Thunb.), and allamanda (Allamanda cathartica L.). All plants were grown in 300-L plastic pots in Arredondo fine sand. There were three fertilizer treatments [quick-release fertilizers (QRF) 16–4–8 and 15–0–15, and slow-release fertilizer (SRF) 8–4–12] applied at 4.9 g N/m2 every 60 days. Water was applied as needed to maintain turgor and turfgrass pots were mowed weekly. Experimental design was a randomized complete block design with four replications. Visual quality ratings and time domain reflectometry (TDR) data were collected weekly. Both turf and ornamentals consumed less water and had higher water use efficiency (WUE) when treated with SRF. Ornamentals consumed from 11% to 83% more water than turf, depending on season. These results may have implications in future research on irrigation management to verify WUE between turf and ornamentals in an urban landscape.
Abstract
Methyl sulfanilylcarbamate (asulam) was effective for the selective control of several grassy weeds in established st. augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze), ‘Tifway’ bermudagrass (Cynodon dactylon L.), and ‘Emerald’ zoysiagrass (Zoysia matrella Merr.). Bahiagrass (Paspalum notatum Flugge) and centipedegrass (Eremochloa ophuroides (Munro) Hack.) were severely injured when asulam was used at a rate of 2.24 kg ai/ha. Thirty-six species of ornamental plants were relatively tolerant to foliage applications of asulam at rates of 2.24 and 4.48 kg ai/ha with growth normal on all but 4 ornamental species 22 weeks following treatment.
60 ORAL SESSION 10 (Abstr. 064–071) Water Stress/Water Utilization–Woody Plants
Silicon (Si) is the second most-abundant element in soils, and its concentration in soil solution ranges from 0.1 to 0.6 mm, which is the same concentration range as some of the major nutrient elements such as calcium, magnesium, phosphorus, and sulfur. Increasing evidence has recently suggested that Si plays important roles in improving plant growth. However, little information is available on Si effects on container-grown ornamental plants, particularly since most are grown in soilless media where Si sources are greatly limited. The objectives of this research were to evaluate Si absorption and translocation in diverse container-grown ornamental plants and to determine whether Si absorption could improve plant growth. Liners from 39 plant species were potted in peat and pine bark-based soilless media and grown in a shaded greenhouse. Plants were fertigated with a Peter's 24–8–16 water-soluble fertilizer containing 0, 50, and 100 mg·L–1 of Si. Once marketable sizes were reached, plants were harvested and fresh and dry weights determined; Si and other nutrient elements in roots and shoots were measured. Results indicated that 32 of the 39 evaluated species were able to absorb Si, with large quantities further transported to shoots. Of the 32 Si-responsive species, 17 showed significant dry weight increases, whereas the other 15 only exhibited Si absorption and translocation with no apparent growth responses. The seven non-responsive plant species showed no significant increases in neither Si absorption and translocation, nor dry weight.
The growth of the ornamental plant industry has rapidly increased over the past several years, creating a strong demand for well-trained graduates and industry workers. It is vital for a person entering this industry to have a solid and broad plant material background. The best ways to learn, sell, and teach plants are through visual materials. Currently, there are few cost-effective resources that provide a person with all the visual information needed to learn plants. To better serve the students and industry workers, the Univ. of Connecticut has developed a free multimedia ornamental plant database on the World Wide Web. The plant database focuses on plants for the New England area (USDA zone 6 and lower). This website brings detailed textual information, thousands of pictures, and audio pronunciations together in one complete package. Plant characteristic information (textual and pictorial) consists of habitat, habit and form, summer foliage, autumn foliage, flowers, fruit, bark, culture, landscape uses, liabilities, ID features, propagation, and cultivar/variety. The major factors and decision processes involved in developing an educational Web site, with emphasis on usability and accessibility are considered. The target audience for this Web site is students as well as the nursery and landscape industry workers, agricultural consultants, extension personnel, landscape architects, and the gardening public.
Seeds of herbaceous ornamental accessions conserved by the USDA National Plant Germplasm System (NPGS) are traditionally produced in summer field cages with honey bees (Apis mellifera) when pollinators are required. Efficient methods to produce high-quality seed in greenhouses may allow for year-round seed production. Flower quantities and effects of pollinators on number and weight of seed produced were studied in field cages and greenhouses at the Ornamental Plant Germplasm Center in 2003 in a randomized complete-block experiment. Honey bees, bumblebees (Bombus impatiens), or blue bottle flies (Diptera calliphoridae) were used as pollinators. Field cages and greenhouse compartments with no pollinator were controls. Cultivars used were Antirrhinum majus `Gum Drop', Coreopsis tinctoria `Plains Bicolor', Dianthus chinensis `Carnation' (NPGS accession NSL 15527), Rudbeckia hirta `Indian Summer', and Tagetes patula `Jaguar'. Seeds were harvested, cleaned, weighed, and 100-seed weights calculated. On average Antirrhinum, Dianthus, Rudbeckia and Tagetes produced more flowers in greenhouses, Coreopsis produced more flowers in the field. Coreopsis and Rudbeckia produced more seed per flower on average with field pollination by honey bees, Antirrhinum and Dianthus produced most with bumblebees in the field, and Tagetes produced most with blue bottle flies in the greenhouse. Each genus had similar 100-seed weights on average in all treatments. Results show pollinators other than honey bees are useful for herbaceous ornamental seed production and that seed production in greenhouses may be an alternative method for seed production of herbaceous ornamentals.
We assessed the capacity for nutrient removal of ornamental water garden plants being grown in treatment-production wetland biofilters. Plant biomass, nutrient uptake, tissue nutrient content, and production potential were compared for five popular ornamental water garden plant species: Typha latifolia L., Iris pseudacorus L., Phalaris arundinacea L. `Picta', Canna glauca L., and Colocasia esculenta (L.) Schott. Plants were grown in triplicate 0.3 m2 × 0.3 m, deep gravelbed mesocosms fed with 20N-20P-20K Peter's fertilizer (Scotts-Sierra Horticultural Products Co., Marysville, Ohio) reconstituted to 100 ppm N. After 120 days, mean species total biomass ranged from 1.4 to 5.6 kg·m -2, while producing 105 to 206 divisions per square meter. Growth for Canna and Colocasia was greatest, while Typha produced the most divisions. Mean tissue N and P concentrations ranged from 18 to 29 and 2.1 to 3.0 mg·g -1, respectively. Maximum plant accumulation of 144 g N/m 2 and 15.6 g P/m2 accounted for 70% of the N and 15% of the P supplied by fertilizer. Mean removal of total N and P ranged from 42% to 90% and 18% to 58%, respectively, and was positively correlated with plant biomass. Nutrient removal ability was ranked as Canna = Colocasia > Typha > Iris = Phalaris.
In 1991, the USDA–ARS North Central Regional Plant Introduction Station made available for distribution 129 accessions of germplasm representing 31 genera of herbaceous ornamentals. This number increased to 329 accessions of 42 genera by 1995. During 1991–95, more than 500 seed packets were distributed to fulfill requests for these plants received from a diverse array of public and private researchers. An analysis of this demand together with expert advice from Crop Germplasm Committees and technical considerations, such as ease of culture and seed production, can help set priorities to plan germplasm regeneration to meet future demand. A recent analysis of demand at U.S. National Plant Germplasm System active sites indicated that demand ranging between 0.23 and 0.97 distributions per available accession per year was typical. Of the 42 ornamental genera analyzed in this study, 9 were demanded more frequently than was typical, 10 were demanded less frequently, with the remainder in the typical range. In order of increasing frequency, the nine genera with the highest distribution rates were Verbena, Gypsophila, Echinacea, Lapeirousia, Delphinium, Cerastium, Baptisia, Lilium, and Tanacetum. Six of these genera are represented only by a single available accession. Notably, Echinacea and Tanacetum are of research interest both as ornamentals and as medicinal/industrial crops. This poster gives a brief overview of the economic value of these genera, display the results of the demand analysis, discuss the results relative to recommendations from Crop Germplasm Committees and requestors, and consider how demand can shape management plans for the acquisition and regeneration of ornamental germplasm.