Sandra B. Wilson and Mack Thetford
Josiah Raymer, Mack Thetford, and Debbie Miller
Seacost Marshelder (Iva imbricata Walter [Asteraceae]), a dominant Atlantic and Gulf region seashore plant, is a broad-leaved plant with a potential for building and stabilizing foredunes in the South Atlantic coast of the United States, and is recognized as an important food for beach mice. Two experiments were conducted where nursery liners were potted as stock plants and produced at four rates of fertility using Osmocote Plus (15N:9P2O5: 12K2O; 8–9 m formulation) applied as a top dress at 5.5, 11.0, 15.0, and 21.0 g/3.7-L container. The experiment was arranged as a CRD with 12 single-plant replicates of each fertility rate. Stock plant growth, cutting production, and subsequent rooting characteristics (percent rooting, root number, length) were evaluated for cuttings harvested at each of four harvests (30-day interval). Stock plant height increased as fertility rate increased for all harvests. After the first harvest, plant height did not differ among fertility rates above 5.5 g. Growth indices demonstrated that a 21.0-g application of fertilizer was necessary to increase stock plant size. The number of cuttings produced per stock plant increased linearly with increasing rate of fertility for all harvests. Cutting weight of individual cuttings increased linearly with an increase in fertilizer rate for harvests one and two, but cutting weight did not differ thereafter. The rooting response differed depending on the time of harvest. Percent rooting decreased with an increase in fertility rate for harvests two and three. Increased fertility rate did result in a decrease in root number for harvest one, but no further decrease was evident thereafter. Root length did not differ among harvest dates or fertility rates.
Josiah Raymer, Mack Thetford, and Debbie L. Miller
Seacoast marshelder (Iva imbricata) is an important coastal species contributing to building of foredunes along the Gulf of Mexico coastal regions. Hurricane activity disrupts natural regeneration, and the need for successful nursery production of sufficient plants for restoration warrants development of efficient propagation and production practices for restoration efforts. The objectives of these experiments were to investigate the effects of stock plant fertility on cutting production of seacoast marshelder and to evaluate the rooting qualities of cuttings harvested from hedged stock. Stock plants were established in 1-gal containers using a pine bark substrate amended with 6 lb/yard3 dolomitic limestone. Plants were fertilized with 15N–3.9P–10K controlled-release fertilizer (Osmocote Plus, 8- to 9-month formulation at 21 °C) applied as a top dressing at the recommended full label rate of 11 g per pot and 5.5, 15, and 21 g per pot (12 pots each) using a completely randomized design. Cuttings were collected and stock plants hedged on a regular interval [Expt. 1 (May to August) and Expt. 2 (August to November)]. Hedging of stock plants reduced height to 20 cm after each successive harvest of cuttings, but stock plant growth index increased with each successive harvest. Stock plant growth and cutting production increased as fertility rate increased, but responses were not consistent across harvest times. This trend was also true for rooting percentage and measures of root quality. Seacoast marshelder stock plant size increased as fertility increased to 15 g but not at 21 g. Inconsistencies in rooting responses across the production period were evident and were attributed to seasonal growth effects. An inverse relationship between rooting percentage and fertility rate was evident from May through July suggesting high levels of fertility should be avoided because rooting percentage, root number, and root length were reduced as fertility rate increased during that time. Conversely, higher fertilizer rates had a neutral to positive effect on rooting of seacoast marshelder during the months of August through November.
Mack Thetford, Stuart L. Warren, and Frank A. Blazich
Uniconazole was applied as a foliar spray at 0, 90, 130, 170, or 210 mg·liter-1 to rooted stem cuttings of `Spectabilis' forsythia (Forsythia ×intermedia Zab.) potted in calcined clay. Plants were harvested 0, 40, 80, 120, and 369 days after treatment (DAT). Treatment with uniconazole at 90 to 210 mg·liter suppressed leaf area and dry weight an average of 16% and 18%, respectively, compared to the nontreated controls when averaged over all harvest periods. Stem and root dry weight suppression was greatest at 80 DAT, 47% and 37%, respectively. Uniconazole suppressed root length from 15% to 36% and root area from 15% to 33% depending on harvest date. Internode length and stem diameter of uniconazole-treated plants were suppressed at all harvests except 369 DAT. Uniconazole resulted in increased and decreased root: shoot ratios 40 and 80 DAT, respectively; while root: shoot ratios were not affected for the remainder of the study. Relative growth rates of leaves, stems, and roots decreased with increasing uniconazole concentration; however, no relative growth rates were suppressed beyond 80 DAT. Generally, mineral nutrient concentrations increased as a result of uniconazole application. The proportion of mineral nutrients allocated to leaves and roots was not affected while the proportion of nutrients allocated to stems decreased with uniconazole application compared to the controls. Chemical name used: (E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole).
Ramon Arancibia, Manuel Palada, Mack Thetford, and Shibu Jose
Specialty cut flowers may be suited to sustainable production system in the tropics and an agroforestry approach was developed to add a commercial value to unused forest areas. Ginger lily (Alpinia purpurata), a specialty tropical cut flower, was planted under a sustainable alley cropping system with moringa (Moringa oleifera), to evaluate the biophysical interactions between system components. Moringa trees were planted in rows 5 m apart and were 5 years old at the time ginger lilies were planted on 1 June 2005. Two rows of ginger lilies spaced 0.6 m in row and 1.7 m between rows were planted on a 1-foot-high bed between moringa rows when trees were about 6 m tall. Alley plot length was 10 m. After a month, plant establishment was 96%. In July, the moringa trees were pruned down to 1.5 m and the biomass (foliage) was used as green manure. Ginger lilies were also mulched with straw. Plots were gradually shaded as moringa shoots developed reducing the photosynthetic photon flux to 40% of direct sun light in September and to 15% four months later. Six months after planting, height and number of shoots in shaded ginger lilies were 58% and 30% of plants in full sun, respectively. Ginger lilies began to flower 5 months after planting in the sunny plots, but no flowers were produced after 7 months in the shady plots. Since soil and tissue nitrate-N was the same between treatments, moringa biomass appears to be insufficient to increase the nutrient status of the crop. In addition, the low light intensity in the alley appears to be suboptimal for growth and production of ginger lilies.
Mack Thetford, Shibu Jose, and Edward H. Fletcher III
The demand for special forest products used in the floral industry has a rapidly expanding market. Woody cuts come from perennial shrubs, trees, or woody vines, and are used as floral design materials for the flowering branches, foliage, fruits, or stems. Evaluation of specialty and woody cut production is needed to determine if these plants may be adapted to sustainable agroforestry production systems. An agroforestry approach to woody cuts production for longleaf pine (Pinus palustris) producers in Florida is a natural approach given the relatively open canopy of this timber species and the occurrence of several native species with ornamental characteristics that are currently utilized on a small scale for woody cuts production. The present approach to evaluating the suitability of these systems utilizes the following objectives: 1) Evaluate the production potential of ornamental species in monoculture and agroforestry silviculture systems and determine the biophysical interactions between system components. This objective will assess system design and its role on system productivity; determine time to ornamental yield. 2) Quantify the cost of establishing ornamentals for woody cuts production in both monoculture and agroforestry systems. This objective will identify and track overhead/fixed costs and variable costs associated with the ornamental cuts and timber crops for monoculture and agroforestry production systems over a 3-year period. 3) Investigate potential markets for the distribution and sale of cut foliage, flowers or stems. This objective will lead to consultations with florists and cut foliage wholesalers about potential market volume, price, and specifications for products produced within the longleaf pine agroforestry production system.
Mack Thetford, Jeffrey G. Norcini, Barry Ballard, and James H. Aldrich
Full sun trial gardens (full sun) were established at Leon County (LC) and Santa Rosa County (SRC), Florida, to evaluate the effect of site on horticultural performance traits pertinent to landscape use (long-term growth, flowering, vigor, overall quality, and survival) of native and nonnative warm season grasses when grown under low-input landscape conditions over a 3-year period. The gardens contained landscape fabric- (LC) or plastic (SRC)-covered rows, with the synthetic mulch at each site covered by 4 inches of hardwood chip mulch. Fifteen native and eight nonnative grass species, and cultivars were evaluated as were the two grass-like species black flowering sedge (Carex nigra) and narrowleaf silkgrass (Pityopsis graminifolia), a native dicot with grass-like foliage. Many of the native species were derived from seeds or plants collected from naturally occurring populations in Florida, and other species or cultivars were obtained from commercial sources. Based on quality ratings and survival, a majority of the species and cultivars were rated as at least being marginally acceptable for 2 years or more, but only six species and cultivars were rated as excellent or good over all 3 years. Four of these six species were native, with 100% survival at both sites occurring only for purpletop tridens (Tridens flavus). The other three native species, gulf hairawn muhly, (Muhlenbergia capillaris var. filipes), ‘Alamo’ switchgrass (Panicum virgatum), and indian woodoats (Chasmanthium latifolium) had high rates of survival. Porcupine grass (Miscanthus sinensis ‘Strictus’) and ‘Cabaret’ silver grass (M. sinensis ssp. condensatus) were the only two nonnative species demonstrating potential for long-term performance in a low-input landscape at both sites. Three of the four cultivars of miscanthus (Miscanthus spp.) survived the entire evaluation period in SRC, while two cultivars suffered losses only in LC, demonstrating the importance of site effects on the long-term performance of individual species or cultivars of grasses. Chalky bluestem (Andropogon capillipes) (Orange County, FL), sand lovegrass (Eragrostis trichoides), giant silver grass (Miscanthus ×giganteus), and bamboo muhly (Muhlenbergia dumosa) each survived 3 years at one site but only 1 year at the other site. Pineland threeawn (wiregrass) (Aristida stricta), ‘Red Baron’ cogon grass (japanese blood grass) (Imperata cylindrical), ‘Hameln’ fountain grass (Pennisetum alopecuroides), black flowering fountain grass (P. alopecuroides ‘Moudry’), and ‘Feesey Form’ ribbon grass (Phalaris arundinaceae) were categorized as marginal for low-input landscapes and could only be considered short-term perennials under the conditions of this test. ‘Morning Light’ silver grass (M. sinensis), coastal bluestem (Schizachyrium maritimum), and ‘Lometa’ indiangrass (Sorghastrum nutans) had good 2-year landscape performance and survived at least 2 years at both sites. Bigtop lovegrass (Eragrostis hirsuta), silver plumegrass (Saccharum alopecuroides), and lopsided indiangrass (Sorghastrum secundum) were categorized as having excellent 1-year landscape performance and have potential for short-term performance under low-input conditions. Chalky bluestem (Andropogon capillipes) (SRC), black flowering sedge, ‘Heavy Metal’ switchgrass (Panicum virgatum), and narrowleaf silkgrass were categorized as having good 1-year landscape performance.
Mack Thetford, Gary W. Knox, and Edwin R. Duke
Full sun trial gardens were established at two sites in northern Florida. Six U.S. native and three non-native warm season grass species were evaluated in a split-plot design. Only eastern gamagrass (Tripsacum dactyloides), elliott's lovegrass (Eragrostis elliottii), gulf hairawn muhly (Muhlenbergia capillaris), little bluestem (Schizachyrium scoparium), and ‘Central Park' maiden grass (Miscanthus sinensis) showed a significant response to supplemental irrigation or fertilization. Supplemental irrigation did not influence foliage height for any of the grasses, whereas supplemental fertilization influenced foliage height only for chinese fountain grass (Pennisetum alopecuroides). The response differences between locations were attributed in part to soil types. This study observed minimal or no response of shoot growth to supplemental irrigation or fertilization for the grass species tested, thereby affirming the broad adaptability and minimal need for inputs for these ornamental landscape plants.
Mack Thetford, Debbie Miller, Kathryn Smith, and Mica Schneider
Survival and subsequent growth of two beach species produced in containers of differing volume and depth were evaluated following transplant on Eglin Air Force Base, Santa Rosa Island, Fla. Rooted cuttings of gulf bluestem (Schizachyrium maritimum) were produced in four container types: 1-gal (gallon), 0.75-gal treepot, 1-qt (quart), or 164-mL Ray leach tube (RLT) containers. Root and shoot biomass of gulf bluestem harvested after 12 weeks in container production were greatest for plants grown in treepot containers and root: shoot ratio decreased as container size increased. Regardless of container size, survival of beach-planted gulf bluestem was 100%. Basal area of plants from standard gallon and treepot containers was similar 11 months after transplant and basal area for plants from treepot containers remained greater than plants from quart or RLT containers. Effect of planting zone [92, 124, 170, and 200 m landward of the Gulf of Mexico (Gulf)] on transplant survival was also evaluated for inkberry (Ilex glabra). Seedling liners of inkberry were produced in 3-gal treepot or gallon containers. Inkberry was taller when grown in 3-gal treepot containers than when grown in gallon containers. Regardless of container size, all inkberry planted 92 m from the Gulf died. Inkberry survival (>75%) when grown in 3-gal treepot containers was two to six times greater than plants grown in gallon containers (15%, 50%, 40%; 124, 170, and 200 m from Gulf, respectively). After 15 months, inkberry grown in 3-gal treepot containers remained larger with 1.5 times the mean maximum height and twice the mean canopy area compared to those grown in gallon containers.
Mack Thetford, Stuart L. Warren', Frank A. Blazich, and Judith F. Thomas
Uniconazole was applied as a foliar spray at 0, 90, 130, 170, or 210 ppm to rooted stem cuttings of `Spectabilis' forsythia (Forsythia xintermedia Zab.) potted in calcined clay. Uniconazole resulted in higher total leaf chlorophyll (chlorophyll + chlorophyll,) concentration and a decreased ratio of chlorophyll a: b. Stomata1 density of the most recently matured leaves increased linearly with increasing uniconazole concentration 40, 60, and 100 days after treatment (DAT). The number of stomata per leaf (stomata1 index) increased linearly with increasing concentration of uniconazole throughout the initial 100 DAT. Uniconazole suppressed stomata1 length at all sampling dates and the level of suppression increased with increasing concentration of uniconazole from 20 to 100 DAT. Stomata1 width was suppressed by uniconazole at 40 DAT. Leaves developed after uniconazole application had higher levels of net photosynthesis when measured 55, 77, and 365 DAT. Stomata1 conductance for uniconazole-treated plants was higher compared to nontreated control (0 mg·liter-1) plants when measured 49, 55, 77, and 365 DAT. Initiation of secondary xylem for stem tissues of uniconazole-treated plants was suppressed and expansion of xylem vessel length and width was less. Secondary phloem tissues of stems from uniconazole-treated plants contained larger numbers of phloem fibers having smaller cross sectional areas than phloem fibers of controls. Chemical name used: (E)-1-(p-Chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-01 (uniconazole).