Progress 06/30/04 to 09/30/09
Outputs
OUTPUTS: Scheiber, S. M.; Vyapari, S. no longer employees at University PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Scheiber, S. M.; Vyapari, S. no longer employees at University
Publications
- No publications reported this period
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Excessive landscape water consumption and contamination of groundwater supplies with nitrates from agricultural endeavors are becoming an increasing concern. Despite regulations aimed at water conservation and reductions in non-point source pollution, water management districts within Florida regulate irrigation frequency but not application volumes. Thus total volume applied can vary in magnitude and potentially result in over-irrigation and increased nitrate leaching. As intensely managed portion of the landscape requiring frequent water and fertilizer applications, flower beds provide an additional origin for non-point source pollution. Many investigations into irrigation and plant establishment have been conducted that applied equivalent volumes at each irrigation. Such methods make discernment between affects of irrigation frequency and quantity on growth difficult. Solenostemon scutellarioides (coleus) were grown in drainage lysimeters in two concurrent experiments to evaluate effects of irrigation quantity and frequency on growth responses, actual evapotranspiration (ETa), leaf gas exchange, and nitrate leaching from simulated landscape beds. Lysimeters in Experiment 1 were irrigated either with 13 mm daily or 13 mm every other day to evaluate the effect of irrigation quantity. In Experiment 2, lysimeters were irrigated every 2 days with 13 mm or every 3 days with 18 mm such that total depth applied was equivalent to determine the impacts of irrigation frequency. Research results are incorporated in several landscape management courses (Landscape and Turfgrass Management, Residential Landscape Design, and Landscape Plant Establishment) at the University of Florida to ensure our future horticultural professionals are appraised of findings that will impact regulations and restrictions. Furthermore, it provides students with the latest information on cultural practices that reduce environmental impacts. Presentations are given to groups including landscape professionals, middle and high school students, community college students, garden clubs, and Master Gardeners. The talks are aimed at stressing the importance of water conservation during both the establishment and post-establishment phases of landscape management as demands on portable water increase with urban expansion. Both practical horticultural knowledge of landscape establishment and maintenance are addressed, as well as, the latest research findings that conserve water in urban landscapes at a level appropriate for the audience. Research findings are frequently presented at scientific meetings and in refereed and non-refereed publications in order to contribute to efforts to reduce landscape water consumption. Finally, reports and presentations are prepared and delivered to regulatory agencies to be used to amend current regulations and make recommendations. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In Experiment 1, daily irrigation increased mean leachate by 59% and doubled nitrate leached compared to every other day (22.9 kg N ha-1 versus 10.8 kg N ha-1, respectively). Total irrigation volumes applied with daily irrigation exceeded every other day irrigation by 88% resulting in higher cumulative ETA with daily irrigation. In Experiment 2, irrigation frequency had no effect on irrigation quantity or nitrate leached. In these experiments, assimilation rates, stomatal conductance, and transpiration rates were influenced by day since irrigation, with values lower on days without irrigation. However, neither irrigation quantity nor frequency affected final shoot dry mass, root dry mass, height and growth indices. Most Florida water management districts permit daily irrigation for 30-60 d following transplant. During the post-establishment period, application frequencies for overhead irrigation ranging from weekly to 3 times per week dependent on municipality and severity of drought conditions. However, the restrictions address frequency and not volume. Similar regulations exist in many locations throughout the country. Unfortunately, these recommendations often lack scientific merit being based primarily on anecdotal data leaving landscape professionals and homeowners with the task of scheduling irrigation despite a lack of information and understanding of plant water needs. This lack of information often results in over-irrigation. Research indicates equivalent size and quality resulting from daily irrigation can be obtained with half the irrigation quantity (every 2 d irrigation), reducing negative environmental impacts from nitrogen depletion and potential contamination of ground water supplies. Finally, provided total application volumes are equivalent, application frequencies can vary and yet still correspond with current regulations without compromising growth and aesthetic quality.
Publications
- Scheiber, S. M., R.C. Beeson, J. Chen, Q. Wang and B. Pearson. 2008. Evaluation of irrigation frequency and volume on leaf gas exchange, growth, and nitrate leaching of coleus in a simulated landscape. HortScience. 43:881-884.
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Progress 10/01/06 to 09/30/07
Outputs
Although new and innovative measures to reduce landscape water consumption are being sought, traditional methods of plant selection and water restrictions prevail. Native species are often promoted as drought tolerant with little information to support or refute such claims. Thus, 10 native and 10 exotic species, commonly utilized in landscapes, were independently evaluated for post-establishment growth and aesthetics under irrigated and non-irrigated landscape conditions. At termination of the experiment, canopy size of eight native [beautyberry (Callicarpa americana), fringe tree (Chionanthus virginicus), yaupon holly (Ilex vomitoria 'Nana'), virginia sweetspire (Itea virginica), wax myrtle (Myrica cerifera), chickasaw plum (Prunus angustifolia), saw palmetto (Serenoa repens), and coontie (Zamia floridana)] and eight exotic [golden dewdrop (Duranta erecta), cape jasmine (Gardenia augusta), crape myrtle (Lagerstroemia indica), oleander (Nerium oleander), japanese
pittosporum (Pittosporum tobira), indian hawthorne (Rhaphiolepis indica), sweet viburnum (Viburnum odoratissimum) and sandankwa viburnum (Viburnum suspensum)] species were similar for irrigated and non-irrigated treatments. Irrigation resulted in larger canopy sizes for two native [walter's viburnum (Viburnum obovatum) and inkberry (Ilex glabra)] and two non-native [japanese privet (Ligustrum japonicum) and fringe flower (Loropetalum chinensis)] species. Among the native species with larger canopy sizes under irrigated conditions, all are indigenous to swamps and streams. With the exception of virginia sweetspire, plant density and dieback were similar for irrigated and non-irrigated plants of all taxa examined. Irrigated and non-irrigated plants were similar aesthetically. Data emphasize the importance of selecting plant material adapted to existing environmental landscape conditions. In regards to water restrictions, many municipalities and water management districts have instituted
watering schedules to regulate landscape water usage. However, emphasis is placed upon irrigation frequency with little regard for total application volumes. To access impacts of irrigation frequency on growth and aesthetic quality, Pentas lanceolata were irrigated every 1, 2, or 3 days with 10 L, 15 L, and 30 L, respectively. Volumes differed for each frequency such that every 3 days a total volume of 30 L was applied to all treatments. Canopy size increased by 30% and 19%, respectively for 1- and 2-day frequencies compared to plants irrigated every 3 days. Throughout the experiment, irrigation frequency had no effect on landscape quality. Although quality was similar among frequencies, irrigation frequency affected growth with more frequent applications producing large plants. Current projects include developing landscape irrigation coefficients for mixed landscapes and continued evaluation of the impacts of irrigation frequency on the establishment of commonly utilized landscape
shrubs.
Impacts
Numerous factors including plant selection and irrigation frequency affect growth and aesthetics of urban landscapes as well as the necessity for supplemental inputs during the establishment and post-establishment phases. Although selection of native species to conserve water in urban landscapes has been recommended, performance in the landscape appears to be associated with factors other than native origin. Furthermore, water restrictions that solely address frequency and not volume can result in over-irrigation particularly in soils with low water holding capacity. By matching environmental conditions with plant selection and/or cultural practices, supplemental inputs can be reduced while quality is maintained.
Publications
- Scheiber, S.M., E.F. Gilman, M. Paz, and K.A. Moore. 2007. Irrigation affects landscape establishment of burford holly, pittosporum, and sweet viburnum HortScience. 42:344-348.
- Vyapari, S., S.M. Scheiber, and E.L. Thralls. 2007. Pre-transplant root ball condition influences growth of plumbago during establishment. HortTechnology. 17:486-490.
- Scheiber, S. M., R.C. Beeson, J. Chen, and Q. Wang. 2008. Evaluation of irrigation frequency and volume on leaf gas exchange, growth, and nitrate leaching of coleus in a simulated landscape. HortScience. Accepted.
- Scheiber, S.M, E.F. Gilman, D.R. Sandrock, M. Paz, C. Wiese and M.M. Brennan. 2008. Post-establishment landscape performance of Florida native and exotic shrubs under irrigated and non-irrigated conditions. HortTechnology. 18:59-67.
- Scheiber, S.M., D.R. Sandrock, and E. Alvarez. 2008. Effect of salt spray concentration on growth and appearance of 'Gracillimus' maiden grass and 'Hamelin' fountain grass. HortTechnology. 18:34-38.
- Alvarez, E., S.M. Scheiber, R.C. Beeson, and D.R. Sandrock. 2007. Drought tolerance responses of purple lovegrass and Adagio maiden grass. HortScience. 42:1695-1699.
- Pearson, B. and S.M. Scheiber. 2007. Growth and aesthetic quality of pentas as influenced by irrigation frequency. HortScience. 42:964-965.
- Scheiber, S.M. and R.C. Beeson. 2007. Landscape growth and aesthetic quality of coleus managed with irrigation deficits. HortTechnology. 17:561-566.
- Scheiber, S. M., R.C. Beeson, and S. Vyapari. 2007. Pentas water use and growth in the landscape as affected by municipal compost and mined field clay soil amendments. HortScience. 42:1744-1747.
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Progress 10/01/05 to 09/30/06
Outputs
Urban landscapes are a dynamic environment with numerous factors affecting growth during establishment and pos-establishment. Plant selection and cultural practices were investigated to promote growth and aesthetic quality with minimal inputs. Non-native Miscanthus sinensis Adagio and native Eragrostis spectabilis were evaluated for drought tolerance in response to irrigation application rates of 0 L, 0.25L, 0.5L, or 0.75L. As irrigation rates increased, plant mass, canopy size, and shoot to root ratios increased for both species, being greatest at the 0.75 L rate. Shoot dry mass, total biomass, and shoot to root ratios were greater for E. spectablis than M. sinensis Adagio. Cumulative water stress integral was also greater for E. spectabilis. Greater growth in conjunction with higher cumulative water stress integrals indicates the native E. spectabilis is more drought tolerant than non-native M. sinensis Adagio. In a related study, Miscanthus sinensis Gracillimus and
Pennisetum alopecuroides Hamelin were subjected to four treatments (100% seawater, 50% seawater, 25% seawater, or 100% deionized water) to determine salt spray tolerance. As seawater concentration increased, root, shoot, whole plant biomass gain, height, flower number, and visual quality decreased for both taxa; however, P. alopecuroides appears to be slightly more tolerant of salt spray than M. sinensis Gracillimus. Plant selection was further investigated by comparing growth and water stress of native Myrica cerifera and non-native Ligustrum japonicum. Each species was irrigated either daily or every three days. Water potentials were recorded on three consecutive days monthly, with cumulative stress intervals calculated. On days without irrigation, water stress was generally greater and affected growth. Myrica irrigated daily had the greatest growth, yet plants receiving irrigation every 3 days had the least growth and greater leaf drop. In contrast, Ligustrum growth responses were
similar between irrigation regimes. Ilex cornuta Burford Nana, Pittosporum tobira Variegata and Viburnum odorotissimum were evaluated for growth, aesthetic quality and establishment rates in response to 2-, 4-, or 7-day irrigation frequencies. Establishment was delayed one to two months for I. cornuta Burford Nana irrigated every 7 d; however, growth and aesthetics were similar among treatments. Leaf area, shoot dry mass, and total biomass increased among P. tobira Variegata and V. odorotissimum irrigated every 2 d. Pittosporum tobira Variegata and V. odorotissimum irrigated every 2 d also had greater canopy size and root dry mass, respectively. Neither water stress nor establishment was affected by irrigation frequency for either species. Current projects include comparisons between tensiometers and dielectric soil moistures probes to provide irrigation at 80%, 60% and 40% of plant available water and effects on water stress, growth and aesthetic quality of Pelargonium hortorum. In
addition, the effect of irrigation regimes to control spread of pathogens, such as Rhizoctonia, among herbaceous perennials in landscapes in being investigated.
Impacts
Plant selection and proper cultural practices are vital for rapid establishment and maintenance of high quality established urban landscapes that require minimal inputs. Native species are often promoted as drought or salt tolerant, yet research indicates origin does not guarantee success in the disturbed environments that characterize urban landscapes. Proper screening for drought and salt tolerance facilitates plant selection that matches environmental conditions, thus reducing inputs without compromising quality. Furthermore, many current recommendations are based on antidotal information and evaluation of cultural practices provides information for improved regulations.
Publications
- Vyapari, S., Scheiber, S. M. & Thralls, E. L. 2006. Pre-transplant root ball conditions influences growth of Plumbago auriculata during landscapes establishment. HortTechnology. In Press
- Scheiber, S.M. and Richard C. Beeson, Jr. 2006. Petunia growth and maintenance in the landscape as influenced by alternative irrigation strategies. HortScience. 41:235-238.
- Scheiber, S. M., R.C. Beeson, and H. Bass. 2006. Comparison of water use efficiency of native and non-native shrub species in the landscape. HortScience. 41:999.
- Scheiber, S.M, Richard C. Beeson, Jr., and Sudeep Vyapari. 2006. Pentas water use and growth in simulated landscapes as affected by municipal compost and mined field clay soil amendments. HortScience Submitted.
- Alvarez, E., S.M. Scheiber, David R. Sandrock, and Richard C. Beeson, Jr. 2006. Drought tolerance responses of purple lovegrass and Adagio maiden grass. HortScience Submitted
- Alvarez, E., S.M. Scheiber, and D.R. Sandrock. 2006. Irrigation requirements and drought responses of two ornamental grass species. HortScience. 41:1009.
- Alvarez, E., David R. Sandrock, and S.M. Scheiber. 2006. Salt spray tolerance of Gracillimus maiden grass and Hamelin fountain grass. HortTechnology Submitted
- Scheiber, S. M., E.F. Gilman, M. Paz, and K.A. Moore. 2006. Irrigation affects landscape establishment of burford holly, pittosporum, and sweet Viburnum. HortScience. In Press
- Scheiber, S.M. and Richard C. Beeson, Jr. 2006. Establishment and growth of begonias in the landscape as affected by root ball condition at transplant. J. Environ. Hort. In Press
- Scheiber, S.M. and R.C. Beeson. 2006. Landscape growth and water use efficiency of coleus managed with irrigation deficits. HortScience. 41:1058.
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Progress 10/01/04 to 09/30/05
Outputs
Cultural practices including irrigation strategies were investigated to determine the effects on increasing establishment rates and decreasing inputs in the landscape environment. Begonia semperflorens were transplanted into an open-sided clear polyethylene covered shelter to evaluate the effect of root ball condition on establishment and growth. Three root ball classes were evaluated: non root-bound (NRB; 6 week old plants), root-bound (RB; 10 week old plants), and root-bound with the bottom 1 cm of the root ball removed (RBM). Non root-bound plants had greater growth rates for both height and canopy size and faster rates of accumulation for cumulative root dry mass and new root dry mass relative to the other treatments tested. Cumulative shoot dry mass, new shoot dry mass, and total biomass accumulation rates were slower among RB plants compared to other rootball conditions. Mean canopy size, shoot dry mass, and biomass of NRB were significantly less at transplant;
however, differences were non-significant by final harvest relative to other treatments. Final mean shoot to root ratios were lower for the NRB treatment relative to RBM. Results indicate smaller, NRB transplants establish faster in the landscape. Furthermore, rootball manipulation is not recommended as it had no significant effect on root establishment or canopy growth of annual bedding plants in the landscape. The study was repeated using Plumbago auriculata with the exception of rootball manipulation technique. Manipulated rootballs were vertically sliced. Results were similar to Begonia. The data indicate that the practice of disrupting root-bound plants has no benefit on establishment or growth of either Begonia or Plumbago in the landscape. Previous research has indicated bedding plants can be maintained at less than field capacity; however, canopy size and aesthetic quality were compromised. Therefore, Solenostemon scutellarioides (coleus) were grown in drainage lysimeters in
an open-sided clear polyethylene covered shelter to access growth characteristics and landscape quality of bedding plants irrigated at various manageable allowable deficits. Using tensiometers, plants were irrigated back to field capacity when 30, 40, or 50% of plant available water has been depleted. Deficits will be evaluated versus a control treatment of 1.25 cm daily irrigation. In addition, plants were grown in an uncovered companion field plot. In a related project, Solenostemon scutellarioides (coleus) were grown in drainage lysimeters to evaluate growth responses and nitrate leaching in relation to different fertilization regimes. Each lysimeter received 1.25 cm of irrigation daily. Each lysimeter received one of four fertilization regimes: controlled release fertilizer - one application; controlled release fertilizer + compost (50% b/v) - one application; compost (50% b/v)- one application; and liquid fertilizer. Growth indices, biomass, irrigation and leachate volumes, leaf
gas exchange measurements, and landscape quality ratings were recorded for both studies. Data is currently undergoing analysis.
Impacts
Cultural practices such as root ball slicing and plant size significantly affect establishment rates and could potentially reduce irrigation requirements as water consumption is less for established landscapes. Furthermore, cultural practices that do not promote establishment should be evaluated since labor accounts for 30-40% of total operational costs in the green industry.
Publications
- Scheiber, S.M., Richard C. Beeson, Jr., and S. Vyapari. 2005. Establishment and growth of begonias in the landscape as affected by root ball condition at transplant. HortScience. 40:985.
- Vyapari, S., Thralls, E.L., and S.M. Scheiber. 2005. Establishment of root-bound Plumbago auriculata Lam. in a landscape. HortScience. 40:1078.
- Scheiber, S.M. and Richard C. Beeson, Jr. 2004. Petunia growth and maintenance in the landscape as influenced by alternative irrigation strategies. HortScience. 39: 771.
- Vyapari, S., S.M. Scheiber, and Richard C. Beeson, Jr. 2004. Effect of soil amendments on growth of Pentas in a simulated landscape. HortScience. 39:790.
- Scheiber, S.M., Beeson, Richard C. Jr. , Chen, J. , Wang, Q. 2003. Evaluation of Various Irrigation Regimes on the Growth and Maintenance of Coleus in the Landscape. HortScience. 38:812.
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Progress 06/30/04 to 12/31/04
Outputs
Solenostemon scutellarioides (coleus) were grown in drainage lysimeters to evaluate growth responses and nitrate leaching of annual bedding plants in relation to different irrigation regimes. Lysimeters were irrigated at one of three rates: 1.25 cm daily, 1.00 cm every other day, and 1.75 cm every 3rd day. Leaf gas exchange measurements, irrigation and leachate volumes, growth indexes, and biomass were recorded. Mean leachate and nitrate volumes were highest with daily irrigation. On days without irrigation, assimilation rates, stomatal conductance, and transpiration rates were generally lower. However, no significant differences were found among treatments for final shoot dry mass, root dry mass, height or growth indices indicating coleus can be maintained with less than daily irrigation regimes. To determine the effect of soil amendments on growth responses of Pentas lanceolata in the landscape, pentas were grown in drainage lysimeters. Treatments were non-amended
top soil (control) and soil amended with either compost (50% by volume) or clay (50% by volume) in the top 15cm. Irrigation was regulated using a tensiometer-controlled automatic irrigation system. When plant available water in each soil type had declined to 70% or less, the plants were irrigated back to field capacity. Irrigation volumes, growth indices, and biomass were recorded. Mean shoot dry weights and shoot to root ratios were significantly higher for plants grown in the compost-amended soil than for the other treatments evaluated. No significant differences were found among treatments for growth indices or root dry weight. Total irrigation volume applied was not significantly affected by soil amendment indicating no benefits of soil amendments for water conservation. However, the data indicates that compost-amended soils produced larger plants with equivalent irrigation volumes. Petunia hybrida Midnight were grown in drainage lysimeters in an open-sided clear polyethylene
covered shelter to evaluate growth responses in response to alternative irrigation strategies. Three irrigation methods were evaluated: tensiometer-controlled irrigation, regularly scheduled irrigation with an automated controller, and human perception of plant water needs. Lysimeters irrigated by an automated controller received 1.3 cm daily. Tensiometer-controlled lysimeters were irrigated when plant available water had declined to70% or less. Growth indices, biomass, irrigation and leachate volumes and leaf gas exchange measurements were recorded. Daily irrigation resulted in significantly higher assimilation rates, shoot dry mass, biomass, shoot to root ratios, and growth indices than the other treatments. Hand-watering and tensiometers resulted in significant decreases in applied irrigation volumes and mean leachate volumes. Visual observations of aesthetic quality revealed noticeable differences among treatments with hand-watered treatments showing the greatest negative
response. Although petunias can be maintained by alternative irrigation strategies, the data indicate significant water stress with reduced landscape quality.
Impacts
Water consumption and corresponding percolate and/or nitrate leaching can be significantly reduced in annual landscape beds through cultural practices such as reduced irrigation regimes, alternative irrigation strategies, or the addition of soil amendments. However, the benefits must be balanced with potential reductions in landscape plant quality and/or canopy size.
Publications
- No publications reported this period
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