Progress 10/01/12 to 09/30/17
Outputs
Target Audience:Research findings were shared with academic audiences and industry professionals. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Graduate students worked on this project for several years and gained valuable experience in nursery and greenhouse production, as well as an understanding of the need for improved production efficiency. How have the results been disseminated to communities of interest?Results were shared at state field days and regional and national meetings with growers and academics. Research have been published in peer-reviewed journals and shared with private industry. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Around 30 experiments were conducted over the duration of this project on main campus and at the Ornamental Research Center in Mobile involving faculty members, graduate students, technicians, and AAES personnel. Research was applied and supported the greenhouse and nursery industry in Alabama, the Southeast, and the U.S. New plant growth regulators were evaluated, as well as existing PGRs.Results led to new labeling and expansion of existing labels, providing growers with additional tools for improved production efficiency of landscape trees and herbaceous plants. Five experiments were completed in 2017 with the objective of determining the optimal application timing and concentration for applying a paclobutrazol substrate drench for plant size control and improved market quality of gerbera daisy. Plants in 5-inch pots were treated with a substrate drench of 0, 1.5, or 3 ppm paclobutrazol or a 2500 ppm daminozide foliar spray at weekly intervals from 2-6 weeks after transplanting (WAT). A 2500 ppm daminozide standard was applied 2 WAT and again 10 days later. Foliage height, plant size index, flower diameter, peduncle length, and quality rating decreased, while days to first open flower (DTF) increased with increasing paclobutrazol concentration regardless of application timing. Increasing WAT resulted in earlier flowering and a reduction in peduncle length, regardless of plant growth retardant (PGR) treatment. Foliage height, size index, flower diameter, peduncle length, and quality rating of plants receiving daminozide weekly were less than or not different from 0 ppm paclobutrazol, but greater than those receiving 1.5 or 3 ppm paclobutrazol. Based on quality ratings, no growth retardant, regardless of concentration or timing produced the highest quality rating. The ineffectiveness of PGR treatments may have been because the study was conducted in the summer when temperatures and light intensities were higher than at other times of the year.
Publications
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Target audience included nursery and greenhousegrowers and applied horticultural researchers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Graduate students worked on this project for several years and gained valuable experience in nursery and greenhouse production, as well as an understanding of the need for improved production efficiency. We have disseminated information from this project at field days and open houses and through seminars. Results have also been published in refereed journals. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to address the goals of this project and results will be submitted to refereed journals during the final year of thsi project.
Impacts
What was accomplished under these goals?
Production efficiency is essential to profitability in the growing of herbaceous and woody landscape plants. Both of the major goals of this project address improved production efficiency. Findings from 2016: 'Coronation Gold' yarrow is a popular herbaceous perennialthat has potential as a flowering potted crop for greenhouse production if plant height can be controlled and flowering improved. Pinching the plant following propagation increased flowering and non-flowering shoots and total offset number and decreased flower stem length without affecting days to flower, but decreased inflorescence diameter. Pinching at 7 weeks after potting resulted in the highest number of flowering and non-flowering shoots and total offsets, the fewest days to flower and intermediate flower stem length. Although pinching increased the number of flowering, non-flowering, and total offsets, it was labor intensive and difficult to remove the apical buds because of the close spacing of the nodes in the vegetative offsets, hence, the practice may not be economical. Daminozide decreased flower stem length without affecting inflorescence diameter or total offset number, but increased days to flower. To be marketable as a potted crop, greater height suppression in this species would be desirable, which may be obtainable with multiple applications of daminozide, but further delays in flowering should be expected. Starting NIL at 4 weeks after pinching resulted in the fewest days to flower, the highest flowering offset number, and a flower stem length about equal to starting NIL treatments earlier, but the effects on flowering offset numbers was not of horticultural importance.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Li, M., J.R. Kessler, Jr., G.J. Keever, and W.G. Foshee. 2016. Pinching, daminozide and night-interrupted lighting start date affect growth and flowering of Achillea x 'Coronation Gold'. J. Environmental Hort. 34:13-18.
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:Research findings were shared with academic audiences and industry professionals. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Graduate studentsworked on this project for several years and gained valuable experience in nursery and greenhouse production, as well as an understanding of the need for improved production efficiency. We have disseminated information from this project at field days and open houses and through seminars. Results have also been published in refereed journals. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to address the goals of this project and results will be submitted to refereed journals.
Impacts
What was accomplished under these goals?
Production efficiency is essential to profitability in the growing of herbaceous and woody landscape plants. Both of the major goals of this project address improved production efficiency. Findings from 2015 are summarized below. Previous studies have indicated that application timing or plant developmental stage plays a role in determining plant response to plant growth regulators (PGRs).Foliar applications of 200 ppm cyclanilide (CYC) were made to 'Snow White' Indian hawthorn (Rhaphiolepis indica 'Snow White') and 'Sky Pencil' holly (Ilex crenata 'Sky Pencil') at three stages of new shoot development: bud break [development stage 1(DS 1)], active shoot elongation (DS 2), and to recently matured shoots (DS 3). A repeat of the experiment in 2008 included an additional application to 'Sky Pencil' holly before bud break (DS 0). Cyclanilide promoted branching of both species, regardless of the developmental stage at application. However, persistent foliar injury to Indian hawthorn treated at bud break reduced end-of-season plant quality compared to plants treated later and to untreated plants. Sky Pencil' holly was tolerant to foliar applications of CYC and the minimal foliar injury that did occur would not have affected marketability. Plants of both species treated at DS 2 and DS 3 were dense, compact, and of higher quality at the end of the growing season than untreated plants. These results indicate a difference in sensitivity of the two species to foliar-applied CYC, that applications should be avoided to Indian hawthorn at bud break, and that the highest quality in 'Sky Pencil' holly was achieved when CYC was applied at later stages of shoot development (DS 2 and DS 3). Recommendations for the timing of transplanting bedding plants from plug flats into larger containers are usually based on plug age, and are given as a range in days or weeks. However, growth rate of bedding plants vary with seed quality, cultural practices, and environmental conditions, among other factors, making time from sowing to transplanting a poor predictor of shoot and root development and subsequent plant performance. We evaluated how seedling development stage, based on plant node counts, at transplanting from plug flats into small pots affected growth and flowering of two commonly grown bedding plants. Time to first flower from transplanting decreased with both species in two experimental runs, except with medallion flower in the second run, as time from sowing to transplanting increased. In contrast, time to flower of both species from sowing increased linearly as time from sowing to transplanting increased. Practical implications of this response are that for earlier flowering, a grower should transplant seedlings from plug flats to larger pots as soon as they can be handled; however, once transplanted, seedlings will require more bench space for longer than if they were held in plug flats until further development. With both globe amaranth and medallion flower, node counts were strongly correlated with time to flower; however, differences in the magnitude of the effect of node counts in two experimental runs indicated that other factors, most likely light intensity and duration, were also affecting time to flower. The effects of these other factors limit the usefulness of developmental stage as a predictor of flowering. Shade trees for high-end markets must be uniform and have dense, symmetrical canopies. To meet these demands, nurserymen prune the lateral shoots and the central leader multiple times throughout production. This is a labor-intensive process, especially when pruning requires working from lifts. The plant growth regulator dikegulac applied as 800 or 1,600 ppm foliar sprays can greatly increase the branching of southern sugar maple and blackgum without the removal of the central leader. With both species, early and mid-season applications were more effective than only an early-season application. Although branching was greatly increased, some mechanical pruning would be necessary to both species to ensure that lateral branches are radially and vertically spaced along the central leader. 'Coronation Gold' yarrow is a widely grown herbaceous perennial that has potential as a flowering potted crop for greenhouse production. Numerous references have been made in production literature to the importance of early fall transplanting of herbaceous perennial liners into final containers to allow sufficient time for vegetative growth before plants are exposed to photo-inductive conditions, a practice known as bulking. This increase in the size of the root system and crown is speculated to promote more shoots of sufficient developmental size to respond to inductive photoperiods, resulting in an increase in flowering shoots. In this study, increasing the bulking duration increased the number of offsets at the end of bulking and flower and flower bud number and reduced days to flower from the beginning of NIL of 'Coronation Gold' yarrow, without affecting plant height. At first flower, plants in all bulking treatments not treated with daminozide (B-Nine) were considered tall for the production containers. However, two foliar applications of daminozide suppressed flower stem length 20% to 43%. Plants bulked longer and treated with daminozide were considered more marketable as a potted crop.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Chappelka, A.H., E.F. Loewenstein, G.L. Somers, G.J. Keever, and N.A. Martin. 2015. Determination of crew size efficiency relative to urban tree inventories. Arbor. & Urban For. 4:223229.
- Type:
Other
Status:
Published
Year Published:
2015
Citation:
Dyer, J.F., B. Barlow, J. Kush, W. Morse, L. Teeter, and G. Keever. 2015. Factors in Alabama landowner interest in harvesting pine straw and willingness to accept prices. Agroforestry Systems. Online. http://link.springer.com/article/10.1007/s10457-015-9816-8 .
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Williamson, Z., G.J. Keever, J.R. Kessler, and J.W. Olive. 2015. Developmental stage of Snow White Indian hawthorn and Sky Pencil holly affects response to cyclanilide. J. Environ. Hort. 33:
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Keever, G.J., J.R. Kessler, Jr., G.B. Fain, and D.C. Mitchell. 2015. Seedling developmental stage at transplanting affects growth and flowering of medallion flower and globe amaranth. J. Environ. Hort. 33:5357.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Keever, G.J., J.R. Kessler, Jr., L.H. Hoffman, and J.C. Stephenson. 2015. Dikegulac sodium concentration and application number affect branching of blackgum and southern sugar maple during container production. J. Environ. Hort. 33:1519.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Li, M., J.R. Kessler, Jr., G.J. Keever, and W.G. Foshee, III. 2015. Bulking duration and daminozide affect growth and flowering of Achillea �Coronation Gold. 2015. Environ. Hort. 33:8488.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Research findings were shared with academic audiences and industry professionals. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? A graduate student worked on this project for several years and gained valuable experience in nursery production, as well as an understanding of the need for improved production efficency. He and others disseminated information from this project at field days and open houses, and through seminars. Results have also been published in refereed journal articlesto address both of these goals. What do you plan to do during the next reporting period to accomplish the goals? Research will continue and results will be submitted to refereed journals.
Impacts
What was accomplished under these goals?
Production efficiency is essential to profitability in the growing of herbaceous and woody landscape plants. Both of the major goals of this project attempt to address improved production efficiency. Three of the findings from 2014 are summarized below. Herbaceous perennials can be forced to flower out-of-season under greenhouse conditions by manipulating temperature and photoperiod. By staggering the initiation of night-interrupted lighting (NIL) from 10 p.m. to 2 a.m. outdoors under nursery conditions, growers in the southern United States have the potential to provide successive crops of LD and intermediate-day herbaceous perennials in peak bloom from spring until the plants' natural flowering period, thus expanding the marketing window of 'Goldsturm' coneflower, 'Miss Manners' obedient plant, 'Peachie's Pick' Stokes aster and other responsive species. However, the start of LDs must be tailored to the individual species and its natural flowering period to avoid excess overlap in peak flowering or a gap between flowering of plants exposed to NIL and those under NP. 'Goldsturm' coneflower, and to a lesser extent, 'Miss Manners' obedient plant, will require intervals of NIL start dates greater than 15 days if NIL is started as early as February 1 and only four start dates are used; the longer interval should not lessen continuous flowering due to this plant's long flowering period. Peak flowering of 'Peachie's Pick' Stoke's aster was continuous from first flower of plants under NIL until flowering of plants under NP and it is possible the same response could have been achieved with fewer NIL start dates. Herbaceous perennials are frequently grown in a vegetative state (bulking) to increase root and canopy size, and to possibly enhance flowering prior to being forced into flower. Information to support the benefits of bulking is common but largely anecdotal.A study evaluated bulking durations established by varying potting dates and the start of night-interrupted lighting (NIL) on two herbaceous perennials grown outdoors under nursery conditions. 'Goldsturm' black-eyed Susan benefitted from longer bulking durations by allowing plants to grow out of juvenility prior to being forced into flower. In addition, longer bulking increased stem and flower counts several fold. Increased bulking was also beneficial to 'Moonbeam' coreopsis. Days to flower decreased with increasing bulking duration, a response not previously reported in scientific literature, while stem counts increased with bulking duration. Based on potting date, fewer coreopsis bulked the shortest duration were marketable compared to those bulked for longer periods. However, the effects of bulking duration on flower plus flower bud counts and height of coreopsis were inconsistent. These results support early fall potting of black-eyed Susan and coreopsis plugs when plants are grown outdoors under nursery conditions in the southern United States, whether forced into flower beginning as early as February or allowed to flower naturally. Landscape trees often require repeated pruning of lateral and terminal shoots during nursery production to develop dense, well-branched canopies. When the central leader of trees is removed, a new leader must usually be reestablished from a lateral shoot to promote height growth, and its attachment to the original shoot may not be as strong, occasionally leading to failure in the landscape. Mechanical pruning is costly and time-consuming, especially when tree canopies must be worked from lifts. The plant growth regulator dikegulac offers growers an additional tool for promoting branching during production of at least the six tree species evaluated in this study without pruning the central leaders, although some mechanical pruning will still be required to ensure branches are spaced optimally along the trunks. Benzyladenine (BA) was not effective on five of the six species evaluated. However, bald cypress treated with BA was well-branched with dense canopies without needing additional mechanical pruning.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
G.J. Keever, J.R. Kessler, and J.R. Stephenson. 2014. Bulking duration affects growth and flowering of herbaceous perennials grown under nursery conditions and forced into flower under night-interrupted lighting outdoors in the southern United States. J. Environ. Hort. 32:19-26.
G.J. Keever, J.R. Kessler, and J.R. Stephenson. 2014. Effects of night-interrupted lighting on growth and flowering duration of herbaceous perennials grown under nursery conditions in the southern United States. J. Environ. Hort. 32:1318.
W.R. Miller, G.J. Keever, J.R. Kessler, and J.L. Sibley. 2014. Dikegulac sodium and benzyladenine effects on six landscape tree species during container production. J. Environ. Hort. 32:203-207.
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? Final data collection for 2013 has not yet been completed. Data will be analyzed and interpreted and plans made for 2014 studies to further address goals of this project..
Impacts
What was accomplished under these goals?
Several species were screened for their response to PGR concentration and application number. In addition, the response of several species to PGR concentration applied at different stages of plant development was determined. A bulking study was completed using herbaceous perennials and the results submitted in a manuscript to the Journal of Environmental Horticulture; this paper is currently under review.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
G.J. Keever, J.R. Kessler, and J.R. Stephenson. 2013. Response of herbaceous perennials to growth retardants applied at different developmental stages when grown under night- interrupted lighting outdoors in the southern United States J. Environ. Hort. 31:101-108.
G.J. Keever, J.R. Kessler, and J.R. Stephenson. 2013. Endofday lighting effects on herbaceous perennials grown under night interrupted lighting outdoors in the southern United States. J. Environ. Hort. 31:16.
K.A. Hester, G. Bi, M.A. Czarnota, A. Fulcher, G.J. Keever, J.H. Lieth, J.D. Orsi, B.E. Whipker, K. Sullivan and C.L. Palmer. 2013. Impact of Augeo, Configure and Florel on hydrangea branching. J. Environ. Hort. 31:2729.
Martin, N.A., A.H. Chappelka, G. Somers, E.F. Loewenstein, and G.J. Keever. 2013. Evaluation of sampling protocol for i-Tree Eco: A case study in predicting ecosystem services at Auburn University. Arboriculture & Urban Forestry 39:5661.
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