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4/16/2012
1
Using Plant Growth Regulators to Improve Plant Architecture in Herbaceous Perennial Plants
Mara GrossmanM.S. student
Department of HorticultureVirginia Tech
IntroductionCommercial production of ornamental plants
Floriculture crops 4.13 billion dollars in 2010
Potted herbaceous perennials 553 million dollars(USDA, 2011)
Liners and plug seedlings over 448 million dollars (USDA, 2009)
Southwest Perennials Inc., Dallas Texas, specializes in herb and perennial liner production
4/16/2012
2
IntroductionProduction challenges for growers
Control plant growth with both physical controls and chemical controls
Plant growth regulators (PGRs) control plant height, branching and flowering.
Van Wingerden International, Inc. located in Asheville, N.C.
IntroductionUsing PGRs
Plants respond in different ways to PGRs depending on species, cultivar, growing conditions, and the PGR utilized (Gent and McAvoy,
2000)
Treating liners prior to transplant can have significant benefits for growers.
Reduced time of application and reduced chemical cost resulting in a more cost effective method of treating plants (Whitman and
Runkle, 2003)
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IntroductionControlling Branching with PGRs
Release apical dominance Increase branching and improve
quality Substitute for pinching Pinching labor intensive Pinching delays growth and
bloom
Goal is to improve plant architecture
Synthetic cytokinin
Cytokinins promote cell division in tissue culture (Miller et. al. 1955)
Application of exogenous cytokinins in many species increases the ratio of cytokinin to auxin in the plant, disrupting apical dominance which controls branching patterns and plant form, and promotes lateral bud out growth (Cline, 1991)
BA has been shown to increase number of branches in herbaceous perennials (Farris et al., 2009; Keever, 1994; Latimer and Freeborn, 2008; Martin and Singletary, 1999)
Configure, Fine Americas Inc., labeled for use on annual and perennial flowering and foliage plants and tropical plants
IntroductionBenzyladenine (BA)
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4
Disrupts cell wall integrity Previously labeled as Atrimmec or Atrinal Primarily has been used to reduce shoot elongation and
increase branching in woody plants (Banko and Stefani, 1995; Bell et al., 1997; Bruner et al., 2002; Sachs et al., 1975)
Little research on herbaceous plants Increased branching on Zinnia, Helianthus, Chrysanthemum,
Boston fern, Kalanchoe, and Gaillardia (Arzee et al., 1977; Carter et al., 1996; Latimer and Freeborn, 2010; Nightingale et al., 1985)
Augeo, OHP, Inc., Mainland PA, labeled for use on bedding plants, herbaceous plants, perennials, woody ornamentals and trees
IntroductionDikegulac Sodium
IntroductionRationale and significance
By testing PGRs and their effect on herbaceous perennials we will:
Improve plant production methods
Strengthen the floriculture industry
Expand our knowledge of plant growth
Improve our ability to make effective PGR recommendations to growers
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To study the effects of branching agents on herbaceous perennial crops during liner production and on finished plants
To improve plant architecture at an earlier stage of production
IntroductionResearch Objectives
Outline
• Introduction
• Exp. 1: Benzyladenine (BA)
• Exp. 2: BA in combination with IBA
• Exp. 3: Dikegulac sodium (DS)
• Exp. 4: Single vs. Multiple Applications, BA and DS
• Conclusions
4/16/2012
6
Experiment One ObjectiveEvaluate the effects of BA on the shoot and root growth of 11 herbaceous perennials during liner production and grow out of finished plants
Exp. 1: Methods and Materials Plants Studied
Agastache ‘Purple Haze’
Aster ‘Professor Kippenburg’
Campanula ‘Cherry Bells’
Cosmos atrosanguineus
Gaura lindheimeri ‘Siskiyou Pink’
Lavandula x intermedia 'Provence’
Leucanthemum x superbum 'Snowcap’
Rosmarinus officinalis 'Hill Hardy'
Salvia nemorosa ‘May Night’
Verbena bonariensis ‘Lollipop’
Veronica ‘Goodness Grows’
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Exp. 1: Methods and Materials
Exp. 1: Methods and MaterialsBA Treatments
After removal from mist BA treatments were applied as foliar sprays:
•0 mg·L-1 (control)•1 application of 300 mg·L-1
•2 applications of 300 mg·L-1
(1st application after removal from mist,2nd application two weeks after 1st application)•1 application of 600 mg·L-1
In all experiments:completely randomized design for each speciesData analyzed by ANOVA
Agastache at time of treatment
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8
Exp. 1: Methods and MaterialsTreatment Application
Foliar sprays at a volume of 210 ml per m2
Sprays applied evenly to square meter plots
Not actively transported in the plant
Exp. 1:Methods and MaterialsData Collection
Data collected at 0, 2, and 3-4 weeks after treatment (WAT)
Plants were then transplanted into quart size pots (1.1 liters)
Grown out for an additional 4 weeks
Data collected at 4 weeks after transplant.
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9
Measurements included:
•Plant height•Average plant width•Lateral branches and leaders or basal branches
•Phytotoxicity•Flowering •Root and shoot dry weights•Root volume and surface area (five species)
Exp. 1:Methods and MaterialsData Collection
Exp. 1: Results and DiscussionBranching effects on finished liners
Nine of eleven crops evaluated showed an increase in branching at time of transplant.
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10
Agastache 3 WAT
40% increase in lateral branches
300x2Untreated 300x1 600x1
Agastache ‘Purple Haze’ at 3 WAT11.6b
16.1a17.6a 16.8a
0
5
10
15
20
Num
ber
of B
ranc
hes
Agastache Lateral Branchesat 3 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Gaura 4 WAT
Untreated 300x1 600x1300x2
Gaura ‘Siskyou Pink’
All BA treatments significantly increased lateral branches and leaders at 4 WAT
7.5b
9.2a 9.3a8.5a
0
2
4
6
8
10
Num
ber
of B
ranc
hes
Gaura Lateral Branches at 4WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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11
Lavandula 4 WAT
Increased branches at higher rates at 4WAT
Increased leaders at all rates of BA treatment
300x2Untreated 300 x1 600 x1
Lavandula x intermedia ‘Provence’
13.4c 14.3bc 15.6ab 16.9a
0
5
10
15
20
Num
ber
of B
ranc
hes
Lavandula Lateral Branchesat 4 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Leucanthemum 4 WAT
Basal branches doubled at 4WAT
Untreated Control
300x2Untreated 300x1 600x1
1.3a
2.5b 2.9b 2.5b
0
1
2
3
4
Num
ber
of B
ranc
hes
Leucanthemum Basal Branchesat 4 WAT
Control (0) 300x1 300x2 600x1
Leucanthemum x superbum ‘Snowcap’Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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12
Untreated 300x1 300x2 600x1
Rosemary 4 WAT
Rosmarinus 'Hill Hardy'
Lateral branches and leaders were increased with all treatments
16.9c20.4b
24.0a 24.3a
0
10
20
30
Num
ber
of B
ranc
hes
Rosemary Lateral Branchesat 4 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Salvia 4 WAT
40% increase in basal branches with one or two applications of 300 mg·L-1
Salvia ‘May Night’
3b
4.2a3.8a
3b
0
1
2
3
4
5
Num
ber
of B
ranc
hes
Salvia Basal Branches at 4 WAT
Control (0) 300x1 300x2 600x1
Untreated 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Verbena 4 WAT
Number of lateral branches was significantly increased at higher rates
Untreated 300x1 300x2 600x1
Verbena bonariensis ‘Lollipop’
2.2c
3.5bc
5.3a
3.8ab
0
1
2
3
4
5
6
Num
ber
of B
ranc
hes
Verbena Lateral Branches at 4 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Veronica 3 WAT
Untreated 300x1 300x2 600x1
Veronica spicata ‘Goodness Grows’
Lateral branching increased 100-200%
Increased leaders with 600x1
2.3c
6b
9.3a
5b
0
2
4
6
8
10
Num
ber
of B
ranc
hes
Veronica Lateral Branches at 3 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Other Results Campanula: unresponsive to treatment with BA
Aster: phytotoxicity: tip burn
Cosmos: phytotoxicity: distorted leaves
Aster ‘Professor Anton Kippenburg’
Untreated 300x2
Cosmos atrosanguineus
Exp. 1: Results and Discussion:Branching Effects After Transplant
Increased branching effects were no longer evident in most plants after growing out for four additional weeks (8 WAT)
Untreated 300x1 300x2 600x1
Veronica spicata ‘Goodness Grows’
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15
Effects of BA on branching after transplant, 8 weeks after treatment
Gaura 80% increase
Lavandula 85% increase (only with two apps. of 300 mg· L-1)
600x1300x2300x1Untreated
600x1300x2300x1Untreated
Lavandula x intermedia ‘Provence’
Gaura ‘Siskyou Pink’
Exp. 1: Results and Discussion:Effects on Roots
600x1300x2300x1Untreated
Leucanthemum x superbum ‘Snowcap’
Four of eleven crops evaluated showed a decrease in root dry weight at time of transplant.
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Effects of BA on root dry weight at time of transplant, 3 or 4 WAT
Agastache Reduced 40%
Cosmos Reduced 40%
Lavandula Reduced only with two applications of 300 mg· L-1
Leucanthemum Reduced 25-40%
Rosemary Increased
Results and Discussion:Effects on Roots
Root Measurements Media was washed off roots by hand
Then roots were scanned using WinRhizo (Regent Instruments Inc., Quebec, Canada) to analyze root surface area and volume
Roots were dried at 66°C (150°F) for 48 hours then weighed
Root surface area and volume were highly correlated with root dry weight
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Root MeasurementsCorrelation Root Dry Weight to Root Surface Area and Volume
Leucanthemum root surface area to root dry weight, bivariate fit
r² = 0.77, p<0.0001
Leucanthemum root volume to root dry weight, bivariate fit
r² = 0.78, p<0.0001
Root Dry Weight to Root Surface Area
Root Dry Weight to Root Volume
r2 p value r2 p value
Agastache 0.87 <0.0001 0.91 <0.0001Gaura 0.73 <0.0001 0.77 <0.0001
Lavandula 0.88 <0.0001 0.95 <0.0001Leucanthemum 0.77 <0.0001 0.78 <0.0001
Salvia 0.84 <0.0001 0.88 <0.0001
Root Measurements
Correlation Root Dry Weight to Root Surface Area and Volume
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Leucanthemum finished plants
Reduction in root dry weight did not affect appearance of finished plants (4 weeks after transplant)
Leucanthemum x superbum ‘Snowcap’
Untreated 600x1300x2300x1
300x2Untreated 300x1 600x1
Root Reduction in Agastache
Root dry weight reduced 40% at 3WAT
0.98a 0.82b0.58c 0.58c
0
0.5
1
1.5
Roo
t Dry
Wei
ght (
g)
Agastache Root Dry Weight (g)at 3 WAT
Control (0) 300x1 300x2 600x1
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Agastache at 8 WAT
Reduction in root dry weight of liners did not affect appearance of finished plants 4 weeks after transplant
600x1300x2300x1Untreated
Agastache ‘Purple Haze’
Exp. 1 Conclusions
BA is safe for use on liners after removal from mist
BA can improve branching during liner production
Decreases in root dry weight did not affect finished plant appearance
Root surface area and root volume are highly correlated with root dry weight
BA has a short term effect on most plants
This indicates a value in reapplying BA to responsive plants shortly after transplanting liners to the finished containers
4/16/2012
20
Outline
• Introduction
• Exp. 1: Benzyladenine (BA)
• Exp. 2: BA in combination with IBA
• Exp. 3: Dikegulac sodium (DS)
• Exp. 4: Single vs. Multiple Applications, BA and DS
• Conclusions
Exp. 2: BA in combination with IBAObjective: To evaluate the effect of BA, IBA and the combination of the
two on the branching and root growth of herbaceous perennial plants during liner production and grow out of finished plants
Plants studied: Agastache ‘Tutti Frutti' Lavandula x intermedia ‘Provence’ Leucanthemum x superbum 'Snowcap' Rosmarinus ‘Hill Hardy’
4/16/2012
21
Indole-3-butyric acid (IBA),an auxin
Active ingredient in many rooting compounds
Commonly used to encourage rooting during propagation (Dole and Wilkins, 2005)
Exp. 2: BA in combination with IBA
0 mg·L-1 (control)
500 mg·L-1 BA (Configure, Fine Americas, Inc.)
1000 mg·L-1 IBA (Hortus IBA Water Soluble Salts 20% IBA , Hortus USA)
500 mg·L-1 BA plus 1000 mg·L-1 IBA
URCs
Treatments applied 1 day after removal from mist
Data collected on finished liners and finished plants
Exp. 2: BA in combination with IBA
4/16/2012
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Exp. 2: Results Root Dry Weight of Liners
Root Dry Weight (g) 2‐3 WAT
Treatment mg∙L‐1 Agastache Lavandula Leucanthemum Rosmarinus
Control 0 0.076ab 0.018 0.131a 0.054
BA 500 0.052bc 0.023 0.102b 0.043
IBA 1000 0.078a 0.025 0.145a 0.047
BA + IBA 500/1000 0.044c 0.018 0.096b 0.041
Rate Effect 0.0224 0.1088 0.0051 0.1459
LSD 0.025 0.007 0.029 0.012
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Root Dry Weight of Finished Plants
Root Dry Weight (g) Finished Plants
Treatment mg∙L‐1 Agastache Lavandula Leucanthemum Rosmarinus
Control 0 0.342 .194ab 1.13b 0.241
BA 500 0.315 .220a 1.01b 0.166
IBA 1000 0.351 .183b 1.36a 0.188
BA + IBA 500/1000 0.273 .147c 0.977b 0.169
Rate Effect 0.5366 0.0005 0.0014 0.059
LSD 0.11834 0.03067 0.19189 0.06003
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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AgastacheBA+IBA treatment
Reduced height, root weight, slight phyto in liners
Reduced flower height in finished plants
BA treatment
increased branches in finished plants
no effect on root weight
BA + IBABA IBAControl
5 WAT
BA + IBABA IBAControl
2 WAT
LavandulaBA+IBA treatment Reduced height, shoot weight of
liners and finished plants Reduced root weight of finished
plants
BA treatment Increased leaders of liners (NS) increase branches
of finished plants No effect on root weight
All treatments Slight phyto on liners Slight tip necrosis,
no longer evident after grow out
BA+ IBABAIBAControl
3 WAT
7 WAT
BA+ IBABA IBAControl
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Leucanthemum No effect on branching
Root dry weight reduced in liners with both BA and BA+IBA treatment
Reduced root dry weight did not affect finished plants
BA + IBABA IBAControl
2 WAT
7 WAT
BA + IBABA IBAControl
Rosmarinus
BA increased branches on liners, reduced branches on finished plants
Slight phyto on liners, tip damage and leaf curling
Phyto no longer evident after grow out
BA + IBABAIBAControl
3 WAT 7 WAT
BA + IBABA IBAControl
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Exp. 2 Conclusions
The addition of IBA to BA did not mitigate BA’s negative rooting effects
IBA or IBA in combination with BA did not increase branching
Outline
• Introduction
• Exp. 1: Benzyladenine (BA)
• Exp. 2: BA in combination with IBA
• Exp. 3: Dikegulac sodium (DS)
• Exp. 4: Single vs. Multiple Applications, BA and DS
• Conclusions
4/16/2012
26
Evaluate the effects dikegulac sodium on the branching of herbaceous perennial plants during liner production and grow out of finished plants
Six herbaceous perennials studied:• Aster ‘Professor Anton Kippenburg’
• Campanula punctata ‘Cherry Bells’
• Cosmos astrosanguineus
• Rosmarinus ‘Hill Hardy’
• Verbena bonariensis ‘Lollipop’
• Veronica ‘Goodness Grows’
Exp. 3: Objective
Exp. 3: Methods and Materials
URCs into 72 size flats
Rooted under mist until roots visible on all 4 sides of plug
Augeo (18% dikegulac sodium) applied as a foliar spray at four concentrations: 0 mg·L-1
400 mg·L-1
800 mg·L-1
1600 mg·L-1
4/16/2012
27
Measurements included: height, width, branches, leaders, phytotoxicity, flowering, root and shoot dry weights.
Data were collected at 0, 2, and 3-4 weeks after treatment (WAT).
Plants were then transplanted into quart (1.1 liter) pots and grown out for an additional 4 weeks.
Exp. 3: Methods and Materials
Exp. 3: Results and Discussion
All six crops evaluated showed an increase in branching at time of transplant.
Four of the six crops evaluated showed an increase in branching after growing out for 3-4 weeks.
4/16/2012
28
Dikegulac sodium on Aster at 3 WAT
DS Concentration mg·L-1
Number of Branches
Number of Leaders
Shoot Dry Wt (g) Height (cm)
0 17.6b 3.4b 0.29ab 11.1ab400 19.8ab 3.1b 0.31a 11.5a800 18.5b 3.6b 0.27b 10.1b
1600 23.3a 4.8a 0.19c 4.8cRate effect 0.033 0.0181 <0.0001 <0.0001
LSD 3.75 1.04 0.035 1.32
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Dikegulac sodium on Aster at 3 WAT
Aster 'Professor Anton Kippenberg'
Untreated 1600
• 40 % increase in leaders and 30% increase in branches in plants treated with 1600 mg·L-1
• Significant decrease in shoot weight and height
• No differences in branching after grow out
4/16/2012
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Dikegulac sodium on Campanulaat 3 WAT
DS Concentration mg·L-1
Number of Branches
Shoot Dry Weight (g) Height (cm)
0 3.6b 0.41 9.8a400 3.0b 0.32 8.6a800 5.0a 0.38 8.8a
1600 3.8ab 0.33 7.0bRate effect 0.0132 0.1437 0.0032
LSD 1.25 0.078 1.51
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Dikegulac sodium on Campanulaat 3 WAT
800 mg·L-1 dikegulac sodium increased branching with no effect on shoot or root dry weight
No differences in branching after grow out
800400Untreated 1600
Campanula punctata 'Cherry Bells'
4/16/2012
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Dikegulac sodium on Cosmos at 3 WAT
DS Concentration mg·L-
1
Number of Branches
Number of Leaders
Shoot Dry Wt (g) Height (cm)
0 17.6b 3.4b 0.39a 22.3ab400 19.8ab 3.1b 0.35a 23.8a800 18.5b 3.6b 0.35a 20.4b
1600 23.3a 4.8a 0.29b 11.4cRate effect 0.033 0.0181 0.0115 <0.0001
LSD 3.75 1.04 0.056 3.24
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Dikegulac sodium on Cosmos at 3 WAT
1600 mg·L-1 dikegulac sodium increased numbers of branches (30%) and leaders (40%) at 3 WAT.
Florel800400Untreated 1600
Cosmos atrosanguineus
4/16/2012
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Dikegulac sodium on Cosmos at 8 WAT
Increased leaders and branches persisted in plants treated with 1600 mg·L-1 dikegulac sodium
800400Untreated 1600
Cosmos atrosanguineus finished plants
Dikegulac sodium on Rosmarinusat 4 WAT
DS Concentration mg·L-1
Number of Branches
Number of Leaders
Shoot Dry Wt. (g) Height (cm)
0 19.7c 1.6c 0.33a 11.3a400 22.8ab 4.0b 0.3a 11.4a800 24.7a 6.2a 0.33a 12.1a
1600 22.6abc 7.3a 0.25b 9.0bRate effect 0.0164 <0.0001 0.0005 <0.0001
LSD 2.92 1.53 0.049 1.48
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
4/16/2012
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Dikegulac sodium on Rosmarinus at 4 WAT
Dikegulac sodium increased numbers of leaders (150-350%) and branches (20%).
800400Untreated 1600
Rosmarinus 'Hill Hardy'
After 4 wk grow out: 800 & 1600 mg·L-1 dikegulac sodium increased numbers of leaders (control 11 vs. treated plants 14-15) and branches (control 46 vs. treated plants 56-64).
800400Untreated 1600
Rosmarinus 'Hill Hardy'
Dikegulac sodium on Rosmarinus at 4 WAT
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Dikegulac sodium on Verbena at 3 WAT
DS Concentration mg·L-1
Number of Branches
Number of Leaders
Shoot Dry Wt. (g) Height (cm)
0 1.3d 1.0b 0.37a 21.1a400 9.2b 1.1b 0.36a 13.9b800 10.1b 1.4a 0.25b 10.7c
1600 12.2a 1.2ab 0.28b 7.1dRate effect <0.0001 0.042 <.0001 <.0001
LSD 1.12 0.259 0.040 1.84
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Dikegulac sodium increased branching: control 1.3 vs. treated plants 9-12 branches.
Dikegulac sodium caused twisting of leaves but plants grew out of symptoms in grow out phase
800400Untreated 1600
Verbena bonariensis 'Lollipop'
Dikegulac sodium on Verbena at 3 WAT
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After 4 wk grow out, 800 and 1600 mg·L-1 dikegulac sodium increased number of branches (control 28 vs. treated plants 32 – 38).
Slight delay in flowering 800 and 1600 mg·L-1
800400Untreated 1600
Verbena bonariensis 'Lollipop'
Dikegulac sodium on Verbena at 8 WAT
Dikegulac sodium on Veronica at 4 WAT
DS Concentration mg·L-1
Number of Branches
Number of Leaders
Shoot Dry Wt. (g) Height (cm)
0 0.6c 1 10a 8.4a400 8.0b 1.1 7.9b 7.5a800 13.5a 1.1 7.7b 4.0b
1600 7.7b 1.2 6.6c 1.1cRate effect <0.0001 0.6504 <.0001 <.0001
LSD 2.65 0.2515 0.9933 1.2166
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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dikegulac sodium increased number of branches (control 0.6 vs treated plants 7.7-13.5)
reduced height and shoot dry weight 800 and 1600 mg·L-1
800400Untreated 1600
Veronica spicata ‘Goodness Grows’
Dikegulac sodium on Veronica at 4 WAT
After 4 wk grow out, all dikegulac sodium treatments increased branching but the 800 and 1600 mg·L-1 treatments caused excessive stunting – plants did not grow out.
Florel spray800400Untreated 1600
Veronica spicata ‘Goodness Grows’
Dikegulac sodium on Veronica at 4 WAT
4/16/2012
36
Exp. 3 conclusions
Dikegulac sodium did increase branching in herbaceous perennials during liner production
PGR response varied by species
Phytotoxicity when noted was transient
Some plants showed persistent increases in branching after transplant and grow out.
Outline
• Introduction
• Exp. 1: Benzyladenine (BA)
• Exp. 2: BA in combination with IBA
• Exp. 3: Dikegulac sodium (DS)
• Exp. 4: Single vs. Multiple Applications, BA and DS
• Conclusions
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Exp. 4: ObjectiveEvaluate the effects of timing of applications of BA and dikegulac sodium on quality of plants as liners and finished plants.
Six herbaceous perennials studied:• Sedum spectabile ‘Autumn Joy'
• Gaillardia aristata ‘Gallo Red’
• Phlox paniculata ‘Bright Eyes’
• Nepeta x faassenii ‘Walker’s Low’
• Delosperma ‘Table Mountain’
• Achillea ‘Moonshine’
Exp. 4: Methods and MaterialsDesign: Split Plot, n = 6
Main Plot = Timing PGR applications Liner: single application after removal from mist Post Transplant: single application 5-7 days after transplant Both: applications at liner AND post transplant
Sub-Plot = PGR concentration 0 mg·L-1 dikegulac sodium 400 mg·L-1 dikegulac sodium 800 mg·L-1 dikegulac sodium 1600 mg·L-1 dikegulac sodium 600 mg·L-1 BA 400 mg·L-1 dikegulac sodium + 600 mg·L-1 BA
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Exp. 4: Methods and Materials URCs
Data as finished liners and after transplant and grow out
Measurements included: height, width, branches, leaders, phytotoxicity, flowering, and shoot dry weights.
Achillea at time of liner treatment
Number of branches3 WAT 6 WAT
Application TimeLiner 8.1 28.3cPost Transplant -- z 34.7bBoth 9 y 57.7aApplication time effect 0.0102 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 2.8e 22.6 25.0d 21.4c400 mg·L-1 DS 5.7d 33.8 26.9cd 60.5b800 mg·L-1 DS 7.0c 28 36.0bc 57.4b1600 mg·L-1 DS 9.5b 27.6 26.9cd 60.9b600 mg·L-1 BA 12.8a 32.3 49.3a 53.6b400 mg·L-1 DS+ 600 mg·L-1 BA 13.4a 25.8 44.3ab 92.6aTreatment effect <0.0001 0.0695 <0.0001 <0.0001
Application Time * PGR Concentration 0.2458 <0.0001z Not treated at this timey Treated only at liner stage at this time
Sedum Number of Branches
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Height (cm)3 WAT 6 WAT
Application TimeLiner 12.4 26.2aPost Transplant -- z 23.8bBoth 12.5y 24.7bApplication time effect 0.6098 <0.001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 13.6a 26.1a 25.1ab 25.4cd400 mg·L-1 DS 13.0abc 27.3a 25.1ab 29.6a800 mg·L-1 DS 13.3ab 26.1a 23.5ab 23.4d1600 mg·L-1 DS 10.1d 22.5b 20.4c 16.0e600 mg·L-1 BA 12.4bc 27.7a 25.9a 28.0ab400 mg·L-1 DS+ 600 mg·L-1 BA 12.3c 27.6a 23.0b 26.0bcTreatment effect <0.0001 0.0021 0.0007 <0.0001
Application Time * PGR Concentration 0.525 <0.0001z Not treated at this timey Treated only at liner stage at this time
Sedum Height
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Shoot Weight (g)3 WAT 6 WAT
Application TimeLiner 0.664 10.0aPost Transplant -- z 7.0cBoth 0.722 y 8.32bApplication time effect 0.0127 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 0.692bc 10.3 7.91b 10.0ab400 mg·L-1 DS 0.752ab 10.6 6.78cd 10.1ab800 mg·L-1 DS 0.627cd 10.5 6.14d 6.24c1600 mg·L-1 DS 0.583d 8.0 4.80e 3.23d600 mg·L-1 BA 0.780a 10.1 9.02a 10.8a400 mg·L-1 DS+ 600 mg·L-1 BA 0.723ab 10.7 7.13bc 9.47bTreatment effect <0.0001 0.0532 <0.0001 <0.0001
Application Time * PGR Concentration 0.5984 <0.0001z Not treated at this timey Treated only at liner stage at this time
Sedum Shoot Weight
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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DS 800x2DS 400x2Untreated DS 1600x2 BA 600x2 DS400 + BA 600x2
DS 800DS 400Untreated DS 1600 BA 600 DS400 + BA 600
DS 800DS 400Untreated DS 1600 BA 600 DS400 + BA 600
Both
Post Transplant
Liner
Phlox Number of BranchesNumber of branches
2 WAT 6 WATApplication Time
Liner 3.6 10.4Post Transplant -- z 11.4Both 3.1y 11.4Application time effect 0.2771 0.3554
PGR Concentration LinerPost
Transplant Both0 mg·L-1 2.1c 9.6 10.1 8.8c
400 mg·L-1 DS 2.0c 9.4 11.8 7.6c
800 mg·L-1 DS 2.7bc 9.5 11.5 10.3bc
1600 mg·L-1 DS 4.5a 10.4 11.3 16.8a
600 mg·L-1 BA 3.8ab 13 11.6 13.8ab
400 mg·L-1 DS+ 600 mg·L-1 BA 5.2a 10.8 11.9 11.3bc
Treatment effect 0.0003 0.2473 0.9329 0.0007
Application Time * PGR Concentration 0.2242 0.0317z Not treated at this time
y Treated only at liner stage at this time
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Flower Stalk Height (cm)6 WAT
Application TimeLiner 17.1Post Transplant 18Both 16.1Application time effect 0.1629
PGR Concentration Mean0 mg·L-1 19.5a400 mg·L-1 DS 16.4bc800 mg·L-1 DS 15.6c1600 mg·L-1 DS 16.2bc600 mg·L-1 BA 18.9ab400 mg·L-1 DS+ 600 mg·L-1 BA 15.5cTreatment effect 0.0150
Application Time * Treatment 0.1891
Phlox Flower Stalk Height
Means followed by the same letter are not significantly different at the p<.05 level, n=6
Both
Post Transplant
Liner
DS 800DS 400Untreated DS 1600 BA 600DS400 + BA 600
DS 800DS 400Untreated DS 1600 BA 600DS400 + BA 600
DS 800x2DS 400x2Untr DS 1600x2 BA 600x2DS400 + BA 600x2
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Nepeta Number of BranchesNumber of branches
2 WAT 5 WATApplication Time
Liner 16.3 171bPost Transplant -- z 200aBoth 17.6 y 213aApplication time effect 0.025 0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 15.4c 179a 159cd 151b400 mg·L-1 DS 15.8c 169a 192bc 171b800 mg·L-1 DS 17.9ab 179a 213b 169b1600 mg·L-1 DS 18.7a 127b 144d 242a600 mg·L-1 BA 16.7bc 181a 294a 261a400 mg·L-1 DS+ 600 mg·L-1 BA 17.3abc 191a 196bc 285aTreatment effect 0.0067 0.0188 <0.0001 0.0001
Application Time * PGR Concentration 0.1139 <0.0001z Not treated at this time
y Treated only at liner stage at this time
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Shoot Weight (g)2 WAT 5 WAT
Application TimeLiner 0.365 8.03aPost Transplant -- z 7.41bBoth 0.337y 6.97cApplication time effect 0.0877 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 0.346 7.55ab 8.11a 7.77bc400 mg·L-1 DS 0.321 8.38a 8.59a 7.19c800 mg·L-1 DS 0.350 8.09ab 7.71a 5.85d1600 mg·L-1 DS 0.325 7.25b 3.24b 3.21e600 mg·L-1 BA 0.387 8.46a 8.20a 9.31a400 mg·L-1 DS+ 600 mg·L-1 BA 0.376 8.46a 8.61a 8.49abTreatment effect 0.117 0.0431 <0.0001 <0.0001
Application Time * PGR Concentration 0.2042 <0.0001z Not treated at this timey Treated only at liner stage at this time
Nepeta Shoot Weight
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Height (cm)2 WAT 5 WAT
Application TimeLiner 22.5 15.7aPost Transplant -- z 13.2bBoth 21.1y 13.2bApplication time effect 0.0004 0.0015
PGR Concentration LinerPost
Transplant Both0 mg·L-1 22.4a 17.4a 19.0a 13.8ab400 mg·L-1 DS 22.0a 14.6b 10.8b 15.4ab800 mg·L-1 DS 21.8a 17.2ab 15.2a 11.0bc1600 mg·L-1 DS 18.9b 11.2c 9.6b 7.0c600 mg·L-1 BA 22.8a 15.8ab 16.2a 18.2a400 mg·L-1 DS+ 600 mg·L-1 BA 22.9a 18.2a 8.6b 14.0abTreatment effect <0.0001 0.0002 <0.0001 0.001
Application Time * PGR Concentration 0.0933 <0.0001z Not treated at this timey Treated only at liner stage at this time
Nepeta Height
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
DS 800DS 400Untreated DS 1600 BA 600 DS400 +BA 600
Both
Post Transplant
Liner
DS 800DS 400Untreated DS 1600 BA 600 DS400 +BA 600
DS 800x2DS 400x2Untreated DS 1600x2 BA 600x2DS400 + BA 600x2
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Gaillardia Number of BranchesNumber of branches
2 WAT 8 WATApplication Time
Liner 5.8 30.8bPost Transplant -- z 29.0bBoth 6.1y 53.0aApplication time effect 0.3635 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 4.8b 28.5b 22.7bc 37.7b400 mg·L-1 DS 5.7b 35.7a 31.2b 40.5b800 mg·L-1 DS 5.1b 32.8ab 31.0b 39.7b1600 mg·L-1 DS 2.5c 19.7c 13.2c 11.8c600 mg·L-1 BA 8.7a 33.4ab 26.8b 100a400 mg·L-1 DS+ 600 mg·L-1 BA 9.1a 34.7ab 49.2a 88.0aTreatment effect <0.0001 0.0006 <0.0001 <0.0001
Application Time * PGR Concentration 0.0183 <0.0001z Not treated at this timey Treated only at liner stage at this time
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Height (cm)2 WAT 8 WAT
Application TimeLiner 6.8 14.0aPost Transplant -- z 12.7bBoth 7.2y 11.9cApplication time effect 0.1016 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 7.7a 14.4a 15.4a 15.0a400 mg·L-1 DS 7.4ab 14.1a 13.9ab 14.8a800 mg·L-1 DS 7.6ab 14.4a 12.4bc 9.6c1600 mg·L-1 DS 6.4c 11.4b 8.9d 4.6d600 mg·L-1 BA 6.8bc 15.1a 14.1a 15.3a400 mg·L-1 DS+ 600 mg·L-1 BA 6.3c 14.9a 11.8c 12.3bTreatment effect 0.0022 0.0002 <0.0001 <0.0001
Application Time * PGR Concentration 0.0593 <0.0001z Not treated at this timey Treated only at liner stage at this time
Gaillardia Height
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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Shoot Weight (g)2 WAT 8 WAT
Application TimeLiner 0.329 4.27aPost Transplant -- z 3.59bBoth 0.332 y 3.57bApplication time effect 0.7808 <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 0.326bc 4.28a 4.79a 4.64b
400 mg·L-1 DS 0.341ab 4.81a 4.38ab 4.05b
800 mg·L-1 DS 0.297cd 4.54a 3.03d 2.02c
1600 mg·L-1 DS 0.274d 2.49b 1.58e 0.688d
600 mg·L-1 BA 0.374a 4.73a 4.10bc 6.12a
400 mg·L-1 DS+ 600 mg·L-1 BA 0.374a 4.73a 3.67c 3.90b
Treatment effect <0.0001 <0.0001 <0.0001 <0.0001
Application Time * PGR Concentration 0.1367 <0.0001z Not treated at this time
y Treated only at liner stage at this time
Gaillardia Shoot Weight
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
Days to First Flower8 WAT
Application TimeLiner 64.7bPost Transplant 49.6aBoth NAApplication time effect <0.0001
PGR Concentration LinerPost
Transplant Both0 mg·L-1 48.5d 52.4 53.5b400 mg·L-1 DS 52.4d 48.3 47.9b800 mg·L-1 DS 64.8c 47.8 82.0a1600 mg·L-1 DS 82.0a 49 NA600 mg·L-1 BA 70.5b 50.5 NA400 mg·L-1 DS+ 600 mg·L-1 BA 70.3b 50 NATreatment effect <0.0001 0.6533 0.0003
Application Time * PGR Concentration <0.0001
Gaillardia Days to First Flower
Means followed by the same letter are not significantly different at the p<.05 level, n=6.
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DS 800DS 400Untreated DS 1600 BA 600 DS400 +BA 600
Both
Post Transplant
Liner
DS 800DS 400Untreated DS 1600 BA 600DS400 +BA 600
DS 800x2DS 400x2Untreated DS 1600x2 BA 600x2DS400 + BA 600x2
Branching Effects on Delosperma and AchilleaDelosperma•No increased branches with any treatment
Achillea•Increased branches only with 2 applications of 600 mg·L-1 BA•Stunting with 2 applications of 800 or 1600 mg·L-1 dikegulac sodium
BA 600x2Untreated
Achillea finished plants treated twice
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Exp. 4: Conclusions
In responsive plants, two treatments caused an increase in branches compared to one treatment
BA increased branches without reducing height or causing phytotoxicity
The combination of BA and dikegulac sodium was effective at increasing branches in 4 of 6 plants studied
Two applications of 1600 mg·L-1 dikegulac sodium caused stunting in most plants studied
Both BA and dikegulac sodium caused flower delay in Gaillardia
Outline
• Introduction
• Exp. 1: Benzyladenine (BA)
• Exp. 2: BA in combination with IBA
• Exp. 3: Dikegulac sodium (DS)
• Exp. 4: Single vs. Multiple Applications, BA and DS
• Conclusions
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Research Objectives To study the effects of branching agents on herbaceous
perennial crops during liner production and on finished plants
To improve plant architecture at an earlier stage of production
Conclusions Treating perennial liners BA and dikegulac sodium before
transplant changed plant architecture by increasing the numbers of branches
Liner quality can be improved with application of PGRs
Results varied by species, as was expected (Gent and McAvoy, 2000)
BA and dikegulac sodium have a short period of activity in plants
A second application of PGRs after transplanting liners may be beneficial
Phytotoxicity is generally transient
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Future Work Timing of application
Multiple applications
Cytokinin analysis
•Dr. Joyce Latimer•Dr. Holly Scoggins•Dr. Eric Ervin•John Freeborn•Jeff Burr•Velva Groover•John James•Shawn Appling•Kevin Harris•Carly Reynolds•J.B. Snelson•Brianna Swanson
Thanks to:
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ReferencesArzee, T., H. LangenDSer and J. Gressel. 1977. Effect of dikegulac, a new growth regulator, on apical growth and development of three Compositae. Bot. Gaz. 138(1):18–28.
Banko, T.J. and M.A. Stefani. 1995. Cutless and Atrimmec for controlling growth of woody landscape plants in containers. J. Environ. Hort.13 (1):22-26.
Bell, M.L., R.A. Larson, and D.A. Bailey. 1997. Vegetative growth responses of florist azaleas to dikegulac, GA4+7, and 6-benzylamino purine. HortScience 32 (4):690-693.
Bruner, L.L., G.J. Keever, J.R. Kessler, Jr., and C.H. Gilliam. 2002. Atrimmec suppresses shoot length and promotes branching of Lonicera x heckrottii ‘Goldflame’ (Goldflame honeysuckle). J. Environ. Hort. 20(2):3-76.
Carter, J., B.P. Singh and W. Whitehead. 1996. Dikegulac, but not benzyladenine, enhances the aesthetic quality of Boston fern. HortScience 31:978-980.
Cline, M.G. Apical dominance. 1991. Bot. Rev. 57:318-358.
Dole, J.M. and H.F. Wilkins, 2005. Floriculture : principles and species. Pearson/Prentice Hall, Upper Saddle River, N.J.
Farris, M.E., G.J. Keever, J.R. Kessler, and J.W. Olive. 2009. Benzyladenine and cyclanilide promote shoot development and flowering of Coreopsis verticillata 'Moonbeam'. J. Environ. Hort. 27(3):176-182.
Gent, M.P.N. and R.J. McAvoy. 2000. Plant growth retardants in ornamental horticulture: a critical appraisal, p. 89-130. In Basra, A.S. (ed.) Plant growth regulators in agriculture and horticulture: their role and commercial uses. Food Products Press, Binghamton.
Keever, G.J. 1994. BA-induced offset formation in Hosta. J. Environ. Hort. 12 (1):36-39.
Latimer, J. and J. Freeborn. 2008. Enhance branching of Echinacea with PGRs. Greenhouse Product News 18(4):24–28.
ReferencesLatimer, J.G. and J. Freeborn. 2010. Branching enhancers, BAigure (6-BA) and DSgeo (dikegulac sodium), affect branching of herbaceous perennials. Proc. Plant Growth Regulat. Soc. Amer. 37:148-152.
Miller, C. O.; Skoog, F.; Von Saltza, M. H.; Strong, F. M. 1955. Kinetin, a Cell Division Factor from Deoxyribonucleic acid. J. Am. Chem. Soc. 77:1392.
Martin, S. and S. Singletary. 1999. N-6 Benzyladenine increases lateral offshoots in a number of perennial species. Proc. Intl. Plant Prop. Soc. 49:329-334.
Nightingale, A.E., S.E. Cross and M.T. Longnecker. 1985. Dikegulac alters growth and flowering of Kalanchoe. HortScience 20:722-724.
Sachs, R.M., H. Hield, and J. DeBie. 1975. Dikegulac: a promising new foliar-applied growth regulator for woody species. HortScience 10 (4):367-369.
Whitman, C. and E. Runkle. 2003. PGR rates and timing for plug production. Greenhouse Product News 13(12):38-43.
USDA 2011. Floriculture Crops 2010 Summary. Cited November 17, 2011. <http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1072>
USDA 2009. Census of Horticultural Specialties.Cited November 17, 2011. <http://www.agcensus.usda.gov/Publications/2007/Online_Highlights/Census_of_Horticulture/HORTIC.pdf>
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For More Information:
Mara Grossman: [email protected]
http://www.horticulture.vt.edu/floriculture
Questions?