Effects of Plant Growth Retardants and Application Timing after Shearing on Growth and Flowering of Coreopsis verticillata `Moonbeam'

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 522a-522
Author(s):  
J. Raymond Kessler ◽  
Gary J. Keever
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Growth Index ◽  
Market Quality ◽  
Growth Retardants ◽  
Application Timing ◽  
Quality Rating ◽  
Plant Growth Retardants ◽  
Herbaceous Perennial ◽  
Short Days

Coreopsis verticillata `Moonbeam' is a herbaceous perennial that may grow too tall in small containers under greenhouse conditions for market acceptance, and therefore may benefit from plant growth retardants. Rooted terminal cuttings produced under short days were given a terminal pinch and transplanted to 10 cm pots. Cuttings were sheared to 6 cm above the pot rim 4 weeks later. Growth retardant treatments consisting of ancymidol drench at 0, 0.125, 0.25, or 0.375 mg a.i./pot; paclobutrazol drench at 0, 0.125, 0.25, or 0.375 mg a.i./pot; daminozide spray at 0, 2550, 5100, or 7650 mg·L–1; paclobutrazol spray at 0, 12, 24, 36, 48, or 60 mg·L–1; or flurprimidol spray at 0, 25, 50, 75, 100, 150, or 200 mg·L–1 were applied 10 days after shearing. Night-breaking lighting using incandescent bulbs was started the same day. The highest rate of ancymidol, paclobutrazol drench, daminozide, and flurprimidol decreased plant height compared to controls by 36, 30, 21, and 36%, respectively. Paclobutrazol sprays were not effective. A market quality rating of four or higher (good, salable) was given to plants treated with daminozide at 5100 or 7650 mg·L–1 or flurprimidol at 150 or 200 mg·L–1. A second experiment was conduced to determine application timing. A daminozide spray at 0, 2550, 5100, or 7650 mg·L–1 was applied 0, 3, 6, 9, 12, or 15 days after shearing. Plant height, growth index and lateral shoot length were least and market quality rating highest when 5100 or 7650 mg·L–1 of daminozide was applied between 6 and 9 days after shearing.

scholarly journals HEIGHT CONTROL OF HERBACEOUS PERENNIALS FORCED USING NIGHT-INTERRUPTED LIGHTING UNDER NURSERY CONDITIONS

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 893f-894
Author(s):  
Gary J. Keever ◽  
J. Raymond Kessler
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Control Plant ◽  
Growth Retardants ◽  
Natural Control ◽  
Height Control ◽  
Herbaceous Perennials ◽  
Quality Rating ◽  
Plant Growth Retardants ◽  
Outdoor Nursery

In previous studies, night-interrupted lighting (NIL) promoted earlier flowering of summer-blooming herbaceous perennials grown under outdoor nursery conditions in the southeastern U.S. However, NIL promoted excessive plant height, thus reducing product quality. Our objective was to control plant height of Coreopsis grandiflora `Early Sunrise' (ES) and Rudbeckia fulgida `Goldsturm' (RG) grown under NIL with plant growth retardants (PGR) without offsetting earlier flowering promoted by NIL. Treatments under NIL were three rates of daminozide, daminozide plus chloromequat, flurprimidol, uniconazole, and NIL and natural controls. Plant height was reduced 3% to 38% in ES and 8% to 31% in RG and time to visible bud was unchanged by all PGR treatments compared to the NIL control. Time to visible bud was unchanged in RG by all PGR treatments and flurprimidol in ES, but the remaining PGR treatments increased time to visible bud compared to the NIL control in ES. Only ES plants treated with daminozide and daminozide plus chloromequat at the two highest rates and all rates of uniconazole were similar in height to the natural control. RG plant heights with the two highest rates of flurprimidol and uniconazole and the highest rate of daminozide plus chloromequat were less than the natural control; heights of plants in the remaining PGR treatments were similar to the natural control. Quality rating was unchanged in RG but was increased in ES by all PGR treatments compared to the NIL control.

scholarly journals Plant Growth Retardants Reduce Peduncle Length of Achillea × `Coronation Gold'

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 602f-603
Author(s):  
J. Raymond Kessler ◽  
Gary J. Keever
Keyword(s):  
Plant Growth ◽  
Growth Index ◽  
Market Quality ◽  
Growth Retardants ◽  
Foliar Sprays ◽  
Quality Ratings ◽  
Flower Diameter ◽  
Plant Growth Retardants ◽  
Peduncle Length

Vegetative offsets of Achillea x `Coronation Gold' were rooted under mist for 3 weeks and potted into 10-cm pots in a greenhouse. Plants were grown under short photoperiods for 6 weeks before being vernalized for 6 weeks at 6 °C. Plants then were provided long photoperiods from night-break lighting. Foliar sprays of daminozide at 0, 2550, 5100, or 7650 mg·L-1, chlormequat at 0, 767, 1534, or 3201 mg·L-1, daminozide + chlormequat at 0, 1275 +, 2550 + or 3825+1534 mg·L-1, flurprimidol at 0, 40, 80, or 120 mg·L-1, paclobutrazol at 0, 32, 64, 96, 128, or 160 mg·L-1 or uniconizole at 0, 11, 22, 33, 44, or 55 mg·L-1 were applied as a spray 1 week after vernalization. Highest market quality ratings were achieved with paclobutrazol at 96 or 128, uniconizole at 22 or 33, daminozide + chlormequat 3825 + 1534, chlormequat at 2301 or flurprimidol at 40 mg·L-1. Peduncle length and growth index decreased linearly for daminozide, chlormequat, and daminozide + chlormequat, and decreased quadratically for flurprimidol, paclobutrazol, and uniconizole with increasing rate. Time to flower increased most in treatments receiving high rates of daminozide. Flower diameter was reduced by the highest rates of flurprimidol and paclobutrazol.

scholarly journals (94) Efficacy of Application Methods and Concentration of Plant Growth Retardants on Growth of Chrysanthemum (Dendranthem ×grandiflorum `Cheasepeake')

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1046A-1046
Author(s):  
Chun Ho Pak ◽  
Seung Won Kang ◽  
Chiwon W. Lee
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Nutrient Solution ◽  
Growth Retardation ◽  
Growth Retardant ◽  
Plant Production ◽  
Growth Retardants ◽  
Total Plant ◽  
Plant Growth Retardants ◽  
Application Methods

Efficacy of application methods and concentration of plant growth retardants on growth of chrysanthemum (Dendranthema ×grandiflorum cv. Cheasepeake) was tested. B-9 or cycocel (CCC) as a growth retardant was applied as drench or subapplication with nutrient solution. In the case of B-9 drench treatments, as B-9 concentrations increased, numbers of flowers and flower buds increased except in the 1500-ppm treatment. Increasing concentration of CCC also resulted in reduction of flower numbers, total plant height, total leaf area, branch number, and fresh weight. Reduction ratio of total plant height in 2000 ppm showed about 56.9% being compared to that of the 100-ppm drench treatment. B-9 or CCC, combined with nutrient solution, was also supplied from the C-channel subirrigation system. The B-9 subapplication treatment showed no significance among these concentrations, but flower numbers, total plant height, average plant height, and leaf numbers decreased as concentrations of CCC increased. B-9 or CCC with the same concentration was drenched after 2 weeks of the first experiment to compare planting time efficacy. Measured data increased until B-9 increased up to 2500 ppm and severe growth retardation resulted from the 5000-ppm treatment. Through this growth retardant application study, the combination of drenching concentration and period of plant growth regulators (PGRs) may result in effective growth retardation and reduction of application concentrations for pot plant production.

scholarly journals Plant Growth Retardants Affect Growth and Flowering of Achillea × ‘Coronation Gold’

2008 ◽  
Vol 26 (1) ◽  
pp. 24-28 ◽  
Author(s):  
J.R. Kessler ◽  
G.J. Keever
Keyword(s):  
Plant Growth ◽  
Growth Index ◽  
Plant Size ◽  
Growth Retardant ◽  
Growth Retardants ◽  
Shoot Height ◽  
Stage Of Development ◽  
Quality Ratings ◽  
Plant Growth Retardants

Abstract An experiment was conducted to determine the effects of several widely used plant growth retardants on plant size and flowering of Achillea × ‘Coronation Gold’. Plants in 10 cm (4 in) pots were grown in a greenhouse and treated with B-Nine at 0, 2550, 5100, or 7650 ppm; Cycocel at 0, 767, 1534, or 2301 ppm; B-Nine/Cycocel at 0, 1275/1534, 2550/1534, or 3825/1534 ppm; Sumagic at 0, 11, 22, 33, 44, or 55 ppm; Bonzi at 0, 32, 64, 96, 128, or 160 ppm; or Cutless at 0, 40, 80, or 120 ppm as a spray 1 week after vernalization. B-Nine, Cycocel, B-Nine/Cycocel, Sumagic, Bonzi, and Cutless reduced shoot height and growth index by 36 and 26%, 39 and 27%, 61 and 41%, 75 and 52%, 52 and 36%, and 75 and 51%, respectively, with the highest rate of each. B-Nine, Cycocel, B-Nine/Cycocel, and Sumagic, but not Bonzi or Cutless, increased the number of days to open inflorescence by 3-5 days with increasing rate. Sumagic, Bonzi, and Cutless reduced inflorescence diameter by up to 15, 18, and 14%, respectively but not B-Nine, Cycocel, or B-Nine/Cycocel. The highest quality ratings of 2.8 to 3.0 were found with B-Nine/Cycocel at 3825/1534 ppm, Sumagic at 22 and 33 ppm, and Bonzi at 64 ppm. Differences between the results in this study and earlier studies implicate the possible impact of differences in experimental environments, container size, or stage of development when the plant growth retardant treatments were applied.

scholarly journals Are plant growth retardants a strategy to decrease lodging and increase yield of sunflower?

2016 ◽  
Vol 7 (1) ◽  
pp. 154 ◽  
Author(s):  
Marcia Eugenia Amaral Carvalho ◽  
Paulo Roberto de Camargo e Castro ◽  
Marcos Vinicius de Castro Ferraz Junior ◽  
Ana Carolina Cabrera Machado Mendes
Keyword(s):  
Plant Growth ◽  
Gibberellic Acid ◽  
Plant Height ◽  
Dry Mass ◽  
The Other ◽  
Alternative Strategy ◽  
Growth Retardants ◽  
Other Hand ◽  
Plant Growth Retardants ◽  
Potential Strategy

One of the major disadvantages of sunflower cultivation is the increased plant height, making it prone to the lodging. The use of plant growth retardants can be an alternative strategy to reduce plant height; however, these compounds may affect productivity. The aim of this study was to evaluate the effects of plant growth retardants on sunflower development and yield. Four treatments were studied: 1- control; 2- gibberellic acid (GA) 10 mg L−1; 3- trinexapac-ethyl (TE) 5 mL L−1, and 4- maleic hidrazide (MH) 8 mL L−1. TE and MH decreased plant height (16.9 and 35.9%, respectively); however, only TE positively influenced capitulim diameter and dry mass (46.7 and 311%, when compared to control) at 60 days after planting (DAP). At 81 DAP, dry mass of capitulum did not differ among control and TE-treated plants. On the other hand, MH impaired diameter and dry mass of capitulum (92.9 and 74.7%, respectively). It can be concluded that the application of TE is a potential strategy to decrease lodging probability without affecting sunflower yield. Furthermore, although MH negatively affected sunflower development, its use on the crop cannot be excluded since other doses, frequencies and moment of application can be studied.

scholarly journals Summer Applications of Plant Growth Retardants Affect Spring Forcing of Hydrangeas

1992 ◽  
Vol 2 (2) ◽  
pp. 213-216 ◽  
Author(s):  
Douglas A. Bailey ◽  
Bernadette Clark
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Residual Effect ◽  
Control Program ◽  
Growth Period ◽  
Shoot Elongation ◽  
Growth Retardants ◽  
Height Control ◽  
Control Programs ◽  
Plant Growth Retardants

Summer spray applications of 5000 ppm daminozide (1× or 2×), 62 ppm paclobutrazol (1× or 2×), or 5 ppm uniconazole (1× or 2×) were applied to seven cultivars (Böttstein, Enziandom, Kasteln, Mathilde Gütges, Merritt's Supreme, Red Star, and Schenkenburg) of florists' hydrangea [Hydrangea macrophylla subsp. macrophylla var. macrophylla (Thunb.) Ser.] to evaluate cultivar response to plant growth retardants (PGRs). Both daminozide treatments and the 2× uniconazole treatment effectively reduced plant height for all cultivars during the summer growth period; cultivars varied in response to the paclobutrazol treatments and the 1× uniconazole treatment. Daminozide and uniconazole treatments resulted in less elongation than all other treatments during forcing for most cultivars tested. Paclobutrazol treatments had no residual effect on shoot elongation during forcing of the cultivars tested. The 2× treatments of all PGRs decreased inflorescence diameter of some of the cultivars tested compared with nonsprayed controls. Results from this study indicate that 1) summer application of PGRs can have a residual effect on plant height and inflorescence diameter of hydrangeas during the spring greenhouse forcing phase; and 2) hydrangea cultivars differ significantly in response to the PGRs tested. Therefore, the need for height control during the spring forcing period of hydrangeas will vary with cultivar, and it will depend on how plants were treated the previous summer growing season. We recommend that producers of dormant hydrangeas provide records of their summer height control program to forcers so that height control programs during spring forcing can be adjusted appropriately.

scholarly journals Phosphorus Restriction as an Alternative to Chemical Plant Growth Retardants in Angelonia and New Guinea Impatiens

2018 ◽  
Vol 28 (2) ◽  
pp. 136-142
Author(s):  
Josh B. Henry ◽  
Ingram McCall ◽  
Brian E. Whipker
Keyword(s):  
Plant Growth ◽  
Stem Elongation ◽  
Control Plant ◽  
Growth Index ◽  
New Guinea ◽  
Chemical Plant ◽  
Growth Retardants ◽  
P Deficiency ◽  
Plant Growth Retardants ◽  
New Guinea Impatiens

Chemical plant growth retardants (PGRs) are commonly used to produce compact bedding plants. Few PGRs are labeled for sensitive species because of the concern of excessive restriction of stem elongation or phytotoxicity. Growers are therefore presented with a dilemma: produce untreated plants that may be too tall or risk applying a PGR that can potentially lead to irreversible aesthetic damage to the plant. Nutrient restriction, specifically of phosphorus (P), may be used to control plant height. This study was conducted to determine if restricting P fertilization yielded comparable growth control to plants produced with PGRs. Two cultivars each of new guinea impatiens (Impatiens hawkeri) and angelonia (Angelonia angustifolia) were grown using five fertilizers that varied by P concentration (0, 2.5, 5, 10, and 20 ppm). Half of the plants from each P fertilizer concentration were treated with paclobutrazol at 4 and 5 weeks after transplant for angelonia and new guinea impatiens, respectively. On termination of the experiment, data were collected for height, diameter, and dry weight, which were used to determine a growth index (GI). Angelonia GI values were maximized with 7–9 ppm P, whereas new guinea impatiens GI was maximized with 8–11 ppm P. Concentrations of 3–5 ppm P provided similar height control to plants grown with nonlimiting P and a paclobutrazol application. Concentrations of ≤2.5 ppm P resulted in low-quality plants with visual symptoms of P deficiency. These results indicate that a narrow range of P concentrations may be used to control stem elongation and keep plants compact.

scholarly journals Controlled Water Deficit as an Alternative to Plant Growth Retardants for Regulation of Poinsettia Stem Elongation

HortScience ◽  
2015 ◽  
Vol 50 (4) ◽  
pp. 565-569 ◽  
Author(s):  
Peter Alem ◽  
Paul A. Thomas ◽  
Marc W. van Iersel
Keyword(s):  
Drought Stress ◽  
Plant Growth ◽  
Plant Height ◽  
Water Deficit ◽  
Stem Elongation ◽  
Alternative Methods ◽  
Growth Retardants ◽  
Target Height ◽  
Height Control ◽  
Plant Growth Retardants

Production of poinsettias (Euphorbia pulcherrima) often involves intensive use of plant growth retardants (PGRs) to regulate height. Height control is necessary for visual appeal and postharvest handling. Since PGRs do not always provide consistent height control and can have unwanted side effects, there is interest in alternative methods of height control. Since turgor potential drives cell expansion, and thus stem elongation, drought stress has potential for regulating plant height. Through soil moisture sensor-controlled irrigation, the severity of drought stress can be both monitored and controlled. The objective of our study was to compare poinsettia ‘Classic Red’ height control using PGRs (spray, mixture of daminozide and chlormequat at 1000 mg·L−1 each and drench, 0.25 mg·L−1 paclobutrazol) with the use of controlled water deficit (WD). Graphical tracking of plant height, using a final target height of 43.5 cm, was used to determine when to apply PGR or controlled WD. In the WD treatment, substrate volumetric water content (θ) was reduced from 0.40 to 0.20 m3·m−3 when actual height exceeded the expected height. PGR applications (spray or drench) reduced poinsettia height to 39 cm, below the final target level of 43.5 cm. WD resulted in a height of 44.5 cm, closest to the target height, while control plants were taller (49.4 cm). There was no effect of PGR drenches or WD on bract size, while spraying PGR reduced bract size by ≈ 40%. Bract chroma was unaffected by WD or PGR treatments. There was no difference in shoot dry weight between PGR- and WD-treated plants. Lateral growth was reduced by the PGR treatments, but not by WD. These results indicate that controlled WD can be used to regulate poinsettia height.

scholarly journals Application Timing of Daminizide and Flurprimidol after Shearing Affects Growth and Flowering of Coreopsis verticillata `Moonbeam'

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 603a-603
Author(s):  
J. Raymond Kessler ◽  
Gary J. Keever
Keyword(s):  
Growth Index ◽  
Plant Size ◽  
Height Growth ◽  
Shoot Length ◽  
Growth Retardants ◽  
Lateral Shoot ◽  
Shoot Height ◽  
Application Timing ◽  
Quality Rating ◽  
Response Surface Regression

Vegetative cuttings of Coreopsis verticillata `Moonbeam' were rooted under intermittent mist, pinched, and potted into 10-cm pots in a greenhouse. Plants were sheared to 6.5 cm above the pot rim 2 weeks after potting and given foliar sprays of daminozide at 0, 2550, 5100, or 7650 mg·L-1 or flurprimidol at 0, 50, 100, or 150 mg·L-1. Night-break lighting to provide long photoperiods was started the day of shearing. Growth retardants were applied at 0, 3, 6, 9, 12, or 15 days after shearing. Daminozide reduced shoot height, growth index, and lateral shoot length compared to the control by 69.3%, 69.2%, and 70.0%, respectively, while increasing quality rating by 67.3% and time to flower by 8 days at 5100 and 7650 mg·L-1. Response surface regression predicted that minimum plant size and maximum quality rating occurred when growth retardants were applied 5.7 to 8.3 days after shearing. Application timing had no effect on responses to flurprimidol. Shoot height, growth index, and lateral shoot length decreased quadratically with increasing rate while quality rating only improved compared to control. Flurprimidol did not cause a flowering delay.

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