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 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.

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 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 (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 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 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 Efficacy of Plant Growth Retardants as Preplant Bulb Dips for Height Control in LA and Oriental Hybrid Lilies

2002 ◽  
Vol 12 (3) ◽  
pp. 426-431 ◽  
Author(s):  
Anil P. Ranwala ◽  
Garry Legnani ◽  
Mary Reitmeier ◽  
Barbara B. Stewart ◽  
William B. Miller
Keyword(s):  
Plant Growth ◽  
Effective Means ◽  
Lilium Longiflorum ◽  
Growth Retardant ◽  
Growth Retardants ◽  
Height Control ◽  
Commercial Plant ◽  
Leaf Yellowing ◽  
Plant Growth Retardants ◽  
High Concentrations

We evaluated preplant bulb dips in three commercial plant growth retardants [ancymidol (A-Rest), paclobutrazol (Bonzi), and uniconazole (Sumagic)] for height control in seven oriental hybrid lily (Lilium) cultivars (Aubade, Berlin, Casa Blanca, Muscadet, Sissi, Star Gazer, and Tom Pouce), and seven LA-hybrid lily [hybrids resulting from crosses between easter lily (Lilium longiflorum) and Asiatic hybrids] cultivars (Aladdin's Dazzle, Best Seller, Cebeco Dazzle, Royal Dream, Royal Parade, Royal Perfume, and Salmon Classic) grown in containers. A 1-min dip into a range of concentrations of each product was used to determine the optimum concentrations for height control. The results indicate that bulb dips, especially with uniconazole and paclobutrazol, can be a highly effective means of height control in hybrid lilies. Cultivars varied in their response to growth retardant treatments. In general, LA-hybrid lilies were much more responsive to the growth retardant treatments than oriental hybrids and required lower rates for comparable height control. Delays in flowering, increased bud abortion and leaf yellowing were observed only with high concentrations of uniconazole or paclobutrazol where the height reduction was also too excessive for a commercially acceptable crop.

scholarly journals Growth and Flowering Response of ‘May Night’ Salvia and ‘Butterfly Blue’ Scabiosa to Growth Retardants

2001 ◽  
Vol 19 (3) ◽  
pp. 145-149
Author(s):  
T.J. Banko ◽  
M.A. Stefani ◽  
M.S. Dills
Keyword(s):  
Plant Growth ◽  
Plant Height ◽  
Linear Increase ◽  
Initial Number ◽  
Growth Retardants ◽  
Chlormequat Chloride ◽  
Flowering Response ◽  
Combination Treatments ◽  
Plant Growth Retardants ◽  
Delayed Flowering

Abstract In a 1999 experiment, Salvia x sylvestris ‘May Night’ and Scabiosa columbaria ‘Butterfly Blue’ were treated with the following plant growth retardants (PGRs) or PGR mixes: B-Nine (daminozide) at 5000 ppm (applied twice); B-Nine at 5000 ppm + Cycocel (chlormequat chloride) at 1500 ppm; Florel (ethephon) at 500 ppm (applied twice); B-Nine at 5000 ppm + Florel at 500 ppm; Sumagic (uniconazole) at 20 ppm; or B-Nine at 5000 ppm + Sumagic at 10 ppm. B-Nine effectively suppressed growth of salvia but not scabiosa, while Florel was effective on both salvia and scabiosa. However, Florel delayed flowering of both species by about 10 days. Sumagic at 20 ppm suppressed growth of scabiosa but not salvia. The PGR combination treatments, in general, were no more effective, and frequently less effective than the more effective PGR for a given species applied alone. In 2000 Florel was applied once to both salvia and scabiosa at 0, 250, 500, 750, and 1000 ppm. B-Nine (5000 ppm) was also applied to salvia, and Sumagic (20 ppm) was applied to scabiosa. Plant height of salvia was suppressed linearly with increasing Florel concentrations up to 42 days after treatment (DAT). Salvia also responded with a linear increase in inflorescence numbers at 32 and 42 DAT. Florel suppressed the height of scabiosa ‘Butterfly Blue’ linearly up to 52 DAT without affecting the initial number of inflorescences. When the first set of inflorescences was removed and a second set developed, there was a linear increase in inflorescence numbers with increasing concentrations of Florel.

scholarly journals Plant Growth Retardant Application to Achillea x ‘Coronation Gold’ and Gaura lindheimeri ‘Corrie's Gold’

2000 ◽  
Vol 18 (3) ◽  
pp. 149-153
Author(s):  
Stephanie E. Burnett ◽  
Gary J. Keever ◽  
Charles H. Gilliam ◽  
J. Raymond Kessler ◽  
Charles Hesselein
Keyword(s):  
Plant Growth ◽  
Untreated Control ◽  
Growth Suppression ◽  
Effective Concentration ◽  
Growth Retardant ◽  
Growth Retardants ◽  
Herbaceous Perennials ◽  
Quality Ratings ◽  
Plant Growth Retardants ◽  
Delayed Flowering

Abstract In two experiments conducted under nursery conditions in 1998 and 1999, the herbaceous perennials, Achillea x ‘Coronation Gold’ and Gaura lindheimeri ‘Corrie's Gold’ were treated with one of four plant growth retardants (PGRs): B-Nine at 2,500, 5,000, or 7,500 ppm; Bonzi at 33, 66, or 99 ppm; Cutless at 50, 100, or 150 ppm; Pistill at 500 or 1,000 ppm; or left untreated. Only Pistill delayed flowering of achillea while Bonzi and Cutless accelerated flowering of achillea. In 1998, B-Nine provided little growth suppression of achillea; however in 1999, when plants were pruned just prior to treatment and thus less reproductively developed, height at the most effective concentration of 7,500 ppm was reduced 33% compared to untreated plants over the duration of the experiment. At the most effective concentration of 99 ppm, Bonzi retarded growth 15% and 31%, over the duration of the experiment, while Cutless at 150 ppm suppressed growth 21% and 46% in 1998 and 1999, respectively, compared to an untreated control. Plants treated with the most effective concentration of Pistill were 13% and 21% shorter than non-treated plants over the duration of the experiment in 1998 and 1999, respectively. However, in 1998 quality ratings of Pistill-treated plants were lower than for control plants, and the duration of control was shorter than with B-Nine, Bonzi, or Cutless in 1999. Only Cutless provided consistent growth suppression of gaura; plants treated with the most effective concentration of 150 ppm were an average of 19% smaller at 60 days after treatment (DAT) in 1998 and 13% smaller than control plants from 28 to 70 DAT in 1999. B-Nine and Pistill provided more transitory control. In 1999, the most effective concentration of B-Nine suppressed growth 9% from 28 to 56 DAT. Plants treated with the most effective concentration of Pistill of 500 ppm averaged 23% smaller at 14 and 28 DAT than control plants. Application of Pistill delayed flowering 11 to 13 days in 1998.

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