Search Results

You are looking at 1 - 10 of 16 items for

  • Author or Editor: James L. Gibson x
Clear All Modify Search
Free access

James L. Gibson and Shannon Crowley

Foliar sprays or root dips of synthetic abscisic acid (s-ABA) have shown to reduce the transpiration rate and subsequently prolong postharvest longevity in a select group of herbaceous ornamental crops. The objective of our study was to determine the impact of s-ABA on postproduction performance of seed impatiens in greenhouse or low light conditions. Market ready Impatiens wallerana `Xtreme Scarlet' plants were sprayed or the root substrate was drenched with s-ABA at 250 or 500 mg·L–1 then boxed for 48 h to represent shipping conditions. Flower number was measured 3 days after application, and again after plants were hydrated following the day when the last treatment wilted 0, 2, 4, 8, 16, or 24 days after application. Visual quality ratings were made 0, 2, 3, 4, 8, 11, 16, or 19 days after application and again after plants were re-irrigated. Drenching the substrate with s-ABA at 500 mg·L–1 maintained foliage and flower turgidity up to 8 days in the greenhouse environment and 16 days in the low light environment. Substrate drenches at 500 mg·L–1 dramatically decreased flower number after removal from the shipping box under greenhouse conditions, and in the low light environment drenching the substrate at 250 mg·L–1 produced similar visual quality results to 500 mg·L–1 16 days after treatment. Plants drenched at 250 mg·L–1 also had the same number of flowers 3 and 20 days after treatment, when compared to 500 mg·L–1. Therefore, impatiens growers should drench the root substrate with s-ABA at 250 mg·L–1 to reduce labor costs associated with hand-watering and prolong postproduction performance in low light conditions, such as indoor retail conditions.

Free access

James L. Gibson and Shannon Crowley

The objective of this study was to compare the effects of flurprimidol or paclobutrazol on the growth of four bedding plant species: nicotiana (Nicotiana ×sanderae), portulaca (Portulaca grandiflora), verbena (Verbena ×hybrida), and zinnia (Zinnia elegans). Plants were treated 10 days after transplanting with foliar sprays of five concentrations (in mg·L–1): 5, 10, 20, 40, or 80 from each plant growth regulator. Phytotoxicity symptoms were not observed on plants sprayed with flurprimidol or paclobutrazol. Foliar sprays of flurprimidol at 20 mg·L–1 and paclobutrazol at 80 mg·L–1 provided sufficient growth control of nicotiana for retail sales, while concentrations of 40 to 80 mg·L–1 flurprimidol produced more compact plants for wholesale production. For portulaca only flurprimidol sprays of 40 and 80 mg·L–1 produced plants that were proportionate to the container. Foliar sprays of flurprimidol at 20 mg·L–1 and paclobutrazol at 40 mg·L–1 controlled growth of verbena and zinnia suitable for retail sales, while concentrations of 40 mg·L–1 flurprimidol and 80 mg·L–1 paclobutrazol provided more compact plants which may be useful for wholesale growers. Concentrations were based under Florida conditions and should be adjusted for other areas.

Full access

James L. Gibson and Brian E. Whipker

Ornamental cabbage and kale (Brassica oleracea var. acephala) plants of cultivars Osaka White and Nagoya Red were treated with paclobutrazol and uniconazole as foliar sprays or substrate drenches. These treatments were compared to the industry standard of daminozide foliar sprays. Applying drenches of paclobutrazol (a.i.) at 4 mg/pot or uniconazole (a.i.) at 1 mg/pot (28,350 mg = 1.0 oz) resulted in 6% or 17%, respectively, shorter `Osaka White' plants while a 2 mg/pot paclobutrazol drench or a uniconazole drench at 0.25 mg/pot resulted in 25% shorter `Nagoya Red' plants. Although effective, the expense of substrate drenches for both plant growth regulators (PGRs) would not be economically feasible for growers to use. Paclobutrazol foliar sprays at concentrations of up to 80 mg·L-1 (ppm) were ineffective in controlling plant height and diameter of either `Osaka White' or `Nagoya Red'. A uniconazole foliar spray of 16 mg·L-1 resulted in 17% shorter `Nagoya Red' plants and 6% shorter `Osaka White' plants. A daminozide foliar spray of 2500 mg·L-1, sprayed twice, resulted in 21% shorter plants for both cultivars. Spraying daminozide would provide optimal height control for the retail grower. Although spraying daminozide twice controlled plant height and costs half the amount of an uniconazole spray at 16 mg·L-1, plant diameter was not affected with daminozide, therefore a wholesale grower who would desire a smaller diameter plant should use a uniconazole spray of 16 mg·L-1.

Full access

James L. Gibson and Brian E. Whipker

Twenty-six ornamental cabbage and kale (Brassica oleracea var. acephala) cultivars were grown in 8-inch (20.8-cm) diameter pots during Fall 1998 to classify their foliage traits and determine their response to the plant growth regulator (PGR) daminozide. Cultivar vigor was classified by height. Foliage characteristics were described and cultivars of ornamental cabbage, notched ornamental kale, and curly ornamental kale were selected for retail or wholesale markets based on the shortest number of days until a significant center color change, the largest center color diameter, and attractive foliage characteristics. Two cultivars treated with 2,500 ppm (mg·L-1) daminozide and eight cultivars treated with 5,000 ppm were significantly smaller in height compared to nontreated plants. Plants were treated 6 weeks after sowing, and the response to the PGRs may have been diminished by the age of the plant. Therefore, to further investigate PGR efficacy, seven outstanding cultivars selected in 1998 were treated with 5,000 ppm daminozide or 5 ppm uniconazole 14 days after potting (4 weeks after sowing) in Fall 1999. Greater control was observed with daminozide at 5,000 ppm in 1999 with a 13% smaller plant height as compared to 9% in 1998, when compared to the nontreated control. For greater height control, PGR applications to ornamental cabbage and kale should be applied 4 weeks after sowing.

Full access

James L. Gibson and Brian E. Whipker

Vigorous osteospermum (Osteospermum ecklonis) cultivars Congo and Wildside received foliar sprays of daminozide or daminozide + chlormequat (Expt. 1). Both cultivars responded similarly to the plant growth regulator (PGR) treatments. Only a limited amount of plant height control occurred using 5,000 mg·L-1 (ppm) daminozide + 1,500 mg·L-1 chlormequat or 5,000 mg·L-1 daminozide + 3,000 mg·L-1 chlormequat. Flowering was delayed, phytotoxicity was observed, while peduncle length increased, suggesting that higher concentrations of daminozide or chlormequat may or not be effective at any concentration and may result in increased phytotoxicity. In Expt. 2, `Lusaka' received foliar sprays or substrate drenches of paclobutrazol or uniconazole. Foliar sprays ≤80 mg·L-1 paclobutrazol or ≤24 mg·L-1 uniconazole were ineffective in controlling plant growth. Substrate drenches of paclobutrazol (a.i.) at 8 to 16 mg/pot (28,350 mg = 1.0 oz) produced compact plants, but at a cost of $0.23 and $0.46/pot, respectively, would not be economically feasible for wholesale producers to use. Uniconazole drenches were effective in producing compact `Lusaka' osteospermum plants. Uniconazole drench concentrations of 0.125 to 0.25 mg/pot were recommended for retail growers, while wholesale growers that desire more compact plants should apply a 0.25 to 0.5 mg/pot drench. Applying uniconazole would cost $0.06 for a 0.25 mg drench or $0.12 for a 0.5 mg drench.

Free access

Christopher B. Cerveny and James L. Gibson

Bougainvillea glabra is a tropical species with reportedly difficulty to propagate. Previous research has shown the importance of talc-based rooting hormones when propagating Bougainvillea, yet little has been published on the efficacy of liquid-based formulations. Therefore, our objective was to determine the optimum concentration of indolebutyric acid potassium salt (KIBA) needed to effectively root semi-hardwood stem cuttings of Bougainvillea `California Gold' and `Helen Johnson'. Sub-terminal cuttings measuring 6.5 cm were harvested from stock plants of Bougainvillea on 3-week intervals from 6 June to 8 Aug. and repeated 6 Sept. to 8 Nov. 2005. Cuttings were dipped 0.5 cm in a solution of 0, 1500, 3000, or 6000 mg·L-1 KIBA or in a 1500-mg·L-1 solution containing indolebutyric acid (IBA) 1%: napthaleneacetic acid (NAA) 0.5% and propagated under mist. Cuttings were evaluated for percent survival, rooting quality (1 = poor; 5 = best), and number of primary and lateral roots 5 weeks after planting (WAP). Differences in `California Gold' for percent survival, average rank, and number of roots were determined not significant at P ≤ 0.05. However, application of rooting hormone to `Helen Johnson' increased rooting quality, number of primary roots, and number of lateral roots by up to 24%, 53%, and 50%, respectively. Results indicated rooting performance was generally improved with application of KIBA; therefore, cuttings of Bougainvillea may benefit from a 1500-mg·L-1 solution. KIBA was also found to be as effective as the industry standard liquid formulation. Growers will have to consider the availability and cost of KIBA when propagating Bougainvillea.

Free access

James L. Gibson and Brian E. Whipker

Ornamental cabbage and kale (Brassica oleracea var. acephala L.) plants of cultivars `Osaka White' and `Nagoya Red' were treated with paclobutrazol and uniconazole as foliar sprays or soil drenches. These treatments were compared to the industry standard of daminozide foliar sprays. Ten plant growth regulator (PGR) drench treatments (in mg a.i./pot) were applied 22 days after potting: paclobutrazol at 1 to 16 and uniconazole at 0.125 to 2. Thirteen PGR foliar sprays (in mg/L) were also applied: paclobutrazol at 5 to 80, uniconazole at 2 to 32, daminozide at 2500, 2500 (twice, with the second application occurring 14 days later), or 5000, and an untreated control. Applying drenches of paclobutrazol at 4 mg or uniconazole at 0.5 mg controlled height by 16 to 25%, but at the cost of $0.11 per pot would not be economically feasible for growers to use. Paclobutrazol foliar sprays at concentrations of up to 80 mg/L were ineffective in controlling plant height and diameter of either `Osaka White' or `Nagoya Red'. Uniconazole foliar sprays between 2 and 8 mg/L were effective in controlling height (by 19%) and diameter (by 15%) as daminozide foliar sprays of 2500 mg/L, sprayed twice, with a cost to the grower of $0.02 per pot.

Free access

James L. Gibson and Brian E. Whipker

Twenty-six ornamental cabbage and kale (Brassica oleracea var. acephala L.) cultivars were transplanted into 20.8-cm (8-inch) pots in Fall 1998 to classify their foliage traits and determine their response to the plant growth regulator (PGR) daminozide. Daminozide foliar sprays were applied at 0, 2500, or 5000 mg·L–1 (ppm) 3 weeks after potting. Two cultivars treated with 2500 mg.L-1 and eight cultivars treated with 5000 mg·L–1 were significantly smaller in height when compared to the nontreated plants. Using the Range/lsd formula, the vigor of the cultivars was classified by height. Foliage characteristics were described and cultivars of ornamental cabbage, notched ornamental kale, and curly ornamental kale were selected based on the shortest number of days until a significant center color change and the largest center color diameter. In Fall 1999, recommended cultivars selected in 1998 were treated with daminozide at 5000 mg·L–1 or uniconazole at 5 mg·L–1 14 days after potting, plus a nontreated control. All cultivars responded similarly to the PGRs with greater control being observed with daminozide with a smaller plant height of 13% as compared to 6% for uniconazole. For effective height control, PGR applications to ornamental cabbage and kale should be applied 2 weeks after potting.

Free access

James L. Gibson and Brian E. Whipker

Current fertilizer recommendations for ornamental cabbage (Brassica oleracea var. acephala DC.) suggest applying 150 to 300 mg·L-1 N until the initiation of color development, after which fertilization should be reduced or discontinued. Because these plants are actively growing during cool weather when coloration is initiated, nutrient deficiencies may reduce overall plant quality. The objectives of this study were to investigate N to K ratios for plant growth of ornamental cabbage and the effects of continual and discontinued fertilization during the period of coloration. Fertilizing with 150 to 200 mg·L-1 N and 150 to 200 mg·L-1 K produced high-quality plants and provided sufficient tissue concentrations of N and K. Center-head coloration was not inhibited by N concentrations as high as 250 mg·L-1. Ceasing fertilization prior to center-head coloration resulted in the rapid depletion of N, P, and K concentrations in the lower foliage, leading to the appearance of deficiency symptoms and lower leaf loss. Plants were still actively growing as measured by increased shoot mass during the early stages of coloration; therefore, growers should continue to provide a complete analysis fertilizer at N concentrations ≥150 mg·L-1 until market date.

Free access

Christopher B. Cerveny, James L. Gibson and James E. Barrett

Orange Jasmine (Murraya paniculata L. Jack) and Texas Star [Tecoma stans (L.) Juss.] are two tropical ornamentals which have become popular in the specialty floriculture crop market because of their outstanding flower characteristics. Unfortunately they are difficult to root and little has been published on how to propagate them effectively. Therefore, the objective of our experiment was to determine the optimum physiological age of stem tissue necessary to effectively root 2-node stem cuttings. Forty-five cm shoots of Murraya were harvested on 27 June and 7 Sept. 2005, and divided into 2-node stem cuttings representing the top, middle, and bottom sections of the stem (soft-wood, semi-hardwood, and hardwood, respectively). Cuttings were measured for stem length and diameter, dipped in a 1,500 mg·L–1 solution containing indolebutyric acid (IBA) 1%: napthaleneacetic acid (NAA) 0.5%, and propagated under mist for 10 weeks in a 4 perlite: 1 vermiculite substrate (by volume). Tecoma followed a similar regime but were harvested once on 13 Sept. and evaluated 4 weeks after planting. Both species were evaluated for percent survival and rooting quality on a 1 to 5 scale; 1 = poor, 5 = best. Stem quality differences in Tecoma cuttings were shown, but did not influence rooting performance or percent survival. Murrayacuttings indicated a similar trend suggesting that age of tissue is not an important factor when propagating these species. However, when comparing the two harvest dates, data from Murraya cuttings showed an increase in survival from 79% and 95% and an increase in rooting quality from 2.72 to 4.26 when harvested in June compared to Sept., respectively. Cuttings harvested in Sept. were also shown to be 17% shorter with a 126% larger diameter than those harvested in June. These data suggest a trend toward a seasonal effect when harvesting cuttings of Murraya paniculatain Florida. Further studies should be conducted to verify this trend and to identify the ideal season for propagation.