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  • Author or Editor: James E. Barrett x
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Abstract

Chrysanthemum morifolium Ramat. plants were grown in media with and without pine bark and treated with drenches of α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol) at 0.25 mg/pot, (2RS,3RS)-l-(4-chlorophenyl)-4,4-dimethyl-2-(l,2,4-triazol-l-yl) pentan-3-ol (PP333) at 0.25 mg/pot, or α-(l-methylethyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidinemethanol (EL-500) at 0.0625 mg/pot, or two 5000 mg/liter foliar sprays of butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide). Foliar sprays of daminozide controlled plant height equally in both media but drenches of ancymidol, PP333, and EL-500 were not effective when pine bark was included in the medium.

Open Access

The influence of several environmental and cultural factors on the efficacy of paclobutrazol liner dips were evaluated for three species of bedding plants: ‘Fancy’ scaevola (Scaevola aemula), ‘Suncatcher Plum’ petunia (Petunia ×hybrida), and ‘Double Fiesta Rose’ impatiens (Impatiens walleriana). The impact of paclobutrazol concentration in the dip solution, location of treatment, root substrate moisture status, and time in the dip solution were investigated. Before the liner dip application, the rooting substrate was brought to a specific percentage of container water capacity (20%–100%). Liners were then dipped in a paclobutrazol solution of the prescribed concentration (1–16 mg·L−1) for a prescribed time interval (10–300 s) in a specific location (open-wall greenhouse, polyethylene-glazed greenhouse under 80% shade fabric, three-wall potting shed, or building interior). Plant size data were collected when the untreated control plants reached a marketable stage. Paclobutrazol concentration and root substrate moisture status had a significant effect on size control, but location and dip duration did not. Size suppression varied by species. Following a liner dip at 2 mg·L−1, scaevola, impatiens, and petunia plants were 44%, 26%, and 11% smaller than the untreated controls, respectively. Petunia plants dipped in a 8 mg·L−1 paclobutrazol solution with substrate moisture status of 100%, 90%, 80%, 70%, 50%, or 20% of container capacity were 11%, 8%, 25%, 30%, 41%, or 42% smaller than the untreated control, respectively (30 s dip duration, open-wall greenhouse). Petunia plants dipped in a solution of 8 mg·L−1 paclobutrazol for 10, 30, 120, or 300 s were all between 18% and 23% smaller than the control (50% of container capacity, open-wall greenhouse). Petunia plants dipped in an 8 mg·L−1 paclobutrazol solution in all four locations were all 20% to 21% smaller than the untreated control.

Full access

Abstract

Pressure chamber and thermocouple psychrometer measurements of leaf water potentials in vegetative Euphorbia pulcherrima Willd. cv. Eckespoint C-l Red were evaluated. The 2 methods agreed within 0.2 MPa between −0.3 and −1.8 MPa and were equal at −1.1 MPa. Minimum daily water potential for nonstressed plants reached −0.67 MPa by 1230 hr. Abaxial water vapor conductance and water potential varied little between 1230 and 1630 hr. When drought was imposed, incipient stomatal closure occurred at −0.8 MPa with full closure observed at −1.2 MPa. Complete loss of turgor pressure occurred at water potentials between −1.2 and −1.4 MPa. The linear correlation coefficient for conductance and leaf-air temperature differential was 0.96, with leaf and air temperature equal when conductance was 0.6 cm·s−1. Xylem pressure potentials of upper leaves on drought-stressed plants declined to −1.7 MPa in 8 days and abscission of proximal leaves began. There was little change in xylem pressure potentials of upper leaves after leaf abscission began.

Open Access

Abstract

Bract necrosis of Euphorbia pulcherrima Willd. ‘Gutbier V-14 Glory’ was most frequently observed on transitional bracts (red leaf-shaped organs attached to the stem in the same alternate phyllotaxy as leaves and subtending the inflorescence). Transitional bracts lacked a palisade layer and their stomatal density was lower than on leaves. Necrosis was prevalent at the transitional bract tips in areas with a brochidodidmous-semicraspedodromous veination pattern. Plant growth was not affected when either fertilization was terminated at bract coloration or when plants were watered at wilt during the period from bract color to anthesis. Necrosis was greatest, however, on plants grown with high fertilizer and water levels. Necrosis may be associated with a toxicity of elements transported through pitted vein endings at the tip of the bract.

Open Access

Abstract

‘Gutbier V-14 Glory’ poinsettia was introduced to the commercial industry in the late 1970s and has been shown to be sensitive to bract necrosis (3). Necrotic spots occasionally develop on the intermediate bracts during the latter parts of the crop cycle. Nell and Barrett (2) found this problem to be worse when plants were provided 300–400 mg/liter Ν at every irrigation and well watered during bract coloration. Symptoms resembled injury due to elemental toxicity or desiccation. Observations in commercial operations suggested that necrosis may be related to fertilizer source or formulation.

Open Access

Abstract

Research indicates P and S leach rapidly from soilless media amended with ordinary superphosphate (2). Since these elements are in the form of anions, an amendment with a high anion exchange capacity may reduce their leaching from soilless media. In the following study, an anion exchange resin was used to test this theory.

Open Access

Abstract

Columns of an incubated (25°C, 11% volumetric moisture for 30 days) 2 milled pine bark : 1 Canadian sphagnum peat : 1 builders’ sand (by volume) medium amended with the equivalent of 270 g P·m−3 from radioactive superphosphate (8.7% P) and the equivalent of 0, 33, 200, or 1200 g Al·m−3 from aluminum acetate (13.2% Al) were leached daily with 16 ml deionized water. Eighty percent of the 32P amendment leached during days one to 21 from the medium not amended with Al, whereas 0.3% leached when amended with 1200 g Al·m−3. Leachate 32P levels ranged from 840, 711, 91, and 2.0 μg·ml−1 on day 1 to 2.3, 3.3, 7.6, and 0.9 μg·ml−1 on day 77 for the medium with Al amendments of 0, 33, 200, and 1200 g·m−3, respectively.

Open Access

Abstract

A 2 pine bark : 1 moss peat: 1 sand (by volume) medium (11% volumetric, 20% gravimetric moisture) amended with 4.2 kg m −3 of dolomitic limestone and 3 kg m−3 of 32P-, 35S-superphosphate (8.7% P, 11.7% S) was incubated (25°C) for either 0, 15, or 30 days. Columns (4 × 15 cm) of the medium for each incubation time received 48 ml of deionized water (pH 5.5) in 3 hr on day 1 and 16 ml in 1 hr on days 2-21. Forty-six and 21% of 32P and 35S, respectively, leached on day 1 when the medium was not incubated. Thirty-one percent and 28% of the 32P and 14% and 13% of the 35S leached on day 1 if the medium had been incubated 15 or 30 days, respectively. Eighty-two percent of the 32P and 66% of the 35S amendment leached from the unincubated medium during the 3 week experimental period. A similar leaching experiment, but with superphosphate in absorbent cotton instead of the soilless medium, indicates superphosphate dissolves readily.

Open Access

Abstract

‘Gutbier V-10 Amy’ (‘Amy’) poinsettia lost more leaves and cyathia after simulated shipping at different temperatures (4°, 16°, or 24°C) and 30 days under interior conditions than ‘Annette Hegg Dark Red’ (‘AHDR’) plants. ‘Amy’ and ‘AHDR’ plants lost a large number of leaves when shipped for more than 4 days at 24°. ‘Amy’ quality was reduced when shipped at 4° due to chilling injury (white lesions on bracts). Bracts less than 2.5 cm long were most sensitive to this injury.

Open Access

Impatiens L. wallerana Hook., Salvia splendens Sello ex Nees, Tagetes erecta L., and Petunia hybrida Vilm. plants in 610-cm3 pots were sprayed with either uniconazole or paclobutrazol at concentrations from 10 to 160 mg·liter-1. For all species, both chemicals reduced plant size compared with untreated control plants, and the effect increased with higher concentrations. Uniconazole produced smaller plants than did paclobutrazol at similar concentrations. For impatiens, salvia, and marigold, there was an interaction between chemical and concentration; the degree of difference between the effects of the chemicals was greater at higher concentrations. For these three species, uniconazole elicited a quadratic response and reached saturation within the concentrations used; however, these concentrations were still in the linear portion of the dose response curve for paclobutrazol. Chemical names used: (2RS,3RS)-1-(4-chlorophenyl)-2-(1,1-dimethylethyl)-(1H-1,2,4-triazol-1-yl)pentan-3-ol (paclobutrazol); (E)-(+)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3-ol (uniconazole).

Free access