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  • Author or Editor: R.A. Larson x
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Abstract

Extended long days or interrupted night photoperiods increased leaf number and top fresh weight, and decreased tuber formation compared with short days with 2 cultivars of the “NonStop” series of tuberous begonia (Begonia X tuberhybrida Voss). Short days increased tuber size and fresh weight and reduced top fresh weight of both cultivars. ‘Double Red’ showed greater leaf number, top fresh weight, tuber fresh weight, and tuber size at 22°C than at 26°, while ‘Double Orange’ showed only greater top fresh weight at 22°. Flowering was enhanced in both cultivars under long days.

Open Access

Abstract

α-Cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol) applied to inherently tall-growing chrysanthemum cultivars controlled ht at concn of 62 mg/liter (0.06 mg/15 cm pot) when applied as a foliar spray, and 0.12 mg/15 cm pot when applied as a soil drench. An thesis was delayed in plants treated with high concn of the growth retardant but flower size and no., and node no. were unaffected.

Open Access

Abstract

Three fundamental different media 3 pine bark (≤ 6mm): 1 sphagnum peat moss:l concrete grade sand; 2 loamy soil: 1 peat moss: 1 perlíte; and a peat-lite mix, (Metro Mix 350) were characterized by available water-holding capacity, bulk density and particle size distribution. All 3 media provided adequate water-holding capacities for container production of ‘Eckespoint C-1 Red’ and ‘Annette Hegg Diva’ poinsettias (Euphorbia pulcherrima Klotzsch ex. Willd.). Total porosity declined and bulk density increased in all media 9 weeks after potting due to shrinkage but there were no additional changes after an additional 4 weeks. Airspace and water buffering capacities did not change during the 13-week period indicating the loss in total porosity resulted in a loss of easily available water. Water release had linear and nonlinear components with respect to moisture tension. Poinsettia root systems appeared to be extensive throughout the growing media; root distributions varied with cultivar and medium.

Open Access

Abstract

Low light intensity caused an increase in size and a delay in flowering of gloxinias (Sinningia speciosa Benth and Hooke cv. Dwarf Delight and Royal Frosted Red). The growth regulators succinic acid-2,2-dimethyl hydrazine (SADH) and (αcyclopropyl-α-(4 methoxyphenyl)-5-prymidinemethanol (ancymidol) decreased plant size and delayed flowering. ‘Dwarf Delight’ showed damage in response to ancymidol at 250 mg/liter and higher but ‘Royal Frosted Red’ showed no damage. SADH caused a noticeable increase in anthocyanin content of the inflorescence and chlorophyll content of the leaves.

Open Access

Abstract

Moisture retention data were collected for five porous materials: soil, phenolic foam, and three combinations of commonly used media components. Two mathematical functions were evaluated for their ability to describe the water content–soil moisture relationship. A cubic polynomial function with linear parameters previously used on container media was compared to a closed-form nonlinear parameter model developed to describe water conductivity in mineral soils. In most tests for precision, adequacy, accuracy, and validation, the nonlinear function was superior to the simpler power series. The nonlinear function provides an excellent tool for describing the water content for media with widely varying physical properties.

Open Access

Abstract

Handling and preparing growing media can have pronounced effects on the “intensity variables” bulk density and equilibrium volume wetness through changes in pore size distribution. These changes in turn affect the container “capacity variables”: the absolute amounts of medium, air, and water in a container. A nonlinear moisture retention function was combined with container geometry in an equilibrium capacity variable (ECV) model that provided accurate predictions of total porosity, container capacity, air space, unavailable water, available water, and solid fraction for several container-medium combinations.

Open Access

Abstract

Plants grown in small containers often show limited growth due to low levels of aeration and water holding capacity in the medium. These levels can be changed by management practices such as medium compaction, medium wetness at time of container filling, container height and volume, peat : vermiculite ratio, particle size, and the use of a wetting agent. A modified equilibrium capacity variable model was applied to an investigation of media-container interactions for short containers (<5 cm tall). Predicted volume percentages for total porosity (TP), container capacity (CC), air space (AS), unavailable water (UW), and available water (AW) were developed from measured moisture retention data and container geometry. AS increased with: 1) increased particle size, 2) increased media moisture at time of container filling, 3) decreased medium compaction, 4) increased wetting agent concentration, 5) decreased ratio of peat : vermiculite, and 6) increased container height. Increased percent AW resulted from smaller particle size, increased media moisture at time of container filling, decreased container compaction, decreased wetting agent concentration, increased ratio of peat : vermiculite and decreased container height.

Open Access

Abstract

Pinched plants of Chrysanthemum morifolium Ramat. ‘Orange Bowl’ and ‘Surf’ grown in a chamber maintained at 22° day/18°C night were transferred to 30° day/26° night at the beginning of week 1, 3, 5, or 7 after start of photoinduction period (15-hr nyctoperiod). Plants remained at high temperatures for 2, 4, 6, 8, or 10 weeks and then were returned to the 22°/18° chamber. Exposure to high temperatures during the first 4 weeks of short days increased the number of nodes, leaf area, stem length, and dry weight of leaves and stems. Rate of floret initiation and perianth differentiation decreased when exposed to high temperatures during the first 4 weeks of short days in ‘Orange Bowl’ but not in ‘Surf’. ‘Orange Bowl’ exposed to high temperatures for 10 weeks from the start of short days flowered 12 days later than plants grown at lower temperatures and formed bracteate buds. Flowering of ‘Orange Bowl’ grown at 22718° during the first 4 weeks of short days, then transferred to high temperatures, was not substantially delayed and flowers developed normally. Flowering was delayed 3 days when ‘Surf’ was exposed to high temperatures for 8 weeks from the start of short days. Exposure to high temperatures did not cause bracteate bud formation in ‘Surf’. With both cultivars, increasing the duration of high temperature exposure increased the time to flowering.

Open Access

The herbaceous perennial species in the genus Sphaeralcea have desirable drought tolerance and aesthetics with potential for low-water use landscapes in the Intermountain West. However, taxonomy of these species is ambiguous, which leads to decreased consumer confidence in the native plant nursery industry. The goal of this study was to test and clarify morphological and genetic differentiation among four putative Sphaeralcea species. Morphological characteristics of the type specimens were used as species references in canonical variate analysis to generate a classification model. This model was then used to assign putative species names to herbarium voucher specimens and to field-collected voucher specimens to clarify genetic variation among species. Field specimens were also classified using Bayesian cluster analyses of amplified fragment length polymorphism (AFLP) genotypes. Sphaeralcea coccinea (Nutt.) Rydb. and S. grossulariifolia (Hook. & Arn.) Rydb. formed a composite group morphologically and genetically distinct from the S. munroana (Douglas) Spach and S. parvifolia A. Nelson composite group. Each composite group displayed genetic isolation by geographic distance. Also, morphological traits of S. munroana and S. parvifolia correlated to geographic distance. Taken together these results suggest that our samples represent two sympatric yet reproductively isolated groups. Distinguishing between these two Sphaeralcea composite groups can create greater consumer confidence in plant material developed for use in Intermountain West low-water landscaping.

Free access

Abstract

Experiments were conducted on the Easter lily cultivars (Lilium longiflorum thunb.) Ace and Nellie White over a 4-year period to compare ancymidol bulb dips to media drenches and foliar spray applications. Several bulb dip concentrations and durations were used. ‘Ace’ plants responded more than ‘Nellie White’ plants to bulb dips, primarily because of more natural vigorous growth of ‘Ace’ plants. A 1-hr dip at 33 ppm gave adequate height control, but flowering was delayed. Reliance on bulb dips to achieve optimum height control may be questionable because ancymidol must be applied before one is certain excessive height will be a problem. Chemical name used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol).

Open Access