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  • Author or Editor: Nancy Howard Agnew x
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Dormant, intact crowns were used to determine the cold hardiness of the herbaceous perennial Heuchera sanguinea `Chatterbox'. Crowns were placed in moist cheesecloth, wrapped in aluminum foil, and subjected to -4,-6,-8,-10,-12,-14, -16, or -18C in a programmable freezer. Regrowth quality ratings and dry-mass measurement decreased linearly with temperature. No regrowth was evident from any crown exposed to -12C or lower temperatures. Freezing dormant plant crowns proved an efficient and reliable technique for estimating cold hardiness of Heuchera `Chatterbox'.

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Problems with iron toxicity are documented for the bedding plant species of geranium and marigold. It was suspected that observed nutrition problems of Chrysanthemum Xsuperbum `Snow Lady' were due to iron toxicity. The objectives of this study were to determine which if any perennial species were sensitive to iron toxicity (iron efficient) and to document any symptoms. Using a sand culture method, C. Xsuperbum `Snow Lady' and `Alaska', and Pelargonium Xhortorum `Red Elite' (as a check) and 3 other perennial species were watered twice daily with a modified Hoaglands I solution with 0.00, 0.02, 0.04, 0.08, 0.16, or 0.32 mM FeEDTA. Only Pelargonium had toxic foliar iron levels (462.2 ppm Fe averaged over all treatments) and showed classic iron toxicity symptoms. C. Xsuperbum `Alaska' showed possible iron toxicity symptoms at 0.08 and 0.16 mM FeEDTA with foliar iron levels of 301.0 ppm Fe and 282.7 ppm Fe, respectively. Below average foliar levels of Mn were observed in all species except Pelargonium. Also noted were: toxic levels of boron in Achillea and deficient levels of copper in Aguilegia.

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Electrolyte leakage and regrowth tests were performed in successive months from September to January to determine cold hardiness of container-grown Sedum spectabile Xtelephium L. `Autumn Joy' and Sedum spectabile Boreau. `Brilliant' plants exposed to natural temperature and photoperiod. Plant crowns were subjected to 0, -3, -6, -9, -12, -15, -18, -21, -24, or -27C in a programmable freezer. Regrowth tests were performed on whole crowns and electrolyte leakage determinations were made on excised tuberous root and crown tissues. Regrowth data indicate both cultivars had killing temperatures of -3C at the September test date, prior to the onset of cold-acclimation. By October, the killing temperature for `Autumn Joy' had dramatically decreased to -12C, with more gradual acclimation occurring thereafter. The killing temperature for `Brilliant' decreased from -3C in October to -18C in November. In this study, maximum hardiness was achieved on the January test date with killing temperatures of -24 and -21C for `Autumn Joy' and `Brilliant', respectively. Correlation coefficients suggest the electrolyte leakage procedure was able to reliably estimate `Autumn Joy' cold hardiness at each test date, but was less accurate for `Brilliant'. Regrowth tests are tedious and qualitative, but remain reliable predictors of plant viability. Electrolyte leakage tests were successful in estimating survival potential of plants exposed to freezing temperatures using either excised crown or tuberous root tissue.

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Abstract

Various concentrations of sodium 2,3:4,6-di-0-isopropylidene-2-keto-L-gu-lonate (dikegulac) sprayed on Rieger begonia (Begonia × hiemalis Fotsch ‘Northern Sunset’) in combination with hand-pinching were compared with a single concentration of (2-chloroethyltrimethyl)ammonium chloride (chlormequat), hand-pinching, and control. Both chemicals and hand pinch were effective in reducing internode length but did not affect overall height, diameter, visual quality, or dry weight. The dikegulac spray in combination with a hand pinch and the 0.10 and 0.16% double dikegulac sprays significantly decreased flower count compared to that of the control.

Open Access

Abstract

Silver thiosulfate (STS) foliar sprays applied 1 and 4 weeks prior to simulated shipping reduced corolla abscission of Streptocarpus × hybridus Voss. Spray concentrations of 0.5, 1.0, and 2.0 mm were all effective in reducing corolla abscission when appropriately timed. Sprays applied 24 hr prior to shipping caused necrotic lesions on the flowers and foliage and proved harmful in the warm, humid environment used in simulated shipping. A combination treatment with STS (2 mm) sprayed 4 weeks and again 24 hr prior to shipping showed the 4-week spray treatment to precondition the plants thereby preventing injurious effects by the 24 hr treatment and decreasing corolla abscission 46.6%. STS folair sprays applied one week prior to shipping at 0.5 him and 1.0 mm prevented corolla abscission with 0% corolla abscission after simulated shipping.

Open Access

Determining consumer preferences for specific plant attributes and plant use can assist in the development of breeding program objectives and marketing strategies. Consumers in Ames, Iowa participated in an intercept-survey to determine their knowledge of, use of, and preference for several varieties of New Guinea Impatiens (Impatiens × hawkeri). Of the population surveyed, 44% had never seen New Guinea Impatiens. Of those that had previously purchased New Guineas, 40% purchased their plants from a retail greenhouse. Outdoor container plantings were the preferred use of New Guinea Impatiens. Mother's Day was chosen by 88% of the respondents as the most appropriate holiday for a gift purchase. Considering plant characteristics, consumers rated condition of the plant as the most important attribute, followed by flower color, flower number, and price. Consumers were asked to rate plants on display comprised of three factors: flower color, leaf variegation, and price. MANOVA was used to determine the most important factor and the trade-off consumers made when expressing a preference for one plant over another.

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A major limiting factor in producing container-grown herbaceous perennials is low-temperature injury to cold sensitive roots and crowns during above ground winter storage. Growers and retailers of these plants understand the need for protection systems, yet specific recommendations are unavailable. The ability of several structureless systems to moderate temperature and protect 16 species of container-grown herbaceous perennials from low-temperature injury was investigated. Two light-excluding treatments consisting of 30 cm of straw between 2 layers of 4 mil white copolymer, and 18 cm deep in-ground beds protected with 1 layer of 4 mil white copolymer and 30 cm of woodchips provided the greatest moderation of winter low and early spring high temperatures but resulted in severe etiolation among test plants, A bonded white copolymer-microform overwintering blanket with translucent properties provided comparable plant survival, and prevented etiolated growth allowing plants to grow rapidly after uncovering, despite dramatic temperature extremes observed beneath this cover.

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Exposure to exogenous ethylene (C2H4) caused corolla abscission of New Guinea impatiens (Impatiens × hawkeri `Sunfire'). Abscission varied with time of exposure and C2H4 concentration. Ethylene at ≥ 1 μl·liter-1 and exposure times of 4 or more hours caused 80% to 100% corolla abscission. Simulated shipping of untreated control plants caused ≈ 65% corolla abscission. Plants pretreated with silver thiosulfate (STS) and (aminooxy)acetic acid (AOA) and subsequently exposed to simulated shipping were not different from one another, and both treatments reduced corolla abscission to ≈ 20% when applied at 1.0 mm. Plants pretreated with STS and exposed to `exogenous C2H4 showed 0% abscission, whereas plants pretreated with AOA showed no reduction in abscission when compared with control plants.

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