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Xiaohua Du, Mengye Wang, Aneta Słomka, and Huichao Liu

interactions are genetic mechanisms that may cause nonadditive phenotypic inheritance in hybrids. However, different views exist on what portion of the heterotic variation is modulated by each of these mechanisms ( Fridman, 2015 ). Viola × wittrockiana Gams

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Geoffrey M. Weaver and Marc W. van Iersel

.J. Jones, M.L. 2010b Benzyladenine and gibberellic acid application prevents abscisic acid-induced leaf chlorosis in pansy and viola HortScience 45 925 933 Weaver, G.M. van Iersel, M.W. 2014 Reducing transpiration of pansies ( Viola ×wittrockiana ) with

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J.E. Erwin, R. Warner, T. Smith, and R. Wagner

Viola × wittrockiana Gams. cvs `Delta Pure Rose' and `Sorbet Yellow Frost' were grown under different photoperiod and temperature treatments (12–24 ± 2°C) for different lengths of time at different stages of development during the first 6 weeks after germination. Plants were grown with ambient light (≈9 hr) at 16°C before and after treatments. Days to anthesis and leaf number were lowest when plants were grown under night interruption from 2200–0200 hr (2 μmol·m–2·s–1 from incandescent lamps) and daylight plus continuous light (100 μmol·m–2·s–1 from high-pressure sodium lamps) for `Sorbet Yellow Frost' and `Delta Pure Rose', respectively. Days to anthesis decreased as temperature increased from 12 to 24°C. Plant height and internode elongation were greatest and least in the night interruption and continuous light treatments, respectively. Branching decreased as temperature increased from 12 to 24°C. Implications of these data with respect to classification of Viola × wittrockiana flower induction and development of prefinished seedlings is discussed.

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Erik S. Runkle and Royal D. Heins

For many plants, light quality has a pronounced effect on plant morphology; light with a low red (R, 600 to 700 nm) to far-red (FR, 700 to 800 nm) ratio promotes stem elongation and a high R: FR, or blue light (B, 400 to 500 nm), suppresses it. In addition, FR light is required for rapid flowering in some species, particularly for long-day plants. Our objective was to quantify how flexible spectral filters, which selectively reduce FR, B, or R, influence plant height and flowering of the quantitative long-day plants Pisum sativum L. `Utrillo' and Viola ×wittrockiana Gams. `Crystal Bowl Yellow'. Plants were grown at 20 °C with reduced FR, B, or R environments or with a neutral density control (C) filter. Calculated phytochrome photoequilebria were 0.78, 0.73, 0.71, or 0.46 for the altered FR, B, C, or R environments, respectively. All filter treatments transmitted a similar photosynthetic photon flux. Sixteen-hour photoperiods were created with natural daylight supplemented with high-pressure sodium lamps positioned above filters. Viola grown under the FR filter never reached 100% flowering within 8 weeks, and visible bud appearance was delayed by at least 17 days compared to all other filters. The R and B filters enhanced peduncle length by at least 25% compared to the C or FR filters. In Pisum, average internode length was 2.2, 2.9, 3.4, and 3.7 cm under the FR, C, B, and R filters, respectively, all statistically different. Fresh and dry shoot weights were similar under the C and FR filters but were at least 35% greater under the B filter and 35% lower under the R filter.

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Genhua Niu, Royal D. Heins, Arthur C. Cameron, and William H. Carlson

Pansy [Viola ×wittrockiana Gams. `Delta Yellow Blotch' (Yellow) and `Delta Primrose Blotch' (Primrose)] plants were grown in a greenhouse under two CO2 concentrations [ambient (≈400 μmol·mol-1) and enriched (≈600 μmol·mol-1)], three daily light integrals (DLI; 4.1, 10.6, and 15.6 mol·m-2·d-1), and nine combinations of day and night temperatures created by moving plants every 12 h among three temperatures (15, 20, and 25 °C). Time to flower decreased and rate of flower development increased as plant average daily temperature (ADT) increased at all DLIs for Yellow or at high and medium DLIs for Primrose. Increasing the DLI from 4.1 to 10.6 mol·m-2·d-1 also decreased time to flower by 4 and 12 days for Yellow and Primrose, respectively. Both cultivars' flower size and Yellow's dry weight [(DW); shoot, flower bud, and total] decreased linearly as plant ADT increased at high and medium DLIs, regardless of how temperature was delivered during day and night. DW in Yellow increased 50% to 100% when DLI increased from 4.1 to 10.6 mol·m-2·d-1 under both CO2 concentrations. Flower size in Yellow and Primrose increased 25% under both CO2 conditions as DLI increased from 4.1 to 10.6 mol·m-2·d-1, but there was no increase between 10.6 and 15.6 mol·m-2·d-1, regardless of CO2 concentration. Plant height and flower peduncle length in Yellow increased linearly as the difference between day and night temperatures (DIF) increased; the increase was larger under lower than higher DLIs. The ratio of leaf length to width (LL/LW) and petiole length in Yellow increased as DIF increased at medium and low DLIs. Carbon dioxide enrichment increased flower size by 4% to 10% and DW by 10% to 30% except for that of the shoot at medium DLI, but did not affect flower developmental rate or morphology. DW of vegetative and reproductive parts of the plant was correlated closely with photothermal ratio, a parameter that describes the combined effect of temperature and light.

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Stanislav V. Magnitskiy, Claudio C. Pasian, Mark A. Bennett, and James D. Metzger

Shoot stretching in plug production reduces quality and makes mechanized transplanting difficult. The objectives of this study were to measure seedling emergence and shoot height of plugs as affected by paclobutrazol application during seed soaking, priming, or coating on seedling emergence and height. Verbena (Verbena ×hybrida Voss. `Quartz White'), pansy (Viola wittrockiana L. `Bingo Yellow Blotch'), and celosia (Celosia cristata L. `New Look') seeds were soaked in water solutions of paclobutrazol and subsequently dried on filter paper at 20 °C for 24 h. Soaking seeds in paclobutrazol solutions before sowing reduced growth and percentage seedling emergence of verbena and pansy but had little effect on those of celosia. Verbena seeds soaked in 50, 200, or 500 mg paclobutrazol/L for 5, 45, or 180 min produced fewer and shorter seedlings than controls. Osmopriming verbena seeds with 10 to 500 mg paclobutrazol/L reduced seedling emergence. Seedling height and emergence percentage of pansy decreased with increasing paclobutrazol concentrations from 2 to 30 mg·L–1 and with soaking time from 1 to 5 min. The elongation of celosia seedlings was reduced by soaking seeds in 10, 50, 200, or 500 mg paclobutrazol/L solutions for 5, 180, or 360 min. However, these reductions were negligible and without any practical application.

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Nicole L. Waterland, Craig A. Campbell, John J. Finer, and Michelle L. Jones

’, Petunia × hybrida ‘Ultra Red’, Tagetes patula ‘Bonanza Orange’, Salvia splendens ‘Picante Scarlet’, and Viola × wittrockiana ‘Bingo Rose Frost’. All bedding plants were obtained as 508-cell packs (111.6 cm 3 /cell) except for salvia (72-plug tray

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Nicole L. Waterland, John J. Finer, and Michelle L. Jones

Methods Plant material Viola × wittrockiana (pansy) ‘Dynamite Purple’ (Kieft-Pro-Seeds), ‘Karma Rose Fire’ (Goldsmith Seeds), or ‘Matrix Blue Frost’ (PanAmerican Seed) and Viola cornuta (viola) ‘Penny Deep Blue’ (Goldsmith Seeds), ‘Skippy

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Brian A. Krug, Brian E. Whipker, Ingram McCall, and Jonathan Frantz

.J. 1961 Distribution of boron in leaves Plant Physiol. 36 420 424 Krug, B.A. Whipker, B.E. Frantz, J.M. McCall, I. 2009 Characterization of calcium and boron deficiency and the effects of temporal disruption of calcium and boron supply on pansy ( Viola

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Wook Oh, Erik S. Runkle, and Ryan M. Warner

( Warrington and Norton, 1991 ). Petunia grown under a higher DLI had more and larger flowers ( Kaczperski et al., 1991 ). In addition, an elevated DLI inhibited stem and peduncle extension growth in pansy ( Viola × wittrockiana Gams.) ( Niu et al., 2000