Effects of Cold and Photoperiod on Flowering of Several Herbaceous Perennial Species

Thirty herbaceous perennial species were treated at 5°C for 0 or 15 weeks. Critical photoperiods for flower initiation and development with and without a cold treatment were determined. Photoperiods were 10, 12, 13, 14, 16, or 24 hours of continuous light or 9 hours plus a 4-hour night interruption. Continuous photo-periodic treatments consisted of 9-hour natural days extended with light from incandescent lamps. Species were categorized into nine response types based on the effects of cold and photoperiod on flowering. Plants had three flowering responses to cold treatment: obligate, facultative, or none. The perennials were obligate long-day, facultative long-day, or day-neutral plants. For example, Campanula carpatica `Blue Clips' had no response to cold and was an obligate long-day plant requiring photoperiods of 16 hours or longer or night interruption for flowering. Rudbeckia fulgida `Goldsturm' had a facultative response to cold and required photoperiods of 14 hours or longer or night interruption for flowering. Veronica longifolia `Sunny Border Blue' had an obligate cold requirement and was day-neutral. Some species responded differently to photoperiod before and after cold. Leucanthemum ×superbum `Snow Cap' flowered as an obligate long-day plant without cold and as a facultative long-day plant after cold. Response categories are discussed.

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Determining the Critical Photoperiod for Flowering of Several Herbaceous Perennial Species

HortScience ◽

10.21273/hortsci.30.4.861a ◽

1995 ◽

Vol 30 (4) ◽

pp. 861A-861

Author(s):

Erik S. Runkle ◽

Royal D. Heins ◽

Arthur C. Cameron ◽

William H. Carlson

Keyword(s):

Plant Height ◽

Cold Treatment ◽

Continuous Light ◽

Flower Initiation ◽

Perennial Species ◽

Critical Photoperiod ◽

Incandescent Lamps ◽

Herbaceous Perennial

Twenty-four herbaceous perennial species were treated at 5C for 0 or 15 weeks. Critical photoperiods for flower initiation and development with and without a cold treatment were determined. Photoperiods were 10, 12, 14, 16, and 24 h of continuous light and 9 h plus a 4-h night interruption. Continuous photoperiodic treatments consisted of 9-h natural days extended with light from incandescent lamps. Response to cold and photoperiod varied by species; Scabiosa caucasica `Butterfly Blue' flowered without a cold treatment under all photoperiods after 8 to 10 weeks of forcing, but plant height increased from 14 to 62 cm as daylength increased. Rudbeckia fulgida `Goldsturm' flowered without cold after 13 to 15 weeks of forcing, but only under 16 hours of continuous light and night interruption treatments. Heuchera sanguinea `Bressingham Hybrids' did not flower without cold under any photoperiod but did flower under all photoperiods with cold. The only Lavendula angustifolia `Munstead Dwarf' plants that flowered without cold were those under 24-h continuous light; ≈60% flowered. After cold, some lavender plants flowered under all photoperiods, and the flowering percentage increased with increasing daylength.

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Influence of Daylength Delivery on Flowering in Several Herbaceous Perennial Species

HortScience ◽

10.21273/hortsci.30.4.861f ◽

1995 ◽

Vol 30 (4) ◽

pp. 861F-861

Author(s):

Cheryl Hamaker ◽

William H. Carlson ◽

Royal D. Heins ◽

Arthur C. Cameron

Keyword(s):

Continuous Light ◽

Flower Induction ◽

Perennial Species ◽

Herbaceous Perennials ◽

Short Day ◽

Long Day ◽

Herbaceous Perennial ◽

Campanula Carpatica

To determine the most effective lighting strategies for flower induction of long-day (LD) plants, 10 species of herbaceous perennials were chilled at 5C for 0 or 12 weeks and then forced at 20C under the following photoperiods: short day, 4-h night interruption (4-h NI), 7-h night interruption (7-h NI), 7-h day extension, 7-h predawn (7-h PD), and 24-h continuous light (24-h). All treatments consisted of a 9-h photoperiod of sunlight supplemented with 90 μmol·m–2 from HPS lamps. LD treatments were delivered by incandescent lights and induced flowering in obligate LD plants. Rate of flowering, height, and bud number at first flower varied among species and LD treatments. Although flowering was accelerated under 24-h and 7-h NI for most species, it was delayed under 24 h for Coreopsis verticillata `Moonbeam' and Campanula carpatica. For unchilled plants of most species, flowering was delayed under 7-h PD compared to other LD treatments. Chilling decreased time to flower and reduced differences between LD treatments. Coreopsis `Moonbeam' and C. Ianceolata `Early Sunrise' were shorter when grown under 4-h NI.

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The effect of vernalization on the heading of Wimmera ryegrass (Lolium rigidum) and on five cultivars of perennial ryegrass (Lolium perenne)

Australian Journal of Experimental Agriculture ◽

10.1071/ea9640352 ◽

1964 ◽

Vol 4 (15) ◽

pp. 352 ◽

Cited By ~ 3

Author(s):

JH Silsbury

Keyword(s):

Lolium Perenne ◽

Perennial Ryegrass ◽

Cold Treatment ◽

Continuous Light ◽

Leaf Number ◽

Lolium Rigidum ◽

Artificial Seed ◽

Mediterranean Origin ◽

Wimmera Ryegrass ◽

Cold Requirement

The responses of annual and perennial ryegrass to 0, 6, and 12 weeks artificial seed vernalization were determined by recording the percentages of plants heading and the leaf numbers at heading for populations of 40 plants grown in a glasshouse under continuous light. All plants of the annual L. rigidum headed without vernalization but the vernalized plants headed at a much lower leaf number than did the unvernalized controls. At least six weeks of cold treatment were needed for complete induction of the five cultivars of L. perenne examined. The vernalization responses of cultivars of Mediterranean origin were similar to those of the Australian Colac. It was shown that late heading in L. perenne is not always associated with a large cold requirement and it is suggested that photoperiod may be an important factor controlling heading of ryegrass in southern Australia.

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Cold Treatments Alter the Photoperiodic Flowering Response of Some Herbaceous Perennial Species

HortScience ◽

10.21273/hortsci.33.3.508c ◽

1998 ◽

Vol 33 (3) ◽

pp. 508c-508

Author(s):

Erik S. Runkle ◽

Royal D. Heins ◽

Arthur C. Cameron ◽

William H. Carlson

Keyword(s):

Cold Treatment ◽

Cold Period ◽

Photoperiodic Induction ◽

Perennial Species ◽

Additional Species ◽

Flowering Response ◽

Herbaceous Perennials ◽

Photoperiodic Flowering ◽

Herbaceous Perennial ◽

Short Days

Many species of herbaceous perennials either require a cold treatment for flowering or exhibit enhanced and more desirable flowering characteristics following a cold period. For some species, the photoperiodic induction of flowering can change following cold treatments, the parameters generally becoming less strict as plants receive longer durations of cold until a saturation duration is reached. To quantify the minimum and saturation durations of cold for flowering under short days (SD) and long days (LD), five species were selected and cooled for 0, 3, 6, 9, 12, or 15 weeks at 5 °C, then forced at 20 °C under 9-h photoperiods without (SD) or with a 4-h night interruption (LD). The effects of cold and photoperiod on flowering varied by species. For example, under SD, 0%, 80%, or 100% of Leucanthemum xsuperbum `Snowcap' flowered after 0, 3, or ≥6 weeks at 5 °C, respectively, and time to flower decreased from 103 to 57 days as the duration of cold increased from 3 to 12 weeks. `Snowcap' cooled for ≥3 weeks, then forced under LD, flowered completely in 45 to 55 days. Flowering percentage of Lavandula angustifolia `Hidcote' reached 100 under LD or SD only when plants were cooled for ≥6 or 15 weeks, respectively. Under LD, flowering percentage of Astilbe chinensis pumila progressively increased from 0 to 100 as cold treatment increased from 0 to 15 weeks; flowering percentage under SD was low regardless of cold treatment. Additional species and flowering characteristics will be discussed.

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Photoperiod and Temperature Interact to Affect Viola × wittrockiana Gams. Development

HortScience ◽

10.21273/hortsci.32.3.466d ◽

1997 ◽

Vol 32 (3) ◽

pp. 466D-466

Author(s):

J.E. Erwin ◽

R. Warner ◽

T. Smith ◽

R. Wagner

Keyword(s):

High Pressure ◽

Plant Height ◽

Continuous Light ◽

Flower Induction ◽

Leaf Number ◽

Ambient Light ◽

Internode Elongation ◽

Before And After ◽

Incandescent Lamps

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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Flowering of Herbaceous Perennials under Various Night Interruption and Cyclic Lighting Treatments

HortScience ◽

10.21273/hortsci.33.4.672 ◽

1998 ◽

Vol 33 (4) ◽

pp. 672-677 ◽

Cited By ~ 23

Author(s):

Erik S. Runkle ◽

Royal D. Heins ◽

Arthur C. Cameron ◽

William H. Carlson

Keyword(s):

Plant Height ◽

Dark Period ◽

Relative Effectiveness ◽

Cold Treatment ◽

Echinacea Purpurea ◽

Herbaceous Perennials ◽

Long Day ◽

Incandescent Lamps ◽

Lighting Regimen ◽

Campanula Carpatica

Six long-day species of herbaceous perennials were grown under six night-interruption (NI) photoperiod treatments to determine their relative effectiveness at inducing flowering. Photoperiods were 9-hour natural days with NI provided by incandescent lamps during the middle of the dark period for the following durations: 0.5, 1, 2, or 4 hours; 6 minutes on, 54 minutes off for 4 hours (10% or 6/54 cyclic lighting); or 6 minutes on, 24 minutes off for 4 hours (20% or 6/24 cyclic lighting). For five species, the experiment was repeated with more mature plants; for the sixth, Rudbeckia fulgida Ait. `Goldsturm', following a cold treatment of 8 weeks at 5 °C. The species generally showed a quantitative flowering response to the NI duration until a saturation duration was reached; as the length of the uninterrupted night break increased, flowering percentage, uniformity, and number and plant height increased and time to flower decreased. Minimum saturation durations of NI were 1 hour for Coreopsis grandiflora Hogg ex Sweet `Early Sunrise' and Hibiscus moscheutos L. `Disco Belle Mixed', 2 hours for Campanula carpatica Jacq. `Blue Clips' and Coreopsis verticillata L. `Moonbeam', and 4 hours for unchilled R. fulgida `Goldsturm'. Echinacea purpurea Moench `Bravado' flowered similarly across all lighting treatments. The 6/24 cyclic lighting regimen induced flowering comparable to that under a continual 4-hour NI for four of the six species and the cold-treated R. fulgida `Goldsturm'. Flowering under the 6/54 regimen was generally incomplete, nonuniform, and delayed compared to that under saturation duration treatments. Three of five species flowered earlier when more mature plants were placed under the NI treatments. Cold-treated R. fulgida `Goldsturm' flowered more rapidly than unchilled plants and the saturation duration of NI decreased to 1 hour.

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Photoperiod and Temperature Interact to Affect Petunia × hybrida Vilm. Development

HortScience ◽

10.21273/hortsci.32.3.502a ◽

1997 ◽

Vol 32 (3) ◽

pp. 502A-502

Author(s):

J.E. Erwin ◽

R. Warner ◽

G.T. Smith ◽

R. Wagner

Keyword(s):

High Pressure ◽

Petunia Hybrida ◽

Day Treatment ◽

Continuous Light ◽

Leaf Number ◽

Ambient Light ◽

Internode Elongation ◽

Before And After ◽

Incandescent Lamps

Petunia × hybrida Vilm. cvs. `Purple Wave', `Celebrity Burgundy', `Fantasy Pink Morn', and `Dreams Red' were treated with temperature and photoperiod treatments for different lengths of time at different stages of development during the first 6 weeks after germination. Plants were grown with ambient light (≈8–9 hr) at 16°C before and after treatments. Flowering was earliest and leaf number below the first flower was lowest when plants were grown under daylight plus 100 μmol·m–2·s–1 continuous light (high-pressure sodium lamps). Flowering did not occur when plants were grown under short-day treatment (8-hr daylight). Plants grown with night interruption lighting from 2200–0200 HR (2 μmol·m–2·s–1 from incandescent lamps) flowered earlier, and with a reduced leaf number compared to plants grown with daylight + a 3-hr day extension from 1700–2000 HR (100 μmol·m–2·s–1 using high-pressure sodium lamps). Plant height and internode elongation were greatest and least in night interruption and continuous light treatments, respectively. `Fantasy Pink Morn' and `Purple Wave' were the earliest and latest cultivars to flower, respectively. Flowering was hastened as temperature increased from 12 to 20°C, but not as temperature was further increased from 20 to 24°C. Branching increased as temperature decreased from 24 to 12°C. Implications of data with respect to classification of petunia flower induction and pre-fi nishing seedlings are discussed.

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Effect of Night-interruption Duration and Cyclic Lighting on Flowering of Obligate Long-day Herbaceous Perennial Plants

HortScience ◽

10.21273/hortsci.31.4.681c ◽

1996 ◽

Vol 31 (4) ◽

pp. 681c-681

Author(s):

Erik S. Runkle ◽

Royal D. Heins ◽

Arthur C. Cameron ◽

William H. Carlson

Keyword(s):

Dark Period ◽

Relative Effectiveness ◽

Echinacea Purpurea ◽

Perennial Plants ◽

Herbaceous Perennials ◽

Long Day ◽

Incandescent Lamps ◽

Herbaceous Perennial ◽

Campanula Carpatica

Six obligate long-day species of herbaceous perennials were grown under six night-interruption treatments to determine their relative effectiveness at inducing flowering. Photoperiods were 9 hours natural days with night interruptions provided by incandescent lamps during the middle of the dark period for the following durations: 0.5, 1, 2, or 4 hours; 6 minutes on, 54 minutes off for 4 hours (10% cyclic lighting); or 6 minutes on, 24 minutes off for 4 hours (20% cyclic lighting). Response to night interruptions varied by species, but five of the six species flowered most rapidly and uniformly under 4-hour night interruption. Few or no Campanula carpatica `Blue Clips', Rudbeckia fulgida `Goldsturm', or Hibiscus ×hybrida `Disco Belle Mixed' plants flowered with 1 hour or less of continuous night-break lighting. All Coreopsis ×grandiflora `Early Sunrise' flowered, but flowering was hastened as the duration of night interruption increased. Echinacea purpurea `Bravado' flowered similarly across all treatments. In general, the effectiveness of the night-interruption treatments at inducing flowering was 4 hours > 2 hours > 20% cyclic > 1 hour > 10% cyclic > 0.5 hour.

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The Response of Long-day Herbaceous Perennials to a Night-interruption at Low Night Temperatures

HortScience ◽

10.21273/hortsci.32.3.484d ◽

1997 ◽

Vol 32 (3) ◽

pp. 484D-484

Author(s):

Alison Frane ◽

Royal Heins ◽

Art Cameron ◽

William Carlson

Keyword(s):

Low Temperature ◽

Early Spring ◽

Perennial Species ◽

Treatment Results ◽

Flower Bud ◽

Herbaceous Perennials ◽

Long Day ◽

Node Count ◽

Herbaceous Perennial ◽

Short Days

A 4-hr night interruption (NI) is an effective way to promote flowering in many long-day herbaceous perennials. Some perennials are grown outdoors in the early spring and often are exposed to low night temperatures. Long days delivered by NI lighting ineffectively promote flowering under low-temperature conditions in some long-day species. The objective of this experiment was to determine the effectiveness of NI long-day lighting treatments delivered at different night temperatures in promoting flowering of several herbaceous perennials. Ten herbaceous perennial species were grown under natural short days augmented with a 4-hr NI. Night temperatures were 2.5, 5, 10, 15, 20, and 25°C with day temperature of 25°C for all treatments. Plants were transferred to 9-hr days at a constant 20°C after 7 weeks of treatment. Results on flowering percentage, date of visible bud and flowering, node count, flower bud count, and plant height at flowering will be presented.

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Phytohormones level in the leaves of Hyoscyamus niger L. during variable photoperiods at the time of flower initiation and differentiation

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1980.022 ◽

2014 ◽

Vol 49 (3) ◽

pp. 245-258

Author(s):

Jan Kopcewicz ◽

Gabriela Centkowska ◽

Krystyna Kriesel

Keyword(s):

Abscisic Acid ◽

Flower Initiation ◽

Hyoscyamus Niger ◽

Long Day ◽

General Decrease ◽

Before And After ◽

Endogenous Phytohormones ◽

Quantitative Changes ◽

Inductive Photoperiod ◽

Short Days

The investigations concern changes in the content of endogenous phytohormones in the leaves of the long-day plant <em>Hyoscyamus niger</em> L. during variable photoperiods applied before and after flower initiation. The results show that alternation of inductive photoperiods with short days leads to quantitative changes in the content of phytohormones. The changeable photoperiod leads to a general decrease in the contents of gibberellins, cytokinins and auxins during the short noninductive days both before and after flower initiation. Alternation of the inductive photoperiod with short days does not influence the content of abscisic acid-like substances before flower initiation and causes an increase of the amount of inhibitors in the postinductive period. The content of hormonal substances is subjected to rhytmical changes related to the periods of light and darkness in the twenty-four hours' cycle.

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