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

The investigations concern changes in the content of endogenous phytohormones in the leaves of the long-day plant Hyoscyamus niger 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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The effect of inductive photoperiod on flower formation and phytohormones level in a long day plant Hyoscyamus niger L.

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1979.021 ◽

2015 ◽

Vol 48 (2) ◽

pp. 255-265 ◽

Cited By ~ 4

Author(s):

J. Kopcewicz ◽

G. Centkowska ◽

K. Kriesel ◽

Y. Yatorska

Keyword(s):

Short Photoperiod ◽

Flower Formation ◽

Flower Initiation ◽

Hyoscyamus Niger ◽

General Increase ◽

Long Day ◽

Inductive Photoperiod ◽

Inductive Period

The anatomical and hormonal investigations on a long day plant Hyoscyamus niger L. during the time of the generative photoinduction have been conducted. The plants were grown during 75 days on a short photoperiod and then they were transferred to long day conditions. The earliest anatomical symptoms of flower initiation were noticed after four long photoperiods. The inductive photoperiod causes also a general increase in the amounts of phytohormones. During the flower evocation the intensive accumulation of cytokinins and gibberellins in leaves takes place. The post-inductive period, in which the development of flower elements happens, is characterized by changing amount of phytohormones. The content of hormonal substances is subjected to the rhytmical changes related to the periods of light and darknees in the twenty four hours' cycle.

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FLORAL INITIATION IN THE LONG-DAY PLANT Rudbeckia hirta

HortScience ◽

10.21273/hortsci.26.6.719a ◽

1991 ◽

Vol 26 (6) ◽

pp. 719A-719

Author(s):

Richard L. Harkess ◽

Robert E. Lyons

Keyword(s):

Methyl Green ◽

Floral Initiation ◽

Serial Sections ◽

Sodium Cacodylate ◽

Rudbeckia Hirta ◽

Long Day ◽

Cacodylate Buffer ◽

Ethanol Series ◽

Inductive Photoperiod ◽

Short Days

A study was undertaken to determine the rate of floral initiation in Rudbeckia hirta. R. hirta plants were grown to maturity, 14-16 leaves, under short days (SD). Paired controls were established by placing half of the plants under long days (LD) with the remainder left under SD. Beginning at the start of LD (day 0), five plants were harvested daily from each photoperiod group for twenty days. Harvested meristems were fixed in 2% paraformaldehyde - 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.0) for 24 hrs, dehydrated in an ethanol series, embedded in paraffin and sectioned at 8 μm. Serial sections were stained with Methyl-green Pyronin, with adjacent sections treated with RNase for nucleic acid comparison. All events of floral initiation were identified, The results of limited inductive photoperiod indicate that 16-18 LD were required for flowering.

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

HortScience ◽

10.21273/hortsci.31.4.581b ◽

1996 ◽

Vol 31 (4) ◽

pp. 581b-581

Author(s):

Erik S. Runkle ◽

Royal D. Heins ◽

Arthur C. Cameron ◽

William H. Carlson

Keyword(s):

Cold Treatment ◽

Continuous Light ◽

Flower Initiation ◽

Perennial Species ◽

Cold Response ◽

Long Day ◽

Before And After ◽

Cold Requirement ◽

Incandescent Lamps ◽

Herbaceous Perennial

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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Influence of night-breaks on flowering and phytohormones content in Hyoscyamus niger L.

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1982.005 ◽

2014 ◽

Vol 51 (1) ◽

pp. 51-58

Author(s):

Jan Kopcewicz ◽

Gabriela Centkowska

Keyword(s):

Shoot Growth ◽

Flower Formation ◽

Endogenous Hormones ◽

Hyoscyamus Niger ◽

General Increase ◽

Long Day ◽

Long Day Plants ◽

Inductive Photoperiod ◽

The Way

Night-breaks caused both stimulated shoot growth and caused formation of flowers as well as a general increase in the content of phytohormones in leaves of the long-day plant Hyoscyamus niger L. At the time of flower formation in night-break treated plants, new gibberellin-like substances also appear. The results show that night-breaks cause similar changes in the phytohormones content as a long inductive photoperiod. It may be assumed that independently of the way of induction, the generative differentiation of long-day plants is always accompanied by a general increase in the amount of endogenous hormones and the appearance of new gibberellins. These results suggest the possibility of a morphogenetic role of hormones, especially gibberellins, in the phenomena of flower formation and differentiation.

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Abscisic Acid and Xanthoxin Contents in the Long-Day Plant Lolium temulentum L. In Relation to Daylength

Functional Plant Biology ◽

10.1071/pp9770217 ◽

1977 ◽

Vol 4 (2) ◽

pp. 217 ◽

Cited By ~ 3

Author(s):

RW King ◽

LT Evans ◽

RD Firn

Keyword(s):

Abscisic Acid ◽

Liquid Chromatography ◽

Shoot Apex ◽

Gas Liquid Chromatography ◽

Consistent Effect ◽

Lolium Temulentum ◽

Long Day ◽

Inductive Photoperiod ◽

Endogenous Aba

In L. temulentum L., flowering can be inhibited by application of abscisic acid (ABA) close to the shoot apex towards the end of an exposure to a single inductive long day. However, analysis by gas-liquid chromatography showed that the contents of endogenous ABA and xanthoxin in L. temulentum leaves are not consistently changed after an inductive photoperiod. Apex extractions carried out when (�)-ABA application near the apex is most inhibitory to flowering also showed no consistent effect of daylength on the content of ABA which was, however, much higher than in leaves. Thus it is unlikely that induction of flowering in L. temulentum by exposure to long days is due to changes in the endogenous levels of ABA and xanthoxin in the leaves or of ABA in the shoot apex.

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Leaf Unfolding Rate in Begonia × hiemulis

HortScience ◽

10.21273/hortsci.27.2.109 ◽

1992 ◽

Vol 27 (2) ◽

pp. 109-110 ◽

Cited By ~ 4

Author(s):

Meriam G. Karlsson

Keyword(s):

Quadratic Function ◽

Similar Rate ◽

Flower Initiation ◽

Light Conditions ◽

Leaf Unfolding ◽

Long Day ◽

Higher Temperature ◽

Response To Temperature ◽

Short Days

The rate of leaf unfolding as a function of temperature was determined for Begonia × hiemalis Fotsch under long-day (16 hours of light) conditions before flower initiation. Irradiance was maintained at 280 ± 20 μmol·m–2·s–1 (16.1 mol·m–2·day–l). The two cultivars Hilda and Ballet had similar rates of leaf unfolding in the range from 13 to 28C. The rate increased to a maximum of 0.116 leaves/day at 21C and then decreased at higher temperature. The following quadratic function (where T is the temperature in °C) was selected to describe initial long-day leaf unfolding rate in B. × hiemalis: leaves/day = -0.2083 + 0.03145 × T – 0.0007631 × T2, (r2 = 0.97). The leaf unfolding response to temperature varied for plants of `Hilda' and `Ballet' during short days (10 hours of light) following the initial long-day period. Plants of `Ballet' continued to unfold leaves at a similar rate as under initial long photoperiods, while the leaf unfolding rate for `Hilda' decreased to half the rate observed under long days.

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Photoperiod and Temperature Influence on Flower Initiation and Development for Euphorbia pulcherrima Grown Under Florida Conditions

HortScience ◽

10.21273/hortsci.33.3.509a ◽

1998 ◽

Vol 33 (3) ◽

pp. 509a-509

Author(s):

C.E. Wieland ◽

J.E. Barrett ◽

D.G. Clark ◽

G. J. Wilfret

Keyword(s):

Subsequent Development ◽

Flower Initiation ◽

Euphorbia Pulcherrima ◽

Floral Initiation ◽

Temperature Influence ◽

Average Temperature ◽

Long Day ◽

Time To Initiation ◽

Growth Room ◽

Maximum Temperatures

Four poinsettia cultivars were grown in glass greenhouses in Gainesville, Fla., in the Fall 1997 to evaluate differences in floral initiation and subsequent development. Three means of regulating photoperiod were 1) natural days 2) long-day lighting to 6 Oct. and then natural days (lights out) 3) long-day lighting to 6 Oct., and then short-day conditions by black cloth for 15 h (black cloth). At 2-day intervals, sample meristems were collected and examined for initiation of reproductive development. Average minimum and maximum temperatures during the first two weeks of October were 22 and 29 °C, respectively, with an average temperature of 25.3 °C. The overall average temperature was 23.2 °C from planting to anthesis. Differences in anthesis dates among cultivars were primarily due to time to initiation vs. rate of development. Under natural days, `Lilo' initiated first on 8 Oct. and `Freedom', `Peterstar', and `Success', followed by 6, 8, and 18 days, respectively. Lights out resulted in `Lilo' initiating 17 Oct., followed by `Freedom', `Peterstar', and `Success' initiating 7, 12, and 15 days later, respectively. Differences between cultivars in time of initiation was reduced under black cloth, where `Lilo' initiated 14 Oct., followed by `Freedom' 2 days later, and `Peterstar' and `Success' 7 days afterward. Initiation was positively correlated to visible bud and anthesis. First color was positively correlated to initiation and visible bud, with the exception of `Lilo'. Growth room studies conducted using various high temperatures and photoperiods indicated similar trends.

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INFLUENCE OF PHOTOPERIOD ON THYROTROPIN RELEASING HORMONE-INDUCED PROLACTIN RELEASE IN EWES

Canadian Journal of Animal Science ◽

10.4141/cjas83-008 ◽

1983 ◽

Vol 63 (1) ◽

pp. 67-73 ◽

Cited By ~ 3

Author(s):

B. E. HOWLAND ◽

D. SONYA ◽

L. M. SANFORD ◽

W. M. PALMER

Keyword(s):

Thyrotropin Releasing Hormone ◽

Day Length ◽

Constant Light ◽

Serum Prolactin ◽

Prolactin Release ◽

Blood Samples ◽

Releasing Hormone ◽

Before And After ◽

Release Curve ◽

Short Days

The influence of photoperiod on serum prolactin levels and prolactin release induced by thyrotropin releasing hormone (TRH) was determined in ewes maintained under the following lighting regimes: Room 1, lighting mimicked natural changes in photoperiod; Room 2, annual photoperiod changes condensed into 6 mo with short days in June; Room 3, same as Room 2 except photoperiod changed abruptly from 16.5 to 8.0 h on 21 Mar. and back to 16.5 h on 21 June; Room 4, constant light. Weekly blood samples were obtained from February to August. Additionally, blood samples were collected before and after treatment with 10 μg TRH on 19 May, 13 June, 27 June and 19 July. Prolactin levels were elevated in ewes exposed to long days or constant light. The mean of all pre-TRH samples was significantly correlated with stress-induced elevations in prolactin (highest pre-TRH value) (r = 0.72) and area under the TRH-induced release curve (r = 0.56). The prolactin release in response to TRH was greatest in ewes exposed to long days or constant light. Abrupt increase of day length elevated pretreatment prolactin levels (P < 0.01) and increased area under the response curve (P < 0.05). Key words: Photoperiod, TRH, prolactin, ewes

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