Floral Initiation in Cestrum nocturnum, a Long-Short Day Plant. III. The Effect of Temperature upon Long Day and Short Day Induction.

Seedlings of Stylosanthes guianensis var. guianensis cv. Cook and cv. Endeavour were grown in naturally lit glasshouses at Brisbane (lat. 27� 30' S.) at 35/30, 30/25 and 25/20�C (day/night), and were sown so as to emerge at 18-day intervals from 18 January to 11 June. Cook behaved as a long day-short day plant, with seedlings emerging after 5 February flowering incompletely or remaining vegetative until the experiment was terminated in mid-October. In the 25/20�C regimen flowering was incomplete in Cook; in Endeavour flowering was delayed but a conventional short-day response was observed. At 35/30�C Endeavour flowering was inhibited in the shortest days of mid-winter, suggesting a stenophotoperiodic response, but short days were confounded with low levels of irradiance. Minimum duration of the phase from emergence to floral initiation was c. 66-70 days in Cook and c. 40-45 days in Endeavour; the duration of the phase floral initiation to flower appearance was linearly and negatively related to temperature.

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Floral Initiation in Cestrum nocturnum, A Long-Short Day Plant. II. A 24-Hour Versus a 16-Hour Photoperiod for Long Day Induction.

PLANT PHYSIOLOGY ◽

10.1104/pp.31.6.429 ◽

1956 ◽

Vol 31 (6) ◽

pp. 429-430 ◽

Cited By ~ 3

Author(s):

Roy M. Sachs

Keyword(s):

Floral Initiation ◽

Short Day ◽

Long Day

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Meristem Ontogenetic Age as the Controlling Factor in Long-day Floral Initiation in Poinsettia

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.117.6.961 ◽

1992 ◽

Vol 117 (6) ◽

pp. 961-965 ◽

Cited By ~ 3

Author(s):

Michael R. Evans ◽

Harold F. Wilkins ◽

Wesley P. Hackett

Keyword(s):

Apical Meristem ◽

Main Axis ◽

Axillary Buds ◽

Euphorbia Pulcherrima ◽

Floral Initiation ◽

Leaf Removal ◽

Node Number ◽

Short Day ◽

Long Day ◽

Root Restriction

The poinsettia [Euphorbia pulcherrima (Willd. ex. Klotzsch)] is a short-day plant (SDP) for floral initiation that will also initiate floral structures (cyathia) under long days (LD) after the apical meristem produces a cultivar-dependent number of nodes (long-day node number). Leaf removal, root restriction, and air layering failed to affect the long-day node number (LDNN) of the apical meristem. Repeated rooting of shoots, which resulted in the removal of nodes, did not affect the total number of nodes initiated by the apical meristem before floral initiation, although the number of nodes intact on the plant at the time of floral initiation was reduced. Reciprocal grafting of axillary buds of `Eckespoint Lilo' and `Gutbier V-14 Glory' plants did not affect the LDNN of the grafted meristem since the LDNN was the same as for nongrafted buds of the same cultivar. Further, grafting axillary buds from different positions along the main axis that differed in LDNN did not affect the LDNN of the grafted meristems. On the basis of these results, it was concluded that LD floral initiation in poinsettia is a function of the ontogenetic age of the meristem and that the LDNN represents a critical ontogenetic age for floral initiation to occur under LD.

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EXAMINATION OF JUVENILITY IN GAILLARDIA PULCHELLA

HortScience ◽

10.21273/hortsci.25.8.848d ◽

1990 ◽

Vol 25 (8) ◽

pp. 848d-848

Author(s):

Kathleen M. Bourke ◽

Robert E. Lyons

Keyword(s):

Floral Initiation ◽

The South ◽

Short Day ◽

Long Day ◽

West Part ◽

Quadratic Response ◽

Histological Results

Gaillardia pulchella is an annual wildflower with ornamental potential native to the South and Southern West part of the U. S. This experiment attempted to further describe the long day (LD) flowering requirement, approximate the length of the juvenility phase, and characterize apical events during floral initiation. Plants were transferred from short day to LD at various leaf numbers and the time to first flower was recorded from the onset of LD. A quadratic response described the data and indicated that a minimum of 19-20 expanded leaves were needed to flower most rapidly (49 days) once placed in LD. Histological results characterizing apical events will also be discussed.

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Daylength affects both free and conjugated indole-3-acetic acid levels in leaves and flowering in Doritis pulcherrima (orchid)

Canadian Journal of Plant Science ◽

10.4141/p03-162 ◽

2004 ◽

Vol 84 (3) ◽

pp. 881-883

Author(s):

Chiung-Kuei Huang, Wen-Shaw Chen ◽

Yun-An Chen

Keyword(s):

Acetic Acid ◽

Key Words ◽

Floral Initiation ◽

Short Day ◽

Long Day ◽

Photoperiodic Treatment ◽

High Level ◽

Indole 3 Acetic Acid ◽

Iaa Conjugates

Total indole-3-acetic acid (IAA) levels (free IAA plus IAA conjugates) in Doritis pulcherrima (Doritis pulcherrima Lindley, cv. S 84-335-2) leaves were threefold lower in plants exposed to 30 d of short-day (SD) conditions than in plants exposed to 30 d of long-day (LD) conditions. Free IAA levels were also significantly lower in SD-treated leaves than those in 0 day of photoperiodic treatment and 30 d of LD. Results indicate that plants exposed to 30 d of SD contained significantly higher levels of ester-IAA and reduced amide-IAA concentrations compared to those grown under LD conditions. A high level of ester-IAA and a reduction of amide-IAA in leaves may be related to increased SD floral initiation ability in D. pulcherrima. Key words: Doritis pulcherrima, floral initiation, indole-3-acetic acid, photoperiod

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The effect of temperature and photoperiod on primary floral induction in three lines of alpine bluegrass

Canadian Journal of Plant Science ◽

10.4141/p96-108 ◽

1997 ◽

Vol 77 (4) ◽

pp. 615-622 ◽

Cited By ~ 1

Author(s):

Michelle Pahl ◽

Barb Darroch

Keyword(s):

Floral Induction ◽

Effect Of Temperature ◽

Short Day ◽

Long Day ◽

Marked Inhibition ◽

Controlled Environments ◽

Primary Induction ◽

Effects Of Temperature ◽

Short Days ◽

Induction Temperature

The effects of temperature and photoperiod on primary floral induction in three lines of alpine bluegrass (Poa alpina L.) were studied in controlled environments. These lines were developed at the Alberta Environmental Centre from single plant accessions collected from the Alberta Rocky Mountains. Plants representing all three lines were subjected to temperatures of 3, 9, and 12 °C under dark (0 h), short-day (8 h), and long-day (18 h) photoperiods for durations of 6, 10, and 14 wk. Plants were subsequently transferred to conditions of 22 °C/15 °C, 18 h photoperiod and heading response was recorded. Primary floral induction was found to be favoured by low temperatures and/or short days with marked inhibition at 12 °C. Complete dark conditions were not inductive. Six weeks of primary induction was suboptimal with only 15% of plants flowering. However, 100% of plants flowered after 10 wk of primary induction at 3 °C under both long-day and short-day conditions. Differences among lines were significant for number of heading plants, number of heads per plant, time to heading, and critical induction duration. Primary induction in line 907 occurred at longer photoperiods, warmer temperatures, and in shorter durations than the other lines indicating a lesser induction requirement. Possible implications are discussed in the use of alpine bluegrass populations for revegetating disturbed mountain sites. Key words: Floral induction, temperature, photoperiod, Poa alpina, alpine bluegrass

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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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Control of torpor and body weight patterns by a seasonal timer in Siberian hamsters

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1989.257.1.r142 ◽

1989 ◽

Vol 257 (1) ◽

pp. R142-R149 ◽

Cited By ~ 8

Author(s):

T. J. Bartness ◽

J. A. Elliott ◽

B. D. Goldman

Keyword(s):

Body Weight ◽

Food Intake ◽

Implant Removal ◽

Daily Torpor ◽

Short Day ◽

Siberian Hamsters ◽

Long Day ◽

Preparatory Phase ◽

Pelage Color ◽

Seasonal Responses

Two experiments were designed to assess whether the short-day-induced patterns of shallow daily torpor, body weight, and other seasonal responses (food intake and pelage pigmentation) exhibited by Siberian hamsters (Phodopus sungorus sungorus) are under the control of a "seasonal timekeeping mechanism" that is independent of reproductive status [testosterone, (T)]. We examined whether the patterning and expression of these seasonal responses were altered by decreases in serum T that accompany gonadal regression during the first 8 wk of short-day exposure (i.e., the "preparatory phase" of the torpor season) or by experimental increases in serum T after this phase. Short-day-housed, castrated hamsters bearing T implants had long-day levels of the hormone and did not exhibit torpor. Appropriate seasonal patterns and levels of torpor, body weight, pelage color stage, and food intake were exhibited after T implant removal although serum T was clamped to long-day levels during the preparatory phase. In animals that were gonad intact during the preparatory phase and were subsequently castrated and given T implants, torpor did not occur as long as the implants were in place. However, the patterns and levels of daily torpor, food intake, and body weight rapidly returned to appropriate seasonal values compared with the castrated, blank-implanted controls on T implant removal; these effects occurred whether the T implants were removed when torpor frequency was increasing, at its peak, or decreasing across the torpor season. T did not affect pelage color stage under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)

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