Gibberellin-mediated suppression of floral initiation in the long-day plant Rhododendron cv. Hatsugiri

2010 ◽  
Vol 124 (2) ◽  
pp. 231-238 ◽  
Author(s):  
R.G. Sharp ◽  
M.A. Else ◽  
W.J. Davies ◽  
R.W. Cameron
Keyword(s):  
Floral Initiation ◽  
Long Day

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

HortScience ◽  
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.

scholarly journals FLORAL INITIATION IN THE LONG-DAY PLANT Rudbeckia hirta

HortScience ◽  
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.

Flowering of Stylosanthes guianensis in controlled temperatures under natural photoperiod

1984 ◽  
Vol 35 (2) ◽  
pp. 219 ◽  
Author(s):  
RL Ison ◽  
LR Humphreys
Keyword(s):  
Floral Initiation ◽  
Minimum Duration ◽  
Stylosanthes Guianensis ◽  
Short Day ◽  
Long Day ◽  
Natural Photoperiod ◽  
Low Levels ◽  
Short Days

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.

Production of the Australian native daisies (Helipterum roseum and Helichrysum bracteatum) for the cut flower market

1989 ◽  
Vol 29 (3) ◽  
pp. 445 ◽  
Author(s):  
KV Sharman ◽  
M Sedgley ◽  
D Aspinall
Keyword(s):  
Stem Length ◽  
Floral Initiation ◽  
Cut Flower ◽  
Planting Time ◽  
Flower Production ◽  
Long Day ◽  
Spring Peak ◽  
Fresh Cut ◽  
Helichrysum Bracteatum ◽  
Optimum Production

Cut flower production of 2 Australian native daisies, Helipterum roseum and Helichrysum bracteatum, was investigated in the glasshouse and outdoors at 4 planting times. Both species exhibited a long day response with floral initiation occurring in any photoperiod but with peak production following longer days. Peaks in bloom production occurred during the spring and summer regardless of planting time. Floral abnormalities were observed in Helipterum roseum in all environments and planting times with the exception of the outdoor winter planting. There was a tendency for inflorescence diameter of both species and stem length of Helipterum roseum to decline with time from anthesis of the apical inflorescence. Optimum production of top quality blooms of Helipterum roseum extended from October to January following planting between autumn and spring. Peak production of Helichrysum bracteatum between December and March can be expected following planting during winter and spring. It may be possible to extend these seasons by weekly planting from autumn to spring. In addition, the imposition of extended photoperiod or night break treatments following summer or autumn planting may fulfil the photoperiod requirements of the plants and stimulate increased production between March and November. It is proposed that both species be considered for the fresh cut flower market, with Helipterum roseum marketed as single stems and Helichrysum bracteatum as sprays.

scholarly journals Temporal Aspects of Vernalization and Flowering in Long-day Storage Onion

2018 ◽  
Vol 143 (6) ◽  
pp. 446-453 ◽  
Author(s):  
Christopher J. D’Angelo ◽  
Irwin L. Goldman
Keyword(s):  
Allium Cepa ◽  
Time Course ◽  
Floral Initiation ◽  
Storage Duration ◽  
Average Decrease ◽  
Long Day ◽  
Temporal Aspects ◽  
The Relationship

Vernalization is an important step for floral initiation in onion (Allium cepa), but our understanding of the minimum vernalization time for long-day storage onions to gain floral competence is limited. A series of time course experiments were conducted over 4 years to determine the effects of vernalization time on sprouting, scape emergence, and flowering in ‘Cortland’, ‘Sherman’, and CUDH2107. We found an endodormancy period is present in the bulbs of these cultivars that lasts for 8 to 10 weeks. In addition, these three accessions achieve optimum uniform scape emergence after chilling for 14 weeks at 10 °C. On average, when bulbs were chilled for 14 weeks, it took 96.8 ± 15.6 days from planting to flowering in all accessions evaluated. As storage duration under vernalizing temperatures increases, the time to sprouting, scape emergence, and flowering decrease. Furthermore, the variance in time from sprouting to scape emergence was greatly reduced between 10 and 12 weeks of storage for ‘Cortland’ and CUDH2107, and between 12 and 14 weeks for ‘Sherman’. After 10 weeks of chilling, each additional week of storage resulted in an average decrease in time to flowering of 4.1%. We also observed large percentages of bulbs flowering without receiving any vernalization. This observation supports our finding that the relationship between vernalization and flowering in long-day storage onion is facultative rather than obligate. These findings help define the relationship between dormancy, vernalization, and flowering in long-day storage onion.

scholarly journals Flowering as metamorphosis: two sequential signals regulate floral initiation in Lolium temulentum

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3661-3668
Author(s):  
C.N. McDaniel ◽  
L.K. Hartnett
Keyword(s):  
Culture Medium ◽  
Floral Initiation ◽  
Leaf Removal ◽  
Synthesis Inhibitor ◽  
Lolium Temulentum ◽  
Long Day ◽  
Exogenous Gibberellin ◽  
Previously Treated

We investigated floral initiation in the long-day monocot Lolium temulentum, strain Ceres, by culturing apices explanted from photoperiodically induced plants at various times after one inductive long day onto medium with, and without, gibberellin. Apices cultured on the first day after the inductive long day usually required gibberellin in the medium to initiate floral morphogenesis while apices explanted on the second day after induction did not require gibberellin. Apices explanted on the first day after induction onto medium without gibberellin grew vegetatively for many days but a several-day exposure to culture medium with gibberellin at any time caused most apices to initiate floral morphogenesis. The gibberellin synthesis inhibitor, ancymidol, when applied to plants before apex excision and when present in the culture medium reduced floral initiation by more than 50% in the absence of added gibberellin in the medium, but it was ineffective in the presence of gibberellin. These results indicated that floral initiation in photoperiodically induced plants resulted from two signals acting at the apex. The first signal induced the apex into a florally determined state and then the second signal, gibberellin, elicited expression of the florally determined state. Leaf removal and culture of apices from plants previously treated with gibberellin provided evidence that the leaf-applied gibberellin did not itself act on the apex to cause floral determination or initiation. Rather, the exogenous gibberellin appeared to stimulate the production of a signal in the leaves that then led to floral initiation.

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

1992 ◽  
Vol 117 (6) ◽  
pp. 961-965 ◽  
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.

scholarly journals Gibberellins and Temperature Influence Long-day Floral Initiation in Poinsettia

1992 ◽  
Vol 117 (6) ◽  
pp. 966-971
Author(s):  
Michael R. Evans ◽  
Harold F. Wilkins ◽  
Wesley P. Hackett
Keyword(s):  
Foliar Spray ◽  
Euphorbia Pulcherrima ◽  
Floral Initiation ◽  
Trimethyl Ammonium Chloride ◽  
Temperature Influence ◽  
Node Number ◽  
Long Day ◽  
Axillary Meristems ◽  
Position Dependence ◽  
Nodal Position

Exogenous foliar spray applications of gibberellic acid (GA3) applied at 7- or 14-day intervals providing 50 or 125 μg per plant inhibited long-day (LD) floral initiation in poinsettia [Euphorbia pulcherrima (Willd. ex. Klotzsch)]. Periodic application of GA3 resulted in an additional number of nodes being produced by the plant before floral initiation equivalent to the number of nodes over which GA3 was applied. Further, GA, application eliminated the nodal position dependence of the long-day node number (LDNN) of axillary meristems observed in control plants. It was concluded that GA3 application inhibited the inclusion of nodes into the LDNN count and thus inhibited ontogenetic aging of the meristem. Exogenous application of GA, also inhibited LD floral initiation, while application of GA4 had no effect. Application of GA7 delayed LD floral initiation, but plants did initiate cyathia by the termination of the experiment. All gibberellins increased the average internode lengths similarly. The gibberllin-biosynthesis inhibitors chlormequat and paclobutrazol had no effect on LD floral initiation when applied as single or multiple foliar sprays or as soil drenches, although heights and internode lengths were reduced by application of the inhibitors. The LDNN of plants grown at 31C was significantly higher than of plants grown at 16, 21, or 26C. All plants eventually initiated cyathia regardless of temperature. When plants were grown under a range of day/night temperatures, an increase in the LDNN occurred only when plants were grown at 31C during the day. Chemical names used: 2-chloroethyl-trimethyl-ammonium chloride (chlormequat); (+/-)-(R*,R*)-β -(4-chlorophenyl)methyl-α -(1,1-dimethylethyl)-1-H-1,2,4-triazole-1-ethanol (paclobutrazol).

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