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).

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 Agronomic Performance and Flowering Behavior in Response to Photoperiod and Vernalization in Barley (Hordeum vulgare L.) Genotypes with Contrasting Drought Tolerance Behavior

2021 ◽  
Author(s):  
Jamal Abu-Elenein ◽  
Rabea Al-Sayaydeh ◽  
Zahera Akkeh ◽  
Zakaria Al-Ajlouni ◽  
AbdRaheem A. Al-Bawalize ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Agronomic Performance ◽  
Short Day ◽  
Drought Tolerant ◽  
Long Day ◽  
Meristem Development ◽  
Rainfed Conditions ◽  
Barley Genotypes

Abstract Background In barley, flowering behavior is a highly regulated and complex process where the appropriate matching of reproductive development with seasonal variation in water availability confer barley adaptation to different environments. In this study, the role of variation in flowering time and drought tolerance in four selected barley genotypes was studied under field and controlled conditions. For this purpose, field trials were conducted for two consecutive seasons at three diverse environments where the studied genotypes were subjected to either rainfed conditions or rainfed plus supplementary irrigation under two different sowing dates. Furthermore, reproductive meristem development in two selected barley genotypes, Rum (drought tolerant) and Steptoe (drought-sensitive) was also assessed in response to both vernalization and water stress under two different photoperiod conditions.Results Variation in the number of days to heading was more pronounced under rainfed conditions than under well water conditions. For agronomic performance, Rum was superior under all tested environments, which assure its general adaptability to multiple environments, while Steptoe was the poorest. The transition to reproductive meristem was faster under vernalized long-day conditions as compared to vernalized short-day conditions. The progress of shoot apical meristem development and heading under long-day conditions was significantly faster in Rum than that of Steptoe. A clear effect of drought stress was observed on shoot apical meristem development in Steptoe. Under short-day conditions, vernalized Rum plants subjected to water deficit showed an advanced meristem development stage a significant earlier HD when compared with non-stressed plants. This early flowering behavior in stressed Rum plants under short-day conditions was accompanied by higher gene expression of the Vrn-H1 gene. Conclusion In conclusion, the integration of vernalization and photoperiod signals in drought-tolerant barley genotypes is associated with early flowering behavior and higher productivity in dry environments.

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.

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 Observations on the development of plants

2015 ◽  
Vol 40 (1) ◽  
pp. 21-40
Author(s):  
A. Listowski ◽  
A. Jaśmianowicz ◽  
M. Iwanejko
Keyword(s):  
Light Intensity ◽  
Elongation Growth ◽  
Axillary Buds ◽  
Low Intensity ◽  
Short Day ◽  
Long Day ◽  
Lateral Shoots ◽  
Leaf Differentiation

The influence of light intensity and daylength on four short-day species of <i>Chenopodium</i> was analysed. The following species were tested: <i>Ch. ficifolium, Ch. glaucum, Ch. rubrum</i> and <i>Ch. hybridum</i>. Under short day, generative initiation was accelerated, the abundance of flowering, and growth and leaf differentiation processes were reduced. Under light of low intensity, the rhythm of development of the plants growing under long day is similar to that under short day. The development of axillary buds indicates a decrease in the intensity of vegetative differentiation and elongation growth, with an enhancement of the generative tonus; the buds in the axils of the highest growing leaves form directly inflorescences without preceding leaf differentiation. Inversion of the shape of leaves on lateral shoots was noted.

A Histological Study of the Grass Heteropogon contortus Infected by the Smut Sorosporium caledonicum

1975 ◽  
Vol 23 (1) ◽  
pp. 51 ◽  
Author(s):  
RA Fullerton
Keyword(s):  
Apical Meristem ◽  
Histological Study ◽  
Axillary Buds ◽  
Clear Relationship ◽  
Floral Initiation ◽  
Bud Development ◽  
Heteropogon Contortus ◽  
Temporal Relationships ◽  
Close Proximity

A study of the spatial and temporal relationships of Heteropogon contortus and the smut Sorosporium caledonicum has been made. It has been shown that hyphae move into the axillary buds on the bases of infected tillers at various stages of bud development. Hyphal distribution in the base of the parent tiller determines whether or not a bud receives mycelium, and the extent to which hyphae grow through the tissues of the buds and young tillers determines whether a tiller bears a sorus or an inflorescence. A sorus forms only if hyphae are close to the apical meristem at the time of floral initiation. Floral initiation occurs abnormally early in smutted tillers which elongate at the beginning of a season. A clear relationship exists between the presence of hyphae in close proximity to the apical meristem, and early floral initiation.

scholarly journals EXAMINATION OF JUVENILITY IN GAILLARDIA PULCHELLA

HortScience ◽  
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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