The effects of gibberellin A3, photoperiod, and age on vegetative growth and flowering in Cosmos bipinnatus var. Sensation

1974 ◽  
Vol 52 (6) ◽  
pp. 1249-1258 ◽  
Author(s):  
Marje Molder ◽  
John N. Owens
Keyword(s):  
Floral Development ◽  
Response Rate ◽  
Developmental Rate ◽  
Intermediate Stage ◽  
Floral Initiation ◽  
Reproductive State ◽  
Apparent Lack ◽  
Cosmos Bipinnatus ◽  
Normal Percentage ◽  
Short Days

Plants of Cosmos bipinnatus Cav. 'Sensation' (a quantitative short-day plant) were grown continuously under conditions favorable or unfavorable for flowering, and some plants in each group were treated with gibberellic acid (GA3). Morphological and anatomical observations revealed that GA3 promoted floral initiation under non-inductive long days but not as efficiently as inductive short days, as judged by the rate of apical transition to the reproductive state. GA3 did not influence the total number of plants that flowered but did increase height growth. Plants treated with GA3 had a normal percentage of initiation, but a much lower developmental rate. Macroscopic recognition of flowering was not possible until the inflorescence stage of the apex.Floral apices of Cosmos are formed by the transition of previously vegetative apices, the apex passing into an intermediate stage typical of most plants held under non-inductive conditions. Transitional, prefloral, and inflorescence stages follow. The formation of an intermediate stage may account for many of the conflicting results observed in physiological studies since there is a great variation in response rate depending on age of plant and stage of the apex at the start of the experiment. Anatomical observations support the findings that although GA3 promotes floral initiation in Cosmos when applied under non-inductive conditions, floral development may not continue, thus resulting in an apparent lack of response. This may also be true of many other plants considered "non-responsive" to GA3 under non-inductive conditions.

Ontogeny and histochemistry of the intermediate and reproductive apices of Cosmos bipinnatus var. Sensation in response to gibberellin A3 and photoperiod

1973 ◽  
Vol 51 (3) ◽  
pp. 535-551 ◽  
Author(s):  
Marje Molder ◽  
John N. Owens
Keyword(s):  
Gibberellic Acid ◽  
Response Rate ◽  
Intermediate Stage ◽  
Floral Initiation ◽  
Transitional Stage ◽  
Zonation Pattern ◽  
Short Day ◽  
Cosmos Bipinnatus ◽  
Cytological Features ◽  
Short Days

Plants of Cosmos bipinnatus Cav. ‘Sensation’ (a quantitative short-day plant) were grown under continuous conditions favorable or unfavorable for flowering, and some plants in each group were treated with gibberellic acid (GA3). Floral apices of Cosmos are formed by the transition of previously vegetative apices. The vegetative apex shows a cytohistological zonation pattern superimposed upon a tunica–corpus organization. The vegetative apex passes into an intermediate stage presumed typical of many plants held under non-inductive conditions. This stage is marked by many cytological features characteristic of both reproductive and vegetative apices but leaves continue to be produced. The presence of the intermediate stage accounts for conflicting results obtained in physiological studies since there is great variation in response rate depending on age of plant and the stage of the apex at the start of an experiment. This stage is followed by a typical transitional stage marked by an increase in RNA content, increased mitotic activity, and a change in zonation. Elongation of the apex and internodes occurs followed by initiation of the involucral bracts and floret primordia, marking the beginning of the prefloral and inflorescence stages respectively.GA3 specifically induces Cosmos to flower under non-inductive conditions thereby influencing floral initiation in a facultative short-day plant. Microscopic examination of the rate of apical transition revealed that GA3 substituted effectively for short days but was not as efficient an inducer as were short days.

Floral Initiation and Development in Relation to the Time of Flowering in Banksia coccinea R.Br and B. menziesii R.Br (Proteaceae)

1990 ◽  
Vol 38 (5) ◽  
pp. 487 ◽  
Author(s):  
AM Fuss ◽  
M Sedgley
Keyword(s):  
Floral Development ◽  
Floral Initiation ◽  
Anther Dehiscence ◽  
Reproductive State ◽  
Vegetative Shoot ◽  
Stage 4 ◽  
Floral Bracts ◽  
Stage 1 ◽  
Characteristic Colour ◽  
Scanning Electron

Floral initiation and development in Banksia coccinea and B. menziesii were investigated using scanning electron microscopy in relation to the time of flowering. Floral initiation in both species occurred in late spring. The sequence of floral development was similar for both species but the timing was different. Ten stages of floral development were identified. Stage 1 was a vegetative meristem. Stage 2 signified the transition to the reproductive state, and was characterised by a broadening of the meristem with the production of involucral bracts. There were increases in both height and diameter of the meristem as common bracts (stage 3), floral bracts (stage 4) and florets (stage 5) were initiated. At stage 6 the developing inflorescences were macroscopically visible. This was followed by appearance (stage 7) and subsequent extension of the florets (stage 8). The styles continued to extend once floret extension had ceased causing the perianth to split and the styles to protrude (stage 9), thus imparting to the inflorescences their characteristic colour. Anther dehiscence occurred prior to anthesis of the floret, and the pollen was deposited on the pollen presenter, a distal modified region of the style. At anthesis (stage 10) styles were released from the perianth limb, presenting pollen to foraging insects and birds. Phyllotaxy was spiral throughout development, with a transition from a single genetic spiral in the vegetative shoot to 13 spirals initiating simultaneously in the developing inflorescence. Floral development was slow, taking from 6 to 8 months in B. menziesii prior to peak anthesis between April and July. In B. coccinea macroscopic inflorescences were not observed until May, with peak anthesis occurring between August and November, 9-12 months after initiation. Inflorescence colour showed wide variation in both species, with red and pink being the dominant colours in B. coccinea and B. menziesii respectively.

scholarly journals Floral Initiation and Vascular Development in Lateral Buds of Kalanchoe

HortScience ◽  
1992 ◽  
Vol 27 (2) ◽  
pp. 144-146
Author(s):  
Raymond Kessler ◽  
Stan P. Myers
Keyword(s):  
Early Development ◽  
Vascular Development ◽  
Vascular Cambium ◽  
Floral Initiation ◽  
Reproductive State ◽  
Lateral Buds ◽  
Kalanchoe Blossfeldiana ◽  
Vascular Connections ◽  
Kalanchoë Blossfeldiana ◽  
Short Days

Early development of lateral buds is demonstrated as one of the evocation events in Kalanchoes (Kalanchoe blossfeldiana Poelln.). Lateral buds of `Cactus Candy', `Gelbe Melody', and `Jupiter' that were ≈5 mm long or less showed no signs of a change to the reproductive state after 21 short days. However, larger lateral buds for `Jupiter' did show floral initiation while those of `Cactus Candy' and `Gelbe Melody' did not. Studies of the vascular arrangement indicate the presence of four dorsal and four ventral bundles connecting leaves to the stem. Vascular connections to lateral buds arise from vascular cambium but do not appear to connect to any of the bundles that supply leaves.

Responses of Some Turkish Wheat Cultivars to Vernalization and Photoperiod

1988 ◽  
Vol 24 (2) ◽  
pp. 237-245
Author(s):  
Serpil Terzioğlu
Keyword(s):  
Bread Wheat ◽  
Normal Development ◽  
Photoperiodic Response ◽  
Reliable Information ◽  
Floral Initiation ◽  
Wheat Cultivars ◽  
Primary Shoot ◽  
Time Of Year ◽  
Short Days

SUMMARYThe vernalization and photoperiodic response of six locally adapted bread wheat cultivars grown under natural daylength conditions during the summer or winter months was examined in glasshouse experiments. The wheat was vernalized by chilling imbibed grains at 2 ± 1°C for 0, 15 or 45 days. Vernalization for 45 days followed by long summer days led to floral initiation in all cultivars within 28 days but vernalization for 0 or 15 days only led to floral initiation in one cultivar. Vernalization followed by long days reduced the time from transplanting to anthesis, resulting in early ear emergence. Vernalization followed by short days accelerated the development of all the cultivars, but normal development could also occur without vernalization at this time of year. Apical differentiation of the primary shoot and its length and development gave the most reliable information on the period of vernalization required.

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.

Investigation of flowering in Banksia baxteri R. Br. and B. hookeriana Meissner for improving pruning practices

1994 ◽  
Vol 34 (8) ◽  
pp. 1209 ◽  
Author(s):  
LJ Rohl ◽  
AM Fuss ◽  
JA Dhaliwal ◽  
MG Webb ◽  
BB Lamont
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Floral Development ◽  
Early Summer ◽  
Stem Length ◽  
First Year ◽  
Floral Initiation ◽  
Scanning Electron

Floral initiation and development in relation to time of flowering were investigated in Banksia baxteri and B. hookeriana with the aid of scanning electron microscopy. Floral initiation occurred in spring in B. baxteri and in early summer in B. hookeriana. Floral development was rapid in B. baxteri (3 months to reach anthesis in summer). In B. hookeriana, development took 5 months, with anthesis occurring in winter. Most B. hookeriana blooms were produced on 2-year-old shoots, while B. baxteri produced about half of its blooms on 2-year-old shoots and almost as many on 3-year-old shoots. In both species, shoots that flowered within 2 years were longer and thicker in their first year than other shoots. A critical minimum stem length was determined for the first year's growth, to be used as a criterion for determining which shoots to remove during pruning. Details are provided for the timing of pruning to achieve maximum bloom production in B. baxteri and B. hookeriana.

Some Effects of Temperature and Light on Floral Initiation and Development in Acacia pycnantha

1985 ◽  
Vol 12 (2) ◽  
pp. 109 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Light Intensity ◽  
Floral Development ◽  
Early Stage ◽  
The Other ◽  
Floral Initiation ◽  
Ambient Conditions ◽  
Low Light ◽  
Floral Primordia ◽  
Effects Of Temperature ◽  
Normal Light

Floral initiation and development in Acacia pycnantha were studied under three environments. Two had ambient southern Australian temperatures of warm summer (mean max. 32°C, mean min. 16°C) and cool winter (mean max. 19°C, mean min. 8°C), one with full sunlight (outside) and the other with 30% light intensity (shadehouse). The other environment (glasshouse) had slightly lower than normal light intensity and a relatively constant year round temperature of mean 28°C maximum and 16°C minimum. Plants were scored for microscopic and macroscopic evidence of floral initiation and development. Floral primordia were initiated all year round under all environments. Floral development proceeded normally under ambient conditions of temperature and light, and anthesis occurred between August and October. Under low light intensity, floral development did not progress beyond a very early stage and macroscopically visible racemes were rare. Under the constant temperatures, floral development proceeded normally up to the stage of microsporogenesis and megasporogenesis. Meiosis did not occur and inflorescence buds ceased growth and were shed from the plant. Plants were transferred between the outside and glasshouse conditions in June, at around the stage of meiosis. Those transferred from outside to the glasshouse did not flower whereas some of those transferred from the glasshouse to outside flowered, but later and for a shorter period than plants maintained outside throughout. It appears that a 70% reduction in sunlight inhibits floral development at an early stage and that temperatures of approximately mean maximum 19°C and minimum 8°C are required for meiosis in Acacia pycnantha.

scholarly journals EFFECT OF PHOTOPERIOD ON FLOWER INITIATION OF COFFEE

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1071a-1071
Author(s):  
Ursula K. Schuch ◽  
Leslie H. Fuchigami ◽  
Mike A. Nagzao
Keyword(s):  
Coffea Arabica ◽  
Flower Initiation ◽  
Artificial Light ◽  
Floral Initiation ◽  
Flower Buds ◽  
Incandescent Light ◽  
Time Period ◽  
Chamber Study ◽  
Coffee Plants ◽  
Short Days

Floral initiation in coffee has been shown to be stimulated by short days in young plants, but the inductive stimulus for mature plants is still not clear. Experiments were conducted to determine whether floral initiation in immature and mature plants is promoted by short photoperiods, and delayed by long photoperiods. In a growth chamber study, 18-month-old coffee (Coffea arabica L. cv. Guatemalan) plants exposed to 8 hr photoperiods developed flower buds after 4 weeks, whereas no floral initiation was observed on the plants exposed to 16 hr photoperiods for ten weeks. Trees growing in the field were illuminated with incandescent light from midnight to 3:00 a.m. from July to December 1989. The control plants received no artificial light during the same time period. Night light interruption delayed flower initiation until the end of December on branches that were fully exposed to the light. On control trees, flower buds started to emerge at the beginning of November. These results indicate that in immature and mature coffee plants floral initiation is stimulated by short days, and delayed by long days.

scholarly journals Obinutuzumab and idelalisib in symptomatic patients with relapsed/refractory Waldenström macroglobulinemia

2021 ◽  
Vol 5 (9) ◽  
pp. 2438-2446
Author(s):  
Cécile Tomowiak ◽  
Stéphanie Poulain ◽  
Charles Herbaux ◽  
Aurore Perrot ◽  
Béatrice Mahé ◽  
...  
Keyword(s):  
Partial Response ◽  
Response Rate ◽  
Liver Toxicity ◽  
Univariate Analysis ◽  
Maintenance Phase ◽  
Induction Phase ◽  
Minor Response ◽  
Apparent Lack ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia

Abstract We present the results of a phase 2 study evaluating the combination of obinutuzumab + idelalisib in relapsed/refractory (R/R) Waldenström macroglobulinemia (WM). The goal was to determine the safety and efficacy of a fixed-duration chemotherapy-free treatment. During the induction phase, patients received idelalisib + obinutuzumab for 6 cycles, followed by a maintenance phase with idelalisib alone for ≤2 years. Forty-eight patients with R/R WM were treated with the induction combination, and 27 patients participated in the maintenance phase. The best responses, reached after a median of 6.5 months (interquartile range, 3.4-7.1; range, 2.6-22.1 months), were very good partial response in 5 patients, partial response in 27 patients, and minor response in 3 patients, leading to overall response rate and major response rate estimates of 71.4% (95% confidence interval [CI], 56.7-83.4) and 65.3% (95% CI, 50.4-78.3), respectively. With a median follow-up of 25.9 months, median progression-free survival was 25.4 months (95% CI, 15.7-29.0). Univariate analysis focusing on molecular screening found no significant impact of CXCR4 genotypes on responses and survivals but a deleterious impact of TP53 mutations on survival. Although there was no grade 5 toxicity, 26 patients were removed from the study because of side effects; the most frequent were neutropenia (9.4%), diarrhea (8.6%), and liver toxicity (9.3%). The combination of idelalisib + obinutuzumab is effective in R/R WM. Nonetheless, the apparent lack of impact of genotype on outcome could give new meaning to targeting of the phosphatidylinositol 3-kinase pathway in WM. This trial was registered at www.clinicaltrials.gov as #NCT02962401.

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