Vegetative Activity of the Main Stem Terminal Bud Under Photoperiod and Flower Removal Treatments in Soybean

1988 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
SV Caffaro ◽  
F Nakayama
Keyword(s):  
Main Stem ◽  
Internode Elongation ◽  
Apical Bud ◽  
Apical Buds ◽  
Long Day ◽  
Flower Abortion ◽  
Terminal Bud ◽  
Photoperiodic Treatment ◽  
The Moment ◽  
Short Days

Effects of photoperiod and flower removal on vegetative activity of the main stem apical bud were examined for an indeterminate ('Williams') and a determinate ('Bragg') soybean cultivar. Plants grew under long day conditions until the V2 stage. Then, they were subjected to three photoperiodic treatments: (1) short days of 9 h of solar radiation during all the experiment (SD); (2) 10 short days followed by long days until the end of the experiment (SD + LD); and (3) long days during all the experiment (LD). From the moment anthesis was reached, half of the plants of each photoperiodic treatment were periodically deflowered. Flower removal induced an additional but limited vegetative growth of the main stem apex, due to the elongation of the youngest internodes. This effect was only seen under SD because long day applications (SD+LD and LD) induced a high flower abortion. On the contrary, long days stimulated internode elongation, leaf expansion and, under LD, delayed anthesis which resulted in enhanced vegetative activity of apical buds and a greater production of nodes and branches. Thus, a close but inverse relation was observed between flower induction and vegetative structure differentiation by apical buds. As in Bragg, Williams may stop vegetative activity of buds by their simple transition to a terminal raceme hence, only posterior differentiated internode elongation will be either limited or stimulated depending on SD or LD conditions, respectively.

scholarly journals 391 THE INFLUENCE OF COLD DURING SEEDLING STAGE AND PHOTOPERIOD ON FORCING PERENNIALS FOR POT PLANTS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 487b-487
Author(s):  
Allan M. Armitage ◽  
Paul Thomas
Keyword(s):  
Plant Height ◽  
Early Spring ◽  
Seedling Stage ◽  
Internode Elongation ◽  
Perennial Species ◽  
Photoperiodic Treatment ◽  
Short Days ◽  
Pot Plants

The influence of cooling, photoperiod and chemical branching on early spring flowering of perennial species was studied. Cooling was provided while plants were in plugs (128 plugs per tray) and dikegulac-sodium, a compound found to induce breaks in other species, was applied prior to, during and after cooling. Plants were cooled in insulated lighted coolers for 4, 8 or 12 weeks at 4C, and brought to a greenhouse with night temperatures between 8-12C. Long and short days were provided in the greenhouse after plants came out of the coolers. Little response to dikegulac occurred, however, Campanula, Sedum, Leontopodium, Catananche, Aubrietia, Arabis, Gypsophila, Anchusa and Aquilegia responded to cooling and photoperiodic treatment. Flowering and vegetative characteristics such as internode elongation and plant height responded to photoperiod and cooling but not all genera responded similarly. Anchusa, Campanula, Aquilegia and Gypsophila flowered significantly earlier under LD compared to SD. Twelve weeks of cooling resulted in flowering of all genera, however, some genera were equally responsive to shorter cooling times.

scholarly journals Juvenility and Photoperiodic Flowering Requirements of Chrysanthemum ×superbum `G. Marconi' and `Snow Lady' Grown under Short- and Long-day Conditions

1995 ◽  
Vol 120 (2) ◽  
pp. 241-245 ◽  
Author(s):  
M. Peggy Damann ◽  
Robert E. Lyons
Keyword(s):  
Microscopic Examination ◽  
Main Stem ◽  
Floral Initiation ◽  
Flower Buds ◽  
Terminal Flower ◽  
True Leaf ◽  
Photoperiodic Flowering ◽  
Long Day ◽  
Cotyledon Stage ◽  
Short Days

Juvenility and flowering requirements of Chrysanthemum ×superbum Bergmans ex J. Ingram `G. Marconi' and `Snow Lady' were examined by growing plants under short days (SDs) and transferring them to long days (LDs) upon reaching specific true leaf stages. `G. Marconi' plants did not flower in continuous SDs and only sparse flowering occurred in plants transferred to LDs. `Snow Lady' plants transferred from SDs to LDs at the cotyledon stage flowered fastest from seeding (75 days) and had the fewest number of main stem leaves and total leaves (9 and 15, respectively) at the time of first flower. Plants moved from SDs to LDs at the 24 true leaf stage flowered 123 days after seeding and averaged 28 leaves on the main stem and 37 total leaves at the time of first flower. To examine apical floral initiation, plants were distributed between SDs and LDs following transplanting and five plants per treatment were sampled each week thereafter. Microscopic examination revealed floral initiation in plants sampled after just 1 week in LDs and, after 5 weeks, macroscopic terminal flower buds were present. Under SDs, apical floral initiation began after 5 weeks, yet, 9 weeks were required for floral initiation in all five plants sampled.

scholarly journals Effects of Ethephon on Stock Plant Management of Coreopsis verticillata, Dianthus caryophyllus, and Veronica longifolia

HortScience ◽  
2007 ◽  
Vol 42 (7) ◽  
pp. 1616-1621 ◽  
Author(s):  
Janelle E. Glady ◽  
N. Suzanne Lang ◽  
Erik S. Runkle
Keyword(s):  
Dianthus Caryophyllus ◽  
Plant Management ◽  
Internode Elongation ◽  
Perennial Species ◽  
Stock Plant ◽  
Long Day ◽  
Leaf Necrosis ◽  
Vegetative Cuttings ◽  
Herbaceous Perennial ◽  
Short Days

Some day-neutral herbaceous perennial species can be difficult to manage as vegetative stock plants because they initiate floral buds under most environmental conditions. Although flowering of many long-day plants can be inhibited by maintaining plants under short days, extension growth is often suppressed, which makes cuttings difficult to harvest. Ethephon (2-chloroethylphosphonic acid) is an ethylene-releasing chemical used to abort flowers, inhibit internode elongation, and promote branching of floriculture crops. The objective of this research was to determine whether ethephon is effective at maintaining vegetative growth and increasing the number of cuttings harvested for three popular perennial species that are difficult to maintain as vegetative plants. Spray applications of ethephon were applied for 10 weeks biweekly (every 2 weeks) or weekly at 0, 400, 600, or 800 mg·L−1. Biweekly applications at 600 mg·L−1 or weekly applications at 400 mg·L−1 increased branching and the number of vegetative cuttings in Coreopsis verticillata L. ‘Moonbeam’ and Veronica longifolia L. ‘Sunny Border Blue’, respectively. Ethephon application increased branching in Dianthus caryophyllus L. ‘Cinnamon Red Hots’, inhibited leaf expansion and stem extension, but did not abort flowers, and induced marginal leaf necrosis at all concentrations tested. Therefore, ethephon application has potential to maintain vegetative stock plants of C. verticillata ‘Moonbeam’ and V. longifolia ‘Sunny Border Blue’ but not D. caryophyllus ‘Cinnamon Red Hots’.

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.

Photoperiod modulates the effects of norepinephrine on lymphocyte proliferation in Siberian hamsters

2003 ◽  
Vol 285 (4) ◽  
pp. R873-R879 ◽  
Author(s):  
Gregory E. Demas ◽  
Timothy J. Bartness ◽  
Randy J. Nelson ◽  
Deborah L. Drazen
Keyword(s):  
Lymphocyte Proliferation ◽  
Splenic Tissue ◽  
Splenocyte Proliferation ◽  
Short Day ◽  
Siberian Hamsters ◽  
Long Day ◽  
Β Adrenergic Receptors ◽  
Short Days

Siberian hamsters ( Phodopus sungorus) rely on photoperiod to coordinate seasonally appropriate changes in physiology, including immune function. Immunity is regulated, in part, by the sympathetic nervous system (SNS), although the precise role of the SNS in regulating photoperiodic changes in immunity remains unspecified. The goal of the present study was to examine the contributions of norepinephrine (NE), the predominant neurotransmitter of the SNS, to photoperiodic changes in lymphocyte proliferation. In experiment 1, animals were maintained in long [16:8-h light-dark cycle (16:8 LD)] or short days (8:16 LD) for 10 wk, and splenic NE content was determined. In experiment 2, in vitro splenocyte proliferation in response to mitogenic stimulation (concanavalin A) was assessed in spleen cell suspensions taken from long- or short-day hamsters in which varying concentrations of NE were added to the cultures. In experiment 3, splenocyte proliferation was examined in the presence of NE and selective α- and β-noradrenergic receptor antagonists (phenoxybenzamine and propranolol, respectively) in vitro. Short-day animals had increased splenic NE content compared with long-day animals. Long-day animals had higher proliferation compared with short-day animals independent of NE. NE (1 μM) further suppressed splenocyte proliferation in short but not long days. Last, NE-induced suppression of proliferation in short-day hamsters was blocked by propranolol but not phenoxybenzamine. The present results suggest that NE plays a role in photoperiodic changes in lymphocyte proliferation. Additionally, the data suggest that the effects of NE on proliferation are specific to activation of β-adrenergic receptors located on splenic tissue. Collectively, these results provide further support that photoperiodic changes in immunity are influenced by changes in SNS activity.

Tagesperiodische antagonistische Schwankungen der Blauviolett- und Gelbrot-Empfindlichkeit als Grundlage der photoperiodischen Diapause-Induktion bei Pieris brassicae

1960 ◽  
Vol 15 (4) ◽  
pp. 205-213 ◽  
Author(s):  
Erwin Bünning ◽  
Gabriele Joerrens
Keyword(s):  
Dark Period ◽  
Red Light ◽  
Pieris Brassicae ◽  
Light Period ◽  
Measuring Process ◽  
The Third ◽  
Long Day ◽  
Critical Daylength ◽  
Qualitative Responses ◽  
Short Days

In Pieris brassicae, diapause is inhibited if long-day conditions are imposed during and immediately after the third molting. The critical daylength is approximately 14 hours. Under short-day conditions with a main light period of 6 or 12 hours’ duration, supplementary light given in the period from 14 to 16 hours after the beginning of the main light period will inhibit diapause. In contrast to this effect of late exposures to light, light given from 1 to 12 hours after the beginning of the main light period promotes diapause. Experiments with extremely long light periods (10—35 hours), but always with a dark period of 10 hours, show that these diurnal fluctuations in quantitative and qualitative responses to light can continue endogenously for several days. Thus, this time-measuring process operates through the mechanism of endogenous diurnal oscillations in just the same way as do photoperiodic reactions in plants.The inhibition of diapause by light in the second half of the diurnal oscillation (under long days or by light interruptions in the dark period) and the promotion by light in the first half (under short days) occur only with light of short wavelengths: ultraviolet, violet, and blue up to about 550 mμ. Yellow and red light act in the opposite fashion, giving diapause inhibition in the first half of the cycle and promotion in the second half. In white light the violet reaction predominates, so that diapause is promoted by short days and inhibited by long days.

scholarly journals Temperature and Photoperiod Influence Flowering and Morphology of Four Petunia spp.

HortScience ◽  
2010 ◽  
Vol 45 (3) ◽  
pp. 365-368 ◽  
Author(s):  
Ryan M. Warner
Keyword(s):  
Base Temperature ◽  
Optimal Temperature ◽  
Flower Bud ◽  
Breeding Programs ◽  
Node Number ◽  
Daily Light Integral ◽  
Long Day ◽  
Light Integral ◽  
Short Days ◽  
Petunia Axillaris

Flowering and morphology of four Petunia Juss. spp. [P. axillaris (Lam.) Britton et al., P. exserta Stehmann, P. integrifolia (Hook.) Schinz & Thell., and P. ×hybrida Vilm.] were evaluated in response to photoperiod and temperature. Photoperiod responses were evaluated under 9-h short days (SD), 9-h photoperiod plus 4-h night-interruption lighting (NI), or a 16-h photoperiod supplemented with high-pressure sodium lamps (16-h HPS). All species flowered earlier under NI than SD and were classified as facultative (quantitative) long-day plants. Increasing the daily light integral within long-day treatments increased flower bud number for P. axillaris only. In a second experiment, crop timing and quality were evaluated in the temperature range of 14 to 26 °C under 16-h HPS. The rate of progress toward flowering for each species increased as temperature increased from 14 to 26 °C, suggesting the optimal temperature for development is at least 26 °C. The calculated base temperature for progress to flowering varied from 0.1 °C for P. exserta to 5.3 °C for P. integrifolia. Flowering of P. axillaris and P. integrifolia was delayed developmentally (i.e., increased node number below the first flower) at 14 °C and 17 °C or less, respectively, compared with higher temperatures. Petunia axillaris and P. integrifolia flower bud numbers decreased as temperature increased, whereas P. ×hybrida flower bud number was similar at all temperatures. The differences in crop timing and quality traits observed for these species suggest that they may be useful sources of variability for petunia breeding programs.

Short-day-like body weight changes do not prevent fat pad compensation after lipectomy in Siberian hamsters

1997 ◽  
Vol 272 (1) ◽  
pp. R68-R77 ◽  
Author(s):  
M. M. Mauer ◽  
T. J. Bartness
Keyword(s):  
Body Weight ◽  
Food Restriction ◽  
Adipocyte Size ◽  
Weight Changes ◽  
Fat Pad ◽  
Body Weight Changes ◽  
Siberian Hamsters ◽  
Long Day ◽  
Long Duration ◽  
Short Days

Long-day (LD)-housed Siberian hamsters show compensatory increases in white adipose tissue (WAT) weight after lipectomy, whereas hamsters exposed to short days (SDs) for a long duration (22 wk) do not. We tested whether SD-induced body weight changes prevent fat pad compensation after lipectomy. In experiment 1, hamsters with lesions of the paraventricular nucleus of the hypothalamus (PVNx) rapidly increased body weight similarly to 22-wk SD-exposed hamsters. In experiment 2, LD-housed hamsters were food restricted for 22 wk and then pair fed with SD-housed hamsters for 12 wk to produce body weight changes mimicking those of ad libitum-fed SD-exposed animals. Epididymal WAT (EWAT) lipectomy (EWATx) of PVNx or food-restricted hamsters elicited compensatory increases in retroperitoneal and inguinal WAT (RWAT and IWAT) weights. Unlike other fat pads, EWAT was less affected by food restriction or PVNx than by SD exposure. In general, food restriction decreased adipocyte number, whereas SD exposure decreased adipocyte size. PVNx increased RWAT adipocyte size and IWAT adipocyte number. These results suggest that the lack of body fat compensation by EWATx hamsters exposed to SDs for a long duration is due to SD-associated responses other than body weight changes per se.

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