Environmental control of reproduction in Themeda australis

1969 ◽  
Vol 17 (3) ◽  
pp. 375 ◽  
Author(s):  
LT Evans ◽  
RB Knox
Keyword(s):  
Environmental Control ◽  
New Guinea ◽  
Reproductive Behaviour ◽  
Northern Territory ◽  
The Other ◽  
Day Length ◽  
Long Day ◽  
Flowering Behaviour ◽  
Ecological Races ◽  
Short Days

Seedlings and older plants of 30 ecological races of Themeda australis were grown under controlled conditions to determine the effect of day length and vernalization on their flowering and on the incidence of apomixis. The races ranged in origin from latitude 6°S. in New Guinea to latitude 43°S, in Tasmania. One race from New Guinea and several from the Northern Territory behaved as strict short-day plants. The more southerly races, on the other hand, and several from north Queensland were long-day plants. In some, long days were required for both initiation and development of the inflorescence, in others apparently only for initiation. Some races required long days as seedlings, but not as older plants. Races from drier inland areas tended to be indifferent to day length in their flowering behaviour. At least four races from the colder areas responded to vernalization. Both the sexual and the aposporous reproductive pathways are described. Two races were wholly sexual in their breeding system and two appeared to be almost entirely aposporous, but most were versatile, displaying both sexual and aposporous reproductive behaviour. In seven races there was some evidence that day length influenced the reproductive pathway, short days causing increased apospory in all cases, regardless of the day length requirements for flowering.

scholarly journals PHOTOPERIODIC CONTROL OF DEVELOPMENTAL GROWTH IN BEGONIA × TUBERHYBRIDA

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1144G-1144
Author(s):  
Meriam G. Karlsson ◽  
Jeffrey W. Werner
Keyword(s):  
Early Development ◽  
Plant Development ◽  
Root Development ◽  
Growth And Development ◽  
Average Rate ◽  
Day Length ◽  
Seedling Height ◽  
Long Day ◽  
Developmental Growth ◽  
Short Days

Plants of Begonia x tuberhybrida `NonStop Orange', `Clips Orange' and `Musical Orange' were exposed to 1, 2, 3 or 4 weeks of short days initiated at 4 stages of plant development (immediately upon germination, 5 weeks after germination, 10 weeks after germination and 15 weeks after germination). Prior to and succeeding short days, plants were exposed to a day length of 16 hours at 100 μmol·m-2s-1. Short days were 9 hours at an irradiance level of 180 μmol·m-2s-1 to give the same total daily irradiance (5.8 mol· m-2day-1) as long day conditions. The temperature was maintained at 21° ± 4°C during the day and 18° ± 2°C during night. The observed growth and development responses were similar among the studied cultivars. During the period of 4 to 8 weeks after germination, the seedling height increased at an average rate of 0.7 mm day-1 for plants grown under long days and 0.3 mm day-1 for short day plants. The photoperiodic conditions did not affect the number of emerging leaves. The root development was more proliferate on plants allowed to develop under long days compared to plants exposed to short days during early development.

scholarly journals TEMPERATURE DURING EARLY DEVELOPMENT AFFECTS PLANT MORPHOLOGY OF BEGONIA × HIEMALIS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1086f-1086
Author(s):  
M. G. Karlsson ◽  
J. W. Werner ◽  
H.C.H. McIntyre
Keyword(s):  
Early Development ◽  
Plant Morphology ◽  
Dry Weight ◽  
Day Length ◽  
Effect Of Temperature ◽  
Flower Number ◽  
Main Shoot ◽  
Long Day ◽  
The Mean ◽  
Short Days

The effect of temperature during the initial long day period on morphology and plant dry weight was determined for Begonia × hiemalis `Hilda'. Multistem cuttings were planted in 10 cm pots and grown at 13°, 16°, 19°, 22°, 25° or 28°C. The day length was 16 hours at an irradiance level of 280 ± 20 μmol·m-2s-1. After 21 days, the plants were moved to a greenhouse maintained at 20° ± 2°C and short days of 10 hours at 125 ± 20 μmol·m-2s-1. The plants were grown under short days for 14 days and then moved to a day length of 16 hours. At data collection 21 days later (56 days from planting), plant height averaged 185 mm for plants initially grown at 13°, 16°, 19° or 22°C while pants originally grown at 25° and 28°C were 40 and 78 mm shorter than plants started at lower temperatures. The mean number of shoots was 4 on plants exposed to 16°, 19°, 22° or 25°C during early development and decrease to 3 shoots for plants grown initially at 13° or 28°C. The average flower number on the main shoot was similar for plants first exposed to low and intermediate temperatures but decreased rapidly to 0 for plants with early exposure to 28°C. Plants in treatments with early temperatures of 19° or 22°C had the largest above ground dry weight at an average 460 mg.

scholarly journals Chrysanthemum Cultivars Differ in Response to Photoperiod when Grown under Far-red Absorbing Filters

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 437A-437
Author(s):  
M.J. McMahon
Keyword(s):  
Acetic Acid ◽  
Ethyl Alcohol ◽  
The Other ◽  
Short Day ◽  
Long Day ◽  
Floral Primordia ◽  
Lateral Branches ◽  
And Control ◽  
Short Days

Two chrysanthemum [Dendranthema × grandiflorum (Ramat) Kitamura] cultivars, Bright Golden Anne and Spears, were grown in unfiltered sunlight (control) or under filters that removed far-red (FR) light under long- or short-day photoperiods for a total of four treatments. Eight plants from each cultivar were exposed to each treatment. Tips of lateral branches were harvested every 3 days and preserved in formalin, acetic acid, 70% ethyl alcohol (5:5:90 by volume), then observed and photographed under a dissecting microscope. In `Spears', all short-day treatments developed floral primoridia at the same time and rate and the development was normal. Under long days and under FR-absorbing filters, floral primordia initiated and developed normally, but was delayed several days compared to short days. Plants under long days and control filters also developed normal primoridia, but at a slower rate than any of the other treatments. In `Bright Golden Anne', only short-day treatments developed normal floral primordia. Development was the same regardless of filter. Under long days, plants under FR-absorbing filters eventually initiated floral primordia, but development was abnormal. No floral primordia developed under long-day and control filter conditions. In all cases, `Spears' primoridia development was much more rapid than `Bright Golden Anne'.

Latitude affects photoperiod-induced changes in immune response in meadow voles (Microtus pennsylvanicus)

2005 ◽  
Vol 83 (10) ◽  
pp. 1271-1278 ◽  
Author(s):  
L M Pyter ◽  
Z M Weil ◽  
R J Nelson
Keyword(s):  
Immune Responses ◽  
Microtus Pennsylvanicus ◽  
Day Length ◽  
Delayed Type Hypersensitivity ◽  
Deer Mice ◽  
Meadow Voles ◽  
Short Day ◽  
Long Day ◽  
Induced Changes ◽  
Short Days

Animals use day length (photoperiod) to time seasonal adaptations to annual changes in their environment. Reproductive adjustments in deer mice (Peromyscus maniculatus (Wagner, 1845)) from high latitudes are more extensive in response to short days than in deer mice from low latitudes. These adjustments may permit individuals to survive the severe seasonal changes (e.g., temperature and food abundance) in high-latitude environments. Immune function is also affected by photoperiod. Short days were predicted to result in elevated immune and reproductive responses in meadow voles (Microtus pennsylvanicus (Ord, 1815)) from the Northwest Territories (NWT), Canada (~62°N), compared with voles from Ohio (OH), USA (~39°N). Male voles from both latitudes were maintained in long or short days for 10 weeks prior to a delayed-type hypersensitivity (DTH) immune challenge. Both populations displayed similar testicular regression and reduction of testosterone concentrations in short days. DTH immune responses, however, diverged between the two populations. DTH immune responses were enhanced in long-day NWT voles and short-day OH voles, but decreased in short-day NWT voles and long-day OH voles. Total and free corticosterone concentrations did not explain the latitudinal differences in immune responses. These results suggest that photoperiod affects reproductive and immune systems differently and that immune responses may reflect other environmental factors.

Reproductive response to photoperiod affects corticosterone and immunoglobulin G concentrations in prairie voles (Microtus ochrogaster)

1996 ◽  
Vol 74 (3) ◽  
pp. 576-581 ◽  
Author(s):  
Randy J. Nelson ◽  
Benjamin Asfaw ◽  
A. Courtney DeVries ◽  
Gregory E. Demas
Keyword(s):  
Immunoglobulin G ◽  
Survival Rates ◽  
Reproductive Organ ◽  
Microtus Ochrogaster ◽  
Day Length ◽  
Seasonal Fluctuations ◽  
Prairie Voles ◽  
Serum Corticosterone ◽  
Long Day ◽  
Short Days

Nontropical rodent species display prominent breeding seasons mediated by photoperiod. Nonreproductive functions also exhibit seasonal changes; for example, fluctuations in adrenal activities may affect immune function and, ultimately, drive seasonal fluctuations in survival rates. The effects of photoperiod on adrenal and splenic masses and serum concentrations of corticosterone and immunoglobulin G (IgG) were evaluated in male prairie voles (Microtus ochrogaster). In one experiment, photoperiodic effects on adrenal and splenic masses and serum corticosterone and IgG levels were assessed in males that maintained "summer-like" reproductive systems after 8 weeks of short-day exposure. In a second experiment, the same parameters were examined in males in which testicular regression occurred after 8 weeks on short days. Voles that maintained reproductive organ size on short days failed to display other photoperiod-mediated differences in body, splenic, or adrenal masses or in serum corticosterone or IgG concentrations. In contrast, voles that underwent reproductive regression in response to short days decreased absolute adrenal mass and body mass compared with long-day animals, and also increased serum corticosterone concentrations and decreased IgG levels compared with their long-day counterparts. Taken together, these data indicate that reproductive responsiveness to day length may be linked to seasonal fluctuations in nonreproductive adaptations.

scholarly journals (71) Day Length Controls Flowering and Height of Sunflower

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1013E-1014
Author(s):  
Meriam Karlsson ◽  
Jeffrey Werner
Keyword(s):  
Plant Height ◽  
Flower Development ◽  
Seedling Development ◽  
The Other ◽  
Day Length ◽  
Flower Buds ◽  
Rate Of Development ◽  
Average Plant ◽  
Short Days ◽  
Average Plant Height

Flowering in response to day length was identified for sunflower (Helianthus annuus L. `Pacino Gold'). Germination and seedling development occurred at 20 °C and long days (ld, 16 hours) following direct seeding into 10-cm pots. Sixteen days after seeding, plants were placed at ld or short days (sd, 8 hours), 20 °C and 8 mol·d-1·m-2. Flowering was recorded at the stage of reflexed petals after 48 sd. At the time of flowering in sd, flower buds were of minute size under ld. Plants started at ld, and moved to sd after 1, 2, or 3 weeks, flowered at similar times as those grown under uninterrupted sd conditions. Four initial weeks of ld delayed flower development with 7 days, compared to a continuous sd environment. On the other hand, 2 to 3 weeks of initial sd followed by ld hastened flowering with 5 to 10 days. With increasing number of early ld from 1 to 4 weeks, plant height at flowering doubled from 20 to 40 cm. Average plant height in continuous sd was 18 cm. Plants grown exclusively or moved to ld after 1 to 4 weeks of sd were similar in height to plants finished at sd with 4 initial weeks of ld. Combinations of sd and ld may be used to manage height and rate of development in the sunflower `Pacino Gold'.

Gonadal hormone-dependent and -independent regulation of immune function by photoperiod in Siberian hamsters

2008 ◽  
Vol 294 (2) ◽  
pp. R384-R392 ◽  
Author(s):  
Brian J. Prendergast ◽  
Scott R. Baillie ◽  
Firdaus S. Dhabhar
Keyword(s):  
Immune Function ◽  
Gonadal Hormones ◽  
Day Length ◽  
Gonadal Hormone ◽  
Testosterone Secretion ◽  
Siberian Hamsters ◽  
Long Day ◽  
Sickness Behaviors ◽  
Immunological Effects ◽  
Short Days

Siberian hamsters ( Phodopus sungorus) exhibit changes in reproductive and immune function in response to seasonal variations in day length. Exposure to short days induces gonadal regression and inhibits testosterone secretion. In parallel, short days enhance immune function: increasing leukocyte numbers and attenuating cytokine and behavioral responses to infection. We examined whether photoperiodic changes in leukocyte phenotypes and sickness behaviors are dependent on concurrent photoperiodic changes in gonadal function. Male hamsters were gonadectomized or sham-gonadectomized and either exposed to short days (9 h light/day; SD) or kept in their natal long-day (15 h light/day; LD) photoperiod for 10–13 wk. Blood samples were obtained for leukocyte enumeration, and hamsters were challenged with bacterial LPS, which induced behavioral (anorexia, reductions in nest building) and somatic (weight loss) sickness responses. Among gonad-intact hamsters, exposure to SD increased total and CD62L+ lymphocytes and CD3+ T lymphocytes in blood and significantly attenuated LPS-induced sickness responses. Independent of photoperiod, castration alone increased total and CD62L+ lymphocyte and CD3+ T lymphocyte numbers and attenuated somatic and anorexic sickness responses. Among castrated hamsters, SD exposure increased lymphocyte numbers and suppressed sickness behaviors. In castrated hamsters, the magnitude of most immunological effects of SD were diminished relative to those evident in gonad-intact hamsters. The SD phenotype in several measures of immunity can be instated via elimination of gonadal hormones alone; however, photoperiodic effects on immune function persist even in castrated hamsters. Thus, photoperiod affects the immune system and neural-immune interactions underlying sickness behaviors via gonadal hormone-dependent and -independent mechanisms.

Effect of photoperiod and gonadectomy on testosterone metabolism in vitro by the prostate of the golden hamster

1983 ◽  
Vol 97 (2) ◽  
pp. 187-191 ◽  
Author(s):  
V. Lucini ◽  
L. Bottoni ◽  
R. Massa
Keyword(s):  
Golden Hamster ◽  
The Other ◽  
Testosterone Metabolism ◽  
Golden Hamsters ◽  
Long Day ◽  
The Mean ◽  
Short Days

Testosterone metabolism was studied in vitro in the prostate of intact and castrated golden hamsters maintained either in short days (8 h light: 16 h darkness, 8L : 16D) or in long days (14L : 10D). Testosterone was found to be converted into 17β-hydroxy-5α-androstan-3-one (5α-DHT), 5α-androstane-3α, 17β-diol, 5α-androstane-3, 17-dione and androstenedione. The mean conversion of testosterone to 5α-DHT was higher in prostates from animals maintained in long days than in short days (P < 0·0025) while that to androstenedione was higher in short days (P <0·0005); no significant changes in the formation of the other three metabolites were noted. Castration of animals maintained in short days resulted in a significant (P <0·05) decrease in the mean conversion to all four metabolites. In contrast, castration of animals kept in a long-day regime caused a significant (P <0·01) decrease in the mean formation of 5α-DHT but a significant (P <0·05) increase in the mean formation of 5α-androstane-3α, 17β-diol.

scholarly journals PHOTOPERIODIC CONTROL OF DEVELOPMENTAL GROWTH IN BEGONIA × TUBERHYBRIDA

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1144g-1144
Author(s):  
Meriam G. Karlsson ◽  
Jeffrey W. Werner
Keyword(s):  
Early Development ◽  
Plant Development ◽  
Root Development ◽  
Growth And Development ◽  
Average Rate ◽  
Day Length ◽  
Seedling Height ◽  
Long Day ◽  
Developmental Growth ◽  
Short Days

Plants of Begonia x tuberhybrida `NonStop Orange', `Clips Orange' and `Musical Orange' were exposed to 1, 2, 3 or 4 weeks of short days initiated at 4 stages of plant development (immediately upon germination, 5 weeks after germination, 10 weeks after germination and 15 weeks after germination). Prior to and succeeding short days, plants were exposed to a day length of 16 hours at 100 μmol·m-2s-1. Short days were 9 hours at an irradiance level of 180 μmol·m-2s-1 to give the same total daily irradiance (5.8 mol· m-2day-1) as long day conditions. The temperature was maintained at 21° ± 4°C during the day and 18° ± 2°C during night. The observed growth and development responses were similar among the studied cultivars. During the period of 4 to 8 weeks after germination, the seedling height increased at an average rate of 0.7 mm day-1 for plants grown under long days and 0.3 mm day-1 for short day plants. The photoperiodic conditions did not affect the number of emerging leaves. The root development was more proliferate on plants allowed to develop under long days compared to plants exposed to short days during early development.

scholarly journals FLOWERING AND GROWTH REGULATOR RESPONSE IN `FREEDOM' COMPARED TO OTHER POINSETTIA CULTIVARS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 634e-634
Author(s):  
James E. Barrett ◽  
Terril A. Nell
Keyword(s):  
Growth Regulator ◽  
Plant Size ◽  
The Other ◽  
Application Time ◽  
Time Of Application ◽  
Long Day ◽  
Short Days

Euphorbia pulcherrima cvs. Freedom, SUPJIBI, and Celebrate 2 were sprayed with paclobutrazol or a tank mix of daminozide and chlormequat at week 40, 41, 42, 43, or 44. Application time had little effect on plant size. The tank mix had greater efficacy on `Freedom' but not on the other cultivars. Interactions for bract size indicated: 1) time of application had less effect on `Freedom', 2) there was little difference between the chemicals on `SUPJIBI', but the tank mix had greater efficacy on the other cultivars, and 3) the tank mix had greater efficacy than paclobutrazol during weeks 41, 42, and 43. `Freedom', `Celebrate 2', `SUPJIBI', and `V-14 Glory' were planted on 8 or 15 Aug. and placed under short days on 12, 19, or 26 Sept. `Freedom' reached anthesis between 30 Oct. and 6 Nov., about 5 days before `SUPJIBI' and `Celebrate 2' and 7-10 days ahead of `V-14 Glory'. `Freedom' planted in Aug. and given short days 14 days apart flowered only 7 days apart (40 to 47 days from start of short days), but when planted in Sept. flowering was in 54 days and each long day resulted in 1 day delay in flowering.

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