Short-Day Cycle Requirements for Floral Initiation of Stylosanthes guianensis (Aublet) Sw. var. guianensis

1985 ◽  
Vol 12 (3) ◽  
pp. 291 ◽  
Author(s):  
RL Ison
Keyword(s):  
Seed Set ◽  
Morphological Changes ◽  
Floral Initiation ◽  
Feasible Method ◽  
Development Stages ◽  
Stylosanthes Guianensis ◽  
Tropical Legume ◽  
Short Day ◽  
Lateral Branches

Mature plants of the tropical legume Stylosanthes guianensis var. guianensis cv. Schofield required 20 short-day (SD) cycles (of 10-h days) for irrevocable commitment to floral initiation when returned to natural long days (LD), although the morphological changes associated with floral initiation were evident after 12-18 SD cycles. Commitment to flowering and spike production were favoured by 20 or more SD cycles. Floret number per spike and percentage seed set were not affected by return to LD. Within individual plants, sections of terminal and branch apices revealed a range of development stages. Terminal apices of well developed lateral branches were able to initiate as soon as, or sooner than, terminal apices of the main branch in this usually determinate plant; this points to individual branches having some autonomy for floral initiation, but suggests dissections made from well developed lateral branches would be a feasible method for determining floral initiation where plant replication is limited.

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.

The long-short day requirement for flowering in Stylosanthes guianensis

1988 ◽  
Vol 39 (2) ◽  
pp. 199 ◽  
Author(s):  
K Trongkongsin ◽  
LR Humphreys
Keyword(s):  
Early Summer ◽  
Controlled Environment ◽  
Floral Initiation ◽  
Previous Exposure ◽  
Spike Density ◽  
Stylosanthes Guianensis ◽  
Short Day ◽  
Seed Crops ◽  
Incandescent Lamps ◽  
Short Days

Five 'tardio' selections of Stylosanthes guianensis ssp. guiunensis var. pauciflora and S. guiunensis var. guianensis cv. Cook were grown in a glasshouse where natural daylength was shortencd, or extended by incandescent lamps. They did not flower or flowered weakly in 152 cycles of 10 h short days (SD), but flowered more rapidly and prolifically if exposed to 30, 60 or 90 16 h long days (LD) followed by 30 10 h cycles than under natural daylength conditions at 27' 30' S. Increasing the previous exposure to LD reduced the number of 10 h cycles to floral initiation. Similar behaviour was exhibited by cv. Bandeirante which did not flower in 131 cycles of 11 h, but which flowered when SD induction followed 45 to 65 cycles of 14 h. Spike density was positively related to number of LD, which favoured first flower appearance on the terminal apices of lateral rather than of main shoots. CIAT 1283 and cv. Cook grown in controlled environment cabinets at 30�/23� (day/night) did not flower in 140 cycles of 10 h SD, but flowered if LD were interposed before SD induction. Cook had a greater LD requirement of 50 cycles of 14 or 15.5 h for floral initiation, whilst CIAT 1283 had a lesser LD requirement and flowered after 20 cycles of 14 or 15.5 h or after 50 cycles of 12.5 h. These data indicate a qualitative long-short day flowering response. This has implications which favour the higher latitudes for seed production and the early summer sowing of seed crops when plants would receive maximum LD exposure before SD induction occurs.

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.

Seed production in Brachiaria decumbens and Paspalum plicatulum as influenced by system of residue disposal

1987 ◽  
Vol 38 (5) ◽  
pp. 869
Author(s):  
WW Stnr ◽  
LR Humphreys
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Nitrogen Supply ◽  
Floral Initiation ◽  
Spikelet Number ◽  
Brachiaria Decumbens ◽  
Short Day ◽  
Cotton South ◽  
Defoliation Treatment

Long-established swards of Brachiaria decumbens cv. Basilisk and of Paspalum plicatulum cv. Rodds Bay at Mt Cotton, south-east Queensland, were cut, field dried and burnt, or cut and the residues removed in late November or early January. Burning initially reduced tillering, especially when the interval between cutting and burning was 7 days, but this difference disappeared in P. plicatulum when there was a long interval to floral initiation. A juvenility requirement was evident in the short day P. plicatulum swards, where late burning or cutting delayed floral initiation 11 days relative to early defoliation. Strong compensatory and hierarchical effects on the components of seed yield occurred, and seed yield was similar in cut or burnt treatments, except for 23% decrease in late cut P. plicatulum. Late defoliated B. decumbens yielded 31% more seed than early defoliated swards, due mainly to reduced spikelet number per raceme (branch). Burning slightly increased synchrony of inflorescence exsertion in P. plicatulum and reduced crop lodging, although in a subordinate experiment with P. plicatulum lodging was positively related to level of nitrogen supply rather than to defoliation treatment.

scholarly journals Ultrastructural analysis of the spermatogenesis in the guinea pig (Cavia porcellus)

2016 ◽  
Vol 36 (suppl 1) ◽  
pp. 89-94 ◽  
Author(s):  
Luciana S. Simões ◽  
Rose E.G. Rici ◽  
Phelipe O. Favaron ◽  
Taís Harumi de Castro Sasahara ◽  
Rodrigo S.N. Barreto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Guinea Pig ◽  
Sexual Development ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Management Systems ◽  
Cavia Porcellus ◽  
Reproductive Parameters ◽  
Development Stages ◽  
Transmission Electron

Abstract: al for both, the establishment of appropriate management systems, and for the use of new species as animal models. In this study, we used light and electron microscopy to characterize the sexual development stages of the guinea pig (Cavia porcellus) in specimens of 30, 45 and 90 days of age. We observed the differentiation of spermatocytes only through transmission electron microscopy in the leptotene, zygotene and pachytene phases of meiosis, in 30-day-old animals. During puberty, there was differentiation of the germinative epithelium and formation of the acrosome. Spermatozoa, however, were not detected. Thus, we could infer that puberty happens after 45 days of age. Sexual maturity was evident in 90-day-old specimens. Our results showed that changes in the testicular germinative epithelium during the postnatal sexual development in guinea pig led to morphological changes, including the ones related to the development of Leydig and Sertoli cells, which are directly related to puberty. In this work, we provide new morphological subsidies for a better understanding of reproductive parameters of this species, enabling its use as an animal model in the field of the reproductive biology.

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'.

scholarly journals The Effect of Daily Light Integral on Floral Initiation of Pelargonium ×domesticum L.H. Bailey

HortScience ◽  
2004 ◽  
Vol 39 (3) ◽  
pp. 529-532
Author(s):  
Marietta M. Loehrlein ◽  
Richard Craig
Keyword(s):  
Morphological Changes ◽  
Genotypic Variation ◽  
Floral Initiation ◽  
Daily Light Integral ◽  
Growth Chambers ◽  
Light Integral ◽  
Chronological Time

Nine cultivars of Pelargonium ×domesticum L.H. Bailey were evaluated for the effect of daily light integral on floral initiation. Plants were grown at four daily light integrals: 5, 10, 15, or 20 mol·m-2·d-1 for a 16-hour photoperiod in environmental growth chambers at constant 15.5 °C. Meristems were examined at 50 mol·m-2 intervals for morphological changes associated with floral initiation. Two phenotypes were identified, cultivars with an association between floral initiation and cumulative irradiance and those with association between floral initiation and chronological time. Genotypic variation was observed among the irradiance-associated phenotypes.

Field environment studies on lupins. I. Developmental patterns in Lupinus angustifolius L., the effects of cultivar, site and planting time

1975 ◽  
Vol 26 (1) ◽  
pp. 81 ◽  
Author(s):  
MW Perry ◽  
ML Poole
Keyword(s):  
Moisture Stress ◽  
Lupinus Angustifolius ◽  
Floral Initiation ◽  
Growth Phases ◽  
Developmental Patterns ◽  
Field Environment ◽  
Cool Environment ◽  
Determinate Growth ◽  
Lateral Branches ◽  
Western Australian

The development of early (Unicrop) and late (Uniharvest) flowering cultivars of Lupinus angustifolius was studied with eight planting times at two climatically contrasting sites representing the main lupin-producing areas in Western Australia. Differences in time from planting to floral initiation and from initiation to first flower, in duration of flowering, and in time of maturity were measured. The major differences in phasic development between the cultivars for the different planting times and sites were for the period from planting to initiation. This is explained in terms of the known vernalization requirement of Uniharvest. As a consequence, initiation of the two cultivars was closest with midwinter planting in the cool environment and farthest apart with eariy planting at the warmer site. For comparable planting times the differences between cultivars for the period from initiation to first flower were small. Duration of flowering and final maturity were mainly influenced by the definite end to the growing season brought on by moisture stress and high temperatures. Differences in photoperiod exerted little influence on development. Growth of the plant was indeterminate, but the presence of terminal inflorescences on the main axis and branches produced a series of easily identified orders of lateral branches. Inflorescences flowered in sequence, extending the duration of flowering as successively higher orders of laterals were formed. Late planting reduced the length of all growth phases but drastically reduced the duration of flowering. The results are discussed in relation to the Western Australian environment, and it is argued that, in such environments, indeterminate growth has potential adaptive advantage over the determinate growth pattern of the cereals.

Effect of age at initiation of short-day treatment on earliness to flower in three Stylosanthes guianensis genotypes

1982 ◽  
Vol 22 (115) ◽  
pp. 83 ◽  
Author(s):  
JW Miles
Keyword(s):  
Growth Rate ◽  
Generation Time ◽  
Day Treatment ◽  
Stem Length ◽  
Juvenile Period ◽  
Stylosanthes Guianensis ◽  
Short Day ◽  
Natural Photoperiod ◽  
Inductive Photoperiod ◽  
Effect Of Age

The number of days from planting to flowering and number of short-day (9 h) cycles to flowering of three Stylosanthes guianensis genotypes were evaluated on seedlings grown for 0, 4, 8, 12, or 16 weeks under natural (approximately 12 h) photoperiod before the start of the short-day treatment. Untreated controls grown continuously under the natural photoperiod were included. All genotypes responded to short-day treatment, flowering earlier than the controls. Differences among genotypes in number of days to flower and in number of short-day cycles to flower under each treatment were found. The number of short-day cycles to flower decreased with increasing age at the start of the short-day treatment, indicating an initial, non-receptive juvenile period. The duration of the juvenile period differed with genotype and was prolonged under short photoperiod. Differences among genotypes in the duration of the juvenile period were not related to differences in growth rate as measured by main stem length. The plant age at the start of short-day treatment that resulted in minimum time to flower ranged among genotypes from 4-1 2 weeks. Initial plant growth under long, non-inductive photoperiod at photosynthetic light intensity with subsequent short-day treatment should decrease time to flower for short-day types of S. guianensis, resulting in a decrease in generation time of glasshouse-grown plants.

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