The Effect of Temperature, Light and Gibberellic Acid (Ga3) on the Germination of Australian Everlasting Daisies (Asteraceae, Tribe Inuleae)

1995 ◽  
Vol 43 (1) ◽  
pp. 93 ◽  
Author(s):  
JA Plummer ◽  
DT Bell
Keyword(s):  
Gibberellic Acid ◽  
Soil Surface ◽  
Light Regime ◽  
Effect Of Temperature ◽  
Extreme Temperatures ◽  
Light Conditions ◽  
Bedding Plants ◽  
Treated Seed ◽  
Germination Requirements ◽  
Survival Of Seedlings

Australian everlasting daisies have considerable potential as bedding plants, but little is known about their germination requirements. In ten taxa of everlasting daisies (Asteraceae, Tribe Inuleae) examined, germination in petri dishes was optimum over the temperature range 10-20°C with little or no germination at more extreme temperatures (5 and 30°C). Light stimulated germination in seven of the ten tare; Erymophyllum ramosum (A. Gray) Wilson, Craspedia sp., Leucochrysum fitzgibbonii (F. Muell.) Wilson, Waitzia suaveolens var. flava Wilson, Rhodanthe chlorocephala subsp. rosea (Hook.) Wilson, R. chlorocephala subsp. splendida (Hemsley) Wilson and R. floribunda (DC.) Wilson. In the dark, gibberellic acid (GA3, 50 mg L-1) stimulated germination to similar levels observed in light-treated seed. Schoenia filifolia subsp. subulifolia and S. cassiniana were not affected by light regime, but in both taxa germination was improved by the addition of GA3. By contrast, germination in Rhodanthe humboldtiana, which also had no response to light, was inhibited by GA3. In most species, germination in the dark was similar over the GA3 concentration range 1-100 mg L-1, but 500 mg L-1 was often inhibitory. Germination was optimised under temperature and light conditions related to maximising survival of seedlings which germinate near the soil surface during winter in the arid interior habitat of central Australia.

scholarly journals Stimulating Germination of Australian Everlasting Daisies

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 760F-760
Author(s):  
J.A. Plummer ◽  
D.T. Bell
Keyword(s):  
Gibberellic Acid ◽  
Floral Display ◽  
Extreme Temperatures ◽  
Influence Of Temperature ◽  
Considerable Potential ◽  
Bedding Plants ◽  
Dry Conditions ◽  
Petri Dishes ◽  
Floral Displays ◽  
Germination Requirements

Australian everlasting daisies (Asteraceae, Tribe Inulae) have considerable potential as bedding plants, but little is known about their germination requirements. Florets have a papery corolla, which imparts considerable longevity of the floral display even under dry conditions. The influence of temperature, light and gibberellic acid (GA3) was determined for several species with spectacular floral displays. Germination in petri dishes was optimum over the range of 10 to 20C, with little or no germination at extreme temperatures. Light stimulated germination in most species with little or no germination occurring under dark conditions. In the dark, GA3 stimulated germination to similar levels observed in light-treated seeds. In most species, germination in the dark was optimum over the GA3 concentration range 1 to 100 mg·liter–1, and 500 mg·liter–1 was often inhibitory.

Germination and persistence in soil of the dimorphic diaspores of Atriplex centralasiatica

2016 ◽  
Vol 26 (3) ◽  
pp. 273-283 ◽  
Author(s):  
Rui Zhang ◽  
Yan Rong Wang ◽  
Jerry M. Baskin ◽  
Carol C. Baskin ◽  
Kai Luo ◽  
...  
Keyword(s):  
Central Asia ◽  
Soil Surface ◽  
Potassium Nitrate ◽  
Flowering Plants ◽  
Light Regime ◽  
Cold Desert ◽  
Natural Dispersal ◽  
Germination Requirements ◽  
Desert Halophyte ◽  
Constant Dark

AbstractThe fruit plus accessory parts, and thus not only the fruit or seed, is the diaspore in some species of flowering plants. Atriplex centralasiatica, a summer annual salt-secreting cold-desert halophyte of central Asia that produces flat and humped diaspores, is such a species. The dispersal/germination units of this diaspore-heteromorphic species are fruits enclosed in persistent ‘bracteoles’. Germination of black and brown fruits (i.e. ‘bracteoles’ removed) of this species has been studied in some detail previously, but little attention has been given to the germination biology of the intact diaspores. The aim of this study was to compare the germination biology of the intact diaspores of A. centralasiatica, and their fates in the field during 12 months on the soil surface and buried at 5-cm depth. Fresh flat diaspores germinated to 42.7–51.3% in light (12-h photoperiod) and to 16.0–59.3% in constant dark, over a temperature range of 15–20/30°C, while no freshly matured humped diaspores did so under any temperature/light regime. Neither gibberellin (GA3) nor potassium nitrate (KNO3) had an effect on germination of either diaspore. Both diaspores readily imbibed water, and removal of ‘bracteoles’ released most of the dormancy. Thus, the ‘bracteoles’ are primarily responsible for diaspore dormancy in A. centralasiatica. Humped diaspores persisted for a longer period in the soil than flat ones. The germination requirements of intact natural dispersal/germination units of A. centralasiatica differ from those previously reported for fruits of this species.

Differences in light and temperature responses determine autumn versus spring germination for seeds of Schoenolirion croceum

2004 ◽  
Vol 82 (10) ◽  
pp. 1429-1437 ◽  
Author(s):  
Jeffrey L Walck ◽  
Siti N Hidayati
Keyword(s):  
Soil Surface ◽  
Early Spring ◽  
Early Summer ◽  
Light Regime ◽  
Late Winter ◽  
Light Conditions ◽  
Germination Phenology ◽  
Temperature Requirements ◽  
Temperature Responses ◽  
Do So

Seeds of the southeastern North American Schoenolirion croceum (Michx.) Wood are dormant when dispersed in late spring to early summer. Fresh seeds buried in soil after dispersal germinate in autumn, whereas those sown on the soil surface do so the following late winter – early spring. To understand this difference in germination phenology, we examined the light and temperature requirements for dormancy break and germination. Seeds germinated to high percentages in darkness over 12:12 h thermoperiods ranging from 15:6 to 35:20 °C following warm stratification (25:15 °C) in darkness, whereas no seeds germinated in light following stratification in light. On the other hand, seeds germinated to high percentages in light and in darkness following cold stratification (5 °C) in light or darkness. Seeds exposed to light during autumn germinated in winter–spring regardless of the light regime in summer or winter–spring, whereas those in darkness during autumn germinated in autumn regardless of the light regime in summer. Thus, light conditions during autumn are critical for determining whether seeds will germinate in autumn versus early spring. In contrast with many other species in which germination phenology is mostly temperature controlled, timing of germination for S. croceum depends on the light conditions in relation to temperatures experienced during dormancy release.Key words: dark, germination phenology, Hyacinthaceae, negative photoblastic seeds, photoecology, seed dormancy.

Dealing with hot rocky environments: Critical thermal maxima and locomotor performance in Leptodactylus lithonaetes (Anura: Leptodactylidae)

2019 ◽  
pp. 155-161 ◽  
Author(s):  
Ivan Beltran
Keyword(s):  
Environmental Temperature ◽  
Extreme Temperature ◽  
Effect Of Temperature ◽  
Maximum Speed ◽  
Locomotor Performance ◽  
Extreme Temperatures ◽  
Physiological Limits ◽  
Fitness Consequences ◽  
Thermal Maximum ◽  
Environmental Temperatures

Environmental temperature has fitness consequences on ectotherm development, ecology and behaviour. Amphibians are especially vulnerable because thermoregulation often trades with appropriate water balance. Although substantial research has evaluated the effect of temperature in amphibian locomotion and physiological limits, there is little information about amphibians living under extreme temperature conditions. Leptodactylus lithonaetes is a frog allegedly specialised to forage and breed on dark granitic outcrops and associated puddles, which reach environmental temperatures well above 40 ˚C. Adults can select thermally favourable microhabitats during the day while tadpoles are constrained to rock puddles and associated temperature fluctuations; we thus established microhabitat temperatures and tested whether the critical thermal maximum (CTmax) of L. lithonaetes is higher in tadpoles compared to adults. In addition, we evaluated the effect of water temperature on locomotor performance of tadpoles. Contrary to our expectations, puddle temperatures were comparable and even lower than those temperatures measured in the microhabitats used by adults in the daytime. Nonetheless, the CTmax was 42.3 ˚C for tadpoles and 39.7 ˚C for adults. Regarding locomotor performance, maximum speed and maximum distance travelled by tadpoles peaked around 34 ˚C, approximately 1 ˚C below the maximum puddle temperatures registered in the puddles. In conclusion, L. lithonaetes tadpoles have a higher CTmax compared to adults, suggesting a longer exposure to extreme temperatures that lead to maintain their physiological performance at high temperatures. We suggest that these conditions are adaptations to face the strong selection forces driven by this granitic habitat.

Seed germination ecology of Sumatran fleabane (Conyza sumatrensis) in relations to various environmental parameters

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Gulshan Mahajan ◽  
Asheneel Prasad ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Light Intensity ◽  
Chloride Concentration ◽  
Soil Surface ◽  
Control Treatment ◽  
Effect Of Temperature ◽  
Burial Depth ◽  
Germination Ecology ◽  
Wide Range ◽  
Dark Conditions

Abstract Sumatran fleabane [Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate susceptible (S) populations of C. sumatrensis. A study was conducted to examine the effect of temperature, light intensity, salt stress, osmotic stress, and burial depth on the germination and emergence of two populations (R and S) of C. sumatrensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C). In light/dark conditions, the R population had higher germination than the S population at 20/10 and 35/25 C. In the dark, the R population had higher germination than the S population at 25/15 C. In the dark, germination was inhibited at 30/20 C and above. Averaged over populations, seed germination of C. sumatrensis was reduced by 97% at zero light intensity (completely dark conditions) compared with full light intensity. Seed germination of C. sumatrensis reduced by 17 and 85% at an osmotic potential of −0.4, and −0.8 MPa, respectively, compared with the control treatment. The R population had lower germination (57%) than the S population (72%) at a sodium chloride concentration of 80 mM. Seed germination was highest on the soil surface and emergence was reduced by 87 and 90% at burial depths of 0.5 and 1.0 cm, respectively. Knowledge gained from this study suggests that a shallow-tillage operation to bury weed seeds in conventional tillage systems, and retention of high residue cover in a zero-till system on the soil surface may inhibit the germination of C. sumatrensis. This study also warrants that the R population may have a greater risk of invasion over a greater part of a year due to germination over a broader temperature range.

scholarly journals The Effect of Temperature, Light and Calcium Carbonate on Seed Germination and Radicle Growth of the Polycarpic Perennial Galium cracoviense (Rubiaceae), a Narrow Endemic Species From Southern Poland

2015 ◽  
Vol 57 (1) ◽  
pp. 70-81 ◽  
Author(s):  
Jeremi Kołodziejek ◽  
Jacek Patykowski
Keyword(s):  
Calcium Carbonate ◽  
Endemic Species ◽  
Soil Surface ◽  
Ion Concentration ◽  
Effect Of Temperature ◽  
Radicle Growth ◽  
Southern Poland ◽  
Narrow Endemic ◽  
Before And After ◽  
Different Temperatures

Abstract Germination responses of Galium cracoviense Ehrend. (Rubiaceae), a narrow endemic species from southern Poland, were tested in light and dark conditions at three constant temperatures (5, 10, or 22°C), before and after cold-wet stratification. Additionally, seeds were germinated under different calcium carbonate (CaCO3) concentrations (1, 5, 10, 15, 20, or 25 mM/L CaCO3) at 22°C in light. The high germination capacity of seeds incubated at different temperatures, shortly after collection, already suggested the absence of dormancy in this species. Thus, the seeds are ready to germinate immediately in the field when water resources are available and the temperature is adequate. Light was a significant factor for G. cracoviense; more seeds germinated in light than in darkness at all temperatures tested. Cold stratification decreased germination especially at higher temperatures. The light requirement for G. cracoviense germination ensures their successful germination on or near the soil surface, and in cracks and crevices in limestone, when temperature and edaphic conditions are favourable. Seeds of this species show temperature enforced dormancy throughout the winter. Germination was significantly affected by calcium carbonate. Non-germinated seeds germinated well after being transferred from higher CaCO3 concentrations to distilled water. The results indicate that the seeds of this species can endure CaCO3 stress without losing their viability and start germination once CaCO3 concentration is reduced. It can be concluded that the seeds of this species require lower Ca2+ ion concentration, moderate temperatures and the presence of light to germinate.

Factors affecting germination of horseweed (Conyza canadensis)

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 898-902 ◽  
Author(s):  
Vijay K. Nandula ◽  
Thomas W. Eubank ◽  
Daniel H. Poston ◽  
Clifford H. Koger ◽  
Krishna N. Reddy
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Conyza Canadensis ◽  
Light Conditions ◽  
Complete Darkness ◽  
Continuous Darkness ◽  
Factors Affecting ◽  
Nacl Concentration ◽  
Alkaline Conditions ◽  
Ph Range

The influence of environmental factors on germination and emergence of horseweed was examined in growth chamber experiments. Germination was highest (61%) under 24/20 C day/night temperature under light. Horseweed seed germination was observed under both light (13 h photoperiod) and complete darkness (24 h), but germination under continuous darkness was only 0 to 15% compared with 0 to 61% under light. All other experiments were conducted under 24/20 C and 13-h light conditions. Germination was 19 to 36% over a pH range from 4 to 10, with a trend toward higher germination under neutral-to-alkaline conditions. Horseweed germination was > 20% at < 40 mM NaCl concentration and lowest (4%) at 160 mM NaCl. These data suggest that even at high soil salinity conditions, horseweed can germinate. Germination of horseweed decreased from 25% to 2% as osmotic potential increased from 0 (distilled water) to −0.8 MPa, indicating that germination can still occur under moderate water stress conditions. Horseweed seedling emergence was at its maximum on the soil surface, and no seedlings emerged from seeds placed at a depth of 0.5 cm or higher.

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