The effect of environmental conditions on the annual dormancy pattern of seeds of Spergula arvensis

1993 ◽  
Vol 71 (1) ◽  
pp. 64-73 ◽  
Author(s):  
Harro J. Bouwmeester ◽  
Cees M. Karssen
Keyword(s):  
Seasonal Changes ◽  
Red Light ◽  
Effect Of Temperature ◽  
Combined Effects ◽  
Germination Test ◽  
Dual Effect ◽  
Descriptive Model ◽  
Weed Seeds ◽  
Field Temperature ◽  
Dormancy Pattern

The effect of environmental factors on the germination of exhumed seeds of Spergula arvensis L. after variable periods of burial in soil was investigated. Seeds were buried in the field and exhumed at regular intervals after which germination was tested over a range of conditions. These tests showed clear seasonal changes in dormancy during 3 successive years. Dormancy was broken in spring and reinduced in autumn at rising and falling temperatures, respectively. In experiments in incubators, greater loss of dormancy occurred at 10 and 15 °C than at 2 and 6 °C. As in the field, induction of dormancy occurred when the preincubation temperature was lowered. The expression of the dormancy pattern was strongly influenced by the germination tests conditions. At 15 °C, seeds germinated during a longer period of the year than at 2 or 30 °C. Irradiation with red light, addition of nitrate, and desiccation of the seeds prior to the germination test strongly stimulated germination. All three factors enabled germination of exhumed seeds during a longer period of the year. When light, nitrate, and desiccation were combined, exhumed seeds could germinate in all seasons. The seasonal germination pattern was modelled with a descriptive model based on the dual effect of temperature, which regulates dormancy and also affects germination. This model closely simulated germination at field temperatures. Germination of exhumed seeds in the field was restricted to the period of overlap between the germination temperature range computed with the model and field temperature. The features of the model supported the hypothesis that dormancy of S. arvensis is regulated by the actual changes in temperature rather than the combined effects of a cold and heat sum. Key words: Spergula arvensis, dormancy pattern, germination, regression model, weed seeds.

scholarly journals Influence of stimulus and oral adaptation temperature on gustatory responses in central taste-sensitive neurons

2015 ◽  
Vol 113 (7) ◽  
pp. 2700-2712 ◽  
Author(s):  
Jinrong Li ◽  
Christian H. Lemon
Keyword(s):  
Thermal Effect ◽  
Concentration Dependence ◽  
Thermal Adaptation ◽  
Effect Of Temperature ◽  
Solitary Tract ◽  
Neural Basis ◽  
Dual Effect ◽  
Cool Water ◽  
Reduced Activity ◽  
Oral Epithelia

The temperature of taste stimuli can modulate gustatory processing. Perceptual data indicate that the adapted temperature of oral epithelia also influences gustation, although little is known about the neural basis of this effect. Here, we electrophysiologically recorded orosensory responses (spikes) to 25°C (cool) and 35°C (warm) solutions of sucrose (0.1 and 0.3 M), NaCl (0.004, 0.1, and 0.3 M), and water from taste-sensitive neurons in the nucleus of the solitary tract in mice under varied thermal adaptation of oral epithelia. Conditions included presentation of taste stimuli isothermal to adaptation temperatures of 25°C (constant cooling) and 35°C (constant warming), delivery of 25°C stimuli following 35°C adaptation (relative cooling), and presentation of 35°C stimuli following 25°C adaptation (relative warming). Responses to sucrose in sucrose-oriented cells ( n = 15) were enhanced under the constant and relative warming conditions compared with constant cooling, where contiguous cooling across adaptation and stimulus periods induced the lowest and longest latency responses to sucrose. Yet compared with constant warming, cooling sucrose following warm adaptation (relative cooling) only marginally reduced activity to 0.1 M sucrose and did not alter responses to 0.3 M sucrose. Thus, warmth adaptation counteracted the attenuation in sucrose activity associated with stimulus cooling. Analysis of sodium-oriented ( n = 25) neurons revealed adaptation to cool water, and cooling taste solutions enhanced unit firing to 0.004 M (perithreshold) NaCl, whereas warmth adaptation and stimulus warming could facilitate activity to 0.3 M NaCl. The concentration dependence of this thermal effect may reflect a dual effect of temperature on the sodium reception mechanism that drives sodium-oriented cells.

scholarly journals Only as strong as the weakest link: structural analysis of the combined effects of elevated temperature and pCO2 on mussel attachment

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Laura A Newcomb ◽  
Matthew N George ◽  
Michael J O’Donnell ◽  
Emily Carrington
Keyword(s):  
Elevated Temperature ◽  
Structural Analysis ◽  
Structural Integrity ◽  
Proximal Region ◽  
Ocean Warming ◽  
Mode Analysis ◽  
Effect Of Temperature ◽  
High Pco2 ◽  
Combined Effects ◽  
Thread Strength

AbstractPredicting how combinations of stressors will affect failure risk is a key challenge for the field of ecomechanics and, more generally, ecophysiology. Environmental conditions often influence the manufacture and durability of biomaterials, inducing structural failure that potentially compromises organismal reproduction, growth, and survival. Species known for tight linkages between structural integrity and survival include bivalve mussels, which produce numerous byssal threads to attach to hard substrate. Among the current environmental threats to marine organisms are ocean warming and acidification. Elevated pCO2 exposure is known to weaken byssal threads by compromising the strength of the adhesive plaque. This study uses structural analysis to evaluate how an additional stressor, elevated temperature, influences byssal thread quality and production. Mussels (Mytilus trossulus) were placed in controlled temperature and pCO2 treatments, and then, newly produced threads were counted and pulled to failure to determine byssus strength. The effects of elevated temperature on mussel attachment were dramatic; mussels produced 60% weaker and 65% fewer threads at 25°C in comparison to 10°C. These effects combine to weaken overall attachment by 64–88% at 25°C. The magnitude of the effect of pCO2 on thread strength was substantially lower than that of temperature and, contrary to our expectations, positive at high pCO2 exposure. Failure mode analysis localized the effect of temperature to the proximal region of the thread, whereas pCO2 affected only the adhesive plaques. The two stressors therefore act independently, and because their respective target regions are interconnected (resisting tension in series), their combined effects on thread strength are exactly equal to the effect of the strongest stressor. Altogether, these results show that mussels, and the coastal communities they support, may be more vulnerable to the negative effects of ocean warming than ocean acidification.

scholarly journals Effects of Climate on Incidence of Campylobacter spp. in Humans and Prevalence in Broiler Flocks in Denmark

2004 ◽  
Vol 70 (12) ◽  
pp. 7474-7480 ◽  
Author(s):  
Mary Evans Patrick ◽  
Lasse Engbo Christiansen ◽  
Michael Wainø ◽  
Steen Ethelberg ◽  
Henrik Madsen ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Linear Models ◽  
Public Health Problem ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Future Research ◽  
Combined Effects ◽  
Average Temperature ◽  
Effects Of Temperature ◽  
Single Predictor

ABSTRACT Campylobacter infections are increasing and pose a serious public health problem in Denmark. Infections in humans and broiler flocks show similar seasonality, suggesting that climate may play a role in infection. We examined the effects of temperature, precipitation, relative humidity, and hours of sunlight on Campylobacter incidence in humans and broiler flocks by using lag dependence functions, locally fitted linear models, and cross validation methods. For humans, the best model included average temperature and sunlight 4 weeks prior to infection; the maximum temperature lagged at 4 weeks was the best single predictor. For broilers, the average and maximum temperatures 3 weeks prior to slaughter gave the best estimate; the average temperature lagged at 3 weeks was the best single predictor. The combined effects of temperature and sunlight or the combined effects of temperature and relative humidity predicted the incidence in humans equally well. For broiler flock incidence these factors explained considerably less. Future research should focus on elements within the broiler environment that may be affected by climate, as well as the interaction of microclimatic factors on and around broiler farms. There is a need to quantify the contribution of broilers as a source of campylobacteriosis in humans and to further examine the effect of temperature on human incidence after this contribution is accounted for. Investigations should be conducted into food consumption and preparation practices and poultry sales that may vary by season.

The effect of weather conditions on harbour seal (Phoca vitulina) haulout behaviour in the Moray Firth, northeast Scotland

1996 ◽  
Vol 74 (10) ◽  
pp. 1806-1811 ◽  
Author(s):  
Kate Grellier ◽  
Paul M. Thompson ◽  
Heather M. Corpe
Keyword(s):  
Significant Relationship ◽  
Seasonal Changes ◽  
Negative Relationship ◽  
Weather Conditions ◽  
Phoca Vitulina ◽  
Effect Of Temperature ◽  
Harbour Seals ◽  
Moray Firth ◽  
A Site ◽  
The Relationship

Abundance data from a 6-year study (1988–1993) of harbour seals (Phoca vitulina) were used to control for seasonal changes in haulout behaviour and assess the effect of temperature and other weather conditions on haulout numbers at a site in Scotland. A significant relationship between Julian day and haulout numbers was consistent between years. In some years, there was also a significant relationship between ambient temperature and haulout numbers, but examination of the residuals around the relationship between haulout numbers and Julian day revealed no evidence for a consistent effect of temperature, wind speed, or wind-chill adjusted temperatures. A weak negative relationship between haulout numbers and both precipitation and cloud cover did exist, but these variables explained little of the variation in seal numbers.

scholarly journals (421) Light and Temperature Interactions in Promoting Lettuce Seed Germination

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1021E-1022
Author(s):  
Samuel Contreras ◽  
David Tay ◽  
Mark Bennett
Keyword(s):  
Red Light ◽  
Light Treatment ◽  
Effect Of Temperature ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Radicle Emergence ◽  
Lettuce Seed Germination ◽  
Temperature Interactions ◽  
Soaking Temperature ◽  
Light Break

Lettuce seeds (Lactuca sativavar. acephalacv. Tango) were used with the objective of determining the effect of temperature, light, and their interactions in promoting germination. Under standard op-timal conditions (20 °C, light), the seed presented 100% germination (radicle emergence 5 d after sowing). Different treatments evaluated germination under dark conditions, with or without a red light break (LB, 28.8 mmol·m-2) 48 h after sowing, and with different combination of temperatures pre- (soaking temperature, ST) and post- (germination temperature, GT) the LB. Germination at constant 20 °C without LB was less than 5%, and with LB, it was around 30%. However, germination was close to 100% at GT of 20 °C when LB was applied after a ST of 10 °C, and around 50% under the same conditions, but without LB. When GT was 30 °C and LB was applied, germination was less than 3% with ST = 30 °C, less than 10% with ST = 20 °C, and around 100% when ST = 10 °C. With ST and GT of 10 °C and 30 °C, respectively, and no LB, germination was less than 5%. Germination at 10 °C constant, with and without LB, was around 90% and 0%, respectively. When ST was 40 °C and LB was applied, germination was around 40% at GT= 20 °C, but less that 3% with GT= 30 °C. In summary, a severe inhibition of germination was observed when seeds were germinated in dark, which was partially reversed by either a light treatment or soaking at 10 °C, and fully reversed when both treatments were applied together. Inhibition of lettuce germination at 30 °C was observed when this temperature was applied after a light treatment, but not when applied before. Possible implications of these results for the phytochrome mechanism of action are discussed.

scholarly journals Investigation of the Combined Effects of Rising Temperature and Pesticide Contamination on the Swimming Behaviour of Alpine Chironomids

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3618
Author(s):  
Valeria Lencioni ◽  
Valeria Di Nica ◽  
Sara Villa
Keyword(s):  
Tracking System ◽  
Video Tracking ◽  
Swimming Behaviour ◽  
Effect Of Temperature ◽  
Combined Effects ◽  
Freshwater Biodiversity ◽  
Alpine Glacier ◽  
Negative Effect ◽  
The Individual ◽  
Reduced Mobility

Some pollutants can be transported through the atmosphere and travel medium–long distances to be deposited in glaciers at high altitude and latitude. The increase in the rate of glacier melting due to global warming can release these pollutants in alpine streams. This study investigated the combined effects of rising temperatures and chlorpyrifos (CPF) contamination on the swimming behaviour of alpine chironomids collected in a shrinking alpine glacier. We assessed the individual and interaction effects of rising temperatures (2–11 °C) and CPF concentrations (0–110 ng L−1) on the swimming behaviour of Diamesa zernyi (Chironomidae) larvae. Distance (mm) and speed (mm s−1) were recorded using a video-tracking system after 24–72 h of treatment. The two stressors caused different effects on distance and speed, with increasing temperature generally causing hyperactivity and CPF from hyperactivity to reduced mobility. Two interactions were detected between stressors when combined: (i) CPF superimposed the effect of temperature on both behavioural endpoints i.e., with 110 ng L−1 of CPF, at 11 °C, larvae moved less; (ii) warming (11 °C) magnified the negative effect of CPF: the smallest distance and slowest speed were recorded at the highest values of the two stressors after 72 h. Our results suggest that water contamination by CPF, even at sub-lethal concentrations, might increase the sensitivity of chironomids to warming, and vice versa, raising concerns about freshwater biodiversity conservation under climate change.

scholarly journals Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata

Marine Drugs ◽  
2014 ◽  
Vol 12 (4) ◽  
pp. 1891-1910 ◽  
Author(s):  
Martin Olofsson ◽  
Teresa Lamela ◽  
Emmelie Nilsson ◽  
Jean-Pascal Bergé ◽  
Victória del Pino ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Nitrogen Concentration ◽  
Nannochloropsis Oculata ◽  
Combined Effects

scholarly journals Combined effects of exploitation and temperature on fish stocks in the Northeast Atlantic

2014 ◽  
Vol 71 (7) ◽  
pp. 1554-1562 ◽  
Author(s):  
Tristan Rouyer ◽  
Jean-Marc Fromentin ◽  
Manuel Hidalgo ◽  
Nils C. Stenseth
Keyword(s):  
Geographical Location ◽  
Geographic Location ◽  
Effect Of Temperature ◽  
Fish Stock ◽  
Combined Effects ◽  
Fish Stocks ◽  
Northeast Atlantic ◽  
Middle Range ◽  
Management Procedures

Abstract Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus been a question of primary importance for fisheries management and conservation. Through the analysis of long-term time-series for 27 fish stocks from the Northeast Atlantic, the present study shows that the sign and intensity of the effect of temperature on biomass are dependent on the geographical location: the stocks located at the southernmost and northernmost latitudes of our study displayed stronger associations with temperature than the stocks located in the middle range of latitudes. As a consequence, the investigation of the combined effects of exploitation and the environment revealed that the stocks at the northern/southern boundaries of the spatial extent of the species were more prone to combined effects. The interplay between geographic location, climate and exploitation thus plays a significant role in fish stock productivity, which is generally ignored during assessment, thus affecting management procedures.

scholarly journals The Role of Manipulating Photoperiod and Temperature in Oocyte Development of the Polychaete Hediste diversicolor (O.F. Müller, 1976)

2020 ◽  
Vol 7 ◽  
Author(s):  
Haiqing Wang ◽  
Andreas Hagemann ◽  
Arne M. Malzahn ◽  
Aleksander Handå ◽  
Marianne Uhre ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Seasonal Changes ◽  
Rate Of Change ◽  
Oocyte Development ◽  
Combined Effects ◽  
Temperature Transition ◽  
Hediste Diversicolor ◽  
Oocyte Growth ◽  
Temperature Regimes

Three different experiments were conducted to examine the oocyte development of the polychaete Hediste diversicolor in response to changing photoperiod and temperature at three different periods of oogenesis. In experiment I, worms collected during summer were reared under constant or decreasing photoperiod and temperatures to test the combined effects of the summer–autumn photoperiod and temperature transition on oogenesis. The result showed females collected during summer showed the highest oocyte growth when exposed to constant temperatures combined with decreasing photoperiod and decreasing temperature combined with constant photoperiod. In experiment II, worms collected in late autumn were under mimicked or shortened seasonal changes in photoperiod to evaluate the effect of accelerated change on oocyte growth. The result showed worms had 1.5 times faster oocyte growth rates when exposed to accelerated rate of change in photoperiod (2.5 times faster). In experiment III, worms collected in spring were exposed to different temperature regimes to examine the effect of raising temperature on the synchronization of oocyte growth and maturation. The results showed worms collected in spring showed increased temperatures will increase oocyte maturation synchronicity. It was concluded temperature and photoperiod transition can increase the oocyte development.

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