Germination requirements of Oenothera biennis seeds during burial under natural seasonal temperature cycles

1994 ◽  
Vol 72 (6) ◽  
pp. 779-782 ◽  
Author(s):  
Carol C. Baskin ◽  
Jerry M. Baskin
Keyword(s):  
Seed Banks ◽  
Late Winter ◽  
Seasonal Temperature ◽  
Oenothera Biennis ◽  
Light Requirement ◽  
Term Survival ◽  
Temperature Changes ◽  
Buried Seeds ◽  
Dormancy Cycles

Buried seeds of Oenothera biennis, which have the potential to form long-lived seed banks, were investigated to determine whether or not they (i) undergo seasonal changes in their dormancy states and (ii) require light for germination. Seeds were buried in soil and exposed to natural seasonal temperature changes. Samples of seeds were exhumed at monthly intervals for 31 months and tested for germination in light and darkness at 12-h daily thermoperiods of 15:6, 20:10, 25:15, 30:15, and 35:20 °C. At maturity in autumn, seeds germinated to 84–95% in light at 30:15 and 35:20 °C, but to 0–69% at other test conditions. By late winter, seeds germinated to 95–100% at the five thermoperiods in light and in darkness. In summer and autumn, germination in light decreased at 15:6 °C, and in darkness it dropped to 0% at 15:6 °C and decreased at 20:10, 25:15, 30:15, and 35:20 °C. Following the second winter of burial, seeds germinated to near 100% at all thermoperiods in light and darkness. Thus, seeds exhibited an annual nondormancy – conditional dormancy cycle, being nondormant from midwinter to late spring and conditionally dormant in summer and autumn. Oenothera biennis is 1 of 10 species whose seeds live for 39–40 years or longer in soil and also have an annual conditional dormancy – nondormancy cycle. Seeds of six of these species, including O. biennis, can germinate in darkness in spring or summer at simulated habitat temperatures. Therefore, a light requirement for germination is not necessarily a prerequisite for long-term survival of buried seeds, and something other than darkness prevents germination of seeds of some species buried in soil. Key words: seed banks, buried seeds, germination, dormancy cycles, light requirement, Oenothera.

Role of temperature and light in the germination ecology of buried seeds of weedy species of disturbed forests. II. Erechtites hieracifolia

1996 ◽  
Vol 74 (12) ◽  
pp. 2002-2005 ◽  
Author(s):  
Carol C. Baskin ◽  
Jerry M. Baskin
Keyword(s):  
Seed Bank ◽  
Full Range ◽  
Soil Disturbance ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Test Conditions ◽  
Buried Seeds ◽  
Weedy Species ◽  
Dormancy Cycles

At maturity in September, about half the seeds (achenes) of Erechtites hieracifolia (Asteraceae) collected in Kentucky were dormant (did not germinate at any test condition), whereas the others were conditionally dormant (germinated only at a narrow range of test conditions). Seeds sown on top of soil in an unheated greenhouse in September failed to germinate in autumn because temperatures were below those required for germination; however, they germinated at comparable temperatures the following spring. Seeds buried in soil in September 1987 and exposed to natural seasonal temperature changes were nondormant (germinated over full range of test conditions) by April 1988, but they entered conditional dormancy by October 1988. Each October through 1995, exhumed seeds exhibited conditional dormancy. Since 89% of the seeds were viable after 8 years of burial, it appears that although seeds of this species are wind dispersed, they also have the potential to form a long-lived seed bank. Thus, soil disturbance at any time from May to September could result in establishment of plants from seeds in the seed bank. Keywords: seed dormancy, Asteraceae, dormancy cycles, buried seeds, light.

Seasonal Changes in the Germination Responses of Buried Witchgrass (Panicum capillare) Seeds

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seasonal Changes ◽  
Late Summer ◽  
Late Spring ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Late Autumn ◽  
Buried Seeds ◽  
Autumn And Winter

Buried seeds of witchgrass (Panicum capillare L., # PANCA) exposed to natural seasonal temperature changes in Lexington, KY, for 0 to 35 months exhibited annual dormancy/nondormancy cycles. Seeds were dormant at maturity in early October. During burial in late autumn and winter, fresh seeds and those that had been buried for 1 and 2 years became nondormant. Nondormant seeds germinated from 76 to 100% in light at daily thermoperiods of 15/6, 20/10, 25/15, 30/15, and 35/20 C, while in darkness they germinated from 1 to 24%. In late spring, seeds lost the ability to germinate in darkness, and by late summer 63 to 100% of them had lost the ability to germinate in light. As seeds became nondormant, they germinated (in light) at high (35/20, 30/15 C) and then at lower (25/15, 20/10, and 15/6 C) temperatures. As seeds reentered dormancy, they lost the ability to germinate (in light) at 15/6 C and at higher thermoperiods 2 to 3 months later.

scholarly journals Toxicity and bioaccumulation of fluoride ion on Branchiura sowerbyi, Beddard, (Oligochaeta, Tubificidae)

Zoosymposia ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. 44-50 ◽  
Author(s):  
STEFANIA DEL PIERO ◽  
LUCIANO MASIERO ◽  
SANDRA CASELLATO
Keyword(s):  
Chemical Analysis ◽  
Aquatic Ecosystems ◽  
Pollution Assessment ◽  
Fluoride Ion ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Branchiura Sowerbyi ◽  
Large Size ◽  
Different Temperatures

Fluoride concentrations are increasing significantly in many aquatic ecosystems as a consequence of human activities (agrochemicals, pharmaceuticals, refrigerants, pesticides, surfactant compounds). Several investigations have revealed that sensitivity to fluorides and safe concentrations vary greatly within classes, families and genera. Aquatic oligochaetes have often been used for pollution assessment and accumulation testing, but no information has been given about tolerance to fluoride ion. Among endobenthic tubificids Branchiura sowerbyi is easily identifiable (evident posterior gills, large size) and particularly useful for tissue requirements in chemical analysis. The purpose of this study was to examine the tolerance of this tubificid to fluoride ion and its bioaccumulation capacity by performing short (LC50 96h) and long-term (18 day) experiments at different temperatures (17°C and 22 °C). LC50 values (91.3 and 61.7 mg/L for 17°C and 22°C respectively), especially in the presence of sediment (267.6 and 80.1 mg/L for 17°C and 22°C respectively) showed that B. sowerbyi is more resistant to fluoride than other freshwater invertebrates. Fluoride became more toxic with increased temperature, demonstrating that seasonal temperature changes could influence the sensitivity of this freshwater tubificid. Bioaccumulation was lower when the organisms were exposed to sodium fluoride in the absence of sediment, indicating that this animal also accumulates fluoride by ingesting sediment. 

scholarly journals Evolution with a seed bank: the population genetic consequences of microbial dormancy

2017 ◽  
Author(s):  
WR Shoemaker ◽  
JT Lennon
Keyword(s):  
Seed Bank ◽  
Population Genetic ◽  
Evolutionary Dynamics ◽  
Phenotypic Diversity ◽  
Seed Banks ◽  
Hedging Strategy ◽  
Term Survival ◽  
Evolutionary Forces ◽  
Growth And Reproduction

ABSTRACTDormancy is a bet-hedging strategy that allows organisms to persist through conditions that are sub-optimal for growth and reproduction by entering a reversible state of reduced metabolic activity. Dormancy allows a population to maintain a reservoir of genetic and phenotypic diversity (i.e., a seed bank) that can contribute to the long-term survival of a population. This strategy can be potentially adaptive and has long been of interest to ecologists and evolutionary biologists. However, comparatively little is known about how dormancy influences the fundamental evolutionary forces of genetic drift, mutation, selection, recombination, and gene flow. Here, we investigate how seed banks affect the processes underpinning evolution by reviewing existing theory, implementing novel simulations, and determining how and when dormancy can influence evolution as a population genetic process. We extend our analysis to examine how seed banks can alter macroevolutionary processes, including rates of speciation and extinction. Through the lens of population genetic theory, we can understand the extent that seed banks influence microbial evolutionary dynamics.

Role of temperature and light in the germination ecology of buried seeds of weedy species of disturbed forests. I. Lobelia inflata

1992 ◽  
Vol 70 (3) ◽  
pp. 589-592 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Banks ◽  
Early Summer ◽  
Light Requirement ◽  
Forest Sites ◽  
Light Requirements ◽  
Lobelia Inflata ◽  
Buried Seeds ◽  
Weedy Species ◽  
Disturbed Forest

Lobelia inflata L. is a weedy species that may be abundant in disturbed forest sites. Temperature and light requirements for germination were determined at 12-h daily thermoperiods of 15:6, 20:10, 25:15, 30:15, and 35:20 °C for seeds exhumed after 0–28 months (September 1987 to February 1990) of burial in soil at near-natural temperatures. At maturity in autumn 1987, 2–15% of the seeds germinated after 15 days incubation at the five thermoperiods in light but 0% germinated in darkness. By January 1988, 68–100% of the seeds germinated in light at all thermoperiods except 15:6 °C. Germination at 20:10, 25:15, and 30:15 °C did not decrease to below 60% during the remainder of the study, and germination at 35:20 °C was less than 60% only four times. Germination at 15:6 °C was erratic with peaks in spring 1988, and in spring to early summer and autumn 1989. Regardless of the season in which seeds were exhumed, they did not germinate in darkness. In a laboratory study, stratification at 5 °C broke dormancy but did not substitute for the light requirement. Seeds of L. inflata have the potential to form long-lived seed banks, and buried seeds can germinate at any time during the growing season if exposed to light. Key words: seed dormancy, seed germination, buried seeds, Lobelia inflata, stratification.

Will the sleeping beauties wake up? Seasonal dormancy cycles in seeds of the holoparasiteCuscuta epithymum

2009 ◽  
Vol 20 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Klaar Meulebrouck ◽  
Kris Verheyen ◽  
Martin Hermy ◽  
Carol Baskin
Keyword(s):  
Room Temperature ◽  
Empirical Studies ◽  
Seasonal Temperature ◽  
Natural Conditions ◽  
Temperature Changes ◽  
Physiological Dormancy ◽  
Spring Temperatures ◽  
Viable Seeds ◽  
Cyclic Changes ◽  
Dormancy Cycles

AbstractSeed banks are often crucial for the survival of plant species, especially short-lived ones. Nevertheless, empirical studies about the fate of seeds under natural conditions are scarce, particularly for parasitic plants. Therefore, fresh seeds of the holoparasiticCuscuta epithymumwere buried in the field under natural conditions in Belgium or kept at room temperature for up to 31 months, and germination was tested periodically by incubating seeds in light at 23°C. BuriedC. epithymumseeds had cyclic changes in their germinability, while those stored dry at room temperature never germinated without scarification. Buried seeds exhibited a seasonal cycle of physiological dormancy, the first to be reported for a species with combinational (i.e. physical+physiological) dormancy. The physiological dormancy of the embryo was broken during winter ( ≤ 5°C) but induced during exposure to late spring temperatures (>10°C). Therefore, germination ofC. epithymumseeds is fine tuned to seasonal temperature changes. Each year only a portion of the viable seeds could germinate. The portion of seeds buried in the soil that remained available for delayed germination, i.e. in the seed bank, decreased rather quickly, with only 8.5% of them being viable after 31 months of burial; all seeds stored in the laboratory remained viable. Nonetheless, we concluded that someC. epithymumseeds are capable of surviving for several years in the soil. These data indicate that the parasite is well adapted to survive in a dynamic heathland landscape where conditions for survival change constantly, but it is still sensitive to local extinction.

scholarly journals Climate Change, Temperature, and Homicide: A Tale of Two Cities, 1895–2015

2020 ◽  
Vol 12 (1) ◽  
pp. 171-181 ◽  
Author(s):  
Michael J. Lynch ◽  
Paul B. Stretesky ◽  
Michael A. Long
Keyword(s):  
Climate Change ◽  
New York ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Temperature Trends ◽  
Two Cities ◽  
Change Temperature ◽  
The Relationship ◽  
Seasonal Weather

AbstractIt has been argued that the temperature increase caused by anthropogenic climate change will produce a significant increase in violent crime. Support for that prediction is often based on statistical analyses of seasonal temperature and crime data cycles across days, months, and quarters and sometimes on large geographic areas. Within-year temperature changes are very large, however, relative to the 30-yr temperature increases employed to measure climate change. In addition, because temperature trends associated with climate change vary geographically, analyses should employ small geographic units for which temperature changes are measured over yearly intervals and for long periods of time. To address these conditions, this study examined the long-term temperature–crime association for homicides in New York and London for 1895–2015. Consistent with previous studies examining seasonal weather and crime patterns, we found a positive correlation between annual homicide rates and temperature, but only at the bivariate level. This relationship became statistically insignificant in both New York and London when gross domestic product is controlled. Moreover, the bivariate relationship between temperature and homicide is statistically insignificant when correcting for nonstationarity. Thus, it does not appear that climate change has led to higher rates of homicide in New York and London over the long term. These nonfindings are important because they suggest that studies of climate change and violence might do well to consider alternative mechanisms that mediate the relationship between climate change and violence.

Does Seed Dormancy Play a Role in the Germination Ecology ofRumex crispus?

Weed Science ◽  
1985 ◽  
Vol 33 (3) ◽  
pp. 340-343 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Dormancy ◽  
Growing Season ◽  
Seasonal Temperature ◽  
Rumex Crispus ◽  
Temperature Changes ◽  
Germination Ecology ◽  
Buried Seeds ◽  
Buried Seed

Seed dormancy does not play a role in the germination ecology of curly dock (Rumex crispusL. ♯ RUMCR). This study confirms reports that freshly matured seeds are nondormant, and it shows that buried seeds exposed to natural seasonal temperature changes remain nondormant. From October 1981 through June 1983, seeds exhumed at monthly intervals germinated 80 to 100% at all thermo-periods. These results do not support suggestions that seeds of curly dock buried in soil enter dormancy. However, the results do explain why seeds of this species in the Beal and Duvel buried-seed experiments germinated when exhumed at various times during the growing season.

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