Influence of maternal environment in developing different levels of physical dormancy and its ecological significance

Plant Ecology ◽  
2015 ◽  
Vol 217 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Ganesh K. Jaganathan
Keyword(s):  
Ecological Significance ◽  
Physical Dormancy ◽  
Maternal Environment ◽  
Different Levels

scholarly journals Physical dormancy in a changing climate

2015 ◽  
Vol 25 (2) ◽  
pp. 66-81 ◽  
Author(s):  
Alice R. Hudson ◽  
David J. Ayre ◽  
Mark K. J. Ooi
Keyword(s):  
Climate Change ◽  
Intraspecific Variation ◽  
Interspecific Variation ◽  
Physical Dormancy ◽  
Maternal Environment ◽  
Successful Recruitment ◽  
Environmental Controls ◽  
The Future ◽  
Germination Timing ◽  
Stochastic Events

AbstractSpecies with physically dormant (PY) seeds make up over 25% of plant species in a number of ecologically important ecosystems around the globe, such as savannah and Mediterranean shrublands. Many of these ecosystems are subject to temporally stochastic events, such as fire and drought; but are in areas projected to experience some of the most extreme climatic changes in the future. Given the importance of PY in controlling germination timing for successful recruitment, we ask how plastic the PY trait is, and if changes to the maternal environment from climate change could alter recruitment. This review focuses on: (1) the evidence for inter- and intraspecific variation in PY; (2) the genetic, maternal and environmental controls involved; and (3) the ecological consequences of (1) and (2) above. Evidence for (within-community) interspecific variation in conditions required to break PY is strong, but for intraspecific variation evidence is contradictory and limited by a paucity of studies. Identifying controllers of variation in PY is complex, there is some suggestion that conditions of the maternal environment may be important, but no consensus on the nature of effects. The implications of PY plasticity for the persistence of seed banks, species and communities under climate change are discussed. We highlight a number of key knowledge gaps, such as a lack of research estimating the components of variation in non-agricultural species, and identify a suite of seed attributes relevant to understanding the potential impacts of climate change on the population dynamics of PY species in the future.

scholarly journals EFFECT OF LIGHT, TEMPERATURE AND SCARIFICATION ON THE GERMINATIVE CAPACITY AND INITIAL GROWTH OF Myroxylon balsamum (L.) HARMS

2018 ◽  
Vol 31 (2) ◽  
pp. 415-423 ◽  
Author(s):  
SOPHIA LOAYZA-CABEZAS ◽  
DANTE ARTURO RODRIGUEZ-TREJO ◽  
ELIZABETH HERNÁNDEZ-ACOSTA ◽  
JUAN ALMARÁZ SUÁREZ
Keyword(s):  
Seed Germination ◽  
Forest Products ◽  
Initial Growth ◽  
Nontimber Forest Products ◽  
Degraded Land ◽  
Physical Dormancy ◽  
Deforestation Rates ◽  
Different Levels ◽  
Effect Of Light

ABSTRACT Myroxylon balsamum is a valuable tropical tree; besides the good quality of its timber it also provides valuable nontimber forest products: balsam and resin. High deforestation rates in the area of distribution and the unregulated extraction of its resin and wood have led M. balsamum to be endangered or threatened. Its regeneration through seeds has been poorly studied, and there are no reports of germination and plasticity under controlled conditions. We evaluated the effect of scarification (longitudinal cut of the fruit and embryo fully exposed) and environmental factors (different levels of light intensities and changing temperatures) on seed germination and the development of seedlings. From the aforementioned, M. balsamum seeds are orthodox and show physical dormancy. In view of these characteristics, M. balsamum can be managed efficiently to initiate conservation programs and restoration in degraded land.

Critical role of air and soil temperature in the development of primary and secondary physical dormancy in Albizia julibrissin (Fabaceae)

2021 ◽  
pp. 1-7
Author(s):  
Ganesh K. Jaganathan ◽  
Matthew Biddick
Keyword(s):  
Moisture Content ◽  
Critical Role ◽  
Canopy Cover ◽  
Physical Dormancy ◽  
Maternal Environment ◽  
Albizia Julibrissin ◽  
Secondary Dormancy ◽  
Data Loggers ◽  
Using Data ◽  
Species Specific

Abstract Physical dormancy (PY) is typically induced by seed coat impermeability that develops once the moisture content of seeds drops below a species-specific threshold. Considering this, we utilized Albizia julibrissin (Fabaceae) to ask (i) whether seeds that mature on the outer branches of trees (directly exposed to sunlight) are more likely to be impermeable than seeds matured under canopy cover; (ii) whether this difference might be explained by the maternal environment in which the seeds mature; and (iii) which conditions impose secondary dormancy following dispersal? Temperature was tracked in both shaded and sun-exposed seed pods throughout the growing season using data-loggers. Temperatures remained lower in pods under canopy cover than those exposed to direct sunlight. Consequently, the moisture content of seeds collected from sun-exposed branches were significantly lower than seeds matured under canopy cover, thereby producing a higher percentage of impermeable seeds. A dispersal-mimicking experiment revealed that seeds matured in sun-exposed branches and subsequently dispersed to an open site for 4 months were more likely to develop impermeability (i.e. secondary dormancy). The opposite was found to be true for seeds matured in shaded branches and subsequently dispersed to a canopy-covered site. We conclude that the microclimate of both the maternal environment in which seeds mature, and the site to which they disperse, determines the development of primary and secondary dormancy, respectively.

The relationship between moisture content and net assimilation rate of lichen thalli and its ecological significance

1972 ◽  
Vol 50 (3) ◽  
pp. 543-555 ◽  
Author(s):  
K. A. Kershaw
Keyword(s):  
Dry Weight ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Ecological Significance ◽  
Southern Ontario ◽  
Percentage Saturation ◽  
Close Relationship ◽  
Net Assimilation ◽  
The Relationship ◽  
Different Levels

The relationship between net assimilation rates and percentage thallus saturation has been investigated in 12 widely occurring lichen species in southern Ontario. Optimum net assimilation rates occur between 35 and 70% of thallus saturation levels for different species. A close relationship has been shown to exist between their ecology and the percentage saturation at which maximum assimilation occurs. Optimum net assimilation rate values range from 0.03 mg CO2/g dry weight in Umbilicaria mammulata up to 0.11 mg CO2/g dry weight in Peltigera praetextata. Five of the species also exhibit a plastic physiology in that maximum net assimilation occurs at different levels of thallus saturation in replicates collected from different microhabitats. The implications of this variability are briefly discussed.

scholarly journals Reproduction and Accompanying Fauna of Red Mason Bee Osmia rufa L. (syn. Osmia bicornis L.) in Areas with Different Levels of Urbanization

2021 ◽  
Vol 65 (1) ◽  
pp. 123-137
Author(s):  
Barbara Zajdel ◽  
Mikołaj Borański ◽  
Kornelia Kucharska ◽  
Dariusz Teper
Keyword(s):  
Habitat Structure ◽  
Population Growth Rate ◽  
Reproductive Parameters ◽  
Solitary Bee ◽  
Ecological Significance ◽  
Habitat Types ◽  
Biological Value ◽  
Urbanized Areas ◽  
Nest Fauna ◽  
Different Levels

Abstract An increasing number of studies show that urbanized areas are habitats of high biological value and ecological significance. Most bee species live in areas altered by man, either in cities - fragmented urban habitats - or in large rural monocultures. Our research is based on three-year observations of population development of the solitary bee Osmia rufa L. in three habitat types: city, suburbs and villages. We compared reproductive parameters and diversity of accompanying nest fauna. Population growth rate was high in all habitats, exceeding five times the number of cocoons placed in the previous year. We found no significant differences in the number of cocoons and brood mortality between areas with different urbanization levels. In nests located in suburbs, parasites and cleptoparasites occupied almost three times more nest chambers than in other habitats. Changes in the habitat structure had a significant impact on the diversity and abundance of accompanying fauna. Our study shows that red mason bees are flexible and easily adapt to new conditions, despite changes caused by urbanization and agriculture.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Memory Processes, Aging, Cognitive Decline, and Neurodegenerative Diseases

2006 ◽  
Vol 11 (4) ◽  
pp. 304-311 ◽  
Author(s):  
Lars-Göran Nilsson
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Neurodegenerative Disease ◽  
Genetic Markers ◽  
Brain Activity ◽  
Memory Performance ◽  
Modeling And Simulations ◽  
Aging And Health ◽  
Explained Variance ◽  
Different Levels

This paper presents four domains of markers that have been found to predict later cognitive impairment and neurodegenerative disease. These four domains are (1) data patterns of memory performance, (2) cardiovascular factors, (3) genetic markers, and (4) brain activity. The critical features of each domain are illustrated with data from the longitudinal Betula Study on memory, aging, and health ( Nilsson et al., 1997 ; Nilsson et al., 2004 ). Up to now, early signs regarding these domains have been examined one by one and it has been found that they are associated with later cognitive impairment and neurodegenerative disease. However, it was also found that each marker accounts for only a very small part of the total variance, implying that single markers should not be used as predictors for cognitive decline or neurodegenerative disease. It is discussed whether modeling and simulations should be used as tools to combine markers at different levels to increase the amount of explained variance.

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