Effects of light, temperature and population variability on the germination of seven Spanish pines

2002 ◽  
Vol 12 (4) ◽  
pp. 261-271 ◽  
Author(s):  
A. Escudero ◽  
F. Pérez-García ◽  
A. L. Luzuriaga
Keyword(s):  
Habitat Preferences ◽  
Population Variability ◽  
Nested Models ◽  
Germination Response ◽  
Germination Characteristics ◽  
Different Populations ◽  
Effects Of Temperature ◽  
Germination Traits ◽  
The Relationship ◽  
Pine Species

AbstractMost Pinus species are obligate seeders. Thus, knowledge of germination characteristics can help in the understanding, prediction and manipulation of the regeneration and dynamics of pine forests. Seven pine species with contrasting habitat preferences and different genetic pairwise distances are present in the Iberian Peninsula and the Canary Islands: P. halepensis, P. nigra, P. pinaster, P. pinea, P. sylvestris, P. uncinata and P. canariensis. These seven pine species comprise an exceptional experimental set to test some questions related to germination traits, such as: (1) What are the effects of light and temperature on germination, taking into account interpopulation variability? (2) Is there any association of germination traits with habitat (montane versus lowland) preferences? and (3) What is the relationship between germination traits and the genetic distance between pine species? P. nigra, P. sylvestris and P. uncinata seeds showed faster germination rates. Seeds of P. nigra and P. sylvestris reached high total germination percentages in every temperature and light treatment, suggesting an opportunistic germination strategy. Unlike montane pines, lowland pines did show significant effects of temperature on germination response: final germination was higher between 15°C and 20°C than at warmer and alternating temperatures. Relatively low temperatures associated with the winter rainy season would favour germination of most of these species. Nested models showed that population variability was the main source of variation in germination response. Thus, there is no phylogenetic control of the germination response and, surprisingly, germination traits were not related to habitat preferences. As a consequence, we believe that studies of the germination characteristics of a pine species should consider different populations.

scholarly journals Metacognitive control processes in question answering: help seeking and withholding answers

2021 ◽  
Author(s):  
Monika Undorf ◽  
Iris Livneh ◽  
Rakefet Ackerman
Keyword(s):  
Help Seeking ◽  
Question Answering ◽  
Monetary Incentives ◽  
Metacognitive Control ◽  
Self Regulated Learning ◽  
Response Strategies ◽  
Seeking Help ◽  
Subjective Confidence ◽  
Different Populations ◽  
The Relationship

AbstractWhen responding to knowledge questions, people monitor their confidence in the knowledge they retrieve from memory and strategically regulate their responses so as to provide answers that are both correct and informative. The current study investigated the association between subjective confidence and the use of two response strategies: seeking help and withholding answers by responding “I don’t know”. Seeking help has been extensively studied as a resource management strategy in self-regulated learning, but has been largely neglected in metacognition research. In contrast, withholding answers has received less attention in educational studies than in metacognition research. Across three experiments, we compared the relationship between subjective confidence and strategy use in conditions where participants could choose between submitting answers and seeking help, between submitting and withholding answers, or between submitting answers, seeking help, and withholding answers. Results consistently showed that the association between confidence and help seeking was weaker than that between confidence and withholding answers. This difference was found for participants from two different populations, remained when participants received monetary incentives for accurate answers, and replicated across two forms of help. Our findings suggest that seeking help is guided by a wider variety of considerations than withholding answers, with some considerations going beyond improving the immediate accuracy of one’s answers. We discuss implications for research on metacognition and regarding question answering in educational and other contexts.

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

scholarly journals Specimen-based analysis of morphology and the environment in ecologically dominant grasses: the power of the herbarium

2018 ◽  
Vol 374 (1763) ◽  
pp. 20170403 ◽  
Author(s):  
Christine A. McAllister ◽  
Michael R. McKain ◽  
Mao Li ◽  
Bess Bookout ◽  
Elizabeth A. Kellogg
Keyword(s):  
Morphological Characters ◽  
Automated Image Analysis ◽  
Climate Variables ◽  
Theme Issue ◽  
Analysis Techniques ◽  
Temperature And Precipitation ◽  
Sessile Spikelet ◽  
Effects Of Temperature ◽  
The Relationship ◽  
Image Analysis Techniques

Herbaria contain a cumulative sample of the world's flora, assembled by thousands of people over centuries. To capitalize on this resource, we conducted a specimen-based analysis of a major clade in the grass tribe Andropogoneae, including the dominant species of the world's grasslands in the genera Andropogon , Schizachyrium , Hyparrhenia and several others. We imaged 186 of the 250 named species of the clade, georeferenced the specimens and extracted climatic variables for each. Using semi- and fully automated image analysis techniques, we extracted spikelet morphological characters and correlated these with environmental variables. We generated chloroplast genome sequences to correct for phylogenetic covariance and here present a new phylogeny for 81 of the species. We confirm and extend earlier studies to show that Andropogon and Schizachyrium are not monophyletic. In addition, we find all morphological and ecological characters are homoplasious but variable among clades. For example, sessile spikelet length is positively correlated with awn length when all accessions are considered, but when separated by clade, the relationship is positive for three sub-clades and negative for three others. Climate variables showed no correlation with morphological variation in the spikelet pair; only very weak effects of temperature and precipitation were detected on macrohair density. This article is part of the theme issue ‘Biological collections for understanding biodiversity in the Anthropocene'.

scholarly journals The Effect of Temperature and Humidity May Reduce the Growth Rate of the Coronavirus Disease 2019 Epidemic

2020 ◽  
Author(s):  
Lei Qin ◽  
Qiang Sun ◽  
Jiani Shao ◽  
Yang Chen ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Effect Of Temperature ◽  
Average Temperature ◽  
Temperature And Humidity ◽  
Scatter Plots ◽  
Low Humidity ◽  
Average Relative Humidity ◽  
Effects Of Temperature ◽  
The Relationship

Abstract Background: The effects of temperature and humidity on the epidemic growth of coronavirus disease 2019 (COVID-19)remains unclear.Methods: Daily scatter plots between the epidemic growth rate (GR) and average temperature (AT) or average relative humidity (ARH) were presented with curve fitting through the “loess” method. The heterogeneity across days and provinces were calculated to assess the necessity of using a longitudinal model. Fixed effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH.Results: An increased AT dramatically reduced the GR when the AT was lower than −5°C, the GR was moderately reduced when the AT ranged from −5°C to 15°C, and the GR increased when the AT exceeded 15°C. An increasedARH increased theGR when the ARH was lower than 72% and reduced theGR when the ARH exceeded 72%.Conclusions: High temperatures and low humidity may reduce the GR of the COVID-19 epidemic. The temperature and humidity curves were not linearly associated with the COVID-19 GR.

Dormancy and Germination of Seed of Eight Populations of Themeda australis

1982 ◽  
Vol 30 (4) ◽  
pp. 373 ◽  
Author(s):  
RH Groves ◽  
MW Hagon ◽  
PS Ramakrishnan
Keyword(s):  
Population Stratification ◽  
Physiological Adaptation ◽  
Dormant Seed ◽  
Seed Formation ◽  
Fresh Seed ◽  
Temperature Regimes ◽  
Germination Characteristics ◽  
Moisture Regimes ◽  
Different Populations ◽  
Climatic Characteristics

Seed of eight populations of Themeda australis (R.Br.) Stapf from sites nith the widest range of climates in Australia and Papua New Guinea (P.N.G.) was tested for its dormancy status and germination responses to different temperature and moisture regimes. The populations were from Lae. P.N.G.. Katherine. N.T.. Mundubbera. Qld. Alice Springs. N.T.. Tantangara. N.S.W.. Adelaide Hills. S.A.. Bunbury, W.A. and Hobart. Tas. Dormancy of fresh seed was negligible in Lae and Mundubbera populations. considerable in the Alice Springs population and intermediate in populations from Katherine and all temperate sites. Addition of gibberellic acid hastened the release from dormancy of seed from Katherine and Bunbury. Exposure of plants to three different temperature regimes during seed formation had an effect on dormancy of the Katherine population. Stratification at 4°C and high alternating daily temperatures (45 20°C) hastened the loss of dormancy of fresh seeds of some populations. Germination of non-dormant seed of the different populations was relatively unaffected b) temperatures between 20 and 40°C. Germination of the Alice Springs population was the most sensitive to increasing water stress and that from Lae the least sensitive. Radicle elongation of seedlings from Alice Springs was significantly greater than that of most other populations at a water potential of - I .0 MPa. The differences reported for seed dormancy and germination characteristics of T. australis populations do not reflect a strong physiological adaptation to the climatic characteristics of the sites from which they were collected.

scholarly journals Germination characteristics of Salicornia patula Duval-Jouve, S. emerici Duval-Jouve, and S. veneta Pign. et Lausi and their occurrence in Croatia

2013 ◽  
Vol 72 (2) ◽  
pp. 347-358 ◽  
Author(s):  
Nina Šajna ◽  
Marjana Regvar ◽  
Simona Kaligarič ◽  
Željko Škvorc ◽  
Mitja Kaligarič
Keyword(s):  
Environmental Factors ◽  
Habitat Preferences ◽  
Seed Morphology ◽  
Salicornia Europaea ◽  
Molecular Analyses ◽  
High Germination ◽  
Germination Characteristics ◽  
Salicornia Patula ◽  
Floral Characters

Abstract - According to recent molecular analyses of Salicornia, we revised the annual glassworts from the Croatian coast, classified until now only as Salicornia europaea. Two species, a diploid Salicornia patula and a tetraploid S. emerici were recognized. They can be easily distinguished by floral characters, but not only by their habitus, which varies extremely according to environmental factors. Both species differ also in seed morphology. Salicornia patula has dimorphic seeds, with larger central seeds reaching high germination rates. Germination patterns helped to explain the habitat preferences. The species rarely co-occur, however. The rare S. patula occupies drier habitats, on coastal mudflats or sands that are irregularly inundated. It occurs within the assoc. Suaedo maritimae-Salicornietum patulae. Salicornia emerici occupies the lowest coastal mudflats, regularly inundated, where nutrient-rich conditions prevail, and forms an almost monotypical assoc. Salicornietum emerici. Due to the synonymy of S. veneta with S. emerici, we exclude the occurrence of S. veneta in Croatia as an independent taxon.

Diversity, spatiotemporal distribution, abundance, species composition and habitat preferences of Ostracoda in Akbük and Akdeniz coastal mesosaline lagoons (Muğla, the South Aegean Region, Turkey)

2015 ◽  
Vol 44 (2) ◽  
Author(s):  
Selçuk Altınsaçlı ◽  
Ferda Perçin-Paçal ◽  
Songül Altınsaçlı
Keyword(s):  
Environmental Factors ◽  
Environmental Variables ◽  
Habitat Preferences ◽  
Aegean Region ◽  
Qualitative And Quantitative ◽  
Ordination Techniques ◽  
Ecological Importance ◽  
The Relationship ◽  
Ostracod Species

AbstractAkdeniz and Akbuk lagoons are part of a shallow coastal ecosystem of great aesthetic and ecological importance, located in Muğla Province in the southern Aegean region of Turkey. In the present study, four expeditions to collect ostracods from these lagoons were conducted in May, July, October, and November of 2008. Benthic samples were obtained monthly and several environmental factors were recorded simultaneously in situ. The ecological preferences of the ostracods were monitored, and qualitative and quantitative samples were collected from three sites in Akdeniz lagoon and two sites in Akbuk lagoon. Three ostracod taxa (Cyprideis torosa, Loxoconcha elliptica and Cytherois fischeri) were identified from the Akdeniz lagoon sampling sites and one species (Cyprideis torosa) from the Akbuk lagoon sampling sites. We present and analyze the dominance and distribution of ostracod assemblages and their relationships to environmental factors: temperature, dissolved oxygen, percentage oxygen saturation, pH, redox potential, salinity, and electrical conductivity) using classification and ordination techniques. Canonical correspondence analysis (CCA) is used to characterize the relationship between ostracods and the environmental variables. Approximately 82% of the correlation between the community composition and environmental variables was explained by the first axis of the CCA ordination for the Akdeniz lagoon. The study revealed that the distribution and population density of ostracod species depends on the physicochemical properties of the environment. The reason for this is that Cyprideis torosa and Loxoconcha elliptica are euryhaline species.

Studies on frost injury to wheat. I. Laboratory freezing tests in relation to the behaviour of varieties in the field

1961 ◽  
Vol 12 (5) ◽  
pp. 767 ◽  
Author(s):  
WV Single
Keyword(s):  
Marked Change ◽  
Unequal Distribution ◽  
Stages Of Growth ◽  
Commercial Cultivation ◽  
Factors Influencing ◽  
Controlled Conditions ◽  
Frost Injury ◽  
Artificial Freezing ◽  
Effects Of Temperature ◽  
The Relationship

Factors influencing the reactions of different varieties of wheat to stem and ear frosting were studied under controlled conditions and in the field. Artificial freezing tests were successful in demonstrating varietal differences in resistance, but these were not always in agreement with behaviour under commercial cultivation. Thus, whereas the American winter wheat Cheyenne showed resistance superior to that of the Australian varieties Bencubbin and Gabo, the observed superiority of Bencubbin over Gabo in the field was not maintained under controlled conditions. A possible explanation for this anomaly lies in the unequal distribution of temperature which obtains within a crop. On several frosty nights the ears and stems of Gabo, owing to their more forward development, were observed to be in a colder zone than those of Bencubbin. These conditions were not reproduced in the freezing cabinet, and comparisons between plants at different stages of growth failed to show any marked change in resistance with age up to the time of ear emergence. The relationship between temperature of freezing and degree of injury was established under different sets of conditions. In one case interaction between the effects of temperature and variety showed that this factor may be of some importance in the interpretation of results of freezing trials.

scholarly journals Assessing the relationship between global warming and mortality: Lag effects of temperature fluctuations by age and mortality categories

2011 ◽  
Vol 159 (7) ◽  
pp. 1789-1793 ◽  
Author(s):  
Weiwei Yu ◽  
Kerrie Mengersen ◽  
Wenbiao Hu ◽  
Yuming Guo ◽  
Xiaochuan Pan ◽  
...  
Keyword(s):  
Global Warming ◽  
Temperature Fluctuations ◽  
Lag Effects ◽  
Effects Of Temperature ◽  
The Relationship
Sign in / Sign up

Export Citation Format

Share Document