scholarly journals Temperature but not moisture response of germination shows phylogenetic constraints while both interact with seed mass and lifespan

2017 ◽  
Vol 27 (2) ◽  
pp. 110-120 ◽  
Author(s):  
Fabien Arène ◽  
Laurence Affre ◽  
Aggeliki Doxa ◽  
Arne Saatkamp
Keyword(s):  
Water Potential ◽  
Seed Size ◽  
Phylogenetic Signal ◽  
Seed Mass ◽  
Base Temperature ◽  
Data Set ◽  
Negative Relation ◽  
Germination Timing ◽  
Germination Traits ◽  
Base Water Potential

AbstractUnderstanding how plant traits interact with climate to determine plant niches is decisive for predicting climate change impacts. While lifespan and seed size modify the importance of germination timing, germination traits such as base temperature and base water potential directly translate climatic conditions into germination timing, impacting performance in later life stages. Yet we do not know how base temperature, base water potential, seed mass, lifespan and climate are related. We tested the relationships between base temperature and base water potential for germination, seed size and lifespan while controlling for bioclimatic regions. We also quantified the phylogenetic signal in germination traits and seed size using Pagel's λ. We used a worldwide data set of germination responses to temperature and moisture, seed size and lifespan of 240 seed plants from 49 families. Both germination temperature and moisture are negatively related to seed size. Annual plants show a negative relation between seed size and base water potential, whereas perennials display a negative relation between base temperature and seed mass. Pagel's λ highlighted the slow evolution of base temperature for germination, comparable to seed mass while base water potential was revealed to be labile. In the future, base water potential and seed mass can be used when moisture niches of plants are to be predicted. Lifespan, seed size and base temperature should be taken into account when analysing thermal limits of species distributions.

Ecological aspects of seed dormancy loss

1998 ◽  
Vol 8 (2) ◽  
pp. 183-192 ◽  
Author(s):  
Phil S. Allen ◽  
Susan E. Meyer
Keyword(s):  
Water Potential ◽  
Seed Dormancy ◽  
Laboratory Data ◽  
Simulation Models ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Seed Biology ◽  
Seed Population ◽  
Germination Timing ◽  
Base Water Potential

AbstractAdvances in seed biology include progress in understanding the ecological significance of seed dormancy mechanisms. This knowledge is being used to make more accurate predictions of germination timing in the field. For several wild species whose seedlings establish in spring, seed populations show relevant variation that can be correlated with habitat conditions. Populations from severe winter sites, where the major risk to seedlings is frost, tend to have long chilling requirements or to germinate very slowly at low temperatures. Populations from warmer sites, where the major risk is drought, are non-dormant and germinate very rapidly under these same conditions. Seed populations from intermediate sites exhibit variation in dormancy levels, both among and within plants, which spreads germination across a considerable time period. For grasses that undergo dry after-ripening, seed dormancy loss can be successfully modelled using hydrothermal time. Dormancy loss for a seed population is associated with a progressive downward shift in the mean base water potential, i.e., the water potential below which half of the seeds will not germinate. Other parameters (hydrothermal time requirement, base temperature and standard deviation of base water potentials) tend to be constant through time. Simulation models for predicting dormancy loss in the field can be created by combining measurements of seed zone temperatures with equations that describe changes in mean base water potential as a function of temperature. Successful validation of these and other models demonstrates that equations based on laboratory data can be used to predict dormancy loss under widely fluctuating field conditions. Future progress may allow prediction of germination timing based on knowledge of intrinsic dormancy characteristics of a seed population and long-term weather patterns in the field.

Hydropriming accelerates seed germination of Medicago sativa under stressful conditions: A thermal and hydrotime model approach

2017 ◽  
Author(s):  
Rong Li ◽  
Dandan Min ◽  
Lijun Chen ◽  
Chunyang Chen ◽  
Xiaowen Hu
Keyword(s):  
Water Potential ◽  
Germination Rate ◽  
High Water ◽  
Nacl Stress ◽  
Base Temperature ◽  
Severe Water Stress ◽  
Hydrotime Model ◽  
Response To Temperature ◽  
Base Water Potential ◽  
Temperature Water

This study determined the effects of priming on germination in response to temperature, water potential and NaCl. Thermal and hydrotime models were utilized to evaluate changes in parameters of the model after priming. Priming reduced the amount of thermal time in both cultivars, but slightly increased the base temperature for germination from 1.0 to 3.5°C in “Longdong”. Priming significantly increased germination rate at high water potential but had no effect at low water potential. Further, priming reduced the hydrotime constant but made the median base water potential value slightly more positive in both cultivars. Thus, priming increased germination rate in water but decrease it under severe water stress. Germination rate was significantly increased in both cultivars under salinity (NaCl) stress. Moreover, priming improved seedling growth in response to temperature, water and salinity stress in both cultivars.

scholarly journals A hydrothermal after-ripening time model for seed dormancy loss in Bromus tectorum L.

2006 ◽  
Vol 16 (1) ◽  
pp. 17-28 ◽  
Author(s):  
Necia B. Bair ◽  
Susan E. Meyer ◽  
Phil S. Allen
Keyword(s):  
Water Potential ◽  
Time Course ◽  
Bromus Tectorum ◽  
Base Temperature ◽  
Time Model ◽  
Seed Collection ◽  
Ripening Time ◽  
Water Potentials ◽  
Ripening Rate ◽  
Base Water Potential

After-ripening, the loss of dormancy under dry conditions, is associated with a decrease in mean base water potential for germination ofBromus tectorumL. seeds. After-ripening rate is a linear function of temperature above a base temperature, so that dormancy loss can be quantified using a thermal after-ripening time (TAR) model. To incorporate storage water potential into TAR, we created a hydrothermal after-ripening time (HTAR) model. Seeds from twoB. tectorumpopulations were stored under controlled temperatures (20 or 30 °C) and water potentials (−400 to −40 MPa). Subsamples were periodically removed from each storage treatment and incubated at 15 or 25 °C to determine germination time courses. Dormancy status (mean base water potential) was calculated from each time course using hydrothermal time equations developed for each seed collection. Seeds stored at −400 MPa did not after-ripen. At water potentials from −400 to −150 MPa, the rate of after-ripening increased approximately linearly with increasing water potential. Between −150 and −80 MPa, there was no further increase in after-ripening rate, while at −40 MPa seeds did not after-ripen and showed loss of vigour. These results suggest that the concept of critical water potential thresholds, previously shown to be associated with metabolic activity and desiccation damage in partially hydrated seeds, is also relevant to the process of after-ripening. The HTAR model generally improved field predictions of dormancy loss when the soil was very dry. Reduced after-ripening rate under such conditions provides an ecologically relevant explanation of how seeds prolong dormancy at high summer soil temperatures.

Hydrothermal Emergence Model for Ripgut Brome (Bromus diandrus)

Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 146-153 ◽  
Author(s):  
Addy L. García ◽  
Jordi Recasens ◽  
Frank Forcella ◽  
Joel Torra ◽  
Aritz Royo-Esnal
Keyword(s):  
Growth Function ◽  
Base Temperature ◽  
Independent Data ◽  
Data Set ◽  
Winter Cereal ◽  
Bromus Diandrus ◽  
Mediterranean Regions ◽  
Cereal Fields ◽  
Base Water Potential ◽  
The Relationship

A model that describes the emergence of ripgut brome was developed using a two-season data set from a no-tilled field in northeastern Spain. The relationship between cumulative emergence and hydrothermal time (HTT) was described by a sigmoid growth function (Chapman). HTT was calculated with a set of water potentials and temperatures, iteratively used, to determine the base water potential and base temperature. Emergence of ripgut brome was well described with a Chapman function. The newly-developed function was validated with four sets of data, two of them belonging to a third season in the same field and the other two coming from independent data from Southern Spain. The model also successfully described the emergence in different field management and tillage systems. This model may be useful for predicting ripgut brome emergence in winter cereal fields of semiarid Mediterranean regions.

scholarly journals Seed Dispersal and Germination Traits of 70 Plant Species Inhabiting the Gurbantunggut Desert in Northwest China

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Huiliang Liu ◽  
Daoyuan Zhang ◽  
Xuejun Yang ◽  
Zhenying Huang ◽  
Shimin Duan ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Seed Size ◽  
Seed Mass ◽  
Northwest China ◽  
Germination Percentage ◽  
Gurbantunggut Desert ◽  
Seed Shape ◽  
Dispersal Syndromes ◽  
Gurbantünggüt Desert ◽  
Germination Traits

Seed dispersal and germination were examined for 70 species from the cold Gurbantunggut Desert in northwest China. Mean and range (3 orders of magnitude) of seed mass were smaller and narrower than those in other floras (5–8 orders of magnitude), which implies that selection favors relatively smaller seeds in this desert. We identified five dispersal syndromes (anemochory, zoochory, autochory, barochory, and ombrohydrochory), and anemochorous species were most abundant. Seed mass (F=3.50,P=0.01), seed size (F=8.31,P<0.01), and seed shape (F=2.62,P=0.04) differed significantly among the five dispersal syndromes and barochorous species were significantly smaller and rounder than the others. There were no significant correlations between seed mass (seed weight) (P=0.15), seed size (P=0.38), or seed shape (variance) (P=0.95) and germination percentage. However, germination percentages differed significantly among the dispersal syndromes (F=3.64,P=0.01) and seeds of ombrohydrochorous species had higher germination percentages than those of the other species. In the Gurbantunggut Desert, the percentage of species with seed dormancy was about 80%. In general, our studies suggest that adaptive strategies in seed dispersal and germination of plants in this area are closely related to the environment in which they live and that they are influenced by natural selection forces.

Modeling the Emergence of Three Arable Bedstraw (Galium) Species

Weed Science ◽  
2010 ◽  
Vol 58 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Aritz Royo-Esnal ◽  
Joel Torra ◽  
Josep Antoni Conesa ◽  
Frank Forcella ◽  
Jordi Recasens
Keyword(s):  
Water Potential ◽  
Seedling Emergence ◽  
Soil Water Potential ◽  
Base Temperature ◽  
Winter Cereal ◽  
Growth Functions ◽  
The United Kingdom ◽  
Mediterranean Regions ◽  
Cereal Fields ◽  
Base Water Potential

Multiyear field data from Spain were used to model seedling emergence for three bedstraw species (Galium) that can coexist in winter cereal fields. The relationships between cumulative emergence and both growing degree days (GDD) and hydrothermal time (HTT) in soil were analyzed as sigmoid growth functions (Weibull). Iterations of base temperature and base water potential were used to optimize the HTT scale. All species were well described with Weibull functions. Both GDD and HTT models provided good descriptions of catchweed bedstraw emergence, as its seedlings have less dependence on soil water potential than false cleavers and threehorn bedstraw, which were described best with HTT. The HTT model for catchweed bedstraw was validated successfully with independent data from the United Kingdom. The models may be useful for predicting bedstraw emergence in semiarid Mediterranean regions and elsewhere.

Temperature and Water Potential as Parameters for Modeling Weed Emergence in Central-Northern Italy

Weed Science ◽  
2010 ◽  
Vol 58 (3) ◽  
pp. 216-222 ◽  
Author(s):  
Roberta Masin ◽  
Donato Loddo ◽  
Stefano Benvenuti ◽  
Maria Clara Zuin ◽  
Mario Macchia ◽  
...  
Keyword(s):  
Water Potential ◽  
Weed Control ◽  
Seedling Emergence ◽  
Thermal Time ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Data Set ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Weed Emergence

Predicting weed emergence dynamics can help farmers to plan more effective weed control. The hydrothermal time concept has been used to model emergence as a function of temperature and water potential. Application of this concept is possible if the specific biological thresholds are known. This article provides a data set of base temperature and water potential of eight maize weeds (velvetleaf, redroot pigweed, common lambsquarters, large crabgrass, barnyardgrass, yellow foxtail, green foxtail, and johnsongrass). For five of these species, two ecotypes from two extreme regions of the predominant maize-growing area in Italy (Veneto and Tuscany), were collected and compared to check possible differences that may arise from using the same thresholds for different populations. Seedling emergence of velvetleaf and johnsongrass were modeled using three different approaches: (1) thermal time calculated assuming 5 C as base temperature for both species; (2) thermal time using the specific estimated base temperatures; and (3) hydrothermal time using the specific, estimated base temperatures and water potentials. All the species had base temperatures greater than 10 C, with the exception of velvetleaf (3.9 to 4.4 C) and common lambsquarters (2.0 to 2.6 C). All species showed a calculated base-water potential equal or up to −1.00 MPa. The thresholds of the two ecotypes were similar for all the studied species, with the exception of redroot pigweed, for which the Veneto ecotype showed a water potential lower than −0.41 MPa, whereas it was −0.62 MPa for the Tuscany ecotype. Similar thresholds have been found to be useful in hydrothermal time models covering two climatic regions where maize is grown in Italy. Furthermore, a comparison between the use of specific, estimated, and common thresholds for modeling weed emergence showed that, for a better determination of weed control timing, it is often necessary to estimate the specific thresholds.

Relationship between accumulated hydrothermal time during seed priming and subsequent seed germination rates

1994 ◽  
Vol 4 (2) ◽  
pp. 63-69 ◽  
Author(s):  
Kent J. Bradford ◽  
Anthony M. Haigh
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Seed Priming ◽  
Threshold Temperature ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Time Model ◽  
Radicle Emergence ◽  
The Times ◽  
Base Water Potential

AbstractSeed germination rates are sensitive to both temperature (T) and water potential (ψ). The times to germination of seeds imbibed at suboptimal T and/or reduced ψ are inversely proportional to the amounts by which T exceeds a base temperature (Tb) and ψ exceeds a base water potential (ψb). Germination rates across a range of suboptimal T and ψ can be normalized on the basis of the hydrothermal time accumulated in excess of these thresholds. However, seeds can also progress metabolically toward germination even at T or ψ too low to allow radicle emergence to occur. Seeds preimbibed at low ψ and dried back, or primed, germinate more rapidly upon subsequent reimbibition. We show here that the increase in germination rates of tomato (Lycopersicon esculentum Mill.) seeds resulting from seed priming is linearly related to the hydrothermal time accumulated during the priming treatment. The threshold temperature (Tmin = 7.05°C) and water potential (ψmin = −2.50 MPa) for metabolic advancement were considerably lower than the corresponding thresholds for radicle emergence of the same seed lot (Tb = 11°C; ψb = −0.71 MPa), allowing the accumulation of hydrothermal priming time that is subsequently expressed as more rapid germination when T or ψ increase. The hydrothermal time model can now be applied to quantify and analyse germination rates of seeds across the entire range of suboptimal T and ψ at which metabolic progress toward radicle emergence is possible.

scholarly journals Germination response of Hylocereus setaceus (Salm-Dyck ex DC: ) Ralf Bauer (Cactaceae) seeds to temperature and reduced water potentials

2010 ◽  
Vol 70 (1) ◽  
pp. 135-144 ◽  
Author(s):  
E. Simão ◽  
M. Takaki ◽  
VJM. Cardoso
Keyword(s):  
Water Potential ◽  
Germination Rate ◽  
Base Temperature ◽  
Temperature Range ◽  
Water Potentials ◽  
Germination Response ◽  
Wide Range ◽  
Optimum Interval ◽  
Time Courses ◽  
Base Water Potential

The germination response of Hylocereus setaceus seeds to isothermic incubation at different water potentials was analysed by using the thermal time and hydrotime models, aiming to describe some germination parameters of the population and to test the validity of the models to describe the response of the seeds to temperature and water potential. Hylocereus setaceus seeds germinated relatively well in a wide range of temperatures and the germination was rate limited from 11 to 20 °C interval and beyond 30 °C until 40 °C, in which the germination rate respectively shifts positively and negatively with temperature. The minimum or base temperature (Tb) for the germination of H. setaceus was 7 °C, and the ceiling temperature varied nearly from 43.5 to 59 °C depending on the percent fraction, with median set on 49.8 °C. The number of degrees day necessary for 50% of the seeds to germinate in the infra-optimum temperature range was 39.3 °C day, whereas at the supra-optimum interval the value of θ = 77 was assumed to be constant throughout. Germination was sensitive to decreasing values of ψ in the medium, and both the germinability and the germination rate shift negatively with the reduction of ψ, but the rate of reduction changed with temperature. The values of base water potential (ψb) shift to zero with increasing temperatures and such variation reflects in the relatively greater effect of low ψ on germination in supra optimum range of T. In general, the model described better the germination time courses at lower than at higher water potentials. The analysis also suggest that Tb may not be independent of ψ and that ψb(g) may change as a function of temperature at the infra-otimum temperature range.

scholarly journals Calculating "Hydrothermal time" to quantify seed germination of tall fescue

2016 ◽  
Vol 78 ◽  
pp. 163-168 ◽  
Author(s):  
S. Sharifiamina ◽  
D.J. Moot ◽  
M. Bloomberg
Keyword(s):  
Water Potential ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Germination Rate ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Effects Of Temperature ◽  
Moisture Conditions ◽  
Base Water Potential ◽  
Moderate Stress

The objective of this study was to quantify the combined effects of temperature and moisture on germination of tall fescue seed. Seeds were incubated for up to 50 days at a range of constant temperatures (5-35ºC) and germinated at five water potentials (0, -0.18, -0.37, -0.63 and -0.95 MPa). The maximum final germination percentages were 94 to 98 at 15-30ºC when water was not limited (0 MPa). Germination rate increased linearly from 5 to 27.5ºC, and then decreased linearly from 27.5 to 32.5ºC. Extrapolation of the sub-optimal temperatures identified a base temperature of 3.5 ± 0.5ºC and an optimum temperature of 27.5ºC. More negative water potential indicative of drier conditions, delayed germination and reduced germination rate. The average base water potential was -0.95 MPa at the suboptimal range of temperatures. An optimum range of germination (80-100%) occurred when temperatures were between 10 and 30ºC and water potential was between 0 to -0.37 MPa (moderate stress). These results provide a matrix of soil temperature and moisture conditions that are expected to result in successful germination and therefore provide the maximum opportunity for emergence of tall fescue seedlings. Keywords: Festuca arundinacea, 'Finesse Q', hydrothermal time

Sign in / Sign up

Export Citation Format

Share Document