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.

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.

A Model for Predicting Common Cocklebur (Xanthium strumarium) Emergence in Soybean

Weed Science ◽  
2007 ◽  
Vol 55 (4) ◽  
pp. 341-345 ◽  
Author(s):  
Jason K. Norsworthy ◽  
Marcos J. Oliveira
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Water Potential ◽  
Thermal Fluctuation ◽  
Parameter Estimates ◽  
Weibull Function ◽  
Base Temperature ◽  
Presence And Absence

The objective of this research was to develop a model to predict common cocklebur seedling emergence in spring tillage and no-spring-tillage systems in the presence and absence of a soybean canopy. A Weibull function was used to accumulate heat units (i.e., growing degree days) at a 2.5 cm soil depth on days when mean soil temperature, soil water potential, and soil thermal fluctuation were above established thresholds. The base temperature, soil water potential, and soil thermal fluctuation thresholds used for model development were 17 C, −100 kPa, and 7.5 C, respectively. A single function adequately described common cocklebur seedling emergence in the presence and absence of drill-seeded soybean from data combined over an artificial (2004) and natural seedbank (2005) (R2= 0.986). Model parameterization differed between the artificial and natural seedbank in the absence of spring tillage, but emergence was adequately described, regardless of soybean presence. Separate parameter estimates for the artificial and natural seedbanks were needed to adequately describe emergence in the system without spring tillage (R2= 0.975 to 0.984). The ability of the model to account for reduced emergence when soil moisture is limited or when daily thermal fluctuation requirements are not met could assist practitioners with assessments associated with field scouting for weeds as well as other management decisions.

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.

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.

THE EFFECT OF SOIL WATER POTENTIAL, TEMPERATURE AND SEEDING DEPTH ON SEEDLING EMERGENCE OF WHEAT

1979 ◽  
Vol 59 (3) ◽  
pp. 259-264 ◽  
Author(s):  
R. DE JONG ◽  
K. F. BEST
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Minimum Temperature ◽  
Seedling Emergence ◽  
Potential Temperature ◽  
Soil Water Potential ◽  
Triticum Aestivum L ◽  
Planting Dates ◽  
Water Potentials ◽  
Soil Temperatures

Daily emergence counts were made on Canthatch wheat (Triticum aestivum L.) grown in five soil types, at four soil temperatures and three water potentials and planted at five different depths. Regardless of soil type, soil water potential or depth of planting, 50% emergence generally occurred within a week at 19.4 and 26.7 °C, and within 2 wk at 12.2 °C, but it took up to 6 wk at 5 °C. The heat sum required to attain 50% seedling emergence did not increase significantly with decreasing soil water potentials, but the minimum temperature for emergence dropped from 1.3 to 0.2 °C as the water potential decreased from −⅓ to −10 bar. It was suggested that the seedlings compensated for the increased water stress by lowering their minimum temperature requirements. Increasing the planting depth not only increased the heat requirement for emergence, but it also increased the variability of emergence, especially at low temperatures. Practical aspects concerning planting dates and depths were considered.

Critical water potentials for germination of wheat cultivars in the dryland Northwest USA

2013 ◽  
Vol 23 (3) ◽  
pp. 189-198 ◽  
Author(s):  
Prabhakar Singh ◽  
Hesham M. Ibrahim ◽  
Markus Flury ◽  
William F. Schillinger ◽  
Thorsten Knappenberger
Keyword(s):  
Winter Wheat ◽  
Water Potential ◽  
Pacific Northwest ◽  
Seedling Emergence ◽  
Soil Water Potential ◽  
Wheat Seedling ◽  
Wheat Cultivars ◽  
Coleoptile Length ◽  
Water Potentials ◽  
Winter Wheat Cultivars

AbstractLow soil water potential limits or prevents germination and emergence of rainfed winter wheat (Triticum aestivum L.). This phenomenon is particularly pronounced in the winter wheat–summer fallow region of the US Inland Pacific Northwest, where wheat is routinely sown deep to reach moisture with 12–15 cm of soil covering the seed. Wide differences in seedling emergence among winter wheat cultivars have been reported, but few previous experiments have examined germination differences among cultivars as a function of water potential. The objective of our laboratory study was to quantify seed germination of five commonly sown winter wheat cultivars (Moro, Xerpha, Eltan, Buchanan and Finley) at seven water potentials, ranging from 0 to − 1.5 MPa. Germination was measured as a function of time for a period of 30 d. At higher water potentials (0 to − 0.5 MPa), all cultivars had germination of more than 90%. At the lowest water potentials ( − 1.0 to − 1.25 MPa), however, Moro consistently exceeded the other cultivars for speed and extent of germination, with total germination of 74% at − 1.0 MPa and 43% at − 1.25 MPa. Since its release in 1966, Moro has been sown by farmers when seed-zone water conditions are marginal. Scientists have long known that coleoptile length is an important factor controlling winter wheat seedling emergence from deep sowing depths. In addition to having a long coleoptile, our data suggest that Moro's known excellent emergence ability from deep sowing depths in dry soils can also be attributed to the ability to germinate at lower water potentials than other cultivars.

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.

scholarly journals Predicting Seedling Emergence of Three Canarygrass (Phalaris) Species under Semi-Arid Conditions Using Parametric and Non-Parametric Models

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 893
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
José María Urbano
Keyword(s):  
Field Experiments ◽  
Seedling Emergence ◽  
Parametric Models ◽  
Base Temperature ◽  
Weed Species ◽  
Emergence Period ◽  
Growing Seasons ◽  
Ceiling Temperature ◽  
Base Water Potential ◽  
Non Parametric

The Phalaris genus includes annual weed species such as short-spiked canarygrass (Phalaris brachystachys Link.), little-seed canarygrass (Phalaris minor Retz.) and hood canarygrass (Phalaris paradoxa L.), which are especially problematic in Spain; as such, there is a need to develop models to predict the timing of their emergence. Field experiments were conducted at two different locations during two (2006/07 and 2007/08) and three (from 2005/06 to 2007/08) growing seasons. In both locations, 500 seeds of each Phalaris species were sown each growing season, simulating rain-fed cereal field conditions. In addition, the models were validated with three, four and eight independent experiments for P. brachystachys, P. minor and P. paradoxa, respectively. The emergence period of the three Phalaris species lasted between 31 and 48 days after sowing (DAS), showing two main flushes. The three cardinal points for parametric and non-parametric models were established to be between −1 °C and 1 °C for base temperature, between 9.8 °C and 11.8 °C for optimal temperature and between 21.2 °C and 23.4 °C for ceiling temperature; base water potential was estimated to be between −1 and −1.1 MPa. Both parametric and non-parametric models obtained similar results and were successfully validated in 12 out of 15 independent experiments.

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