Evaluation of dormancy and germination responses to temperature inCarduus acanthoides and Anagallis arvensisusing a screening system, and relationship with field-observed emergence patterns

2000 ◽  
Vol 10 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Betina C. Kruk ◽  
Roberto L. Benech-Arnold
Keyword(s):  
Prolonged Exposure ◽  
Seasonal Pattern ◽  
Thermal Conditions ◽  
Thermal Time ◽  
Base Temperature ◽  
Dormancy Release ◽  
Carduus Acanthoides ◽  
Thermal Range ◽  
Dry Storage ◽  
Time Required

AbstractExperiments on the facultative winter annuals Carduus acanthoides and Anagallis arvensis were performed: (i) to determine thermal conditions that induce or release dormancy, (ii) to investigate to what extent changes in dormancy level resulting from those thermal conditions explain the seasonal pattern of emergence of these species, and (iii) to estimate required thermal time and base temperature for the germination of non-dormant seeds. Carduus acanthoides required high temperatures followed by decreasing temperatures for dormancy release; however, low winter temperatures did not induce secondary dormancy as expected for a winter annual. To the contrary, low temperatures stimulated dormancy release in the long term. InA. arvensis, dormancy relief was enhanced by dry storage at 25°C, and the response to low temperature was different depending on moisture conditions. Prolonged exposure to moist-chilling increased the dormancy level of the population, while dry storage at 4°C relieved dormancy. For both species, changes in the thermal range permissive for germination as a result of dormancy modifications explained to a large extent the timing of the emergence periods observed in the field. In neither species did base temperature for germination change with the dormancy level of the population. Thermal time required forgermination ofC. acanthoidesvaried with dormancy, while forA. arvensisseeds it was constant.

Functional and quantitative analysis of seed thermal responses in prostrate knotweed (Polygonum aviculare) and common purslane (Portulaca oleracea)

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 83-90 ◽  
Author(s):  
B. C. Kruk ◽  
R. L. Benech-Arnold
Keyword(s):  
Quantitative Analysis ◽  
Seedling Emergence ◽  
Screening Method ◽  
Thermal Conditions ◽  
Thermal Time ◽  
Base Temperature ◽  
Emergence Period ◽  
Thermal Range ◽  
Polygonum Aviculare ◽  
Common Purslane

A screening method was used to characterize seed thermal responses of prostrate knotweed and common purslane, two important weeds invading wheat in the humid Pampa. Through this method, it was possible to detect thermal conditions that induce or break dormancy in both species. In addition, we were able to quantify changes in dormancy level in seed populations as a function of time of burial after dispersal, through changes in width of the thermal range within which germination can occur. Plotting the overlap of this thermal range and observed soil temperature throughout the year allowed the prediction of the seedling emergence period. This prediction was in agreement with observed seedling emergence in the field for both species, during 2 consecutive yr. From the analysis carried out under laboratory conditions, it was also possible to estimate required thermal time for germination of the nondormant fraction of the population and the base temperature above which thermal time is accumulated. The results obtained from this study are the basis for the formulation of seed germination models that predict not only the occurrence of seedling emergence in the field, but also the dynamics of germination within those periods.

Effects of Temperature, Soil Water Status and Depth of Planting on Germination and Emergence of Maize (Zea Mays) Adapted to Semi-Arid Eastern Kenya

1993 ◽  
Vol 29 (3) ◽  
pp. 351-364 ◽  
Author(s):  
J. K. Itabari ◽  
P. J. Gregory ◽  
R. K. Jones
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Status ◽  
Soil Water Potential ◽  
Thermal Time ◽  
Controlled Environment ◽  
Base Temperature ◽  
Matric Potential ◽  
Effects Of Temperature ◽  
Time Required

SUMMARYThe effects of temperature and soil water potential on maize germination were investigated in controlled environment conditions and the effects of depth of planting and a mulch on maize emergence were studied in a field experiment in eastern Kenya. The rate of germination increased to an optimum temperature of 33.6°C above a base temperature of 6.1°C and decreased above the optimum to zero germination at 42.9°C. The thermal time for median germination increased from 51.5°Cd to 56.4°Cd as soil matric potential decreased from -5 to -40 kPa. Soil water content, depth of planting, and their interaction had significant (P < 0.001) effects on final germination and emergence but mulch, or any interactions involving mulch, had no such effects. Increasing depth of planting by 1 cm increased the thermal time required for emergence by 2.8°Cd, and decreasing water content by 1% increased the thermal time required for emergence by 3.2°Cd.Germinación y emergencia del maíz

Thermal requirements and germination niche breadth of Polygonum ferrugineum Wedd. from southeastern Brazil

2021 ◽  
pp. 1-7
Author(s):  
Andréa R. Marques ◽  
Ana Letícia B. R. Gonçalves ◽  
Fábio S. Santos ◽  
Diego Batlla ◽  
Roberto Benech-Arnold ◽  
...  
Keyword(s):  
Seed Germination ◽  
Niche Breadth ◽  
Thermal Time ◽  
Southeastern Brazil ◽  
Base Temperature ◽  
Light Conditions ◽  
Thermal Requirements ◽  
Thermal Range ◽  
Thermal Limits ◽  
Ceiling Temperature

Abstract Temperature may regulate seed dormancy and germination and determine the geographical distribution of species. The present study investigated the thermal limits for seed germination of Polygonum ferrugineum (Polygonaceae), an aquatic emergent herb distributed throughout tropical and subtropical America. Seed germination responses to light and temperature were evaluated both before (control) and after stratification at 10, 15 and 20°C for 7, 14 and 28 d. Germination of control seeds was ~50% at 10 and 15°C, and they did not germinate from 20 to 30°C. The best stratification treatment was 7 d at 10°C, where seed germination was >76% in the dark for all temperatures, except at 30°C, and < 60% in light conditions. A thermal time approach was applied to the seed germination results. Base temperature (Tb) was 6.3°C for non-dormant seeds and optimal temperature (To) was 20.6°C, ceiling temperature (Tc (<50)) was 32.8°C, and thermal time requirement for 50% germination was 44.4°Cd. We concluded that a fraction of P. ferrugineum seeds is dormant, has a narrow thermal niche to germinate (10 and 15°C) and that cold stratification (10°C) alleviated dormancy and amplified the thermal range permissive for germination of the species. Consequently, P. ferrugineum is expected to occur in colder environments, for example, at high altitudes. Higher temperatures decrease the probabilities of alleviate dormancy and the ability of their seeds to germinate.

scholarly journals DNA Methylation Analysis of Dormancy Release in Almond (Prunus dulcis) Flower Buds Using Epi-Genotyping by Sequencing

2018 ◽  
Vol 19 (11) ◽  
pp. 3542 ◽  
Author(s):  
Ángela Prudencio ◽  
Olaf Werner ◽  
Pedro Martínez-García ◽  
Federico Dicenta ◽  
Rosa Ros ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Prunus Persica ◽  
Prolonged Exposure ◽  
Genotyping By Sequencing ◽  
Fruit Trees ◽  
Prunus Dulcis ◽  
Dormancy Release ◽  
Release Process ◽  
Cold Temperatures ◽  
Reduced Representation

DNA methylation and histone post-translational modifications have been described as epigenetic regulation mechanisms involved in developmental transitions in plants, including seasonal changes in fruit trees. In species like almond (Prunus dulcis (Mill.) D.A: Webb), prolonged exposure to cold temperatures is required for dormancy release and flowering. Aiming to identify genomic regions with differential methylation states in response to chill accumulation, we carried out Illumina reduced-representation genome sequencing on bisulfite-treated DNA from floral buds. To do this, we analyzed almond genotypes with different chilling requirements and flowering times both before and after dormancy release for two consecutive years. The study was performed using epi-Genotyping by Sequencing (epi-GBS). A total of 7317 fragments were sequenced and the samples compared. Out of these fragments, 677 were identified as differentially methylated between the almond genotypes. Mapping these fragments using the Prunus persica (L.) Batsch v.2 genome as reference provided information about coding regions linked to early and late flowering methylation markers. Additionally, the methylation state of ten gene-coding sequences was found to be linked to the dormancy release process.

scholarly journals Seed Germination Variation among Crop Years from a Pinus sylvestris Clonal Seed Orchard

2019 ◽  
pp. 1-14
Author(s):  
Melusi Rampart
Keyword(s):  
Seed Germination ◽  
Seed Weight ◽  
Seed Orchard ◽  
Climatic Conditions ◽  
Thermal Time ◽  
Base Temperature ◽  
Germination Capacity ◽  
Seed Collection ◽  
Clonal Seed Orchard ◽  
The Mean

Maternal effects were assessed by germinating seeds sourced over multiple years from the same cloned mother trees, comparing germination capacity and rate between crop years. The relationships between climatic variables, seed characteristics and germination capacity were determined, and thermal time parameters were used to predict seed dormancy release and germination under the climatic conditions in the year after seed collection. There were significant differences in seed weight (P < 0.05), seed length and embryo occupancy (both P < 0.001) among crop years. Temperature during the seed development period explained 70% of the variation in seed weight and 63% of the variation in embryo occupancy. Germination capacity was significantly (P <0.001) different among crop years, among temperatures and among chilling durations, and thermal time requirements for germination increased from older (2007) to younger (2012) seeds. The mean base temperature without chilling was 7.1°C, while after chilling it was 4.6°C and 3.6°C for four and eight weeks chilling respectively. The mean thermal time to 50% germination without chilling was 135.1°Cd, while after chilling it was 118.3°Cd and 154.0°Cd for four and eight weeks chilling respectively. This experiment demonstrates that year-to-year differences in the environment experienced by mother trees during seed maturation can affect seed germination characteristics.

scholarly journals Temperatura-base e soma térmica para a Zínia ‘Profusion Cherry’ envasada cultivada em ambiente protegido

2016 ◽  
Vol 21 (3) ◽  
pp. 376
Author(s):  
Charleston Gonçalves ◽  
Carlos Eduardo Ferreira Castro ◽  
Mário José Pedro Júnior ◽  
Maria Luiza Sant’anna Tucci
Keyword(s):  
New Species ◽  
Thermal Time ◽  
Base Temperature ◽  
Degree Days ◽  
Consumer Market ◽  
Open Flower ◽  
Lack Of Information ◽  
Protected Cultivation

The growing of consumer market demands introduction of new species of flowers and cultivars primarily for production under protected cultivation. The zinnia by the quickness of production can be regarded as an alternative, however demand studies by the lack of information in the literature. We evaluated the duration of different periods, the base temperature and thermal accumulation, expressed as degree-days for the potted zinnia ‘Profusion Cherry’, conducted under protected cultivation for different phenological subperiods. The test was conducted in a greenhouse covered with plastic and closed laterally with shading-net and the duration of subperiods were made to twenty times after sowing. The base temperature was determined by relative development and values-based temperature and thermal time in degree-days (DD). The results for the different phases were, respectively: first open flower-planting: 4.1 °C and GD 838, first open flower - 50% of flowers open: 3.0 °C and 184 GD and 50% of flowers open - senescence: 6.9 °C and 238 GD.

scholarly journals Opportunistic Germination Behaviour of Gypsophila (Caryophyllaceae) in Two Priority Habitats from Semi-arid Mediterranean Steppes

2011 ◽  
Vol 39 (1) ◽  
pp. 18 ◽  
Author(s):  
Felix MORUNO ◽  
Pilar SORIANO ◽  
Oscar VICENTE ◽  
Monica BOSCAIU ◽  
Elena ESTRELLES
Keyword(s):  
Seed Germination ◽  
Climatic Conditions ◽  
Thermal Time ◽  
Distribution Area ◽  
Base Temperature ◽  
Additional Information ◽  
High Viability ◽  
Germination Behaviour ◽  
Alternating Temperature

Gypsophila tomentosa and G. struthium are closely related species, characteristic of two European priority habitats, salt and gypsum inland steppes, respectively. Germination strategies of the two taxa were investigated in plants from two nearby populations, growing under the same climatic conditions but on different types of soil, and belonging to different plant communities. Their germination patterns were studied at five constant temperatures in darkness: 5oC, 10oC, 15oC, 20oC and 25oC, and the base temperature and the thermal time requirement were calculated. As the distribution area of both species is subjected to a Mediterranean continental climate with significant differences between day and night, the possible preferences for an alternating temperature regime (25/10oC) were contrasted, as well as the influence of cold stratification and freezing. The effects on seed germination of light at constant 20oC and a 12/12 h photoperiod were also compared in the two species. The main conclusions of the work are the similarity of behaviour of both species, with an absence of seed dormancy, their opportunistic germination strategy, and water availability as the principal limitation to seed germination and plant establishment. The base temperature and thermal time indicate higher competitiveness of G. struthium at low temperatures, but seed germination of G. tomentosa is the most efficient at temperatures higher than 13.3oC. Optimal temperature and illumination conditions for nursery propagation depend on the species. The high viability of seeds observed after freezing prove the orthodox character of these seeds, providing additional information for long term seed conservation procedures.

Modeling germination of smallflower umbrella sedge (Cyperus difformis L.) seeds from rice fields in California across suboptimal temperatures

2019 ◽  
Vol 33 (5) ◽  
pp. 733-738 ◽  
Author(s):  
Rafael M. Pedroso ◽  
Durval Dourado Neto ◽  
Ricardo Victoria Filho ◽  
Albert J. Fischer ◽  
Kassim Al-Khatib
Keyword(s):  
Growth Models ◽  
Rice Fields ◽  
Control Measures ◽  
Thermal Time ◽  
Model Parameters ◽  
Base Temperature ◽  
Probit Regression ◽  
Time Model ◽  
Thermal Requirements ◽  
Thermal Time Model

AbstractSmallflower umbrella sedge is a prolific C3 weed commonly found in rice fields in 47 countries. The increasing infestation of herbicide-resistant smallflower umbrella sedge populations threatens rice production. Our objectives for this study were to characterize thermal requirements for germination of smallflower umbrella sedge seeds from rice fields in California and to parameterize a population thermal-time model for smallflower umbrella sedge germination. Because the use of modeling techniques is hampered by the lack of thermal-time model parameters for smallflower umbrella sedge seed germination, trials were carried out by placing field-collected seeds in a thermogradient table set at constant temperatures of 11.7 to 41.7 C. Germination was assessed daily for 30 d, and the whole experiment was repeated a month later. Using probit regression analysis, thermal time to median germination [θT(50)], base temperature for germination (Tb), and SD of thermal times for germination [σθT(50)] were estimated from germination data, and model parameters were derived using the Solver tool in Microsoft Excel®. Germination rates increased linearly below the estimated optimum temperatures of 33.5 to 36 C. Estimated Tb averaged 16.7 C, whereas θT(50) equaled 17.1 degree-days and σθT(50) was only 0.1 degree-day. The estimated Tb for smallflower umbrella sedge is remarkably higher than that of japonica and indica types of rice, as well as Tb of important weeds in the Echinochloa complex. Relative to the latter, smallflower umbrella sedge has lower thermal-time requirements to germination and greater germination synchronicity. However, it would also initiate germination much later because of its higher Tb, given low soil temperatures early in the rice growing season in California. When integrated into weed growth models, these results might help optimize the timing and efficacy of smallflower umbrella sedge control measures.

The movement pattern of horses around race meetings in New Zealand

2015 ◽  
Vol 55 (8) ◽  
pp. 1075 ◽  
Author(s):  
S. M. Rosanowski ◽  
C. W. Rogers ◽  
C. F. Bolwell ◽  
N. Cogger
Keyword(s):  
Infectious Disease ◽  
New Zealand ◽  
Seasonal Pattern ◽  
Movement Pattern ◽  
Infectious Disease Control ◽  
Harness Racing ◽  
Time Required ◽  
And Control ◽  
Thoroughbred Racing ◽  
Selection Of

In order to describe the implications of racehorse movement on the potential spread and control of infectious disease in New Zealand, the movement of horses due to regular racing activities needed to be quantified. Race meeting, trainer and starter data were collected in 2009 from the governing bodies for the two racing codes in New Zealand; Harness Racing New Zealand and New Zealand Thoroughbred Racing. During 2009, 507 Thoroughbred and 506 Standardbred race meetings were held. A random selection of 42 Standardbred and 39 Thoroughbred race meetings were taken from all race meetings held in 2009 and the distances travelled by trainers to these race meetings were determined. The trainers attending selected race meetings represented 50% (1135/2287) of all registered trainers in 2009. There was no seasonal pattern of when race meetings were held between racing codes (P = 0.18) or by race type (P = 0.83). There were significant differences in the distance travelled by trainers to race meetings, by racing code (P < 0.001). Thoroughbred trainers travelled a median of 91 km (IQR 40–203 km), while Standardbred trainers travelled a median of 45 km (IQR 24–113 km) (P < 0.001). Within each racing code, trainers travelled further to attend premier races than other types of race meetings (P < 0.001). These data demonstrate there is higher potential for more widespread disease dissemination from premier race meetings compared with other types of race meetings. Additionally, lack of a seasonal pattern indicates that a widespread outbreak could occur at any time of the year. Widespread disease dissemination would increase the logistic effort required for effective infectious disease control and has the potential to increase the time required to achieve control.

An analysis of the frequency and timing of false break events in the Mediterranean region of Western Australia

2001 ◽  
Vol 52 (3) ◽  
pp. 367 ◽  
Author(s):  
R. Chapman ◽  
S. Asseng
Keyword(s):  
Western Australia ◽  
Mediterranean Region ◽  
Meteorological Data ◽  
Seasonal Pattern ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dormancy Release ◽  
The Poor ◽  
Time Periods ◽  
The Mediterranean

Historical meteorological data were used to estimate the frequency and timing of false break events at 10 locations in the annual pasture and wheat producing area in the Mediterranean climatic region of Western Australia. The seasonal pattern of false breaks identified by this analysis was compared with the dynamics of dormancy release in a field population of subterranean clover (Trifolium subterraneum L.) to determine the influence that these events may have on the legume content of annual pasture communities in this region. False break events were estimated to occur on approximately 2 of every 3 years (611–72% of years) with no significant differences across the area investigated. Changes in the risk of false break events were examined over discrete time periods. The period of greatest risk was predicted to occur during early autumn (early March to mid April). Seed softening is virtually complete in subterranean clover at this point. The seed bank strategy of this species is, therefore, not well adapted to withstand the effects of false breaks. This might largely explain the poor persistence of subterranean clover in the annual pasture communities in the Mediterranean region of Western Australia. The legume content of these pastures might be improved by selecting species with late dormancy release strategies that will give better protection from false breaks.

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