Thermal time requirements for germination of four annual clover species

Nori, Hollena; Moot, D. J.; Black, Amanda

doi:10.1080/00288233.2013.863786

Cited by 16 publications

(12 citation statements)

References 15 publications

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“…Under non-limiting water conditions, no trend was found for the sequence of θ 0.8 -θ 0.2 and σ values that were obtained for any of the crops studied. However, the shape of the function used to model the variation of t 0.8 -t 0.2 with temperature ( Figure 5) is similar to that of the time course of germination as a function of temperature for any germinated fraction (Olivier and Annadale 1998;Nori, Moot, and Black 2014), i.e., the dispersion expressed by t 0. 8 -t 0.2 is close to minimum values across a relatively wide thermal range and increases at both ends.…”

Section: Discussionmentioning

confidence: 74%

Modeling the spread of germination of four Mediterranean crops at different temperatures

Andrade

Cadima

Abreu

2019

Journal of Crop Improvement

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Minimizing the dispersion of germination across time allows greater uniformity during crop development. The aim of this paper was to model the spread of germination, under nonlimiting water conditions and as a function of temperature, of four Mediterranean crops: pea (Pisum sativum L.), broad bean (Vicia faba L.), corn (Zea mays L.) and sorghum (Sorghum vulgare L.). Experiments were performed using a thermogradient plate. Four temperature ranges suitable for the thermal responses of each crop were used. Dispersion was expressed as standard deviation (σ) of the frequency distribution of thermal times in the population, modeled by a probit regression and by differences between both accumulated temperatures above the base temperature (θ 0.8-θ 0.2) or chronological times (t 0.8-t 0.2) required to reach 0.2 and 0.8 of final germination. Estimates of σ were obtained both within thermal ranges defined by applying the plateau-shaped model to the rate vs. temperature relationship and at single temperatures. The differences (θ 0.8-θ 0.2) and (t 0.8-t 0.2) were evaluated for each temperature. Reference values were successfully assigned to the germination dispersion of each crop, either to the different thermal ranges used or to single temperatures. Furthermore, a thermal range ensuring minimum values of dispersion was obtained for each crop using a polynomial equation to model the variation of t 0.8-t 0.2 on the set of temperatures used. The dimension of this thermal range was larger for winter than for summer crops. Crop competitiveness depends on the indicators used to assess dispersion. The results allow farmers to choose between different crops and thus optimize germination.

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Section: Discussionmentioning

confidence: 74%

Modeling the spread of germination of four Mediterranean crops at different temperatures

Andrade

Cadima

Abreu

2019

Journal of Crop Improvement

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“…However, most studies use the thermal time model to investigate intraspecific variation of germination or differences between several species [3,[14][15][16]. However, comparison of thermal time model parameters between large numbers of species and between different functional groups is lacking [17,18].…”

Section: Introductionmentioning

confidence: 99%

A Modified Thermal Time Model Quantifying Germination Response to Temperature for C3 and C4 Species in Temperate Grassland

2015

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Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C4 and 15 C3 species were germinated at a range of constant temperatures from 5 °C to 40 °C. We used a modified thermal time model to calculate germination parameters at suboptimal temperatures. Generally, the optimal germination temperature was higher for C4 species than for C3 species. The thermal time constant for the 50% germination percentile was significantly higher for C3 than C4 species. The thermal time constant of perennials was significantly higher than that of annuals. However, differences in base temperatures were not significant between C3 and C4, or annuals and perennial species. The relationship between germination rate and seed mass depended on plant functional type and temperature, while the base temperature and thermal time constant of C3 and C4 species exhibited no significant relationship with seed mass. The results illustrate differences in germination characteristics between C3 and C4 species. Seed mass does not affect germination parameters, plant life cycle matters, however.

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“…High Gf and Ef values depend essentially on temperature, if water is not a limiting factor [16]. Values of Gf tend to be high and more or less constant along a fairly broad thermal range, but are significantly lower at both lower and higher extreme temperatures [17,26,39]. The variation of Ef with temperature follows a similar pattern to that of Gf [5,40].…”

Section: Size (Sz)mentioning

confidence: 91%

“…Since both Gf and Ef are nearly constant over a relatively wide thermal range (see previous subsection) and the time course of cumulative percentage for either germination [39] or emergence [48] processes approximately follow a sigmoidal (S-shaped) curve regardless of temperature, both times tG and tE (in days) required for the germination or the emergence of a fraction of Gf or Ef, respectively were obtained by linear interpolations between observed germination or emergence percentiles [32].…”

Section: Speed (Sp)mentioning

confidence: 99%

Optimizing the establishment of bean and maize varieties in tropical environments

Andrade

Mateus²,

Cadima

et al. 2021

IOP Conf. Ser.: Earth Environ. Sci.

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The successful establishment of any crop is the initial indication of its productivity. Optimizing the establishment of a crop implies ensuring generalized, fast and concentrated emergence. This work studies optimal temperature ranges, under non-limiting water conditions, for both germination and emergence of two bean (Phaseolus vulgaris L.) varieties (catarina and ervilha) and two maize (Zea mays L.) varieties (matuba and sam3). Experiments used a thermogradient plate. Petri dishes were used for germination experiments. Emergence experiments were performed in aluminium containers filled with packed portions of a sandy loam clay textured soil. Size, speed and spread of both germination and emergence were measured at different temperatures by Cu-CuNi thermocouples. Thermal ranges with optimal counts of both germination and emergence [To1 sz , To2 sz ] were identified using a flattened bell curve function. Speed was maximized for either germination or emergence over thermal ranges [To1 sp , To2 sp ] defined using the plateau model to relate either germination or emergence rates with temperature. Ranges along which the spread of both germination and emergence are nearly minimized [To1 sd , To2 sd ] were identified with the aid of even-degree polynomials. The intersection of all three thermal ranges gave rise to optimal temperature ranges [To1, To2] for germination (OTRG) of the four varieties in study and for emergence (OTRE) of three of them. In general, the lower thermal limit of OTRG was determined by speed (To1 = To1 sp ) and the upper thermal limit by size (To2 = To2 sz ). OTRE begins at To1 sp for ervilha and sam3 and at To1 sd for catarina and ends at To2 sz for catarina and at To2 sd for the others. The endpoints and length of both the OTRG and OTRE were also found to be crop-dependent. Thus, farmers can choose between crops and optimize their establishment. The identification of these parameters may also be useful in assessing weather forecasts and for warning systems and agro-climatic zoning. The influence of the substrate used in each experiment was also discussed.

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Thermal time requirements for germination of four annual clover species

Cited by 16 publications

References 15 publications

Modeling the spread of germination of four Mediterranean crops at different temperatures

Modeling the spread of germination of four Mediterranean crops at different temperatures

A Modified Thermal Time Model Quantifying Germination Response to Temperature for C3 and C4 Species in Temperate Grassland

Optimizing the establishment of bean and maize varieties in tropical environments

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