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The influence of temperature on seed germination rate in grain legumes. I. Acomparison of chickpea, lentil, soybean and cowpea at constant temperatures
Abstract
For a single seed population of each of four species of grain legume positive linear relationships were shown between temperature
and rate of germination for different fractions (G) of each population, from a base temperature, Tb(G), at which germination rate is zero, to an optimum temperature, To(G) at which germination rate is maximal. At constant temperatures warmer than To(G) there were negative relations (probably linear) between temperature and rate of germination to the maximum temperature for
germination, Tm(G), Within each population Tb(G) did not differ, but it did vary between species, viz.0.0°C, 0.25°C, 4.and 8.5°C for chickpea (Cicer arietinum L.), lentil (Lens culinaris Medic.), soyabean (Glycine max [ Merr.) and cowpea (Vigna unguiculata [L.] Walp.), respectively. In contrast, To(G) varied both within each population and also between the four species: 80% of seeds in each population had To(G) values within the range 31.8°C to 33.8 °C, 24.0°C to 24.4°C, 34.0°C to 34.5°C and 33.2°C to >40°C, respectively. Values
of Tm(G) were much more vanable: the 80% population range was 48 .0°C to 60.8°C for chickpea, 31.8°C to 34.4°C for lentil and 46.8°C
to 55.2°C for soyabean; reliable estimates could not be made for cowpea, but the results suggest higher and more variable
values of Tm(G) than in the other three species. At sub-optimal temperatures the distribution of thermal time for the different fractions
of each population was normal, except for lentil where it was log-normal. A single equation is proposed to describe the influence
of sub-optimal temperatures on rates of germination for whole seed populations. At supra-optimal temperatures, variation in
thermal time for the different fractions of each population was only slight. The implications of these findings for the adaptation
of grain legume crops to different environments, and for the screening of germplasm, are discussed.
... For each temperature, cumulative germination was plotted as a function of time and a Boltzman sigmoidal curve fitted, from which the time to achieve 50% germination (t 50 ) of the seed population was estimated (Farias and Dantas, 2022). The reciprocal of these t 50 (germination rate, GR= 1/t 50 ) were plotted against temperature and the sub-and supraoptimal germination temperature ranges were identified (Covell et al., 1986). Linear regressions of both sets of data in each germination fraction were used to estimate the x-intercept and slope of each regression line. ...
... A similar thermal-germination rate analysis in the supra-optimal range identified the ceiling temperature (T c ), above which there is no germination. Optimum temperature (T o ) was calculated as the intercept of sub-and supra-optimal temperature range curves (Covell et al., 1986). The thermal time of the population that germinated at sub-optimal temperatures (θTsub) and that of the population that germinated at supra-optimal temperatures (θTsupra) were calculated according to Covell et al. (1986). ...
... Optimum temperature (T o ) was calculated as the intercept of sub-and supra-optimal temperature range curves (Covell et al., 1986). The thermal time of the population that germinated at sub-optimal temperatures (θTsub) and that of the population that germinated at supra-optimal temperatures (θTsupra) were calculated according to Covell et al. (1986). Hydrotime (using data obtained in assay for seed germination in different osmotic potentials) and halotime (using data obtained in assay for seed germination in different salinity levels) models were obtained in the same manner (Seal et Journal of Seed Science, v.45, e202345013, 2023Science, v.45, e202345013, al., 2018Dantas et al., 2020). ...
Seed production, quality and germination are likely to be affected by a drastic climate change in semi-arid areas predicted for the end of the century. We evaluated Anadenanthera colubrina var. cebil (Griseb.) Altschu (Fabaceae) seeds of different sizes, populations and harvest years for germination and tolerance to environmental stresses aiming to predict impacts of future climate. Seeds were accessed for germination temperature, salinity and osmotic limits and requirements. Germination of large and small seeds harvested in different populations was evaluated in optimum and stressful temperature, salinity and water deficit. A glasshouse pot assay tested weekly irrigation regimes and seedlings emergence and growth. Optimal temperature for seeds germination was 34.8 oC and limits were 5.6 oC and 50.9 oC. Large and small-sized seeds do not differ in germination, however small seeds are more efficient in stressful conditions. Seedlings can emerge and grow under small weekly irrigation for four months. The predicted increase in temperature will not impair germination, however, the time available for seedling establishment will decrease due to lacking rainfall. The increase in the amount of small-sized seeds produced in drought years is a strategy for coping with harsh environments, rather than a decrease in seed quality.
... These assumptions are most often related to cardinal-temperature concepts that describe the range of temperature over which seeds of a particular species can germinate. Three cardinal temperatures have been recognized: Base temperature (T b ) below which germination does not proceed; an optimal temperature (T o ) at which the rate of germination is highest; and a maximum or ceiling temperature (T c ) above which germination ceases [33][34][35][36][37][38][39][40]. The T b for germination of any fraction of the seed population is considered to be a constant, while T c varies among each percentile fraction in a normal distribution [35,36]. ...
... Three cardinal temperatures have been recognized: Base temperature (T b ) below which germination does not proceed; an optimal temperature (T o ) at which the rate of germination is highest; and a maximum or ceiling temperature (T c ) above which germination ceases [33][34][35][36][37][38][39][40]. The T b for germination of any fraction of the seed population is considered to be a constant, while T c varies among each percentile fraction in a normal distribution [35,36]. The temperature has an impact on plant growth and development, so estimating the cardinal temperatures is essential. ...
... Cumulative germination of S. hispanica at10,15,20,25,30,35,40, and 45 • C. Values are expressed as mean ± SD of five independent replicates. Statistical analysis was performed using Kruskal-Wallis followed by a Dunn's multiple comparison test. ...
Temperature is the main factor that impacts germination and therefore the success of annual crops, such as chia (Salvia hispanica L.), whose seeds are known for their high nutritional value related to its oil. The effect of temperature on germination is related to cardinal-temperature concepts that describe the range of temperature over which seeds of a particular species can germinate. Therefore, in this study, in addition to calculated germinative parameters such as total germination and germination rate of S. hispanica seeds, the effectiveness of non-linear models for estimating the cardinal temperatures of chia seeds was also determined. We observed that germination of S. hispanica occurred in cold to moderate-high temperatures (10–35 °C), having an optimal range between 25 and 35 °C, with the highest GR and t50 at 30 °C. Temperatures higher than 35 °C significantly reduced germination. Output parameters of the different non-linear models showed that the response of chia germination to temperature was best explained by beta models (B). Cardinal temperatures calculated by the B1 model for chia germination were: 2.52 ± 6.82 °C for the base, 30.45 ± 0.32 °C for the optimum, and 48.58 ± 2.93 °C for the ceiling temperature.
... Further, many studies evaluated the effect of water potential and temperature in seed germination ability modeled by hydrothermal time models [14][15][16]. This model has been multiple purposes to process seed germination Selected Acacia Species from Sub-Sahara, Savanna Regions progress also provide measuring of yield coefficients and the physiological time those frequently used to show potential rank temperature, screen germplasms and water probable responses of species [14,[17][18][19]. ...
... Further, many studies evaluated the effect of water potential and temperature in seed germination ability modeled by hydrothermal time models [14][15][16]. This model has been multiple purposes to process seed germination Selected Acacia Species from Sub-Sahara, Savanna Regions progress also provide measuring of yield coefficients and the physiological time those frequently used to show potential rank temperature, screen germplasms and water probable responses of species [14,[17][18][19]. The borders defined as three models to get the measure of germination response of water stress and temperature. ...
... Shorter germination time, emergence overall seedbed environmental and broad temperature range of germination, leading to homogeneity, the best crop establishment and improved harvest yield and quality, particularly under stress and the abnormal situation in the field are the typical responses to seed priming [1,30]. Moreover, the influence of temperature and water potential on seed germination could be modeled by hydrothermal time models [14][15][16]31]. There are little data about the effect of osmotic stress and temperature on Acacia seed germination [5,[32][33][34]. ...
... to the data in which: G(t) = cumulative germination over time, t; b = slope at the inflection point; Gmax = maximum germination as t approaches infinity; and t 50 = time at which germination reaches half the Gmax (Mesgaran et al., 2013;Onofri et al., 2018). From each cumulative curve we calculated the germination rate (GR), which is the reciprocal of the time required to reach 50% germination (GR = 1/t 50 ) (Chen et al., 2021;Covell et al., 1986;Martínez-Villegas et al., 2018;Picapietra et al., 2020). The germination rate (1/t 50 ) for all the treatments was plotted against temperature (x axis). ...
... The germination rate (1/t 50 ) for all the treatments was plotted against temperature (x axis). We performed a nonlinear least squares (nls) analysis to assess the x-intercept of both the suboptimal and supra-optimal temperature ranges, giving estimates of the base temperature (T b ) below which germination rate (1/t 50 ) is zero and ceiling temperature (T C ) above which germination rate (1/t 50 ) is also zero (Covell et al., 1986). From the intersection of the non-linear regression of suboptimal and supra-optimal temperature, we estimated the optimal temperature (T O ) at which GR is maximized (Washitani, 1987;Hardegree, 2006;Chen et al., 2021). ...
... From the intersection of the non-linear regression of suboptimal and supra-optimal temperature, we estimated the optimal temperature (T O ) at which GR is maximized (Washitani, 1987;Hardegree, 2006;Chen et al., 2021). Also, the thermal-time at 50% of the final germination (Growing Degree Day = GDD 50 ) for the sub-optimal temperatures was calculated as the reciprocal of the slope of the nonlinear regression (Covell et al., 1986;Giolo et al., 2019;López et al., 2019;Martínez-Villegas et al., 2018;Picapietra et al., 2020). ...
Exploring the mechanisms that promote population divergence represents a central point in evolutionary ecology. Along their distribution, species commonly experience contrasting environmental conditions, which impose local selection pressures to which populations tend to adapt resulting, for example, in ways to deal with resource shortage or abundance. In this study, we explored if germination performance varies under different levels of temperature, water potential and salinity among populations of Prosopis laevigata, a widespread mesquite species from the arid and semi-arid zones of Mexico. Given the wide distribution of P. laevigata and the sensitivity of the germination phase to environmental conditions, we hypothesized the existence of differential responses during this crucial stage of plant development. Thus, we expected germination in populations of P. laevigata from more arid zones to be less sensitive to high temperatures, salinity, and water deficit. Also, we explored if the exploitation–tolerance trade-off guides the differentiation of P. laevigata populations in germination performance under varying conditions. Germination of all populations was very sensitive to water scarcity but not to variation in temperature or salinity. We identified two major axes of trait covariation in germination physiology: one defined by tolerance of germination to water and saline stress versus germination velocity, and the other defined by the tolerance to extreme temperatures. We found evidence that variation in tolerance among the populations was related with their distribution along environmental gradients. Overall, populations with a higher capacity to germinate under water deficit stress, salinity, and extreme temperatures inhabit warmer and more saline areas. Our study provides strong evidence of existing local adaptations during germination of P. laevigata from across its distribution in the arid lands of Mexico.
... Obtaining the Tolerance Thresholds: based on the results of germination for each osmotic potential, Boltzmann sigmoidal curves were fitted (cumulative germination × time) to estimate the time required for germination of 50% of the seed population (t 50 ). The germination rate (GR) was calculated as a reciprocal function of this time (1/t 50 ) (Covell et al., 1986). ...
... For each seed lot, the hydrotime (θH PEG ; MPa.d -1 ) and halotime (θH NaCl ; MPa.d -1 ) to germination at suboptimal osmotic potentials were calculated (Covell et al., 1986;Seal et al., 2018;Seal et al., 2021) and a repeated probit analysis was performed in Genstat (v. 14.2.6967; ...
Erythrina velutina Willd is a native Fabaceae with wide occurrence, mainly in the Caatinga Domain with multiple uses. This study aimed to compare the vulnerability/tolerance of seeds of four accessions of E. velutina to osmotic stresses. Four replications were conducted with 25 seeds, germinated in osmotic solutions of NaCl or PEG up to -1.73 MPa. Seeds that did not germinate after 14 days were recovered in distilled water. Obtained data were fitted in Boltzmann curves and t50 and synchrony were evaluated. A probit analysis was performed, and hydrotime and halotime models were constructed. In distilled water, the germination curve was similar for all accessions. When the concentration of salt or PEG in the substrate increased, the accessions differentiated into two groups. Two accessions - Jutaí 2012 and Jutaí 2015 - maintained high germination up to -0.86 MPa NaCl, while Caboclo 2008 and Caiçara 2011 accessions presented a lower germination speed. The hydrotime and halotime analyses separated the germination response of accessions according to their physiological quality and tolerance to osmotic and saline conditions. Seeds viability was maintained at both stresses, since germination was reestablished at distilled water, thus constituting a crucial response for this species’ survival and conservation.
... For the germination process in the sub-optimal temperature range, the inverse of the slope of the regression lines was calculated for each percentile and the germination percentage data were transformed into probits. The sub-optimal thermal time was calculated following the Equation (3) below [73]: ...
... The following Equation (4) describes the accumulated temperature in a time the seeds required to the germination process in the supra-optimal range of temperatures [73]: ...
Swietenia macrophylla is an economically important tree species propagated by seeds that lose their viability in a short time, making seed germination a key stage for the species recruitment. The objective of this study was to determine the cardinal temperatures and thermal time for seed germination of S. macrophylla; and its potential distribution under different climate change scenarios. Seeds were placed in germination chambers at constant temperatures from 5 to 45 °C and their thermal responses modelled using a thermal time approach. In addition, the potential biogeographic distribution was projected according to the Community Climate System Model version 4 (CCSM4). Germination rate reached its maximum at 37.3 ± 1.3 °C (To); seed germination decreased to near zero at 52.7 ± 2.2 °C (ceiling temperature, Tc) and at 12.8 ± 2.4 °C (base temperature, Tb). The suboptimal thermal time θ150 needed for 50% germination was ca. 190 °Cd, which in the current scenario is accumulated in 20 days. The CCSM4 model estimates an increase of the potential distribution of the species of 12.3 to 18.3% compared to the current scenario. The temperature had an important effect on the physiological processes of the seeds. With the increase in temperature, the thermal needs for germination are completed in less time, so the species will not be affected in its distribution. Although the distribution of the species may not be affected, it is crucial to generate sustainable management strategies to ensure its long-term conservation.
... Cavell et ;al., 1986 ;Ellis et al., 1987 Ellis andButcher, 1988 هم مطالعات برخی در اما ) سقف دمای ( کردند گزارش ثابت را Garcia-Huidobro et al., 1982;Orozco-Segovia et al., 1996 . ...
In order to investigate the changes in cardinal temperatures of wild mustard seed germination during the dormancy elimination, a split plot experiment was conducted as completely randomized design in three replications in the Seed Research Laboratory of Agricultural and Resource University Natural Gorgan in 2017. The main factor was different temperatures (5, 10, 15, 20, 25 and 30°C) and sub-factor was different concentrations of gibberellic acid (GA: 0, 100, 300, 500, 1000, 1500, 2000 ppm). A dent-like function was used to describe the response of the germination rate to temperature. For different germination stages, the base temperature decreased from 2.9 to 3.4 °C in GA0 towards -1.2 to -2/0 °C in GA2000; the ceiling temperature was 25 °C at GA0 and increased to 33.3 °C in GA2000; the temperature tolerance range from 21.6 to 22.1 °C in GA0 reached 32.4 to 35.1 °C in GA2000. Due to cardinal temperature changes, the dormancy of wild mustard is a non-deep physiological dormancy type 1. Seeds with dormancy initially have the highest germination at low temperatures, and when they come out of dormancy, they germinate at high temperatures and the temperature range of germination increase. The estimated parameters in the present study can be useful in simulation models of seed bank and for further studies on the biology and ecology of wild mustard.
... How trait-environment interactions can shape the germination response through the thermal niche has been comprehensively modelled in the laboratory (Catelotti et al., 2020;Thompson and Ceriani, 2003) and in situ (Blandino et al., 2022;Porceddu et al., 2013). Thermal time models in combination with relevant environmental parameters have been widely used to investigate thermal niche and germination responses to accumulated temperature in crop and wild species (Covell et al., 1986;Dantas et al., 2020;Garcia-Huidobro et al., 1982b;Hardegree, 2006;Maleki et al., 2021;Porceddu et al., 2013;Pritchard and Manger, 1990). Previous studies have shown that variation in threshold-type responses to ongoing environmental conditions among species may reflect the seeds' thermal memory of the maternal environment (Fernández-Pascual et al., 2019), as evidenced by the cumulative thermal effects on seed development (Baskin and Baskin, 2014;Daws et al., 2004) and varying levels of seed dormancy (Porceddu et al., 2013;Pritchard et al., 1999). ...
The germination niche of plant species depends primarily on the seeds' responsiveness to temperature and water potential. However, to appreciate future climate risks to natural regeneration through germination, a global level synthesis across species is needed. We performed a meta-regression and phylogenetic patterning of primary data from 377 studies on 486 species, including trees, grasses, crops and wild species, to determine patterns and co-correlants in the cardinal values that define species' germination niches. We found positive correlations between base temperature and other germination traits related to cardinal temperatures suggesting that plant species alter base temperature values in harmony with other thermal traits as a highly efficient adaptation strategy to coping with harsh conditions. A negative correlation was found between thermal time and base temperature, and positive correlations between other cardinal temperatures and base temperature. Mean values of thermal time indicate that annual crops germinate more rapidly compared to wild species, potentially as a consequence of domestication, and tropical tree seeds the slowest. Dryland species (Cactaceae and Agavaceae) have the widest upper thermal and lower moisture niches, indicative of abilities to grow under harsh conditions, while forages have the narrowest thermal and moisture niches, suggesting higher sensitivity to frost or drought. We propose a new conceptual framework for future research on germination niche as shaped by thermal and moisture traits. Our database represents a unique source of information to further determine the vegetation boundaries of wild or cultivated species, including within simulation studies on plant species adaptations under changing land-use and climate.
... In addition to direct stress to the plant, wind speeds can also contribute to soil erosion. Colton (2018) also demonstrated a reduction in sediment temperatures, which can inhibit or slow germination as well as contribute to overall plant mortality (Covell et al., 1986;MaChado and Paulsen, 2001) but may prove beneficial in extreme environments where high temperatures can hinder plant establishment. ...
Large dam removals are increasing in frequency and the response of natural and managed revegetation is a critical consideration for managed restoration of dewatered reservoir landscapes post dam removal. The removal of two large dams on the Elwha River in 2011-2014 provides insight into reservoir revegetation. We review literature and datasets from 2012 through 2018, 1-6 years since reservoir dewatering, to compare pre-dam removal predictions on the Elwha to post-dam removal of natural revegetation, managed revegetation effects and invasive non-native vegetation response. Pre-dam removal hypotheses about natural revegetation did not predict species performance on reservoir sediments, seed rain patterns, or seed bank response. Sediment texture and landform affected multiple aspects of revegetation, including vegetation cover, species richness, woody stem densities and species composition. Reservoir drawdown timing influenced species composition and seedling densities. Predictions about managed revegetation effects were mixed. Planting trees and shrubs did not accelerate woody cover but did increase species richness. Seeding reduced non-native vegetation frequency and species richness, had no effect on vegetation cover on fine sediments, but increased vegetation cover on coarse sediments. Planting trees and shrubs during drawdown appeared to result in higher survival rates compared to plantings installed 1+ years post drawdown. Seeding Lupinus rivularis (riverbank lupine) on coarse sediments was successful and increased foliar nitrogen in planted conifers. Invasive non-native vegetation was correctly predicted to be more abundant in the Aldwell reservoir but did not preclude native species establishment in either reservoir, likely due to rapid establishment of native species and robust management that occurred before, during and after dam removal.
... The authors reported that drying temperature, drying rate, and seed temperature showed extremely significant negative correlations with germination energy, germination rate, germination index, and vigor index [21]. For a single seed population of each of four species of grain legume studied by Covell et al. [22], positive linear relationships were shown between temperature and rate of germination for different fractions of each population, from a base temperature, at which germination rate was zero, to an optimum temperature, at which germination rate was maximal. Subsequently, Ellis et al. [23] reported that a screening procedure which required information on the progress of germination at only four temperatures was able to define the response of the rate of seed germination to sub-and supra-optimal temperatures for whole seed populations of each of five bean genotypes. ...
In this study, three distinct and unique modes of greenhouse drying are introduced: solar, solar-exhaust gas, and exhaust gas modes of drying. The effect of drying black nightshade seeds in the three modes was studied, using germinability as a measure of quality. In solar mode, seeds were dried from a moisture content of 89.34% (db) to 7.13% (db) with the greenhouse dryer room air temperature range of 14.82-58.46°C and relative humidity of 9.40-88.03%. In solar-exhaust gas mode drying was performed from 92.57% (db) to 6.07% (db) within a temperature range of 34.49-61.97°C and relative humidity of 7.10-39.27%. In exhaust gas mode black nightshade seeds were dried from an initial moisture content of 88.84% (db) to a final one of 9.42% (db) when the greenhouse dryer room air temperature ranged from 25.75 to 30.77°C and relative humidity inside the dryer was between 51.88 and 83.98%. The results show that exhaust gas drying mode had a difference of 12.5% when its mean germination percentage was compared to solar mode of drying. Moreover, a 16.2% difference in means of germination percentage was recorded when solar-exhaust gas mode of drying was compared to exhaust gas mode. The highest mean germination percentage was recorded at 89% for exhaust gas drying mode because black nightshade seeds were subjected to temperatures ranging from 25.75 to 30.77°C. Modified Giner's model predicted germination changes of black nightshade seeds more accurately than modified Sharp's model due to the higher coefficient of determination (0.6896 > 0.6853) and lower root mean squared error (6.1554 < 6.4519). The activation energy in the modified Giner's model was found to be 7.034×10 33 Joule/mole through model fitting to experimental data. In conclusion, it is recommended that the feasibility of exhaust gas energy use in drying be expanded to seeds of other African vegetable crops.
... Cool temperature treatments delayed germination rates by 1-4 days among the species groups studied, compared to the fastest germination rate in the warm temperature treatments. Rapid and uniform germination is generally a favourable trait for seedling establishment (Covell et al. 1986;Blum 2018) and species competitiveness. Serradella species groups demonstrated (with a higher hazard ratio) that they were more likely to germinate at any temperature (and more rapidly in the case of yellow serradella) than burr medic or subterranean clover. ...
Cool temperatures can limit productivity of temperate grazing systems as poor pasture growth rates in winter create feed shortages for livestock. Ornithopus spp. (serradella) are broadly adapted annual pasture legumes that produce high-quality forage in soil types considered marginal for other temperate legume species. However, serradella establishment is perceived to be difficult in cool-season environments. We used survival analysis to compare germination rate and seedling emergence for two serradella species (yellow serradella and French serradella) against three reference species (Medicago sativa, M. polymorpha and Trifolium subterraneum) in four temperature treatments (10/5, 15/10, 20/15 and 25/20°C; max/min). We also compared shoot relative growth rate and photosynthetic rate at 15/10°C (cool) and 23/18°C (warm). Cool temperatures (10/5, 15/10°C) did not slow germination rates for serradella relative to the reference species, but warm temperatures (20/15, 25/20°C) delayed emergence and reduced post-emergent shoot growth rates. Once established, Ornithopus spp. had similar mean photosynthetic rates and stomatal conductance at cool temperatures to the reference species. We conclude that, contrary to common perception, cool temperatures did not adversely influence germination, emergence, or early growth of Ornithopus spp. relative to the reference species.
... The effect of temperature on sclerotial germination could be defined by the thermal-time concept (Alvardo and Bradford 2002;Bierhuizen and Wagenvoort 1974;Covell et al. 1986) represented by Equation (i). ...
Athelia rolfsii, causal agent of “southern blight” disease, is a soilborne fungal pathogen with a wide host range of more than 500 species. This study's objectives were to (i) quantify the effects of two environmental factors, temperature and soil moisture, on germination of A. rolfsii inoculum (sclerotia), which is a critical event for the onset of disease epidemics and (ii) predict the timing of sclerotial germination by applying population-based threshold-type hydrothermal time (HTT) models. We conducted in vitro germination experiments with three isolates of A. rolfsii isolated from peanuts, which were tested at five temperatures ( T), ranging from 17 to 40°C, four matric potentials (Ψ m) between −0.12 and −1.57 MPa, and two soil types (fine sand and loamy fine sand), using a factorial design. When Ψ m was maintained between −0.12 and −0.53 MPa, T from 22 to 34°C was found to be conducive to sclerotial germination (>50%). The HTT models were fitted for a range of T (22 to 34°C) and Ψ m (−0.12 to −1.57 MPa) that accounted for 84% or more of variation in the timing of sclerotial germination. The estimated base T ranged between 0 and 4.5°C and the estimated base Ψ m between −2.96 and −1.52 MPa. The results suggest that the HTT modeling approach is a suitable means of predicting the timing of A. rolfsii sclerotial germination. This HTT methodology can potentially be tested to fine-tune fungicide application timing and in-season A. rolfsii management strategies.
[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
... Too little rain may dry out the soils in rainfed areas, causing weak and small plants that may not withstand the weather over the subsequent growth stages (Heng et al., 2009). Lower or higher temperature can slow down the seed germination process (Covell et al., 1986). ...
... In lentil, temperatures above 24.4°C reduce the rate of germination (Covell et al. 1986). The consequence of heat stress is decline in percentage of germination, abnormal growth of seedlings, degeneration of nodules, loss in cell membrane stability, reduction in plant biomass, early flowering, increase in lipid peroxidation and decrease in photosynthetic efficiency (Jiang and Huang, 2001a, b;Sehgal et al. 2017). ...
Worldwide, abiotic stresses including heat and drought are the major obstructions that threaten the agricultural production. Development of climate-resilient cultivars is the easy and economical way to combat drought and heat stress with limited resources. Plants do follow adaptation strategies to mitigate the impact of stress and lead to alteration in some of the morphological traits such as leaf rolling, leaf angle, cuticular wax content, stomatal conductance, deep root system, altered signalling and metabolic pathways. Targeting such traits along with the economical yield will help to identify suitable genotypes which perform better under stress environment. The basic step is to explore the available physiological trait variation among the cultivars, germplasm set and wild relatives to main stream alleles of importance to breeding material from the donor parent. Conventional and advanced breeding strategies can be implemented to develop climate-resilient cultivars with the suitable breeding and screening methods. As a key factor hybridization and selection along with the implication of advanced breeding methods like MABB, MARS, GS and transgenic approach make it easy and accurate to develop varieties in less time. Linkage, QTL and genome-wide association mapping helps to identify the genomic region of interest to target during marker-aided breeding approaches. A cocktail of breeding methods from conventional to transgenic may help in the development of high-yielding climate-resilient varieties which can help to serve farmers to escape from glitch of crop loss due to dry spell during cropping season. The recent advancement and methodologies regarding drought and heat tolerance breeding in wheat are discussed in this chapter along with the difficulties posed.KeywordsDroughtHeatWheatPhysiological breedingMolecular markers
... Linear regressions were estimated using the germination rate values to determine base and maximum temperatures (Tb and Tm, respectively) (Covell et al., 1986). The optimal temperature (To) was estimated by the intersection between these two regression lines (Hardegree, 2006). ...
Palm trees are propagated almost exclusively by seeds and each species germinates under a certain temperature range. In this sense, the two-way thermogradient plate may be used to determine temperature limits for germination and seed response to temperature. The objective was to define the alternating temperature regime promoting higher and faster seed germination of Carpentaria acuminata and Phoenix canariensis palms using a two-way thermogradient plate. This equipment allowed 64 combinations of alternating and constant temperatures, ranging from 6.97 to 36.42 ºC for C. acuminata, and 7.96 to 35.94 ºC for P. canariensis. Seeds were sown in Petri dishes (25 x 9 cm) containing 1% water agar. Linear regressions were estimated to determine cardinal temperatures. After 50 days, non-germinated seeds were transferred from the two-way thermogradient plate to a germination chamber at 30 °C. The temperature regime promoting highest seed germination percentage of C. acuminata was 30.45/33.00 °C (day/night), with minimum, optimum, and maximum temperatures of 9.13, 28.53, and 36.33 °C, respectively. For seed germination of P. canariensis, the most appropriate temperature regime was 29.77/17.93 °C (day/night), with minimum, optimum, and maximum temperatures of 9.53, 28.03, and 35.43 °C, respectively.
Keywords
Arecaceae; cardinal temperatures; Carpentaria acuminata ; palm propagation; Phoenix canariensis ; temperature sensitivity
... t pathogens (Genchev , 1988) . The first few hours during imbibition appear particularly critical. Similar problems have been noted in soybean (Obendorf and Hobbs , 1970;Leopold , 1980;Orr et al., 1983 ), where studies suggest cell membrane function is adversely affected by cool temperatures and rapid rehydration of seed with low moisture content. Covell et al . ( 1986 ) reported that germination rates of various legume species may be analyzed in such a way that germination response is a simple function of three base temperatures. ...
... Thermal time models can be important for determining germination speed across a range of temperatures [25,26]. Using equations generated from the 50% percentile from cumulative germination time courses, the optimal germination temperature was 29.6 • C, the base temperature was 3.4 • C and the upper ceiling temperature was 42.6 • C ( Figure 2). ...
Industrial hemp (Cannabis sativa L.) as a grain and fiber crop is experiencing a resurgence in North America. Due to governmental prohibition, there has been limited information on regional agronomic production systems including basic information on seed germination. This study was initiated to provide basic information on the relationship between temperature and germination in hemp seed. Germination was measured at constant temperatures ranging from 3 to 42 °C. Cardinal temperatures were determined for two industrial oil crop hemp cultivars (‘Georgina’ and ‘Victoria’). The optimal germination temperature indicated by a high mean germination percentage and rate was between 19 and 30 °C. Optimal (29.6 °C), base (3.4 °C) and ceiling (42.6 °C) temperatures were calculated from a linear regression of the germination rates to reach 50% germination for each temperature. The thermal time for ‘Georgina’ and ‘Victoria’ to reach 50% germination at suboptimal temperatures was 694 and 714 °C h, respectively. The osmotic and solid matrix-primed hemp seeds germinated faster than the untreated seeds, but the final germination percentages were not different. The primed seeds germinated faster at supraoptimal temperatures but did not impact final germination percentages in the thermally inhibited seeds.
... By varying the value of T b and conducting repeated regressions on the complete data set conducted at multiple temperatures, the value resulting in the minimum residual error, or maximum R 2 value, can be identified. The value of log θ T (50) is the thermal time at which the line crosses probit (50%) = 0, and the inverse of the slope of the line is the value of σθ T , indicating the variation in θ T across germination fractions ( Fig. 12b; Covell et al., 1986). Similarly, time courses at different constant ψ values can be normalized on a probit regression representing the sensitivity thresholds among seeds in the population (Fig. 12c): ...
... Controlled environment experiments were conducted at 20°C constant room temperature, and soil temperature within the soil tubes was 20.0°C (±0.7°C) across all experiments. Degree-hours were calculated using 20°C and a base temperature of 0°C for both species (Covell et al. 1986;Ellis and Barrett 1994;Sleimi et al. 2013;Rohban et al. 2018). ...
Context Germination and emergence are key to successful annual crop establishment. Emergence rate depends on germination rate, sowing depth, and rate of pre-emergent shoot elongation. The rate at which a shoot grows prior to emerging from the soil becomes significant when crops such as chickpea (Cicer arietinum L.) and lentil (Lens culinaris Medik.) are deep sown to utilise moisture below the conventional sowing zone. Aims In seeds of contrasting size, we aimed to compare the ability of chickpera and lentil varieties to emerge from deep sowing. Here we describe genetic variation for epicotyl growth rate, and phenotypic variation for epicotyl and root growth rates and biomass partitioning, of chickpea and lentil, as they relate to seed size. We further assess the impact of deep sowing and soil type on emergence, establishment and yield of the two species. Methods Epicotyl elongation rates, root growth and seedling biomass partitioning were determined in controlled environment studies, using soil tubes. Field trials were conducted on two different soil types at two sowing depths. Key results Most of the variance in epicotyl growth rate could be attributed to species rather than variety. Although epicotyl emergence was faster in lentil, chickpea epicotyl growth rates were higher than those in lentils and unrelated to seed size, whereas growth rates in lentils were weakly correlated to seed size (r = 0.31). Root development and epicotyl diameter appeared to be traded for maintenance of growth in smaller seeds of both species. In the field, sowing depth did not affect emergence, establishment or yield of chickpeas at either site. Deeper sowing resulted in minor reductions in emergence of lentil at one site, although biomass and yield were not affected. Conclusions Emergence of both crops was unaffected by deep sowing (to at least 200 mm) under controlled environment and sandy field conditions. There was minimal genetic variation for the measured parameters within a species. Seed size was of little importance for emergence rate; however, shoot growth rate from small seeds was maintained by reducing seedling vigour. Implications Seed size should be considered when deep sowing lentils in order to maintain high seedling vigour. Further work is needed to understand how environmental factors influence seedling emergence from depth.
... By varying the value of T b and conducting repeated regressions on the complete data set conducted at multiple temperatures, the value resulting in the minimum residual error, or maximum R 2 value, can be identified. The value of log θ T (50) is the thermal time at which the line crosses probit (50%) = 0, and the inverse of the slope of the line is the value of σθ T , indicating the variation in θ T across germination fractions ( Fig. 12b; Covell et al., 1986). Similarly, time courses at different constant ψ values can be normalized on a probit regression representing the sensitivity thresholds among seeds in the population (Fig. 12c): ...
Achieving rapid and uniform stand establishment in crops requires a combination of high-quality seeds and appropriate environmental conditions. In particular, temperature and soil moisture (or water potential) are the major factors influencing germination in the field. In this chapter, we focus on the application of population-based threshold (PBT) models to characterize seed germination time courses and how environmental and technological inputs influence them. Viewing seed quality as a product of the behavior of populations of individual seeds is critical for understanding the causes and consequences of poor performance. Quantitatively characterizing seed population features enables their use in seed sorting and seed enhancement, and provides phenotypes for use in research, breeding, conservation and restoration. We believe that PBT models are essential tools to enable full utilization of new advances in seed technology to improve seed quality and enable successful stand establishment in agriculture or in natural settings.
... The modeling approaches used in this study take into consideration the different germination characteristics of the various percentiles within the populations. These differences were reflected by the b parameter in Equation 4, which represents the maximal value of GR (Covell et al. 1986;Ordoñez-Salanueva et al. 2015;Rowse and Finch-Savage 2003). The insight gained into the ...
Silverleaf nightshade ( Solanum elaeagnifolium Cav.) has become a highly troublesome weed in irrigated summer crops in Israel. Since herbicide-based options to control this weed are limited, the best way to improve weed control is through a study of its biology, particularly its germination dynamics. The main objective of this study was thus to determine the impact of temperature on the seed germination dynamics of S. elaeagnifolium and to develop a temperature-based (thermal) prediction model for three S. elaeagnifolium populations growing in different ecosystems in Israel. To this end, a laboratory study was undertaken in which the germination proportion of S. elaeagnifolium seeds were monitored under seven temperature regimes: 2/8, 7/13, 12/18, 17/23, 22/28, 27/33 and 32/38 C (night/day). In addition, the impact of alternating temperature regimes between night and day temperatures (of 0, 2, 4, 6, 8 and 10 C), that were averaged over 20 and 25 C, was determined. It was found that the three populations shared similar germination characteristics and dynamics. An alternation of ≥ 6 C between night and day temperatures was needed for optimal germination, with no germination taking place under constant temperatures. In all three populations, the minimal requirement for germination was a 12/18 C (night/day) regime, with the final germination proportion lying between 0.25 and 0.36. The highest final germination proportion ≥0.8 was observed for the 17/23 C regime in all three populations. Modeling the germination rate as a function of temperature allowed us to determine cardinal temperatures for all three populations taken together, with the values being T b = 10.8 C (base temperature), T o = 23.8 C (optimal temperature) and T c = 35.9 C (ceiling temperature). These biological parameters allowed accurate (RMSE<0.06%) prediction of S. elaeagnifolium seed germination over the entire temperature range.
... Temperatures above 24.4°C slow down lentil germination (Covell et al. 1986). Reduced germination percentage, uneven seedling growth, nodule disintegration, deterioration of cell membrane stability, early flowering, reduction in plant biomass, decreased photosynthetic efficiency, and increased lipid peroxidation are all effects of heat stress (Chakraborty and Pradhan 2010;Ellis and Barrett 1994;Muehlbauer et al. 2006;Sehgal et al. 2017). ...
Lentil (Lens culinaris subsp. culinaris) is a self-pollinated cool season food legume crop and it ranks fifth in global production of pulses. Lentils have an excellent nutritional profile and are easily digestible pulse crop. Global climate change lead to high incidence of abiotic and biotic stresses that impeded the production and productivity of lentil. The major abiotic stresses impacting lentil are salinity, waterlogging, cold, drought and heat that limits the crop yield and to resolve this it is important to develop climate resilient lentil varieties. In this chapter, we discussed the impact of several abiotic stresses on lentil production, genetics, genomics including mapping of quantitative traits and incorporating the identified genes with the assistance of marker assisted breeding and transcriptomics for development of abiotic stress tolerance in lentil. To achieve the goal of developing tolerant varieties utilization of the genetic resources through screening, selection and introgression is the key of any breeding program. The advance genomic technologies can complement conventional breeding approaches for acceleration of breeding programs by increasing the precision and reducing the time through identification of candidate genes, gene mapping, marker assisted selection. Precise and repeatable phenotypic screening techniques are essentially required to screen the germplasm and breeding material which help in developing cultivars tolerant to abiotic stresses. Limited reports are available on tolerance to abiotic stresses in lentil and further investigations is required to understand the underlying genetic mechanism.
... In lentil, temperatures above 24.4°C reduce the rate of germination (Covell et al. 1986). The consequence of heat stress is decline in percentage of germination, abnormal growth of seedlings, degeneration of nodules, loss in cell membrane stability, reduction in plant biomass, early flowering, increase in lipid peroxidation and decrease in photosynthetic efficiency (Jiang and Huang, 2001a, b;Sehgal et al. 2017). ...
Cowpea (Vignaunguiculata L.Walp.) belongs to Papillinoideae tribe of the Fabaceae (Legume) family and is also commonly known as black eyed-pea, crowder pea and southern pea (Singh et al. 1997). Cowpea is an important annual legume crop grown in subtropical and tropical regions (recent reviews in Carvalho et al. 2017). Thus, the crop has worldwide importance. As a legume, cowpea has trifoliate leaves which serve as good fodder but is mostly grown for its edible seeds which are rich in protein, vitamins and minerals. Apart from the seed the green pods can also be used as a vegetable (Hadiet al. 2012). Cowpea seeds have a protein content of up to 25% and are high in micronutrients and essential amino acids like iron and lysine, respectively, which makes them a complementary pulse to the cereal based diets of many consumers in developing countries. Furthermore, cowpea grain is a heart healthyfood with a low fat content of 1.3%, fibre content of 1.8%, and carbohydrate content of 67% made up mostly of complex sugars that are digested slowly by the human gut. In this review we summarize the studies on the abiotic stress tolerances found in this important crop, including those to various environmental or drought limitations such as drought, temperature extremes, and salinity. Germplasm with traits for tolerance are described and approaches to classical and molecular breeding of cowpeas given.KeywordsCowpeaStressToleranceGenes and diversity
... Moot et al. (2000) found that the T b for germination and emergence of temperate herbage species were ≤ 4 ℃ and thermal time (Tt) requirement for germination ranged from 40 ℃d to 160 ℃d. The information about the germination and seedling emergence response to temperature is essential to characterise the planting windows and assessing suitability of crops to different growing environments (Covell, 1986 ...
In this study, we define the cardinal temperatures and thermal time for germination and emergence of pigeonpea genotypes. Seeds of six genotypes were subjected to constant temperatures ranging between 5 and 50°C in petri dishes with filter paper (germination) and with media (emergence) were placed in a thermal gradient plate. A nonlinear bent-stick model fitted to the rate of development to germination and emergence resulted in parameters predicting cardinal temperatures including base ( T b ), optimum ( T o ), maximum ( T m ), and thermal time. Estimated T b for 50% germination and emergence were 8.4 and 10.8°C, respectively, with no significant differences between genotypes. Optimum temperatures were 33.8 and 37.9°C for germination and emergence, respectively, with genotypes differing significantly. Thermal time for 50% germination and emergence varied significantly among genotypes. The results suggest that genotypic responses to the temperature are typical for their tropical origin and hence their suitability for cropping in summer dominant rainfall regions insubtropical Australia.
... In this model, the germination rate is regressed separately against temperature for two extreme of temperatures (below and above optimum temperature). Base temperature and maximum temperature are the intercepts of each regression line (Covell et al., 1986;Phartyal et al., 2003). The results of the present study confirmed that in the absence of other limiting factors (e.g., light, water), seed germination of S. striata and T. polycephalum is highly influenced by temperature. ...
Scrophularia striata and Tanacetum polycephalum are important medicinal plants in Iran which are rich inessential oils, bitter substances, and sesquiterpene lactones. The present study was conducted to compare fournon-linear regression models (segmented, beta, beta modified and Dent-like) to describe the germination ratetemperaturerelationships of Scrophularia striata and Tanacetum polycephalum over eight and seven constanttemperatures, respectively, to find cardinal temperatures and thermal time requirements to reach differentgermination percentiles. An iterative optimization method was used to calibrate the models and differentstatistical indices including RMSE, coefficient of determination (R2), and AICc were applied to compare theirperformance. The beta model was found to be the best model to predict germination rate of Scrophulariastriata at D10, D50 and D90 (R2 = 0.96, R2 = 0.97, R2 = 0.95; RMSE = 0.005, 0.001 and 0.001, respectively).According to this model outputs, the base, optimum, and the maximum temperatures for germination wereestimated as 1.21 ± 0.39, 25.91 ± 0.33 and 46.35 ± 4.12 °C, respectively. Also the segmented model wasfound to be the best model to predict germination rate of Tanacetum polycephalum at D10, D50 and D90 (R2= 0.98, R2 = 0.98, R2 = 0.98; RMSE = 0.067, 0.59 and 0.56, respectively). According to the model outputs, thebase, optimum, and the maximum temperatures for germination were estimated as 0.44±1.15, 26.95±0.75 and38.33±0.98 oC, respectively. It seems these two medicinal plants need moderate optimum temperature for seedgermination.
... The high temperature characterized Janata might be the reason for the early germination at this site. Similar results confirmed by [19], who stated that faster germination temperature occurs at high temperature. Furthermore, [20] indicated that the optimal temperature for seed germination of winter legume crops is about 10-15 0 C and high germination temperatures are considered to be 22-35 o C. ...
... Occurrence of phenological stages (date of 50% flowering, date of physiological maturity), were recorded in calendar days, then converted into thermal units using a base temperature of 0°C for C. arietinum and V. faba, 2°C for L. culinaris, 3.5°C for L. sativus, 4.1°C for T. foenum-graecum (Covell et al., 1986;Lamichhane et al., 2020), 4.7°C for L. tetragonolobus (Moot et al., 2000), 6°C for P. vulgaris (López et al., 2003) and 8.5°C for Vigna sp. (Craufurd et al., 1996). ...
Pulses are generally recognized for their multiple nutritional and environmental benefits. However,most legume species can be defined as orphan crops. This underlines the lack of knowledge onlegume diversity and the importance of studying this diversity and elucidating how it supports thefunctioning of agro-ecosystems. Functional trait approach could guide the inclusion of pulses intoagro-ecosystems to provide one or more services. This work aimed at synthetizing current knowledgeon the functional diversity of cultivated pulses at the interspecific level as well as producing newinsights on the relationships between pulses functional trait variation and agro-ecosystemsfunctioning. We focused on agro-ecosystem properties hypothesized to be good indicators of threespecific agro-ecosystem services related to food provision in low-input systems: yield under dryconditions, nitrogen (N) fixation, and competitiveness toward weeds. We combined concepts andmethods from functional ecology, crop physiology and agronomy. We applied multivariate statisticalmethods to data collected from the literature and to data collected from an original field experimentto explore traits-agro-ecosystem properties relationships under multiple environments (literaturedata) or optimal environmental conditions (field experiment). A controlled experiment in potsallowed to assess the effect of water deficit on key processes such as transpiration and biological Nfixation. Our results highlighted covariation patterns and trade-offs between agro-ecologicalproperties supported by different pulses species. Pulses diversity was also described throughfunctional traits and indicated leaf traits as key drivers of inter- and intra-species variability. Nitrogencontent of plant organ and seeds traits also captured a great part of pulses diversity. Those traits wererelated to agro-ecosystem properties. Although they were predicted by multiple alternativecombinations of traits it was possible to identify that leaf N content was an important predictor ofpulses agro-ecosystem properties. We compared different approaches (meta-analysis andexperimental) and discussed intra-species variability. Controlled experiment revealed a large intraand interspecific variability in the response of N fixation and transpiration dynamics, as well asrelationships between leaf traits, C/N metabolism, and soil drying-responses of growth, transpiration,and N2 fixation. We also discussed the intrinsic limitations of trait-based approach and pertinencefor its application to agro-ecosystem diversification.
... Fast emergence improves competitiveness with weeds [3] and avoids the exposure of both seeds and seedlings to soil pathogens [4], especially at low temperatures [5], as well as to sudden soil-drying conditions, mainly at high temperatures [6]. Although germination of the seed population spread out across time may be a survival strategy [7], a more concentrated germination is required to ensure greater uniformity during postgermination development and for crop duration [8]. ...
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 [T o1 sz , T o2 sz ] were identified using a flattened bell curve function. Speed was maximized for either germination or emergence over thermal ranges [T o1 sp , T o2 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 [T o1 sd , T o2 sd ] were identified with the aid of even-degree polynomials. The intersection of all three thermal ranges gave rise to optimal temperature ranges [T o1 , T o2 ] for germination (OTR G ) of the four varieties in study and for emergence (OTR E ) of three of them. In general, the lower thermal limit of OTRg was determined by speed (T o1 = T o1 sp ) and the upper thermal limit by size (T o2 = T o2 sz ). OTRe begins at T o1 sp for ervilha and sam3 and at T o1 sd for catarina and ends at T o2 sz for catarina and at T o2 sd for the others. The endpoints and length of both the OTR G and OTR E 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.
... Base temperature variation among cultivars occurs in some, but not all, crops. Covell et al. (1986) did not find any variations among base temperatures of different chickpea species. Conversely, Mwale et al. (1994) reported variations in base temperature among different species of sunflower (Helianthus annuus L.). ...
Quantitative information about temperature effects on germination components in safflower is scarce. e objective of this study was to describe the trend of cumulative germination at different temperatures and determine cardinal temperatures and thermal time for safflower germination. ree safflower cultivars, Esfahan, Goldasht and Padideh, were germinated at temperatures ranging from 5-40°C, with 5°C intervals. Germination was recorded from 7-14 d in 8-12 h intervals. Fitting a logistic function on cumulative germination data at different temperatures showed that maximum germination was obtained at temperatures of 5-30°C for Esfahan, 5-20°C for Padideh, and 10-15°C for Goldasht. Optimal germination temperature was 30°C for Esfahan and Padideh, and 25°C for Goldasht. In addition, beta, dent-like and segmented functions were used to describe the relationship between germination rate and temperature. Response of germination rate to temperature was best described by a segmented function due to higher R2 and lower root mean square of deviations between predicted and observed hours to germination, and lower standard error for estimating function parameters. Using this function, base, optimum and ceiling emergence temperatures were estimated to be 5, 32 and 48°C, respectively. e physiological hour requirements for germination were 23 h for Goldasht, 17.8 h for Esfahan and 16.4 h for Padideh, equivalent to daily thermal time of 19.7, 28.9 and 16.7°C d − 1, respectively.
An extremely important oil crop in the world, Helianthus annuus L. is one of the world's most significant members of the Asteraceae family. The rate and extent of seed germination and agronomic features are consistently affecting by temperature (T) and changes in water potential (ψ). A broad hydrothermal time model with T and ψ components could explain sunflower responses over suboptimal T and ψ. A lab experiment was performed using the HTT model to discover both T and ψ and their interactive effects on sunflower germination and also to figure out the cardinal Ts values. The sunflower seeds were germinated at temperatures (15 °C, 20 °C, 25 °C and 30 °C); each Ts had five constant ψs of 0, 0.3, 0.6, 0.9, and 1.2 MPa via PEG 6000 as osmotic stress inducer. The results revealed that highest germination index was found in seed grown at 20 °C in distilled water (0 MPa) and the lowest at 30 °C with osmotic stress of (− 1.2 MPa). The highest value of germination rate index was found in seed grown at 20 °C in distilled water (0 MPa) and the lowest at 15 °C with an osmotic stress of (− 1.2 MPa). In conclusion, water potential, temperature, and their interactions have a considerable impact on seed germination rate, and other metrics (GI, SVI-I, GRI, GE, SVI-II, and MGT). Seeds sown at 20 °C with zero water potential showed high germination metrics such as GE, GP, GRI, and T50%. The maximum value to TTsub noted at 30 °C in − 0.9 MPa osmotic stress and the minimum value was calculated at 15 °C in − 1.2 MPa osmotic stress. The result of TTsupra recorded highest at 15 °C in controlled group (0 MPa). Moreover, θH was highest at 30 °C in controlled condition (0 MPa) and minimum value was observed at 20 °C under − 1.2 MPa osmotic stress. The value of θHTT were maximum at 30 °C in controlled group (0 MPa) and minimum value was recorded at 15 °C under − 1.2 MPa osmotic potential. The base, optimum and ceiling temperatures for sunflower germination metrics in this experiment were noted 6.8, 20 and 30 °C respectively.
Tohum çimlenme ve fide çıkış dönemlerindeki yüksek sıcaklıklar mercimeğin fide tesisi ve tane veriminde önemli azalmalara neden olabilir. Laboratuvar koşullarında yürütülen bu araştırmada 16 mercimek çeşidi artan sıcaklıklarda (20, 25, 30, 35, 40, 45 °C) tohum çimlenmesi ve fide çıkış özellikleri yönünden değerlendirilmiştir. İncelenen özellikler yönünden çeşitler arasında önemli farklar belirlenmiştir. Yüksek sıcaklıklar incelenen çimlenme ve çıkış özelliklerini olumsuz etkilemiş, bu özellikler yönünden çeşit x sıcaklık etkileşimleri önemli bulunmuştur. Hiçbir çeşitte 40 ve 45 °C uygulamalarında çimlenme; 35, 40 ve 45 °C uygulamalarında çıkış olmamıştır. Çimlenme yüzdesi, çimlenme indeksi, çimlenme süresi, çimlenme güç indeksi, çıkış yüzdesi, çıkış indeksi, çıkış süresi ve çıkış güç indeksi ölçütleri esas alınarak, Gümrah, Emre 20 ve Meyveci 2001 çeşitleri çimlenme ve çıkış dönemlerindeki yüksek sıcaklıklara en dayanıklı olarak tanımlanmıştır. Bu çeşitler, ekim zamanında toprak sıcaklığı yüksek olan çevrelerde verim avantajı sağlayabilir ve ilgili ıslah programlarında ebeveyn olarak kullanılabilir.
This study was done to evaluate different linear and nonlinear regression models to determination of cardinal temperatures and biological day's requirement for emergence of lentil. Therefore, a split plot experiment was conducted based on three replications. Seeds of lentil (Gacgsaran, Kimia and Bilehsovar) were sown in field at 12 different dates. Beta, dent-like and segmented models were applied to evaluate the relationship between germination rate and temperature. Root mean square deviation (RMSD), coefficient of determination (R2), variation coefficient (CV) and linear regression coefficients (a and b) were used to select the perfect model. Results of models fitting indicated that the response of lentil emergence to temperature is best described by a segmented model. Cardinal temperatures estimated by this model were -1.27 to -1.62°C for base temperature, 23.15 to 25.92°C for optimum temperature and 30°C for ceiling temperature based on air temperature. There was not any significant difference among cultivars in view of in base temperature and optimum temperature but cultivars had significant difference in biological days. The biological day’s requirement was 6.99, 8.56 and 8.78 for Bilehsovar, Gacgsaran, and Kimia, respectively. The quantitative information provided in the present study can be used to predict the emergence of lentil cultivars. The main applicable result of this study was that reaction of seedling of the lentil is describable best by the use of segmented model, so this model and its derived parameters are applicable in predicting emergence in some given lentil cultivars.
این مطالعه برای بررسی واکنش سبز شدن 4 رقم نخود (بیوونیج، آرمان، هاشم و جم) نسبت به دما در 12 تاریخ کاشت (هر ماه یکی) در شرایط محیطی گرگان در طول سالهای زراعی 81-1380 و 82-1381 انجام شد. برای کمی کردن واکنش سبز شدن نسبت به دما از مدل دندان مانند استفاده شد. با استفاده از این مدل، دماهای کاردینال یا اصلی (پایه، مطلوب تحتانی و مطلوب فوقانی) و تعداد روز بیولوژیک مورد نیاز برای سبز شدن نسبتهای مختلف جمعیت تعیین شد. دمای سقف بهطور ثابت 39 درجه سلسیوس در نظر گرفته شد. دماهای پایه، مطلوب تحتانی و مطلوب فوقانی برای 50% جمعیت در بین ارقام اختلاف معنیداری نشان ندادند و بهترتیب 5/4، 2/20 و 0/29 درجه سلسیوس برآورد شدند. دمای پایه برای جمیع ارقام برای 10 و 90 درصد جمعیت بهترتیب 4/3 و 0/3 درجه سلسیوس، دمای مطلوب تحتانی 8/23 و 0/20 درجه سلسیوس و دمای مطلوب فوقانی 3/30 و 0/30 درجه سلسیوس برآورد شدند. در هر یک از نسبتهای 10، 50 و 90 درصد سبز شدن بین ارقام از نظر تعداد روز بیولوژیک مورد نیاز برای سبز شدن اختلاف معنیداری مشاهده نشد. تعداد روز بیولوژیک مورد نیاز برای سبز شدن برای 10 درصد جمعیت 4/4 روز، برای 50 درصد جمعیت 1/6 روز و برای 90 درصد جمعیت 9/7 روز برآورد شد. با استفاده از پارامترهای برآورد شده در این تحقیق و آمار هواشناسی، میتوان زمان سبز شدن برای نسبتهای مختلف جمعیت را پیشبینی کرد.
This study compared the seed germination of 30 tree species from Central Amazonia using a wide temperature range (5‑40°C with 12 hours of light daily). Seeds were submitted to pre-germination treatments, whenever necessary, sown on vermiculite or germitest paper, and normal seedling development was assessed until stabilisation. With the same data set, seeds’ optimal germination temperature (T opt ) was determined by comparing the following approaches: (i) 2-step, the temperature with the highest germination and the shortest time to seed population reach 50% of germination was chosen; (ii) the highest Germination Speed Index (GSI); (iii) using the formula developed by Olff and collaborators (Olff’s approach); (iv) three species were evaluated with Covell’s approach; and (v) new formulas for T opt calculation are proposed, based on germination success and five different variables of germination rate (Cipriani’s approach). Comparing the results, T opt differed between 0.6-10.0°C. GSI and 2-step indicated generally higher values than Olff’s formula. The minimum and maximum T opt differences between Cipriani’s approaches were between 0.1-2.2°C. Our study showed that T opt should be determined for each species as, even the 30 Amazonian tree species of the same habitat, T opt ranged between 22.5 and 32.5°C.
Quanti cation of germination niches under salt stress, temperature, and their interaction using population-based threshold models is important to predict seedling emergence patterns. Seeds of Sarcocornia fruticosa, Sarcocornia alpini, and Salicornia emerici were treated with various temperatures at different NaCl concentrations. Results indicated that the median base NaCl concentration was roughly steady (0.68, 0.73, and 0.70M, respectively) at sub-optimal temperature, then decreased linearly at supra-optimal temperature until the ceiling temperature (T c). The estimated base, optimum and ceiling temperatures, in water, were − 0.5, 15 and 29°C for Sarcocornia fruticosa, − 2.5, 11 and 24°C for Sarcocornia alpini, and 9.5, 25 and 40°C for Salicornia emerici, respectively. At all species, the base temperature has not changed with the salinity while both optimum and ceiling temperatures decreased. Also, Salicornia emerici showed rapid and synchronized germination when salinity decreases during the rainy season coinciding with favorable temperatures compared with other species.
There has been a lot of research on biotic stresses in lentils because they are visible and lead to decline in production and quality losses. Abiotic stresses, on the other hand, are rapidly being identified as key reasons for the low and unpredictable yield of lentils in many regions. Changes in climate, soils, and climate-soil interactions affect lentil productivity and quality directly or indirectly through their influence on foliar and soil-borne diseases, pests, and rhizobia in each growing zone. Furthermore, the relative tolerance of a cultivar and/or the effect of specific cultural control approaches can vary the effects of a specific stress. Salinity, waterlogging, cold, drought, and heat are the key abiotic factors that affect lentil output, and it is critical to produce climate-robust lentil cultivars to address these issues. The implications of several abiotic stresses on lentil production, genetics, and genomics, including mapping of quantitative traits and incorporating the identified genes with the help of marker-assisted selection breeding, and transcriptomics for the advancement of abiotic stress tolerance in lentil are all covered in this chapter. By identifying candidate genes, gene mapping, and marker-assisted selection, advanced genomic tools can supplement traditional breeding procedures to accelerate breeding projects by enhancing accuracy and saving time. There are few reports on lentil resilience to abiotic stress factors, and more work is needed to investigate the inherited biological process. Evaluating germplasm and breeding material for cultivars resistant to abiotic stressors necessitates the use of rigorous and reproducible phenotypic testing approaches. Systemic application of pan-omics with novel omics technologies will fast-track lentil breeding programmes. Additionally, artificial intelligence (AI) algorithms can help in simulating yield under climate change, leading to predicting the genetic gain. Use of machine learning (ML) in quantitative trait locus (QTL) mining will further enhance the understanding of genetic determinants of abiotic stress in lentils.
Invasive annual grasses now dominate millions of hectares of rangeland in the Intermountain Western United States. Local annual grass distribution, however, has been shown to follow landscape patterns of slope, aspect, and elevation that are correlated with ecological resilience to stress and disturbance and resistance to annual grass invasion. Although these patterns have previously been linked to soil-climate classes, several mechanistic factors in native-plant seedling establishment are also associated with both topography and seasonal weather patterns in the year following planting. In this study we used the Simultaneous Heat and Water (SHAW) model to estimate long-term weather effects on soil microclimate and hydrothermal-germination models to predict germination response of one fast- and one slow-germinating native grass as a function of planting date, slope, aspect, and elevation in the Boise Foothills in southwestern Idaho. Higher elevation and northerly aspect sites are more likely to defer germination of seeded species until late enough in the fall that they avoid postgermination/preemergence freezing mortality. These sites are also more favorable for survival of emerged seedlings through mid to late summer. Slope, aspect, and elevation effects on modeled restoration outcomes are consistent with previously modeled general patterns of ecological resilience and resistance as a function of soil hydrothermal class, but inclusion of slope and aspect effects may produce finer-scale metrics for mapping these patterns over space. The probabilistic nature of microclimatic variability as a function of elevation may yield useful insights into successful restoration approaches for reestablishment of native plant communities in lower-elevation ecosystems with inherently lower ecological resilience and resistance. The generally arid climate in this region, however, may limit successful restoration outcomes at lower elevation in most years even under conditions of long-term annual grass control.
Seed germination is one of the most critical plant growth stages regulated by temperature (T) and water potential (Ψ). This experiment was conducted to quantify the seed germination response of two quinoa (Chenopodium quinoa) cultivars (Sajama and Titicaca) to T and Ψ using hydro time (HT) and hydrothermal time (HTT) models. The results showed that T, Ψ, and their interaction significantly affected the maximum germination percentage (MGP) of both cultivars. Based on the results of the segmented model fit at Ψ = 0 MPa, the minimum (Tb), optimum (To), and maximum T (Tc) in Sajama was estimated at 6.9, 21.9 and 34.9 °C, respectively and in Titicaca were estimated 8.0, 21.8 and 33.6 °C, respectively. While using the HTT model at different T and ѱ the Tb was estimated by 8.28 and 8.39 °C for Sajama and Titicaca, respectively, the To also estimated 26.96 for Sajama and 27.21 °C for Titicaca. Also, using the modified HTT model, the To estimated 27.46 for Sajama and 27.31 °C for Titicaca. There was an increase in hydro time constant (θH) when T increased at supra-optimal Ts (from 17 to 70 MPa h−1) as well as when the T decreased at sub-optimal Ts (from 17 to 79 MPa h−1). Also, it was observed that change of the T from To to Tb and Tc increased base Ψ (ψb) so that for each degree Celsius decrease of T at sub-optimal Ts, the ψb increased by 0.032 and 0.034 MPa in Sajama and Titicaca, respectively. Each degree Celsius increase of T at supra-optimal Ts also increased ψb by 0.021 MPa in Sajama and 0.020 MPa in Titicaca. Using HT and HTT to predict germination rate for the 50% of germination (GR50) revealed that they had acceptable accuracy (HT, R2 = 0.97, and = 0.99 for Sajama and Titicaca, respectively; HTT, R2 = 0.87 for Sajama and = 0.90 for Titicaca). The results of this experiment provide data for future simulating models of quinoa growth and development.
The germination niche of plant species depends primarily on the seeds’ responsiveness to temperature and water potential. However, to appreciate future climate risks to natural regeneration through germination, a global level synthesis across species is needed. We performed a meta-regression of primary data from 377 studies on 528 species, including trees, grasses, crops and wild species, to determine patterns and co-correlants in the cardinal values that define species’ germination niche. A negative correlation was found between thermal time and base temperature, and positive correlations between other cardinal temperatures and base temperature. Mean values of thermal time indicate that annual crops germinate more rapidly compared to wild species and tropical tree seeds the slowest. Dryland species (Cactaceae and Agavaceae) have the widest upper thermal and lower moisture niche, indicative of an ability to grow under harsh conditions, while forages have the narrowest thermal and moisture niche, suggesting higher sensitivity to frost or drought. We propose a new conceptual framework for understanding germination niche as shaped by thermal and moisture traits. Our database represents a unique source of information to further determine the vegetation boundaries of wild or cultivated species, including within simulation studies on plant species adaptations under changing land-use and climate.
Adverse weather conditions, particularly freezing or drought, are often associated with poor seedling establishment following restoration seeding in drylands like the Great Basin sagebrush steppe (USA). Management decisions such as planting date or seed source could improve restoration outcomes by reducing seedling exposure to weather barriers. We simulated the effects of management and environmental factors on seedling exposure to post‐germination barriers for bottlebrush squirreltail (Elymus elymoides), Sandberg bluegrass (Poa secunda), and bluebunch wheatgrass (Pseudoroegneria spicata). We combined germination timing models with daily soil moisture and temperature estimates to calculate yearly germination favorability and post‐germination freezing and drought barriers for three planting dates (Oct. 15, Nov. 15, and Mar. 15) and three seed sources or cultivars per species for 5000 sites in each of 40 yrs (water years 1980‐2019). We tested the effects of site environmental variables (elevation, mean annual precipitation, heat load, and clay content) and management choices (seed source and planting date) on germination favorability and barrier occurrence (mean) and variability (coefficient of variation). Seedling exposure to barriers was strongly linked to management decisions in addition to site mean precipitation and elevation. Later fall plantings and seed sources with slower germination (lower mean germination favorability) were less likely to encounter freezing and drought barriers. These results suggest that management actions can play a role comparable to site environmental variables in reducing exposure of vulnerable seedlings to adverse weather conditions and subsequent effects on restoration outcomes. This article is protected by copyright. All rights reserved.
Lentil (Lens culinaris Medikus) is important rainfed winter season grain legume for diversification of cereal-based cropping system worldwide. The crop originated in Near East and spread to different region establishing in wide range of agro-ecology. Lentil is cultivated in more than 50 countries. Lentil grains are rich sources of protein, prebiotic carbohydrates, micronutrients, and vitamins. Lentil is important staple food in regions with low income. The productivity of lentil is low due to poor seedling vigour, high flower drop, low pod set, poor dry matter accumulation, and susceptibility to biotic and abiotic stresses. Biotic and abiotic stresses induced by climate change pose challenge to lentil cultivation. Discovery of new genes and quantitative trait loci offer opportunity to breeders for improving lentil varieties for higher grain yield, nutritive value, and tolerance to biotic and abiotic stresses. In this chapter, we discuss the present challenges and opportunities for lentil improvement.Keywords
Lens culinaris
OriginHybridizationBreedingBiotic and abiotic stressesNutritional quality
The dynamics of weed seedbanks result from a complex interaction among seed attributes (i.e. morphology, physiology, and chemical composition), the surrounding biota (i.e. predators and microflora), and the environment. Either persistency or transiency will result from the outcome of this complex interaction, although a lack of dormancy would almost certainly preclude persistency. For that reason, a thorough understanding of (i) dormancy in seedbanks, (ii) the way in which changes in dormancy are driven by the environment, and (iii) the mechanisms for sensing their environment in the short term (i.e. light requirement for dormancy termination) is essential for predicting the behavior of weed populations and their dynamics. Even though, dormancy in seeds that lack defenses against predators or microflora attack, or with deficient repair mechanisms to ensure seed longevity, would be useless for persistence. Each of these features are discussed throughout this chapter in an attempt to understand the functional ecology of weed seedbanks as a strategy for weed persistence.
Plant species response to projected climate change would be diverse and dependent on species site specific climate. Therefore, information on species site specific response will be required to build regional species specific adaptation plan. For this identification and implementation of tools and techniques that can predict plant responses to projected climate change would be crucial. There are various methods that can be employed to model species response and mechanistic model is one of the reliable models that can predict the impact. Mechanistic model Tree and Climate Assessment- Germination and Establishment Model (TACA-GEM) has largely been used to predict the climate change impact on wild and agricultural species by identifying resilient species for plantation and cultivation under projected change. TACA-GEM was utilized to predict the impact of climate change on agricultural species in three ecological zones representing eastern mountain, hilly and tropical (Terai) regions considering eight cereals and lentil species in Nepal. Species physiological and phenological parameters with germination experimental data were used to calibrate the model to a range of climate change scenarios by the 2050s. The findings indicate that rainfall is one of the primary factors influencing species germination probability and timing. Moderate rainfall with warm climate projected benefitted germination in tropical site (Saptari) while higher rainfall and colder climate projected was adverse to the germination of most of the species in Bhojpur. The germination probability displayed by wheat and chickpea suggests that these species are the most resilient to projected climatic conditions by the 2050s across all the sites. The study successfully demonstrated site specific species vulnerability to a range of climate conditions. Thus, similar research activity can be employed in different land types to identify resilient crop species for future cultivation.KeywordsEnvironmentInfluenceAgricultural cropsResponseModelingVulnerability
Late watergrass is a competitive weed of rice that is well-adapted to both aerobic and anaerobic environments. Cultural controls such as a stale-seedbed and alternating from wet- to dry-seeding have been proposed as management options. However, the effects of these systems on its emergence and early growth are unknown. The objective of this study was to modify a previously-developed population-based threshold model (PBTM) to predict emergence and early growth under field conditions. In 2013, a series of experiments were conducted at the California Rice Experiment Station (CRES) in Biggs, CA to evaluate emergence and early growth of multiple-herbicide resistant and susceptible late watergrass at four burial depths (0.5, 2, 4, and 6 cm) under three irrigation regimes: Continuously Flooded (CF), Daily Flush (DF) and Intermittent Flush (IF). Resistant plants emerged at a significantly higher rate under the IF treatment (p < 0.05). Both biotypes showed decreasing emergence with increasing depth, and no plants emerged from the 4 or 6 cm depths in the CF treatment. Using the Gompertz growth curve, resistant plants had greater predicted growth rates ( k ), lower predicted maximum heights ( h max ), and a shorter time to predicted maximum growth rate ( t m ) than susceptible plants under the CF and DF treatments. Under the IF treatment, the susceptible plants had greater k , lower h max and shorter time to predicted t m . Information about burial depth and irrigation was incorporated into a previously-developed PBTM for late watergrass, and validated at the CRES in a field with a susceptible late watergrass population in 2013 and 2014, under two irrigation systems, CF and IF. Model fit was best in the CF treatments (average AIC = 199.05) compared to the IF treatments (average AIC = 208.6).
Black nightshade ( Solanum nigrum L.) is one of the worst weeds in crop fields, and it spreads mainly by the dispersal of seeds. Temperature is one of the key environmental factors affecting seed germination. We investigated the seed germination response to temperature in six populations of S. nigrum from mid to northern China and derived mathematical models from germination data. The results showed that S. nigrum seeds exhibit distinct germination responses to temperature within the range of 15 to 35 °C. The optimum temperatures for the populations XJ1600, JL1697 and HLJ2134 were 30 °C, and those for the populations NMG1704, HN2160 and LN2209 were 25 °C, 20 °C and 15 °C, respectively. Based on the nonlinear fitting and thermal time models, the predicted base temperatures of the six populations ranged from 2.3 to 6.4 °C, and the required accumulated growing degree days (GDD) ranged from 50.3 to 106.0 °C·d. The base temperatures and the accumulated GDD for germination differed among populations, and there was a significant negative correlation. HLJ2134 population required a high base temperature and accumulated GDD for germination, indicating that it might highly adapted to a warmer and moister environment. Based on the different germination responses of S. nigrum populations to temperature, the thermal time model reflects an innate relationship between base temperature and accumulated GDD required for initiation of seed germination, which provides a better basis for predicting seedling emergence and the timing for optimal control of S. nigrum under field conditions.
Factorial combinations of three photoperiods (10, 13 and 16 h), two day temperatures (18 and 28 °C) and two night temperatures (5 and 13 °C) were imposed on nodulated plants of six diverse genotypes (cultivars and land-races) of lentil (Lens culinaris Medic.) grown in pots in growth cabinets from vernalized (1.5 ± 0.5 °C for 30 d) or non-vernalized seeds (i.e. 144 'treatment' combinations). The times from sowing to the appearance of first open flowers were recorded. Vernalization, long days and warm temperatures hastened flowering but genotypes differed in relative sensitivity to each of these factors and in time to flowering in the same most-inductive environment. Rates of progress towards flowering (i.e. 1 f, the reciprocals of the times to first flower, f) in all genotypes, vernalized or not, were linear functions of both mean temperature, t ̄, and photoperiod, p, with no interaction between the two terms. So, over a wide range of conditions (covering the photo-thermal regimes experienced by lentil crops world-wide), time to flowering can be described by the equation: 1 f= a + b t ̄ + cp, where a, b and c are constants which differ between genotypes and the values of which provide a sound basis for screening germplasm for sensitivity to temperature and photoperiod. Although these two environmental factors affect the same phonological event (i.e. time to flowering) our data suggest the responses are under separate genetic control. Seed vernalization consistently increased the values of both a and b in all genotypes. The implications of these collective findings for the screening of lentil germplasm are discussed.
A method of recording germination curves by fitting the linear and the two non-linear parameters of a normal function to germination data is presented and applied to some data of Veronica arvensis L.
The germination data could be adequately described by this method. This method has been compared with orthogonal polynomial regressions.
Factorial combinations of two photoperiods (12 and 15 h), three day temperatures (20, 25 and 30 °C) and three night temperatures (10, 15 and 20 °C) were imposed on nodulated plants of nine chickpea genotypes (Cicer arietinum L.) grown in pots in growth cabinets. The times to first appearance of open flowers were recorded. For all genotypes, the rates of progress towards flowering (the reciprocals of the times taken to flower) were linear functions of mean temperature. There were no interactions between mean temperature and photoperiod but the longer photoperiod increased the rate of progress towards flowering. These effects were independent of both radiation integral (the product of irradiance and photoperiod) and the vegetative stature of the plant. Taken in conjunction with evidence from work on other long-day species, it is suggested that the photo-thermal response of flowering in chickpeas, over the range of environments normally experienced by the crop, may be described by the equation: 1/f = a+bi+cp in which f is the number of days from sowing to first flower, i is mean temperature and p is photoperiod. The values of the constants a, b and c vary between genotypes and provide the basis for screening genotypes for sensitivity to temperature and photoperiod.
Factorial combinations of four photoperiods (10 h, 11 h 40 min, 13 h 20 min and 15 h) and three night temperatures (14, 19 and 24 °C) combined with a single day temperature (30 °C) were imposed on nodulated plants of 11 cowpea accessions [ Vigna unguiculata (L) Walp.] grown in pots in growth cabinets. The times to first appearance of flower buds, open flowers and mature pods were recorded. Linear relationships were established between the reciprocal of the times taken to flower and both mean diurnal temperature and photoperiod. When the equations describing these two responses are solved, the time to flower in any given photothermal regime is predicted by whichever solution calls for the greater delay in flowering. Thus in different circumstances flowering is controlled exclusively by either mean temperature or photoperiod. The value of the critical photoperiod is temperature-dependent and a further equation, derived from the first two, predicts this relationship. Considered together as a quantitative model these relationships suggest simple field methods for screening genotypes to determine photo-thermal response surfaces.
Several models have been proposed to describe germination rates, but most are limited in statistical analysis and biological
meaning of indices. Therefore, a mathematical model is proposed to utilize the logistic function. The function was defined
as an overall response including time, temperature, and the interaction between time and temperature. Cumulative germination
percentages over time were used to develop the model.
Germination tests were conducted on indiangrass (Sorghastrum nutans (L.) Nash) strain ‘IG-2C-F1’, at constant temperatures of 9, 12, 15, 20, 25, and 30 °C. The function fitted the observed
data over six temperatures at r2 = 0.99. Time to reach 10% of final germination (Gt10) increased from 2.5 d at 30 °C to 44.0 d at 9 °C, and Gt50 (time to reach 50% of final germination) increased from 3.6 d at 30 °C to 53.8 d at 9 °C. True germination rate (% d−1) for each temperature was maximum at Gt50. A linear model of 1/Gt50 versus temperature was used to estimate the base temperature of 8.3 °C for germination. An Arrhenius plot indicated a change
occurred between 20 °C and 25 °C for temperature response of germination. Published data on hypocotyl growth of Cucumis melo L. were recalculated using the model. Absolute growth rates showed a temperature response similar to the published weighted-mean
elongation rates. Base temperature for hypocotyl growth of C. melo was estimated as 8.8 °C. The proposed model proved to be useful in calculating and interpreting germination and growth kinetics.
Two approaches to the study of germination data
- M A Nichols
- W Heydecker
NICHOLS, M. A., and HEYDECKER, W., 1968. Two approaches to the study of germination data. Proceedings of the International Seed Testing Association, 33, 531-40.
Temperature and leaf appearance in chickpea
- K H M Siddique
- C Marshall
- R H Sedgeley
SIDDIQUE, K. H. M., MARSHALL, C, and SEDGELEY, R. H., 1983. Temperature and leaf appearance in chickpea. International Chickpea Newsletter, 9, 14-15.
Eds) 1985a. Grain legume crops. Collins, London. 1985i>. Photo-thermal regulation of flowering in soyabean
- R J Summerfield
SUMMERFIELD, R. J., and ROBERTS, E. H., (Eds) 1985a. Grain legume crops. Collins, London. 1985i>. Photo-thermal regulation of flowering in soyabean. In Proceedings World Soyabean Research Conference. III. Ed. R. Shibles. Westview Press, Colorado. Pp. 848-57.