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The influence of temperature on seed germination rate in grain legumes: II. intraspecific variation in chickpea (Cicer arietinum L.) AT constant temperatures
Abstract
Positive linear relationships were shown between constant temperatures and the rates of progress of germination to different percentiles, G, for single populations of each of five genotypes of chickpea (Cicer anetinum L.). The base temperature, Tb, at which the rate of germination is zero, was 0·0°C for all germination percentiles of all genotypes. The optimum temperature, To(G), at which rate of germination is most rapid, varied between the five genotypes and also between percentiles within at least one population. Over the sub-optimal temperature range, i.e. from Tb to To(G), the distribution of thermal times within each population was normal. Consequently a single equation was applied to describe the influence of sub-optimal temperatures on rate of germination of all seeds within each population of each genotype. The precision with which optimum temperature, Tb(G), could be defined varied between populations. In each of three genotypes there was a negative linear relationship between temperature above Tb(G) and rate of germination. For all seeds within any of these three populations thermal time at supra-optimal temperatures was constant. Variation in the time taken to germinate at supra-optimal temperatures was a consequence of normal variation in the ceiling temperature, To(G)—the temperature at or above which rate of progress to germination percentile G is zero. A new approach to defining the response of seed germination rate to temperature is proposed for use in germplasm screening programmes.
In two populations final percentage germination was influenced by temperature. The optimum constant temperature for maximum final germination was between 10°C and 15°C in these populations; approximately 15°C cooler than the optimum temperature for rate of germination. It is suggested that laboratory tests of chickpea germination should be carried out at temperatures between 10°C and 15°C.
... The literature describing temperature and sowing depth effects on seedling emergence in chickpea is scarce, but there are some studies on germination in laboratory. Covell et al. (1986) and Ellis et al. (1986) reported a base temperature of 0 8C, an optimum temperature of 25-33 8C and a ceiling temperature of 48-61 8C for germination in six chickpea genotypes. Auld et al. (1988) studied laboratory germination and radicle elongation of 10 chickpea lines at 5, 13 and 20 8C and reported that the highest germination and radicle elongation occurred at 20 8C. ...
... Ceiling temperature was fixed at 40 8C findings of other researchers where the segmented function adequately described the response of germination, leaf appearance and development rate to temperature in different crops (e.g., Olsen et al., 1993;Mwale et al., 1994;Robertson et al., 2002). Covell et al. (1986) and Ellis et al. (1986) used a segmented function to determine cardinal temperatures for germination of chickpea. Various temperature response curves have been used to describe the effect of temperature on crop development and growth process. ...
... Base temperature (4.5 8C) obtained in this study for emergence was significantly higher than that found by Covell et al. (1986) and Ellis et al. (1986) for germination of chickpea (0 8C) and that found by Siddique and Sedgley (1986) for leaf appearance of chickpea in the field. It may be necessary for cardinal temperatures to change depending on phenological stage (Ritchie and NeSmith, 1991). ...
Quantitative information about temperature and sowing depth effects on seedling emergence in chickpea (Cicer arietinum L.) is scarce. The main objective of this study was to develop a seedling emergence model for chickpea. To do this, a field experiment with a range of sowing dates and a pot experiment were conducted to determine cardinal temperatures and physiological days (i.e., number of days under optimum temperatures) required for seedling emergence, and to quantify the response of seedling emergence to sowing depth. In the field experiment, four chickpea cultivars were sown at 11 dates and time to emergence and emergence percentage were evaluated. Sowing depth was 5 cm. Several linear and non-linear functions were used to describe the relationship between emergence rate and temperature. The pot experiment was conducted in a controlled-temperature room (21 AE 1 8C) using five sowing depths (2.5-14 cm). Results showed that the response of chickpea emergence to temperature is best described by a dent-like function with cardinal temperatures of 4.5 8C for base, 20.2 8C for lower optimum, 29.3 8C for upper optimum and 40 8C for ceiling temperature. Six physiological days (equivalent to a thermal time of 94 8C days) was required from sowing to emergence at a sowing depth of 5 cm. The physiological days requirement increased by 0.9 days for each centimetre increase in sowing depth. Based on the results from the field and pot experiments, a seedling emergence model was constructed. This model successfully simulated emergence date (range 4-140 days) in spring, winter and 'dormant' sowing dates across Iran. Using an example for North West Iran, it was shown how this model could be used to optimise sowing management, including the local 'dormant sowing' practice, whereby the crop is sown prior to winter for early emergence in the following spring. #
... Several indices have been used to calculate temperature thresholds, including the inverse of time to reach 50% germination (1/D 50 ), percent germination per day, the final germination percent, and various rate indices Wiese and Binning, 1987;Holt and Orcutt, 1996;Cave et al., 2011;Mijani et al., 2017). Among which, 1/ D 50 is a widely used and recommended one (Alvarado and Bradford, 2002;Ellis et al., 1986;Hardegree et al., 2008;Soltani et al., 2006). ...
... Despite the agreement among researchers on 1/D 50 , many studies have proved its weakness in the actual calculation of the temperature thresholds (Wiese and Binning, 1987;Holt and Orcutt, 1996;Cave et al., 2011;Mijani et al., 2017). The thermal time model based on the normal distribution is also commonly used to predict the seed germination progress over a wide range of temperatures Ellis et al., 1986), and applied to the release of seed dormancy (Wang et al., 2009). This model assumes the same cardinal temperatures based on both the final germination (germination percent) and its rate. ...
... to develop a thermal time model that fitted all the datasets together simultaneously and predicted the temperature thresholds. These are mostly based on the germination rate (D 50 −1 , the inverse of the time to reach 50 percent of final germination) (Alvarado and Bradford, 2002;Ellis et al., 1986). Since the D 50 could not be estimated by both models, we were not able to calculate the D 50 −1 . ...
Tubers are the main means of propagation in purple nutsedge (Cyperus rotundus L.), one of the most troublesome weeds competing in crop and pasture systems throughout the world. Tuber sprouting is highly linked to temperature, the main environmental factor limiting the growth of purple nutsedge. In the present study, a new thermal time model was developed for describing the temperature-dependent tuber sprouting of purple nutsedge. This model was validated based on results from a laboratory tuber sprouting experiment performed under different temperature regimes. The proposed model is an integration of three equations comprising those of Gompertz, Dent like, and Segmented (GDS) functions, developed for describing cumulative sprouting, final sprouting and sprouting rate of purple nutsedge tubers respectively. The Gompertz-based model fitted the data well (R² = 0.94, RMSE %< 10). This model was also able to predict lag time (time up to start of sprouting), final sprouting and sprouting rate. A Weibull-based model was only able to estimate temperature thresholds based on the final sprouting. Whereas, the GDS model predicted related temperature thresholds according to both final sprouting (optimal in the range of 20.31–29.72°C) and the absolute sprouting rate (optimum at 29.96°C). In conclusion, the proposed model is simple and includes parameters of a biological significance, simultaneously generating estimates of useful temperature thresholds and fitting cumulative tuber sprouting of purple nutsedge. Our study has also proved the superiority of the absolute sprouting rate index when calculating the temperature thresholds.
... The thermal time model that we propose here accurately explained the germination dynamics of both seed types of wild mustard in response to T over sub-and supraoptimal ranges. The Weibull-based thermal time model that we introduced in this paper not only inherited the useful attributes of others (Garcia-Huidobro et al. 1982;Covell et al. 1986;Ellis et al. 1986;Hardegree 2006;del Monte et al. 2014), but also included some additional features as discussed below. ...
... If the germination percentage of the seed population is less than 100% for any reason, the fitting of the conventional model to the data are inevitably possible only by applying a correction factor and consequently ignoring the fraction of dormant or dead seeds (e.g., Covell et al. 1986;Ellis et al. 1986;del Monte and Tarquis 1997;Brown and Mayer 1988). The thermal time model proposed in this study, unlike the conventional model, can be used under circumstances where the germination percentage decreases to different levels due to poor quality, dormancy, or seed treatments. ...
... Another advantage of the model presented in this study is that it describes changes in both percentage and rate of germination with temperature; whereas, for example, nonlinear regression models are fitted only to the germination rate data without considering the effect of temperature on final germination (e.g., Kamkar et al. 2012;Derakhshan et al. 2014). In this study, the optimum temperature was estimated as a parameter of the model through the thermal time model fitting procedure, while in almost all previous studies (e.g., Covell et al. 1986;Ellis et al. 1986;Hardegree 2006;del Monte et al. 2014;Derakhshan et al. 2018), it has been guessed or inferred from a separate analysis outside the thermal time framework. In the current study, the relationship of germination rate with temperature appeared curved around optimum temperature, which is in agreement with the results obtained from studies on other species such as carrot (Daucus carota) and onion (Allium cepa) (Rowse and Finch-Savage 2003), sesame (Sesamum indicum) (Bakhshandeh et al. 2017), and cantaloupe (Cucumis melo) and radish (Raphanus sativus) (Bakhshandeh and Gholamhossieni 2019). ...
Wild mustard (Sinapis arvensis L.) is well-known as a serious weed of cultivated land, particularly in cereal crops. It produces large amounts of heteromorphic (black and brown) seeds. This study aimed to estimate the critical temperature thresholds of wild mustard heteromorphic seeds. For this purpose, a novel Weibull-based thermal time model was developed, which was applied to compare the germination characteristics of the heteromorphic seeds of wild mustard. Germination was investigated by exposing the seeds to eight constant temperatures of 7.5, 10, 15, 20, 25, 30, 35, and 37.5 °C. Over both the sub- and supra-optimal ranges, the proposed model reasonably explained the germination patterns of both seed types in response to temperature. Heteromorphic seeds of wild mustard exhibited different germination behaviors in response to temperature. Brown seeds were more cold-tolerant and could germinate rapidly to a high percentage (68%) in a wider range of temperature environments (2.78-38.05 °C); black seeds germinated at a narrower temperature range (4.99-37.97 °C), and a large proportion of seeds remained dormant (77%). These differences can lead to the temporal distribution of seed germination throughout the growing season.
... The concentrations of the undiluted inoculums (0:5) were 6,392,000 (K), 132,472 (L), 467,814 (M), 2,980,000 (N), and 8,180,000 (O) CFU/mL. After the experiment, the following germinability parameters were calculated using the standard formulas below (Ellis et al. 1986;Abdul-Baki and Anderson 1973;AOSA, 1991;Salehzade et al. 2009 (Ellis et al. 1986) • Where f is the number of seeds germinated on day x • Germination index (GIX) = (8 × N1) + (7 × N2) +(6 × N3) + ⋯ + (1 × N8) (Salehzade et al. 2009) Where N1 , N2, N3…N8 represent the number of seeds that germinated on the first, second, third until the eighth day and 8, 9, 7, …1 are the weights given to the number of germinated seeds on the first, second, third day up to the eighth day. ...
... The concentrations of the undiluted inoculums (0:5) were 6,392,000 (K), 132,472 (L), 467,814 (M), 2,980,000 (N), and 8,180,000 (O) CFU/mL. After the experiment, the following germinability parameters were calculated using the standard formulas below (Ellis et al. 1986;Abdul-Baki and Anderson 1973;AOSA, 1991;Salehzade et al. 2009 (Ellis et al. 1986) • Where f is the number of seeds germinated on day x • Germination index (GIX) = (8 × N1) + (7 × N2) +(6 × N3) + ⋯ + (1 × N8) (Salehzade et al. 2009) Where N1 , N2, N3…N8 represent the number of seeds that germinated on the first, second, third until the eighth day and 8, 9, 7, …1 are the weights given to the number of germinated seeds on the first, second, third day up to the eighth day. ...
The expected increase in agrochemical usage as a result of the projected increase in the world’s population in the coming years will further raise the specter of environmental damage and health challenges. This study aimed to evaluate the effects of steeping duration and initial inoculum concentration sequentially on the growth promotion potential of some bacterial species viz-a-viz five economic crops (cowpea, soybean, sorghum, sesame, and okra) in Nigeria. For the steeping-duration experiment, the different surface-sterilized seeds were steeped for increasing durations (1, 2, 3, 4, and 5 h) in broth cultures of five rhizobacterial isolates: Serratia liquefaciens, (OP830504), S. liquefaciens (OP830503), Providencia rettgeri (OP830491), P. rettgeri (OP830498), and Bacillus cereus (OP830501). The seeds were planted in transparent containers that contained blotters and incubated for 8 days. Similarly, the experiment for inoculum concentration was carried out using different initial bacterial concentrations (4:1, 3:2, 2:3, 1:4, and 0:5 water dilutions). At the end of both experiments, final germination percentage, mean germination time, germination index, and vigor index were estimated. Although, results showed that optimal steeping duration was largely restricted to 1, 2, or 3 h, especially for final germination percentage and seedling vigor index, no consistent trend was observed between concentration of inoculum used for treatment and the germinability parameters measured. This study highlights the general adequacy of a short steeping duration under low initial inoculum concentration for biopriming experiments involving the use of bacterial inoculums.
... Nano-fertilizers can increase the effectiveness of nutrient use three-fold, as well as provide improved stress resistance [2]. The rate of germination is affected by environmental factors such as abiotic stress, including draught, low temperatures [3], salination [4], and heavy metal toxicity [5]. Many researchers have also studied the impact of nanoparticles on the germination and growth of plants with a view to promoting the use of such compounds in agriculture [6]. ...
... Grupa IHAR Seed Plant, were used in the experiments. Nanomaterials for the laboratory and field experiments were obtained in the form of two commercially available compounds, sold in 1 dm 3 bottles containing nanosilver and nanocopper colloids concentrated at ≥0.1% silver (ITP-1KAg PO) and ≥0.1% copper (ITP-1KCu PO), respectively, marketed by ITP-SYSTEM Sp. z o.o. from Dąbrowa Górnicza. ...
The present study focuses on the impact of copper and silver nanoparticles on the chemical composition and physical properties of rapeseeds and rape sprouts. The seeds and sprouts were obtained from winter rape grown in a three-year cultivation (2018–2020) treated with silver (AgNP) and copper (CuNP) nanoparticles. In addition, the effect of the freeze-drying temperature (20; 40; 60 °C) on selected properties of the sprouts was studied. Spraying growing plants with nanoparticles resulted, in most cases, and depending on the year, in a reduction in the mass of seeds (MTS) by 9.5% (single nanoparticles spray ×1 CuNP in 2018), an increase in the fat content (by 8.80% for ×1 CuNP in 2018), a reduction in the protein content (by 12.93% for ×1 CuNP in 2018) and flavonoid content (by up to 58% for ×1 AgNP and CuNP in 2018), as well as increase in the glucosinolates content by 25% (for double nanoparticles spray ×2 AgNP in 2019). For the sprouts obtained from the rapeseeds, in most cases, a decrease in the content of flavonoids was observed (26.68% for ×1 AgNP; 20 °C in 2018), depending on the year of cultivation, the nanoparticles used, and the drying temperature. The obtained results remain inconclusive, which encourages the authors to undertake further research.
... 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]. ...
... The value of T c (50) able to get from the regression of the time when g = 50% and probit (g) = 0. θ T was evaluated by the iterative method. The θ T produced the least residual was considered to be the best estimate of θ T [31]. For hydro time model [45,46]. ...
... Although chickpea has a wide temperature range for germination, it has been reported that it cannot germinate above 45°C [108]. There are many different ranges such as 10°C-15°C [109] and 28°C-33°C [110] at optimum temperatures for seed germination. In addition, it was found that chickpea could germinate between about 32°C and 34°C [111]. ...
... Chickpea is grown in tropical, subtropical, and temperate regions, and has developed sensitivity to low temperature during the cultivation process involved in agricultural selection [44,136]. The optimum temperature demand for chickpea in early vegetative stages ranges from 21°C to 32°C, and the optimum temperature demand in flowering stages ranges from 18°C to 29°C [109,124,137]. ...
Chickpea, a cool-season legume is the major source of protein specifically for people in developing countries. In modern chickpea, domestication and subsequent breeding are the major bottlenecks for the reduction of genetic diversity. The reduction in the trait variation, generate the necessity to find the genetic diversity of the wild relatives to develop the climate-resilient crop. Abiotic stresses, namely, drought, heat, cold, and salinity, enhanced by climate change have been significantly affecting the chickpea yield and production. These major barriers affecting the productivity of chickpea are forecasted to be unpredictable stressors due to climate change in years to come. In this context, various studies had been reported to evaluate the potential of wild Cicer species against different abiotic stress. These studies have demonstrated the presence of considerable genetic diversity among Cicer wild species for tolerance against abiotic and biotic stresses. The presence of a rich repository for traits conferring resistance to stresses in wild Cicer species can be exploited through wide hybridization. The resulting transgressive segregations present in the pre-breeding populations can be used for the development of trait-specific stress-tolerant chickpea genotypes. In this chapter, we have reviewed environmental stresses hampered on the yield of chickpea and updated potential hidden resources of resistance to these stressors to improve climate-resilient chickpea varieties.
... • Final germination percentage (FGP) = total number of germinated seeds/total number of seeds sownÂ100% 30 • Mean germination time (MGT) = ∑fxf 31 Where f is the number of seeds germinated on day x ...
Seed priming enhances germination and growth, which are important determinants of crop yield. This study was carried out to assess the effect of priming duration and metabolite concentration on the priming of five (5) different crops, using the metabolites of five (5) bacterial isolates. The crop seeds were treated in the cold-extracted metabolites of the five isolates at five (5) different priming durations (1, 2, 3, 4, and 5 h) and then in five metabolite concentrations (200, 400, 600, 800, and 1000 mg/L) of the five extracted metabolites at the optimal priming duration determined in the first experiment. Characterization of the cold-extracted metabolites was also carried out using gas-chromatography-mass spectrometry (GC-MS). Results revealed that priming cowpea and soybean for longer durations (< 3 h) could hinder their growth and development. Lower concentrations were observed to be optimal for cowpea and soybean, but for sesame and okra, there was no detectable pattern with metabolite concentration. The GC-MS revealed the presence of some molecules (e.g. hexadecanoic acid) that have shown plant growth promotion potential in other studies. This study showed that seeds with large endosperm, such as, cowpea and soybean, are more prone to the deleterious effects of treatment for longer durations. Further experiments should be carried out to isolate and purify the bioactive moieties for further studies and onward application.
... Chickpea genotypes exhibit varying thermo-tolerance i.e., up to 45 ˚C, during seed germination [7], with optimum temperatures ranging from 10 °C to 33 °C [8,9]. High temperatures can lead to reduced pollen viability, pod abortion, and low seed filling [10][11][12]. ...
Background
Chickpea is prone to many abiotic stresses such as heat, drought, salinity, etc. which cause severe loss in yield. Tolerance towards these stresses is quantitative in nature and many studies have been done to map the loci influencing these traits in different populations using different markers. This study is an attempt to meta-analyse those reported loci projected over a high-density consensus map to provide a more accurate information on the regions influencing heat, drought, cold and salinity tolerance in chickpea.
Results
A meta-analysis of QTL reported to be responsible for tolerance to drought, heat, cold and salinity stress tolerance in chickpeas was done. A total of 1512 QTL responsible for the concerned abiotic stress tolerance were collected from literature, of which 1189 were projected on a chickpea consensus genetic map. The QTL meta-analysis predicted 59 MQTL spread over all 8 chromosomes, responsible for these 4 kinds of abiotic stress tolerance in chickpea. The physical locations of 23 MQTL were validated by various marker-trait associations and genome-wide association studies. Out of these reported MQTL, CaMQAST1.1, CaMQAST4.1, CaMQAST4.4, CaMQAST7.8, and CaMQAST8.2 were suggested to be useful for different breeding approaches as they were responsible for high per cent variance explained (PVE), had small intervals and encompassed a large number of originally reported QTL. Many putative candidate genes that might be responsible for directly or indirectly conferring abiotic stress tolerance were identified in the region covered by 4 major MQTL- CaMQAST1.1, CaMQAST4.4, CaMQAST7.7, and CaMQAST6.4, such as heat shock proteins, auxin and gibberellin response factors, etc.
Conclusion
The results of this study should be useful for the breeders and researchers to develop new chickpea varieties which are tolerant to drought, heat, cold, and salinity stresses.
... Once cotyledons appeared, the number of germinated seeds was counted every 24 h for seven days. The seed germination percentage was calculated as the total number of seeds germinated over the seven day period/total number of seed planted × 100% (Ellis et al. 1986). Four-week-old WT and OE1 seedlings were stressed using 100 mM NaCl. ...
This study may enhance our understanding of AvFLS function in plants under salt stress and may provide a new tool for the improvement of plant salt tolerance in the field. We isolated and identified AvFLS from Apocynum venetum. To further characterize the potential role of AvFLS in salt tolerance and to explore the relationship between FLS and salt resistance, we generated transgenic Arabidopsis lines overexpressing AvFLS. Tissue-specific expression analysis and salt-stress experiments identified AvFLS as a salt-inducible gene that is highly expressed in leaves of A. venetum. Subcellular localization analysis showed that AvFLS was located in the cytoplasm, consistent with other plant FLS proteins.The overexpression of AvFLS in Arabidopsis thaliana significantly improved the salt-stress tolerance of the transgenic plants: under salt stress, transgenic Arabidopsis exhibited improved flavonoid accumulation, seed germination rate, plant growth, chlorophyll content, and fresh weight compared to wild-type plants. Comparison of malonaldehyde (MDA), soluble sugar, and proline contents between the transgenic and wild-type plants indicated that the improved salt tolerance associated with AvFLS overexpression was due to decreased membrane damage. AvFLS overexpression also led to the upregulation of endogenous Arabidopsis genes involved in flavonoid biosynthesis. The results of this study demonstrate the potential utility of the AvFLS gene for molecular crop breeding, both to increase the contents of valuable flavonoids and to improve crop productivity in saline fields.
... Temperaturas do ar abaixo de 4,5 °C normalmente não permitem germinação das sementes. A taxa máxima de germinação tende a ocorrer na faixa de 25 °C a 35 °C, dependendo do genótipo (Ellis et al., 1986). Cubero (1987) afirma que o intervalo de temperatura do ar entre 28 °C e 33 °C é o ideal para a germinação de grão-de-bico. ...
... To estimate the cardinal temperatures using a dent-like model, the following equation was used (Ellis et al., 1986). ...
Seed germination is a crucial stage in the life cycle of plants. It determines their growth and reproduction success. Temperature is one of the most important environmental factors that affect seed germination. This research aimed to estimate the cardinal temperatures and the thermal time requirement for seed germination. The effects of different temperature levels were evaluated on the germination characteristics of tomatoes (Lycopersicon esculentum cv. 'Early CH'). An experiment was conducted using a completely randomized design with four replications and seven temperature levels, i.e. 5, 10, 15, 20, 25, 30, and 35 ° C. The relationship between germination rate and temperature was described and the cardinal temperatures for the seed germination of tomato (cv. 'Early CH') were calculated. Four regression models were used: segmented, dent-like, original beta, and modified beta. The highest germination percentage (81-86%) and vigor index (4.04-5.47 cm) were similarly obtained in the 20-30 °C range. The highest germination rate (5/7 seeds per day) was observed at 25 °C. The lowest mean germination time (4.5-4.84 days) occurred in the 20-25 °C range. Germination characteristics were significantly different when the temperature increased above 30 °C. While measuring the regression models, the segmented model was best for estimating the cardinal temperature of this cultivar. In general, cardinal temperatures for seed germination were estimated using a superior regression model for minimum (0.5-3 °C), optimal (25-26 °C), and maximum (35.4-40 °C) temperatures. Additionally, the thermal time model accurately predicted the seed germination process (R2 = 0.90). The amount of thermal time to achieve 50% germination in this cultivar was estimated at 1848.29 degree-hours.
... Seed germinated count was taken after 8 days from plated date and expressed as percentage according to the following equation [25]. ...
In order to investigate the effects of drought stress, exogenous hormones on germination components of Cicer areitinum L., a laboratory experiment was conducted in a factorial randomized design with three replications. Cicer is a major legume crop of Himalaya. During the present investigation the seeds collected from 1450masl altitude of Himachal Pradesh and were subjected to three levels (4%, 8% and 16%) of polyethylene glycol (PEG-6000) and five conditions of exogenous hormones (IAA and GA3) Hormones were applied to drought stressed Cicer seed samples in order to alleviate the drought stress, germination percentage, root length were evaluated after the 16 days of germination test. The results showed that the rate of germination decreases as the level of drought was increased. Application of hormones increased the rate of germination and other factors in comparison to control condition. The results of present study demonstrate the role of hormones in alleviation of PEG imposed drought stress in Cicer areitinum seedlings.
... The first segment of the regression in the sub-optimal range was used to estimate the x-intercept of each regression line, i.e., base temperature or Tb, while for the supra-optimal range the second segment was used to estimate the x-intercept, i.e., ceiling temperature or Tc [27]. An average of the x-intercept among fractions in the sub-optimal and supra-optimal temperature range was calculated to establish the Tb and Tc [93]. Parameters for 10-40% only were obtained with these models, due to the few available points of 50-80% percentiles at supra-optimal range to perform the respective regressions (at least five experimental data points). ...
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.
... Studies conducted by Gracia-Huidobro et al in (1982) and Schimpf et al. (1977) reported positive correlation of germination rate and percentage with temperature up to an optimum. After this point, the rate of germination decreases at maximum temperature to zero (Ellis et al., 1986). The effect of a specific environmental factor on germination is commonly characterized by a sigmoidal curve, relating the germination percentage to time and quantified by standard normal distribution (Janssen, 1973). ...
... The base temperature is the minimum threshold temperature below which plant development stops. The base temperature in chickpeas is considered 0 • C [45]. ...
Heat-related traits in chickpea (Cicer arietinum L.) play a crucial role in reducing the harmful effect of heat stress, as the increase in heat stress is predicted to occur in the coming years due to global warming as a result of climate change. The advantage of multiple pods per peduncle and compound (imparipinnate) leaf traits in kabuli chickpea has not been properly revealed under heat stress conditions. We, therefore, want (i) to provide insight into the advantage of multiple pods and compound leaf traits over single pod per node and simple (unifoliolate) leaf traits, and (ii) to determine the highest direct and indirect effects of agro-morphological traits on seed yield in chickpeas under rainfed conditions with prevailing heat stress. With a delayed sowing time, the plants were subjected to heat stress of more than 43 °C in flowering and pod setting stages under field conditions. According to the number of pods per node and leaf shape, plants were evaluated for yield and yield components, and were divided into six groups, namely (i) single-pod and compound leaf, (ii) single-pod and simple leaf, (iii) double-pods and compound leaf, (iv) double-pods and simple leaf, (v) multi-pods and compound leaf, and (vi) multi-pods and simple leaf. Plants with multi-pods and compound leaf traits had the highest seed yield, followed by plants with double-pods and compound leaf, while plants with single-pod and simple leaf had the lowest yield. The number of seeds and pods per plant, 100-seed weight, and leaf shape were the highest determinants of seed yield under heat stress conditions. It was concluded that multi-pods per peduncle and compound leaf traits had an obviously incontrovertible advantage in kabuli chickpeas under heat stress conditions. The plant shapes that nature has evolved for millions of years, which are mostly found in wild plants, have been proven by the current study to have a better fitness ability than plants shaped by human hands.
... The seed germination and seedling establishment of white clover might be highly correlated to soil and climatic conditions at time of planting. This has been demonstrated in many other legume species, such as chickpea (Cicer arietinum L.) [16], red clover (Trifolium pratense L.) [17,18], and yellow sweet clover (Melilotus officinalis L.) [19]. ...
White clover (Trifolium repens L.) is cultivated as a forage crop and planted in various landscapes for soil conservation. There are numerous reports of failed white clover stands each year. A good understanding of the seed germination biology of white clover in relation to environmental factors is essential to achieve successful stand establishment. A series of experiments were conducted to investigate the impacts of light, temperature, planting depth, drought, and salt stress on seed germination and the emergence of white clover. White clover is negatively photoblastic, and seed germination averaged 63 and 66% under light and complete dark conditions 4 weeks after planting (WAP), respectively. Temperature affected the seed germination speed and rate. At 1 WAP, seeds incubated at 15 to 25 °C demonstrated a significantly higher germination rate than the low temperatures at 5 and 10 °C; however, the germination rate did not differ among the temperature treatments at 4 WAP. The results suggest that white clover germination decreases with increasing sowing depths, and the seeds should be sown on the soil surface or shallowly buried at a depth ≤1 cm to achieve an optimal emergence. White clover seeds exhibited high sensitivity to drought and salinity stress. The osmotic potential and NaCl concentration required to inhibit 50% seed germination were −0.19 MPa and 62.4 mM, respectively. Overall, these findings provide quantifiable explanations for inconsistent establishment observed in field conditions. The results obtained in this research can be used to develop effective planting strategies and support the successful establishment of white clover stands.
... Tb is the intercept point of a positive linear regression obtained when plotting the inverse time to germination as a function of temperature and it determines the sub-optimal range of temperatures. Following Ellis et al. [70] a linear regression was calculated to obtain the parameters for each germination percentage. The mean value of x-intercept (β0) was calculated and used to generate a second linear regression for each percentile. ...
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.
... 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. ...
... The germination of chickpea, starts the growth process of a quiescent or dormant embryo, and is evidenced by the growth of the embryonic axis (de Rueda et al., 1994). In chickpea, 0 0 C has been proposed to be the base temperature for germination (Singh and Dahliwal, 1972;Siddique et al., 1983;Ellis et al., 1986;Calcagno and Gallo, 1993). Thus, in freezing soils, chickpea will not germinate. ...
Chickpea is the third major cool season grain legume crop in the world after dry bean
and field pea. Chickpea faces various abiotic stresses during its life cycle such as
drought, cold, terminal heat and salinity. Cold temperature stress represents a major
limiting factor in chickpea production. The reproductive stage represents the most
vulnerable phase within where plenty of damaging events may take place, such as, the
juvenile buds drop, aborted pods, reduced pollen viability and stigma receptivity,
inhibited pollen tube growth and ultimately, deteriorated seed quality and seed yield.
So also the rise in temperature beyond certain optimum level is detrimental to the crop
growth causing severe injuries that are collectively termed as ‘heat stress’. Being a cool
season crop, chickpea also susceptible to high temperature (30–35°) for few days at
flowering stage and can cause substantial yield loss. Both high and low temperature
stresses cause grain yield loss. Recent chickpea breeding programmes targeting both
high and low temperature stresses have been initiated by many countries including
India, with global centres such as ICARDA and ICRISAT supporting the wider effort
through the characterization and exploitation of genetic resources. Screening for
tolerance to temperature stresses has identified many promising sources of tolerance to
both high and low temperature in chickpea. This review provides a comprehensive
account of the current information regarding the effects of high and low temperature
stress to chickpea. Future research directed toward understanding the mechanisms
involved in cold and heat tolerance of chickpea is also suggested.
... Posteriormente, se ejecutó la regresión lineal para obtener los parámetros de cada percentil de germinación (Ellis et al., 1986). Se calculó el valor medio de la intercepción x (β 0 ) y se utilizó para ejecutar una segunda regresión lineal de cada percentil de germinación, se obtuvo otra β 0 , el promedio de ambos valores representó la temperatura base de germinación para cada variedad de quinoa. ...
The effect of ten temperatures (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 °C) on germination of Chenopodium quinoa Suyana and Tunkahuan was evaluated. The seeds of each variety were harvested during the spring-summer 2017 cycle in Texcoco, state of Mexico and donated for this research in February 2019. The experimental units were 100 x 15 mm Petri dishes, with two double discs of absorbent paper moistened with 5 mL of distilled water, and 100 seeds of Suyana or Tunkahuan. The treatments with five replicates were each one of the temperatures. For germination, five experimental units of each variety were placed into incubators under total darkness, adjusted to the mentioned temperatures ± 0.5 °C. The following parameters were evaluated: total germination, germination rate, average germination (t50) and cardinal temperatures. In the Tunkahuan variety, germination higher than 90 % occurred between 5 and 40 °C, whereas in Suyana it occurred between 15 and 35 °C. Germination rate was higher in Suyana than in Tunkahuan and it occurred between 30 and 40 °C. The t50 value was obtained in less time in Tunkahuan (7.1 h) than in Suyana (8.1 h). Basal, optimum and maximum temperatures were: 2.3 and 1.8; 30.2 and 33.2; 48.8 and 62.2 °C for Suyana and Tunkahuan, respectively. In conclusion, Tunkahuan seeds germinated successfully in a wider range of temperatures, which could improve their establishment in arid and warm areas.
... A factorial arranged completely randomized design with three replications was used to assess the impact of the priming treatments through key assessment parameters (Table 3). n is the number of seeds germinated on each day counted, whilst D is the day of counting n. [26] Root Vigor Index RVI RVI = RL × GP RL is the root length (cm), and GP is the germination percentage. ...
Agriculture in Mali, a country in Sahelian West Africa, strongly depends on rainfall and concurrently has a low adaptive capacity, making it consequently one of the most vulnerable regions to climate change worldwide. Since early-season drought limits crop germination, and hence growth, ultimately yield during rain-fed depending on production is commonly experienced nowadays in Mali. Germination and establishment of key crops such as the staple sorghum could be improved by seed priming. The effects of hydro-priming with different water sources (e.g., distilled, tap, rain, river, well water) were evaluated respectively for three priming time durations in tepid e.g., at 25 °C (4, 8, and 12 h) and by hot water at 70 °C (in contrast to 10, 20, and 30 min.) in 2014 and 2015. Seed germination and seedling development of nine sorghum genotypes were monitored. Compared to non-primed seed treatments, hydro-priming significantly [p = 0.01] improved final germination percentage, germination rate index, total seedling length, root length, root vigor index, shoot length, and seedling dry weight. The priming with water from wells and rivers resulted in significant higher seed germination (85%) and seedling development, compared to the three other sources of water. Seed germination rate, uniformity, and speed were enhanced by hydro-priming also. It is argued that hydro-priming is a safe and simple method that effectively improve seed germination and seedling development of sorghum. If used in crop fields, the above most promising genotypes may contribute to managing early season drought and avoid failure of seed germination and crop failure in high climate variability contexts.
... Many studies have found that the germination rate (GR g , the reciprocal of time to a given germination fraction, 1/t g ) is linearly related to temperature (Gummerson, 1986;Bradford, 2002;Hardegree, 2006;Hu et al., 2015;Felipe Daibes and Cardoso, 2018;Carhuancho León et al., 2020;Zhang et al., 2020). Thus, the thermal time model has been developed to evaluate the effect of temperature on progress towards germination Ellis et al., 1986;Gummerson, 1986;Allen et al., 2000;Bradford, 2002). In this model, several parameters were fitted and used to quantify temperature requirements for seed germination, such as the cardinal temperatures (T b , T o and T c ) and thermal time (θ T , the thermal time required to reach the germination requirement of individual seeds in the population) (Bradford, 2002;Hu et al., 2015;Saberali and Shirmohamadi-Aliakbarkhani, 2020;Zhang et al., 2020). ...
Thermal time models have been widely applied to predict temperature requirements for seed germination. Generally, a log-normal distribution for thermal time [θ T(g) ] is used in such models at suboptimal temperatures to examine the variation in time to germination arising from variation in θ T(g) within a seed population. Recently, additional distribution functions have been used in thermal time models to predict seed germination dynamics. However, the most suitable kind of the distribution function to use in thermal time models, especially at suboptimal temperatures, has not been determined. Five distributions (log-normal, Gumbel, logistic, Weibull and log-logistic) were used in thermal time models over a range of temperatures to fit the germination data for 15 species. The results showed that a more flexible model with the log-logistic distribution, rather than the log-normal distribution, provided the best explanation of θ T(g) variation in 13 species at suboptimal temperatures. Thus, at least at suboptimal temperatures, the log-logistic distribution is an appropriate candidate among the five distributions used in this study. Therefore, the distribution of parameters [θ T(g) ] should be considered when using thermal time models to prevent large deviations; furthermore, an appropriate equation should be selected before using such a model to make predictions.
... In fact, there is a minimum ('base temperature', T b ) and a maximum temperature ('ceiling temperature', T c ) between which germination occurs and an optimal temperature (T o ) at which it occurs at the highest speed (Dürr et al., 2015). Many models of the response to temperature in crops (Garcia-Huidobro et al., 1982;Covell et al., 1986;Ellis et al., 1986;Dürr et al., 2015) and wild species (Pritchard and Manger, 1990;Seal et al., 2017;Tudela-Isanta et al., 2018) have been developed using the cardinal temperatures. T b , in particular, is a distinctive species trait (Dürr et al., 2015). ...
The influence of temperature and water availability on seed germination can vary across the geographic range of species with a large distribution. Betula pendula is a widely spread European tree that has differentiated into two narrowly distributed taxa, endemic to Mediterranean mountains: Betula aetnensis in Sicily and B. fontqueri in Spain and Morocco. We tested the hypothesis that the regeneration niche, expressed by temperature and water potential thresholds, varies across these species and is influenced by the local climate. Seeds were collected from six populations of B. pendula , one of B. fontqueri and two of B. aetnensis . Germination tests were conducted between 5 and 30°C. The thermal thresholds were calculated before and after cold stratification. The osmotic potential tested ranged from 0 to −1.5 MPa. Time to reach 30 and 50% of germination was calculated by fitting non-linear models. Germination was promoted by high temperatures, but the response to stratification was heterogeneous. T b and Ψ b differed between and within species. T b ranged between 2.22 and 8.94°C for unstratified seeds. Mediterranean species had higher drought tolerance, while B. pendula showed contrasting responses to low water potential. Ψ b reached a minimum value of −1.15 MPa in B. fontqueri . High temperatures influenced the T b of unstratified seeds negatively, while, after stratification, the T b increased with precipitation in the driest month. The heterogeneity observed could reflect higher genetic variability in marginal populations of silver birch. Knowledge of their germination ecology may be useful to mitigate future impacts of climate change on core populations of B. pendula .
Seed priming enhances germination and growth, which are important determinants of crop yield. This study was carried out to assess the effect of steeping duration and metabolite concentration on the priming of five (5) different crops, using the metabolites of five (5) bacterial isolates. The crop seeds were treated in the cold-extracted metabolites of the five isolates at five (5) different steeping durations (1, 2, 3, 4, and 5 h) and then in five metabolite concentrations (200, 400, 600, 800, and 1000 mg/L) of the five extracted metabolites at the optimal steeping duration determined in the first experiment. Characterization of the cold-extracted metabolites was also carried out using gas-chromatography-mass spectrometry (GC-MS). Results revealed that steeping cowpea and soybean for longer durations (< 3 h) could hinder their growth and development. Lower concentrations were observed to be optimal for cowpea and soybean, but for sesame and okra, there was no detectable pattern with metabolite concentration. The GC-MS revealed the presence of some molecules (e.g. hexadecanoic acid) that have shown plant growth promotion potential in other studies. This study showed that seeds with large endosperm, such as, cowpea and soybean, are more prone to the deleterious effects of treatment for longer durations. Further experiments should be carried out to isolate and purify the bioactive moieties for further studies and onward application.
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.
Aims
Seed priming represents a viable, low-cost approach to improving germination and plant growth. This study aimed to assess the effects of steeping duration and inoculum concentration of seed crops on germinability enhancement of seed primed in cultures of Bacillus species from rhizospheres. The seeds used were cowpea (Vigna unguiculata), soya bean (Glycine max), sorghum (Sorghum bicolor), sesame (Sesamum indicum), and okra (Abelmoschus esculentus).
Methods
A total of five Bacillus species (four species of B. cereus and one species of B. thuringiensis) were used for priming the seeds. For the effect of steeping duration on germinability, viable surface-sterilized seeds were primed in growth broth cultures of the respective isolates. Every one hour, for a five-hour duration, a known number of seeds were withdrawn from the cultures and sown. In the case of initial inoculum, seeds were steeped in different dilutions of the bacterial cultures at the optimal steeping duration obtained in the first study before planting. At the expiration of planting duration, final germination percentage, germination time, germination index, and seedling vigor index of the respective seeds were estimated.
Results
The results highlight the importance of steeping duration for seeds such as cowpea and soybean, and the effect of inoculum concentration was less drastic than that of steeping duration.
Conlcusion
Further field studies need to be carried out to validate these results, using results here as baseline data.
Background
Seed quality, an important determinant of germination and vigor potential, can be improved through seed priming. This study was therefore aimed at assessing the effects of steeping duration and inoculum concentration on the germination and seedling growth of five seed crops through priming with growth-promoting rhizobacteria.
Methods
Broth cultures of five bacterial strains, belonging to Providencia vermicola (2 strains), P. rettgeri (2 strains), and Bacillus cereus (1 strain), isolated from rhizosphere were used for priming in the study. Seeds of cowpea ( Vigna unguiculata ), soybean ( Glycine max ), sorghum ( Sorghum bicolor ), sesame ( Sesamum indicum ), and okra ( Abelmoschus esculentus ) were used as experimental materials. To determine the effects of steeping duration, viable seeds of the respective crops were primed with broth cultures of the respective isolates and allowed to stand for a known duration (1, 2, 3, 4, or 5 h). Then, another set of viable seeds was steeped in varying concentrations of the bacterial cultures for a period that was determined to be the optimal steeping duration in the first experiment.
Result
At the expiration of both experiments, final germination, mean germination time, germination index, and vigor index of the respective seeds were estimated. Generally, higher final germination and seedling vigor index values were restricted to shorter steeping periods for cowpea and soybean. With respect to inoculum concentration, there was no consistent pattern with the parameters.
Conclusion
The study revealed the primacy of steeping duration over inoculum concentration with respect to bacterial priming.
Vigorous germination and growth are linked to crop yield. This study was carried out to assess the effect of steeping duration and metabolite concentration on priming of 5 different crops, using the metabolites of five (5) bacterial isolates that were also characterized through Gas Chromatography-Mass Spectrometry (GC-MS). The crop seeds were steeped in cold-extracted metabolites of the 5 isolates for a known period (1, 2, 3, 4, and 5 h) and then also in different metabolites concentrations for a known duration determined as optimal in the first experiment. Characterization of cold-extracted metabolites was also carried out using GCMS. The results of this study revealed that steeping cowpea and soybean for longer durations (< 3 h) could be inhibitory to growth and development. For concentration it was either a case of lower concentration being optimal or there was no detectable pattern with concentration. The metabolites of the different isolates revealed the present of some common molecules, and some of the GCMS-identified metabolites (e.g., Hexadecanoic acid) have been shown to possess growth promotion properties in other studies. This study highlights that large endosperm seeds such as cowpea and soybean are more prone to the negative effects of steeping for longer durations, and further experiments should be carried out to isolate and purify the bioactive moieties for further studies and onward application.
Climate change is shifting temperatures from historical patterns, globally impacting
forest composition and resilience. Seed germination is temperature-sensitive,
making the persistence of populations and colonization of available habitats vulnerable to warming. This study assessed germination response to temperature in foundation trees in south-western Australia's Mediterranean-type climate forests (Eucalyptus marginata (jarrah) and Corymbia calophylla (marri)) to estimate the thermal niche and vulnerability among populations. Seeds from the species' entire distribution were collected from 12 co-occurring populations. Germination thermal niche was investigated using a thermal gradient plate (5–40° C). Five constant temperatures between 9 and 33°C were used to test how the germination niche (1) differs between species, (2) varies among populations, and (3) relates to the climate of origin. Germination response differed among species; jarrah had a lower optimal temperature and thermal limit than marri (To 15.3°C, 21.2°C; ED50 23.4°C, 31°C, respectively). The thermal limit for germination differed among populations within both species, yet only marri showed evidence for adaptation to thermal origins. While marri has the capacity for germination at higher thermal temperatures, jarrah is more vulnerable to global warming exceeding safety margins. This discrepancy is predicted to alter species distributions and forest composition in the future.
The germination process and seedling growth are crucial stages in the life history of a plant that are severely affected in the face of salinity, osmotic, and extreme temperature conditions. Therefore, this study aimed to investigate the efficacy of osmopriming with calcium chloride (CaCl2) on the tolerance responses of biological parameters of germination to the combined temperature (T) and sodium chloride (NaCl)-induced osmotic potential (Ψ) conditions using a developed hydrotime model. The germination behavior of Ca2+-primed and non-primed seeds was analyzed at different T (1, 5, 10, 15, 20, and 25 °C) and NaCl-induced Ψ (0, − 0.4, − 0.8, − 1.2, − 1.6, − 2, and − 2.4 MPa) conditions. According to the hydrotime model, Ca2+-primed seeds demonstrated a higher tolerance to the joint impacts of chilling and NaCl-induced osmotic conditions than those of non-primed ones. Generally, the priming treatment significantly ameliorated the extent, timing, uniformity of germination, and seedling vigor index at all examined hydro-thermal conditions compared with control seeds. This significance was associated with shifted ecophysiological parameters regarding hydrotime (ϴH), base water potential (Ψb), time taken for germination of a specific percentile (t(g)), and standard deviation of hydrotime (σϴ) toward the lower values following Ca2+-priming treatment, indicating a greater salinity tolerance. Hence, the presented biological parameters can easily be used to predict the physiological changes of germination under environmental factors over time. Also, results suggest that recommended Ca2+-priming treatment could be a time- and cost-effective method for improving quinoa cultivation in salt agriculture, especially in arid lands.
The germination process and seedling development are the determining steps in the plant lifecycle that are the most sensitive to adverse environmental conditions. Therefore, this study was conducted to explore the effects of temperature and osmotic potential on germination responses using threshold models and to establish an optimal priming protocol for improving tolerance responses against osmotic stress in early growth stages. The results demonstrated that osmotic stress of - 0.8 MPa significantly influenced the extent, timing, and speed of seed germination. In addition, priming treatments led to an enhanced performance of early growth stages in response to osmotic stress. Based on thermal-time and hydro-time models, the predicted physiological parameters of the median thermal-time at sub-optimal temperature ( θ T 50 = 909.09 ∘ C h), the median ceiling temperature for 50% germination (Tc(50) = 39.29 °C), the common base temperature (Tb = 7.88 °C), the constant thermal-time at supra-optimal temperature ( θ T = 805.96 °C h), the threshold water potential (Ψb(50) = - 1.13 MPa), and the hydro-time constant ( θ H = 56.09 MPa h) quantitatively describe the tolerance threshold of the germination process under different osmotic and temperature conditions. The results also showed that the efficiency of seed treatments depended on the priming conditions, including temperature, duration, and also concentration of the priming agent. However, the treatments of gibberellic acid (5 days, 10 °C, 100 ppm), salicylic acid (5 days, 10 °C, 50 ppm), calcium chloride (3 days, 10 °C, 10 mM), potassium nitrate (3 days, 10 °C, 100 mM), and hydro-priming (3 days, 10 °C) were optimal protocols of each priming method, resulting in an increased seed vigor under osmotic stress. Hence, the predicted biological parameters could easily be applied to determine the physiological changes of germination under environmental factors over time. Also, results suggest that recommended osmo-, hydro-, and hormonal-priming treatments could be efficient methods for ameliorating the osmotic tolerance in the post-priming stages of this plant, especially in arid lands.
Supplementary information:
The online version contains supplementary material available at 10.1007/s12298-022-01229-w.
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.
Predicting the germination behavior of parthenium weed against different conditions of temperature and osmotic stress is helpful for studying the growth and development history of parthenium in different ecological contexts. Sustainable weed control strategies based on population-based threshold (PBT) models are profitable tools for crop planting date, herbicide application, and tillage operation time. To predict the emergence of parthenium by using thermal time (TT), hydrotime (HT), and hydrothermal time (HTT) analyses, seeds were exposed to varying constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) and water potentials (− 0.25, − 0.5, − 0.75, and − 1.0 MPa) under a controlled environment. Parthenium seeds showed better responses in terms of higher germination percentage and lower germination time at 20 and 25°C. The use of the germination modeling approach proposed the base temperature (7.2°C), optimum temperature (20°C), and ceiling temperature (42.8°C) for this weed. Moreover, germination behavior was also studied at different water potentials under different temperature regimes (10, 20, and 30°C). The HTT model predicted higher germination percentages (82.8 and 54.8%) of parthenium seeds at water potentials from 0 to −0.25 MPa, respectively, under a temperature of 20°C, and also identified a base water potential (Ψb(50) of − 0.54 MPa for germination. In conclusion, the use of the HTT modeling approach is helpful for predicting the emergence response of parthenium in a changing climate and ultimately supportive in time scheduling of parthenium weed management in cropping systems.
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.
بهمنظور بررسی اثر دماهای مختلف بر جوانهزنی و تعیین دمای کاردینال جوانهزنی (دمای پایه، مطلوب و بیشینه جوانهزنی) سورگوم، آزمایشی بهصورت طرح کامل تصادفی در 3 تکرار 50 بذری در دماهای 5، 10، 15، 20، 25، 30، 35 و 40 درجه سانتیگراد به اجرا درآمد. با استفاده از مدل لجستیک 3 پارامتره جوانهزنی بذر سورگوم در دماهای مختلف کمیسازی شد و درصد و زمان رسیدن به 50 درصد جوانهزنی بهدست آمد. جهت کمیسازی واکنش سرعت جوانهزنی بذر سورگوم به دما از 3 مدل رگرسیون غیرخطی دو تکهای، دندان مانند و بتا استفاده شد. نتایج نشان داد که دما علاوه بر درصد جوانهزنی بر سرعت جوانهزنی نیز اثر گذار است. در مقایسه 3 مدل استفاده شده با توجه به پارامترهای RMSE، CV، SE و نمودار خط 1:1، مناسبترین مدل جهت تخمین دماهای کاردینال سورگوم مدل دوتکهای گزارش شد. دمای پایه، مطلوب و سقف با استفاده از مدل دوتکهای بهترتیب 52/9، 49/28 و 23/42 درجه سانتیگراد بود. بنابراین با استفاده از مدل دوتکهای و پارامترهای تخمین زده شده میتوان از این مدل در تهیه و ارزیابی مدلهای پیشبینی جوانهزنی بذر سورگوم استفاده کرد.
Herbs have been utilized for all time as the significant sours of medication. Medical plants are significant by optional metabolites, for example; Silybum marianum, is a remedial herb with a thousand years history of utilization. It is a blend of flavonoids, called silybin, which isn't just the major silymarin component but at the same time is the most dynamic element of this extract, which has been affirmed in different studies. This compound has a place with the flavonoid group known as flavonolignan. Silybin's structure comprises in two fundamental units. The first depends on a taxifolins, the second a phenyllpropanoid unit, which for this situation is conyferil liquor. These two units are connected together into one structure by an oxeran ring contains mixes (taxifolin, silychristin, silydianin, silybinin A and silybinin B. The present study is fundamentally centered on the medicinal important of Silybum marianum, its utility as a medicinal plant for the treatment of different issue of mind, cardiovascular, hepatic, kidney, and oxidative stress also, malignant growth is outstanding. As far as its medicinal properties, Silybum has no symptoms. In any case, it might cause mild nausea or gastrointestinal difficulties in uncommon cases. The leaves, seeds or some of the time the entire plant is utilized inmedicinal preparation.
Extended abstract
Introduction: Purple nutsedge (Cyperus rotundus L.) is one of the problematic weeds worldwide prevalent in tropical and subtropical regions. Tubers are the major organs through which purple nutsedge is propagated, whereas its seeds have a low ability to germinate. Therefore, evaluation of the response of tubers
against environmental agents is great of importance to know the germination and emergence time.
Germination, in turn, is mostly affected by temperature, among other environmental factors. Various models that are recognized as the Thermal Time model have been introduced to describe the seed germination pattern against temperature. Since predicting the emergence of reproductive organs through the modeling is great of
importance for improving the control strategies; the present study was carried out to investigate the response
of tuber sprouting of purple nutsedge (Cyperus rotundus) against temperature using thermal time models.
Material and methods: The experiment was carried out as a randomized complete block design with three replications in a germinator. Each replicate was placed on a separate shelf. For each replicate, 15 tubers were placed inside a 20 cm Petri dish on a filter paper and then 100 ml of water was added. The experiment was performed separately for constant temperatures of 10, 15, 20, 25, 30, 35, and 40 °C in absolute darkness.
To analyze the data as modeling, five thermal time models were evaluated based on the statistical distributions of normal, Weibull, Gumble, logistic and log-logistic. Indices such as R2, RMSE, RMSE%, and AICc were used to evaluate the models.
Results: The results showed that all models predicted the germination response of purple nutsedge tuber
with high accuracy (R2= 0.95). A comparison of models based on AICc values showed significant superiority of the Gumble model over other models. According to this index, there was no difference between logistic and log-logistic models with normal. Among the models, Weibull was identified as the most inappropriate model. Different models estimated the final germination (Gmax) between 0.93 to 0.94 (93 to 94%). The base temperature was estimated through different models from 7.10 to 7.47 °C. Among the models, the model based on the Gumble distribution proved the skew to the right of the thermal time and Tm. According to the Gumble model, the thermal time parameters required to reach 50% germination (θT (50)) equals 123.8 ° C day and the maximum temperature for germination at 50% probability (Tc (50)) was estimated to be 46.10 ° C.
Conclusion: the thermal time model based on the Gumble probability distribution was most plausible among the models. Also, a distributed right skewness related to the thermal time and Tm was proved through the Gumble model. The parameters obtained from the Gumble model can be used to predict the sprouting of
purple nutsedge tubers.
Keywords: Vegetative organs, Gumble distribution, Cardinal temperatures, Modelling
Highlights:
1- Thermal time models were evaluated for the prediction of tuber sprouting of purple nutsedge.
2- The thermal time model based on the Gumble distribution was superior to the normal distribution.
3- Thermal time and Tm for tuber sprouting of purple nutsedge were distributed as right skewness.
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.
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.
Increase in the food demand and unprecedented level of environmental stresses have created major challenges to ensure global food security. Under such circumstances, wild species of crops serve as a genetic reservoir to improve yield, quality and adaptability of modern cultivars. Previously reported work of the introduction of genes from wild to cultivated species has drawn the attention of plant scientists towards the role of wild species in crop improvement. Contemporary genomic tools can also be exploited to understand the genetic architecture and diversity of crop wild relatives for their efficient use in practical plant breeding. Considering the value of wild genetic resources in sustainable agriculture, numerous worldwide efforts have been made for its preservation. In view of its importance, this chapter is written on a broader prospective to highlight the utilization and conservation of crop wild germplasm.
The genus Gossypium is comprised of more than 50 genetically diverse species with different origins and ploidy levels. Each of cultivated and wild species is a source of unique alleles to improve cotton crop under ever increasing fiber demand and rapidly evolving climatic factors. Formerly, most of the improvement has been made in cotton germplasm by utilizing the genetic diversity of only cultivated types of species. The plenty of examples are reported for the utilization of wild cotton species in plant breeding despite of the fact of proven to be a novel genetic resource. The major hindrance was the transfer of genetic material which is now easier as compared to past due to advancement of gene transfer methods and technologies. Therefore, the conservation and utilization of cotton wild germplasm have gained much importance and is now become imperative to sustain the yield and quality of cotton fibers. This chapter highlights the background and potential of wild species of cotton to improve yield, quality, and adaptability of modern cultivars.
Harmful effects of climate change, human interference, and environmental stresses have opened new challenges for food security and natural variability. Like other crops, the domestication of barley has led toward a significant reduction in genetic diversity and created hurdles to develop well-adapted cultivars. One of the best solutions toward these challenges is the exploitation of crop wild germplasm that niche in extreme geographical locations. Wild progenitors have potential to transfer adaptation loci in modern cultivars, which will make them fit for changing climate. Wild barley could be the potential source for genetic variability and increasing capability to withstand against biotic and abiotic stress factors and can be collected from its natural area of distribution, especially from the Mediterranean region. In this chapter, we have highlighted the significance of wild germplasm of barley and adaptive genes they have for various biotic and abiotic stress resistance/tolerance.
Chickpea, the second most important pulse crop, delivers multiple benefits to farming systems—a lower footprint with reduced use of synthetic nitrogen and soil improvements, and enhanced livestock and human health due to its superior dietary quality with valuable proteins, minerals, vitamins, and fibers. However, if chickpea is to fully deliver these benefits, the crops need greater productivity and resilience to a changing climate. If realized, chickpea has much potential to contribute to the growing food demand of our global family and address the problem of undernourishment in developing countries of Asia and Africa. Tremendous progress has been made over the past decade on removing the bottleneck of narrow genetic diversity by broadening the genetic base of cultivated chickpeas through the incorporation of crop wild relatives and landraces. However, increases in chickpea productivity have been slow with average yields of about 1 t/ha, stagnated or threatened by multiple biotic and abiotic stresses. To boost productivity and global production, improved cultivars have to be bred and developed with resistance to region-specific diseases and environmental stresses. Recent developments have capitalized on modern genomic tools and enabled implementing successful genomics-assisted breeding of improved cultivars adapted to biotic and abiotic stresses in various environments, and these can yield up to >2 t/ha. This chapter provides an overview of chickpea’s nutritional profile, current production constraints, crop phenology, genetic improvement, genomic resources, cropping systems, seed systems as well as web-based resources for current and future chickpea improvement programs.
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.
In field investigations in a sandy-loam soil, probit percentage seedling emergence of commercial and aged seed lots of spring wheat (Triticum aestivum L., cv. Timmo) was a positive linear function of probit percentage laboratory germination and mean soil temperature and a negative linear function of percentage soil moisture content over the ranges 12·1–15·5% moisture content and 7·0–11·0 °C. In a laboratory investigation using the same soil a similar form of relationship was observed in six lots over a range of constant soil moisture contents between 10 and 18% and at constant soil temperatures of 8 and 20 °C. In all cases there was no interaction between any of these determinants of seedling emergence.
Linear relationships between the mean rate of seedling emergence in the field (i.e. reciprocal of mean emergence time) and probit percentage laboratory germination and mean soil temperature were shown, but there was no obvious effect of mean scil moisture content between 12·1 and 15·5% on rate of field emergence. Seed lots of different percentage laboratory germination had the same base tsmperature for emergence (1·9 °C): differences between seed lots in mean emergence rate were due to different thermal time (day-degree) requirements for emergence; the thermal times required were a function of probit percentage germination in a standard laboratory test. The implications of these results in providing better advice on sowing rates are discussed.
The germination of pearl millet (Pennisetum typhoides S. & H.) seeds was investigated at constant temperatures between 12
°C and 47 °C on a thermal gradient plate.
The rate of germination increased linearly with temperature from a base Tb to a sharply defined optimum To beyond which the rate decreased linearly with temperature, reaching zero at Tm. The linearity of the response both above and below To allowed time and temperature to be combined in a thermal time at which a specified fraction of the seeds germinated. Within
the population Tb and Tm were constant.
The quantification of ageing and survival in orthodox seeds
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