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Percentage germination (a, c, e) and mean germination time (b, d, f ) of S. pohlii and S. camporum seeds at 10, 15, 20, 25, 30 and 35 °C, and S. ferrugineus seeds at 10, 15, 20 and 25 °C, under fluorescent light (80 µmol m –2 s –1 ). Columns represent mean values (n=6) and vertical bars are S.D. Different letters show significant differences (p=0.05) between treatments, and the absence of letters indicates a lack of significant differences between treatments.
Source publication
In this descriptive paper, we described germination responses of Styrax pohlii, S. camporum and S. ferrugineus seeds at 5, 10, 15, 20, 25, 30, 35, 40 and 45 °C. We also assessed the percentage germination (%G) of S. pohlii seeds with different seed water contents because, as a forest species, it seems to have recalcitrant seed behavior. Intrigued b...
Contexts in source publication
Context 1
... not germinating under these temperatures, S. ferrugineus seeds did not germinate at 30 and 35 °C. S. pohlii seeds exhibited the same %G when exposed to 10, 15, 20, 25 and 30 °C, but at 35 °C seeds of this species showed lower %G as compared to the other temperatures ( Figure 1a). In addition, the mean germination time (T) was the lowest at 20 °C for S. pohlii seeds (Figure 1b). ...
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... pohlii seeds exhibited the same %G when exposed to 10, 15, 20, 25 and 30 °C, but at 35 °C seeds of this species showed lower %G as compared to the other temperatures ( Figure 1a). In addition, the mean germination time (T) was the lowest at 20 °C for S. pohlii seeds (Figure 1b). S. camporum seeds showed great variation in %G assessed at different temperatures, however, this species showed the best germination performance at 25 °C, although this result did not differ from %G measured at 20, 30 and 35 °C (Figure 1c). ...
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... addition, the mean germination time (T) was the lowest at 20 °C for S. pohlii seeds (Figure 1b). S. camporum seeds showed great variation in %G assessed at different temperatures, however, this species showed the best germination performance at 25 °C, although this result did not differ from %G measured at 20, 30 and 35 °C (Figure 1c). In addition, S. camporum seeds seemed to best distribute germination over time at 25 °C (Figure 2b,e,h,k,n,q). ...
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... seeds of S. pohlii and S. camporum that did not germinate at temperatures ranging from 10 to 35 °C were not viable after 60 and 90 days, respectively, as evidenced by the tetrazolium test. S. ferrugineus seeds showed conspicuously low %G (Figure 1e) and similar T at 10, 15, 20 and 25 °C (Figure 1f). Compared to seeds of S. pohlii (best %G = 82±6.5% at 20 °C; Figure 1a,b) and S. camporum (best %G = 64±14 at 25 °C; Figure 1c,d), S. ferrugineus seeds, in general, exhibited less than half of %G values of the other two species, and after 90 days, 50% of these seeds remained viable. ...
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... seeds of S. pohlii and S. camporum that did not germinate at temperatures ranging from 10 to 35 °C were not viable after 60 and 90 days, respectively, as evidenced by the tetrazolium test. S. ferrugineus seeds showed conspicuously low %G (Figure 1e) and similar T at 10, 15, 20 and 25 °C (Figure 1f). Compared to seeds of S. pohlii (best %G = 82±6.5% at 20 °C; Figure 1a,b) and S. camporum (best %G = 64±14 at 25 °C; Figure 1c,d), S. ferrugineus seeds, in general, exhibited less than half of %G values of the other two species, and after 90 days, 50% of these seeds remained viable. ...
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... ferrugineus seeds showed conspicuously low %G (Figure 1e) and similar T at 10, 15, 20 and 25 °C (Figure 1f). Compared to seeds of S. pohlii (best %G = 82±6.5% at 20 °C; Figure 1a,b) and S. camporum (best %G = 64±14 at 25 °C; Figure 1c,d), S. ferrugineus seeds, in general, exhibited less than half of %G values of the other two species, and after 90 days, 50% of these seeds remained viable. ...
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... ferrugineus seeds showed conspicuously low %G (Figure 1e) and similar T at 10, 15, 20 and 25 °C (Figure 1f). Compared to seeds of S. pohlii (best %G = 82±6.5% at 20 °C; Figure 1a,b) and S. camporum (best %G = 64±14 at 25 °C; Figure 1c,d), S. ferrugineus seeds, in general, exhibited less than half of %G values of the other two species, and after 90 days, 50% of these seeds remained viable. ...
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... temperatures for seed germination, or 'cardinal temperatures', define in a species-specific manner the range of temperature at which germination is possible, allowing inferences about the origin of species (Labouriau, 1983). Seeds of S. pohlii and S. camporum, which are typical of forest physiognomies of the Cerrado, germinate in a wide range of temperatures (Figure 1a,c) in relation to seeds of S. ferrugineus (Figure 1e), which is a typical savanna species. Considering the optimal temperature for germination as the one that promotes the highest %G within the lowest mean Figura 3. Relative frequency of germination of S. pohlii seeds, at 25 °C and under fluorescent light (80 µmol m -2 s -1 ), in response to seed water contents of 50%, 43%, 32% and 12%. ...
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... temperatures for seed germination, or 'cardinal temperatures', define in a species-specific manner the range of temperature at which germination is possible, allowing inferences about the origin of species (Labouriau, 1983). Seeds of S. pohlii and S. camporum, which are typical of forest physiognomies of the Cerrado, germinate in a wide range of temperatures (Figure 1a,c) in relation to seeds of S. ferrugineus (Figure 1e), which is a typical savanna species. Considering the optimal temperature for germination as the one that promotes the highest %G within the lowest mean Figura 3. Relative frequency of germination of S. pohlii seeds, at 25 °C and under fluorescent light (80 µmol m -2 s -1 ), in response to seed water contents of 50%, 43%, 32% and 12%. ...
Context 10
... this descriptive study, we used important data on seed germination performances of three Styrax species obtained under laboratory conditions and complemented with germination data of these three species obtained in the field ( Kissmann et al., 2012), which constituted useful information to discuss the distribution patterns of these congeneric species in Cerrado areas in Brazil. germination time (Bewley and Black, 1994), our results showed that the optimal temperature for S. pohlii was 20 °C (Figure 1a,b), and for S. camporum, it was 25 °C (Figure 1c,d). The ability of these seeds to germinate within a wide range of temperatures may represent a competitive advantage in Cerrado areas. ...
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... this descriptive study, we used important data on seed germination performances of three Styrax species obtained under laboratory conditions and complemented with germination data of these three species obtained in the field ( Kissmann et al., 2012), which constituted useful information to discuss the distribution patterns of these congeneric species in Cerrado areas in Brazil. germination time (Bewley and Black, 1994), our results showed that the optimal temperature for S. pohlii was 20 °C (Figure 1a,b), and for S. camporum, it was 25 °C (Figure 1c,d). The ability of these seeds to germinate within a wide range of temperatures may represent a competitive advantage in Cerrado areas. ...
Context 12
... the germination performance of S. ferrugineus seeds is particularly intriguing. Under field conditions ( Kissmann et al., 2012), 40% of seeds of each of the three species had germinated after 60 days, but in the present study S. ferrugineus seeds showed 10% germination, regardless of temperature (Figure 1e). We did not test alternate temperatures (e.g. ...
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Citations
... Such plants usually have mechanical or chemical inhibitors in the fruit, either in the exocarp, pulp or seed coat, to achieve the needed dormancy (Jordano, 2000). Once the fruit is consumed by the zoochoric agent, these inhibitors are removed either through digestion by saliva or passage through their alimentary canal and thus improve germination potential when finally dispersed to distant locations (Kiepiel and Johnson, 2019;Kissmann and Habermann, 2013;Pegman et al., 2017;Yagihashi et al., 1998). ...
Zoochoric plants usually produce fruits with a mechanical barrier in the exocarp, or chemical inhibitors in the fruit pulp (mesocarp) or seed coat (endocarp) to achieve required dormancy. Tamarindus indica L. is one such zoochoric tree species, but the role of possible bioactive chemicals in the ecology of its fruit and seed dispersal has not been explored before. We investigated the germination inhibitory effects of T. indica fruit pulp by comparing germination of intact T. indica fruits with depulped T. indica seeds. This experiment revealed that attached pulp (including exocarp) delayed or decreased germination via an unverified mechanism. We then analyzed the pulp (including exocarp) to find out if there was a dominant bioactive chemical, by creating extracts using both alcohol and aqueous fractionation, and then analyzed them using GLC-MS analysis. We discovered that tartaric acid was the main bioactive chemical present in the methanol fraction (but not aqueous), so decided to test its effect on T. indica seed germination. We exposed viable depulped T. indica seeds to varying concentrations of pure tartaric acid in distilled water and found germination inhibition was observed at a concentration of 0.4 mg/ml. Therefore, since tartaric acid is the major chemical component in T. indica fruit pulp, it is possible that it could play a crucial role in the zoochoric dispersal of seeds by inhibiting germination while they are still attached to the tree or have just fallen close to the parent tree so that they have an opportunity to reach distant sites favorable for germination.
... (Styracaceae) were collected from ten adult plants (trees) from Cerrado fragments in the municipalities of Corumbataí and Itirapina, São Paulo state, Southeastern Brazil. The seeds germinated under controlled conditions (germination chamber at constant 25 °C), according to Kissmann and Habermann (2013). The seedlings were cultivated in a substrate (Plantmax, Campinas, SP, Brazil) without Al in a greenhouse, under semi-controlled conditions. ...
Styrax camporum Pohl. (Styracaceae) is a woody species that grows on acidic soils from the Brazilian savanna with high aluminum (Al) saturation (m% > 50%), where it accumulates ~ 1500 mg Al per kg dry leaves. Using nutrient solution, a previous study showed that 1480 μM Al causes toxicity symptoms, which raises the question whether less than 1480 μM Al could cause beneficial effects on this species. Here, we checked possible altered gas exchange rates, damage to organelles in root tips and the association between Al exposure and mitochondria occurrence in cells of root tips, once organic acids from Krebs cycle exuded by the roots of this species when exposed to Al have been recently evidenced. Five-month-old plants were grown in nutrient solution with 0, 740 and 1480 μM Al for 90 days. Plants exposed to 1480 μM Al showed less developed root system, reduced plant height and low gas exchange rates in relation to those exposed to 0 and 740 μM Al, confirming that 1480 μM Al is toxic to S. camporum. However, plants exposed to 0 and 740 μM Al had similar number of leaves, plant height, root biomass, root length, total plant biomass and gas exchange rates, indicating that no beneficial effects from 740 μM Al could be noted on this species. In plants exposed to 0 and 740 μM Al, mitochondria were noted at the root tip, while at 1480 μM Al these organelles were not evident due to the conspicuous vacuolation of root cells. S. camporum shows limited tolerance to Al in nutrient solution. In addition, this species is not dependent on Al to grow and develop because the plants grew well under 0 and 740 μM Al.
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Key message
Styrax camporum, an Al-accumulating species from the Cerrado, seems to rely on the exudation of citric and oxalic acids to avoid excessive Al.
Abstract
Organic acid (OA) exudation by the roots of plants to chelate aluminum (Al) and forming non-toxic complexes is a known mechanism of Al exclusion in some plants, including some Al-accumulating species. The Cerrado vegetation in South America is composed of Al non-accumulating species and some Al-accumulating species from few families, all growing healthy on acidic soils with high Al saturation but never tested for OA exudation. We elected Styrax camporum (Styracaceae), a Cerrado woody species that accumulates in their leaves approximately 1500 mg Al kg⁻¹ dry mass, to examine whether plantlets of this species exude OAs in response to changes in Al concentrations in a nutrient solution, for 30 days. Citric, malic and oxalic acids exuded by the roots of this species were cumulatively measured in nutrient solutions containing 0, 740 and 1480 μM Al. Also, we measured the Al concentration of whole plantlets at 0 and 30 days. Malic acid was not exuded by the plantlets, but it was detected inside root tips of plantlets exposed to Al. Plantlets exposed to 740 μM Al released more oxalic and citric acid in the nutrient solution than those exposed to 0 and 1480 μM Al after 30 days. On the other hand, between 0 and 30 days, plantlets exposed to 740 μM Al increased the Al concentration (in whole plantlet) by three times while those exposed to 1480 μM Al, by seven times. This higher OA exudation associated with lower Al uptake at 740 μM Al suggests an Al exclusion mechanism that is impaired at higher Al concentrations. This is the first report showing that an Al-accumulating species from the Cerrado exudes OAs in response to the Al concentration in the root environment.
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Cardinal temperatures and thermal time are valuable information for scheduling year-round production of seed-propagated species. In this study, thermal germination behavior of three species of the family Fabaceae, Onobrychis subnitens Bornm., Onobrychis scrobiculata Boiss. and Vicia variabilis Grossh., from Kurdistan Province, Iran were quantified. Seeds of these species were germinated at temperatures of 5– 35°C. Three nonlinear regression models (segmented, beta, and dent-like) were used to estimate cardinal temperatures. After examining O.subnitens, findings showed that the segmented model is the best model for predicting cardinal temperatures. The base, optimum, and maximum temperatures were 1.23, 17.22 and 41.10°C, respectively. The thermal time required for 50% germination was 21.29 degree-days. For O.scrobiculata, segmented and dent-like models were equal. The base, optimum and maximum temperatures of seed germination were 5.5, 18.8–19.76 and 38.14°C, respectively. The thermal time required for 50% germination was 25.87 degree-days. For V.variabilis, there was no difference between the segmented and dent-like models and each one could be chosen. Accordingly, the base, optimum, and maximum temperatures of seed germination were-1.2, 20 and 35.13°C, respectively. The thermal time required for 50% germination was 60.9 degree-days. Based on the germination percentage, germination rate and thermal time requirement, O.subnitens is preferred for use in the arid and semi-arid rangeland improvement project.
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... It has been observed in remnants of Cerradão, cerrado sensu stricto, and other forestinfluenced environments within Cerrado areas (Nakajima and Monteiro 1987). Its seeds are dispersed during the dry season (April-August) and are relatively easy to germinate (Kissmann and Habermann 2013), growing into five-leaf plants within approximately eight months. ...
In the Cerrado vegetation, generally known as ‘Brazilian savanna’, aluminum (Al) accumulating and non-accumulating plants coexist, growing on soils that are acidic, poor in nutrients and rich in Al. Differing from Al-sensitive species, these plants are not expected to experience Al injuries. Using Styrax camporum, a non-accumulating plant, we recorded biometric variations in leaves, shoots and roots of young plants exposed to 0 and 1480 μM Al in a nutrient solution. Photosynthetic responses were measured bi-weekly over 91 days. Plants exposed to Al drastically reduced flushing, indicating that Al interferes with the functioning of the shoot apex. Aluminum caused low CO2 assimilation rate, largely explained by low stomatal conductance, while Al-induced decrease in photochemical performance occurred only on some dates during the experiment. In addition, the absorbed Al was mostly retained in the roots. Although counter-intuitive, as this species grows on Al-rich soils, we noted that high Al availability impairs lateral root formation, causing an impact on water uptake and gas exchange rates of this species.
... ROSSATTO, D.R.; TONIATO, M.T.Z.; DURIGAN, G. Flora fanerogâmica nãoarbórea do cerrado na Estação Ecológica de Assis, Estado de São Paulo.Grubb 1977), podendo determinar a distribuição ecológica e geográfica em espécies vegetais (Brändle et al. 2003;Donohue et al. 2010). Diversos estudos investigaram a relação entre amplitude de nicho de germinação e distribuição ecológica e geográfica em espécies vegetais e resultados contraditórios têm sido encontrados (Thompson et al. 1998;Thompson et al. 1999;Brändle et al. 2003;Thompson & Ceriani 2003;Ranieri et al. 2012;Silveira et al. 2012;Kissmann & Habermann 2013). Portanto, as evidências da associação dos requerimentos de germinação com a distribuição ecológica e/ou geográfica nas espécies vegetais ainda são inconsistentes (Donohue et al. 2010). ...
... Considering that micro-climatic conditions tend to be more unstable and limiting at typical savanna (Salazar et al., 2012), the strategy of spreading germination through time may increase the chances of seedling survival and establishment, when conditions become suitable. This trait was reported in other typical savanna species (Kissmann and Habermann, 2013;Mendes-Rodrigues et al., 2011;Ribeiro and Borghetti, 2014;Simão et al., 2013). This strategy would also help seedling survival at the beginning of the rainy season (dispersal time of M. barrosoae), when rainfall varies in intensity and frequency in the Cerrado region (Oliveira, 2008). ...
