Threshold temperatures for seed germination in nine species of<i>Verbascum</i>(Scrophulariaceae)

Catara, Stefania; Cristaudo, A; Gualtieri, Andrea; Galesi, Rosario; Impelluso, Carmen; Onofri, Andrea

doi:10.1017/s0960258515000343

Cited by 24 publications

(15 citation statements)

References 56 publications

(67 reference statements)

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“…This result indicates that they have the ability to germinate with high sun exposure. Generally, smallseeded species are positively photoblastic, because they need to germinate on top of the soil surface where emerging seedlings can immediately take advantage of light to photosynthesize, and thus became independent of the reserves stored inside the cotyledons (Catara et al 2016, Cristaudo et al 2016. However, the ability to germinate (although with lower percentages) also in the total darkness, indicates that seeds of both our study species can germinate also when buried by sand (that is a very common phenomenon in deserts).…”

Section: Discussionmentioning

confidence: 72%

Does perianth colour affect the seed germination of two desert shrubs under different storage periods and conditions?

Bhatt

Santo

2018

Nordic Journal of Botany

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Haloxylon salicornicum and Salsola vermiculata (Amaranthaceae) are two perennial shrubs producing fruits with differently coloured perianths (yellow vs pink) on separate individuals. To test the impact of different storage periods (four, eight and twelve months) and temperature conditions (freezing, room temperature and natural field temperatures) on the seed germination of the two seed categories, germination tests were carried out on both species. For both species, collected from wild plants in the Arabian desert (Qatar), seed germination was tested under two photoperiods (light 12/12; dark 24 hours) at 20/30°C for winged (intact) and de‐winged seeds. For each species, all the considered factors (perianth colour, wing presence, photoperiod, storage period and storage conditions) had significant effects on seed germination (p < 0.001), while the interactions among factors varied in their level of significance depending on the species. In both species, yellow seeds germinated considerably better than the pink ones, the presence of wings slowed the germination, and both storage period and temperature conditions highly influenced their germination ability. Our results indicate that seeds from different perianth colours have different germination strategies to delay their germination and distribute the species through time by escaping germination time by imposing some kind of after‐ripening or seed dormancy. The variation in storage time and storage conditions might help in extending their germination period, where one set of seeds germinate immediately, and the other set of seeds becomes dormant and thus contributes to the formation of a soil seed bank for the long‐term recruitment of seedlings. This study highlights an ecological advantageous strategy for these two species growing in the unpredictable desert habitat.

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Section: Discussionmentioning

confidence: 72%

Does perianth colour affect the seed germination of two desert shrubs under different storage periods and conditions?

Bhatt

Santo

2018

Nordic Journal of Botany

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“…These GR values were derived from the fitted log-logistic curves at constant temperature in alternating light regimes. GRg values were used to fit the following model, taken from Catara et al [42] and Masin et al [43]:…”

Section: Modeling Germination Rates As a Function Of Temperaturementioning

confidence: 99%

Effects of Light, Temperature, and Soil Depth on the Germination and Emergence of Conyza canadensis (L.) Cronq.

et al. 2019

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Understanding the dynamics of invasive species under global climate change requires knowledge about the effects of environmental factors on germination and emergence. We considered Conyza canadensis (L.) Cronq., an invasive species that is quickly invading Southern European agricultural systems, and performed germination assays in growth chambers at eight constant temperatures with alternating light (2.5, 5, 10, 15, 20, 25, 30, and 40 °C, with 12 h/12 h—light/dark), three alternating temperatures in alternating light (12/18, 17/23, and 22/28 °C, with 12 h/12 h—light/dark) and three fixed temperatures (15, 20, and 25 °C) in complete darkness. Furthermore, emergence assays were performed in pots considering four depths (0, 2.5, 5, and 10 mm), three temperatures with alternating light (15, 20, and 25 °C) and un-treated or pre-treated seeds (water imbibition and light for two days). C. canadensis was able to germinate in a wide range of temperatures (from 5–10 °C to 30 °C). The highest germination capacity was observed at 15 °C (light/dark); no differences were observed at 17/23 and 22/28 °C with respect to 20 and 25 °C (light/dark), while germinations were significantly reduced at 12/18 °C. The lowest germination time was observed at 25 °C (light/dark) and it was significantly increased at 12/18 °C and in darkness. The highest emergence was from 0 mm depth; pre-treatment significantly increased the emergence from 2.5 mm and 5 mm depth, but not from 10 mm depth. Modeling germination rates as a function of temperature allowed us to determine Tb = 6.8 °C (base temperature) and Tc = 35.8 °C (ceiling temperature). In light of these results, the potential for C. canadensis to spread into new environments and possible new management methods are discussed.

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“…Based on a thermal time approach, a non‐linear (exponential‐type) model was instead proposed by Catara et al . (), assuming a non‐symmetric relationship between GR and temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The latter model may be preferred because it describes a curved relationship between GR and temperature near to the optimal value, which might be more realistic from a biological point of view. Previous work (Catara et al ., ) suggests that an exponential model might be promising for base temperature estimation studies, and in this study, we compared it to the most widely used function, that is the broken‐stick model, attractive for the simplicity of its linear segments (Andreucci et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Can alternating temperatures be used to estimate base temperature for seed germination?

et al. 2017

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Modelling weed seedling emergence pattern appears to be a promising approach in the development of effective weed management programmes based on the selection of optimal timing of control operations. Thermal and hydrothermal time models propose that seed germination rates are proportional to the amount by which temperature and water potential exceed threshold values for these environmental factors. Hence, base temperature for seed germination is a fundamental biological parameter for the prediction of weed emergence. A series of laboratory experiments were conducted to estimate base temperature in three weed species belonging to the Asteraceae family, predominant in conservation tillage fields in north-eastern Italy. The traditional method based on germination assays at constant temperatures was compared with a method based on assays at alternating temperatures. The latter might represent an alternative to the former for those species which do not germinate or only poorly under constant temperatures. Base temperature was estimated by regressing the reciprocal of the median germination time on temperature comparing two functions, a broken-stick and an exponential-type model. Both models showed good fit to all data in the whole temperature range and in almost all cases provided similar estimates of base temperature. The main result is that, for the weed species examined in this study, the use of alternating temperatures for base temperature estimation appears to be possible. However, further research is required to test if the use of germination assays performed at alternating temperatures can be a suitable method to estimate base temperature of species that have too low germination at constant temperatures.

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Threshold temperatures for seed germination in nine species ofVerbascum(Scrophulariaceae)

Cited by 24 publications

References 56 publications

Does perianth colour affect the seed germination of two desert shrubs under different storage periods and conditions?

Does perianth colour affect the seed germination of two desert shrubs under different storage periods and conditions?

Effects of Light, Temperature, and Soil Depth on the Germination and Emergence of Conyza canadensis (L.) Cronq.

Can alternating temperatures be used to estimate base temperature for seed germination?

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