Seed germination ecology of the endemic Iberian winter annualsIberis pectinataandZiziphora aragonensis

2009 ◽  
Vol 19 (3) ◽  
pp. 155-169 ◽  
Author(s):  
Miguel Á. Copete ◽  
José M. Herranz ◽  
Pablo Ferrandis
Keyword(s):  
High Temperatures ◽  
Natural Habitat ◽  
Ex Situ ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Germination Ecology ◽  
Physiological Dormancy ◽  
Seed Age ◽  
Winter Annual ◽  
Population Reinforcement

AbstractThe germination ecology of the winter annual Iberian endemicsIberis pectinataandZiziphora aragonensiswas investigated in order to better understand adaptations of rare species to their natural habitat and to improveex-situpropagation techniques and management of their habitat. Specifically, we analysed the following aspects: (1) influence of temperature, light conditions and seed age on germination patterns; (2) phenology of germination; (3) germinative response of buried seeds to seasonal temperature changes; and (4) temperature requirements for induction and breaking of secondary dormancy. Germination was substantially lower in darkness than with a photoperiod in both taxa, with this difference being more pronounced inZ. aragonensis. Freshly matured seeds showed conditional physiological dormancy, germinating at low and medium temperatures but not at high temperatures (28/14 and 32/18°C). Germination capability increased with time of dry storage in both species, suggesting the existence of non-deep physiological dormancy. Under greenhouse conditions, germination of both taxa was mostly concentrated in autumn (October–November), while spring percentages were less than 1% of total accumulated germination recorded during the study.I. pectinataandZ. aragonensisseeds buried and exposed to natural seasonal temperature variations in an unheated greenhouse came out of conditional dormancy in summer and re-entered it in winter, thus exhibiting an annual conditional dormancy/non-dormancy cycle. Dormant seeds of both species which were stratified at 28/14 or 32/18°C during an 8-week period, were non-dormant when they were subsequently incubated over a range of temperatures from 5 to 25/10°C. Non-dormant seeds were induced into dormancy when stratified at 5 or 15/4°C for 8 weeks, showing a particularly low germination response at high temperatures. Recommendations for wild-population reinforcement programmes and for the management of the natural habitat of both endemics are discussed.

scholarly journals Circuit robustness to temperature perturbation is altered by neuromodulators

2017 ◽  
Author(s):  
Sara A. Haddad ◽  
Eve Marder
Keyword(s):  
High Temperatures ◽  
Temperature Perturbation ◽  
Seasonal Temperature ◽  
Cancer Borealis ◽  
Temperature Changes ◽  
Animal Diversity ◽  
Effects Of Temperature ◽  
Work Done ◽  
Phase Relationships ◽  
Pyloric Rhythm

SUMMARYIn the ocean, the crab, Cancer borealis, is subject to daily and seasonal temperature changes. Previous work, done in the presence of descending modulatory inputs, had shown that the pyloric rhythm of the crab increases in frequency as temperature increases, but maintains its characteristic phase relationships until it “crashes” at extreme high temperatures. To study the interaction between neuromodulators and temperature perturbations, we studied the effects of temperature on preparations from which the descending modulatory inputs were removed. Under these conditions the pyloric rhythm was destabilized. We then studied the effects of temperature on preparations in the presence of oxotremorine, proctolin, and serotonin. Oxotremorine and proctolin enhanced the robustness of the pyloric rhythm, while serotonin made the rhythm less robust. These experiments reveal considerable animal-to-animal diversity in their crash stability, consistent with the interpretation that cryptic differences in many cell and network parameters are revealed by extreme perturbations.

Will the sleeping beauties wake up? Seasonal dormancy cycles in seeds of the holoparasiteCuscuta epithymum

2009 ◽  
Vol 20 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Klaar Meulebrouck ◽  
Kris Verheyen ◽  
Martin Hermy ◽  
Carol Baskin
Keyword(s):  
Room Temperature ◽  
Empirical Studies ◽  
Seasonal Temperature ◽  
Natural Conditions ◽  
Temperature Changes ◽  
Physiological Dormancy ◽  
Spring Temperatures ◽  
Viable Seeds ◽  
Cyclic Changes ◽  
Dormancy Cycles

AbstractSeed banks are often crucial for the survival of plant species, especially short-lived ones. Nevertheless, empirical studies about the fate of seeds under natural conditions are scarce, particularly for parasitic plants. Therefore, fresh seeds of the holoparasiticCuscuta epithymumwere buried in the field under natural conditions in Belgium or kept at room temperature for up to 31 months, and germination was tested periodically by incubating seeds in light at 23°C. BuriedC. epithymumseeds had cyclic changes in their germinability, while those stored dry at room temperature never germinated without scarification. Buried seeds exhibited a seasonal cycle of physiological dormancy, the first to be reported for a species with combinational (i.e. physical+physiological) dormancy. The physiological dormancy of the embryo was broken during winter ( ≤ 5°C) but induced during exposure to late spring temperatures (>10°C). Therefore, germination ofC. epithymumseeds is fine tuned to seasonal temperature changes. Each year only a portion of the viable seeds could germinate. The portion of seeds buried in the soil that remained available for delayed germination, i.e. in the seed bank, decreased rather quickly, with only 8.5% of them being viable after 31 months of burial; all seeds stored in the laboratory remained viable. Nonetheless, we concluded that someC. epithymumseeds are capable of surviving for several years in the soil. These data indicate that the parasite is well adapted to survive in a dynamic heathland landscape where conditions for survival change constantly, but it is still sensitive to local extinction.

Does Seed Dormancy Play a Role in the Germination Ecology ofRumex crispus?

Weed Science ◽  
1985 ◽  
Vol 33 (3) ◽  
pp. 340-343 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Dormancy ◽  
Growing Season ◽  
Seasonal Temperature ◽  
Rumex Crispus ◽  
Temperature Changes ◽  
Germination Ecology ◽  
Buried Seeds ◽  
Buried Seed

Seed dormancy does not play a role in the germination ecology of curly dock (Rumex crispusL. ♯ RUMCR). This study confirms reports that freshly matured seeds are nondormant, and it shows that buried seeds exposed to natural seasonal temperature changes remain nondormant. From October 1981 through June 1983, seeds exhumed at monthly intervals germinated 80 to 100% at all thermo-periods. These results do not support suggestions that seeds of curly dock buried in soil enter dormancy. However, the results do explain why seeds of this species in the Beal and Duvel buried-seed experiments germinated when exhumed at various times during the growing season.

Investigation of 18 physiologically dormant Australian native species: germination response, environmental correlations and the implications for conservation

2020 ◽  
pp. 1-9
Author(s):  
Justin C. Collette ◽  
Mark K.J. Ooi
Keyword(s):  
Native Species ◽  
Strong Dependence ◽  
Ex Situ ◽  
Source Population ◽  
Seasonal Temperature ◽  
Environmental Correlations ◽  
Rainfall Season ◽  
Germination Response ◽  
Rainfall Seasonality ◽  
Germination Experiments

Abstract For physiologically dormant (PD) species in fire-prone environments, dormancy can be both complex due to the interaction between fire and seasonal cues, and extremely deep due to long intervals between recruitment events. Due to this complexity, there are knowledge gaps particularly surrounding the dormancy depth and cues of long-lived perennial PD species. This can be problematic for both in situ and ex situ species management. We used germination experiments that tested seasonal temperature, smoke, dark and heat for 18 PD shrub species distributed across temperate fire-prone Australia and assessed how germination was correlated with environmental factors associated with their home environments. We found extremely high levels of dormancy, with only eight species germinating above 10% and three species producing no germination at all. Seven of these eight species had quite specific seasonal temperature requirements and/or very strong responses to smoke cues. The maximum germination for each species was positively correlated with the mean temperature of the source population but negatively correlated with rainfall seasonality and driest months. The strong dependence on a smoke cue for some of the study species, along with examples from other studies, provides evidence that an obligate smoke response could be a fire-adapted germination cue. Germination response correlated with rainfall season of the source populations is a pattern which has often been assumed but little comparative data across sites with different rainfall seasonality exists. Further investigation of a broader range of species from different rainfall season environments would help to elucidate this knowledge gap.

A parametrized model of seasonal temperature changes in lakes

1990 ◽  
Vol 5 (1) ◽  
pp. 12-25 ◽  
Author(s):  
S.S. Zilitinkevich ◽  
V.A. Rumyantzev
Keyword(s):  
Seasonal Temperature ◽  
Temperature Changes

scholarly journals The Seasonal Cycle of Blocking and Associated Physical Mechanisms in the Australian Region and Relationship with Rainfall

2013 ◽  
Vol 141 (12) ◽  
pp. 4534-4553 ◽  
Author(s):  
M. J. Pook ◽  
J. S. Risbey ◽  
P. C. McIntosh ◽  
C. C. Ummenhofer ◽  
A. G. Marshall ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Seasonal Temperature ◽  
Ocean Fronts ◽  
Temperature Changes ◽  
Physical Mechanisms ◽  
Australian Region ◽  
Continental Antarctica ◽  
Positive Correlations ◽  
Blocking Index

Abstract The seasonal cycle of blocking in the Australian region is shown to be associated with major seasonal temperature changes over continental Antarctica (approximately 15°–35°C) and Australia (about 8°–17°C) and with minor changes over the surrounding oceans (below 5°C). These changes are superimposed on a favorable background state for blocking in the region resulting from a conjunction of physical influences. These include the geographical configuration and topography of the Australian and Antarctic continents and the positive west to east gradient of sea surface temperature in the Indo-Australian sector of the Southern Ocean. Blocking is represented by a blocking index (BI) developed by the Australian Bureau of Meteorology. The BI has a marked seasonal cycle that reflects seasonal changes in the strength of the westerly winds in the midtroposphere at selected latitudes. Significant correlations between the BI at Australian longitudes and rainfall have been demonstrated in southern and central Australia for the austral autumn, winter, and spring. Patchy positive correlations are evident in the south during summer but significant negative correlations are apparent in the central tropical north. By decomposing the rainfall into its contributions from identifiable synoptic types during the April–October growing season, it is shown that the high correlation between blocking and rainfall in southern Australia is explained by the component of rainfall associated with cutoff lows. These systems form the cyclonic components of blocking dipoles. In contrast, there is no significant correlation between the BI and rainfall from Southern Ocean fronts.

Germination ecology of winter annual grasses in Mediterranean climates: Applications for soil cover in olive groves

2018 ◽  
Vol 262 ◽  
pp. 29-35 ◽  
Author(s):  
Borja Jiménez-Alfaro ◽  
Matías Hernández-González ◽  
Eduardo Fernández-Pascual ◽  
Peter Toorop ◽  
Stephanie Frischie ◽  
...  
Keyword(s):  
Soil Cover ◽  
Germination Ecology ◽  
Annual Grasses ◽  
Olive Groves ◽  
Winter Annual

An Account of Fruit and Seed Morphology, Germination and Seedling growth of Four Species of Salacia L

2019 ◽  
Vol 26 (3) ◽  
pp. 145-150
Author(s):  
Chitra Chandrasenan Rajeswary ◽  
◽  
S. Bindu ◽  
S.M. Shareef ◽  
V.S. Hima ◽  
...  
Keyword(s):  
Ex Situ Conservation ◽  
Natural Habitat ◽  
Seed Morphology ◽  
Juvenile Stage ◽  
Ex Situ ◽  
Seedling Vigour ◽  
Critical Moisture ◽  
Salacia Oblonga ◽  
Seedling Characters ◽  
Propagation Material

Seeds are the most effective and thriving propagation material of Salacia. As part of ex-situ conservation programme, four highly sought Salacia species, viz., Salacia brunoniana Wight & Arn., Salacia fruticosa Wall. Salacia malabarica Gamble and Salacia oblonga Wall. through fruit, seed and seedling characterization was carried out. For this, phenology and morphology of fruits and seeds with reference to polymorphism were documented. Effect of fresh and desiccated moisture content especially that of critical moisture were tested to understand the extent of viability of seeds. Since, these species became threatened in their natural habitat; attempts were made to standardize their seed germination characters and seedlings were raised. Seedling characters along with seedling vigour were documented up to 6 leaf stage and also an identification key was made based on their seedling characters which would aid in the demarcation of the species at their juvenile stage.

Sign in / Sign up

Export Citation Format

Share Document