Germination strategies of annual forbs from south-eastern Australian semiarid grasslands

2012 ◽  
Vol 60 (4) ◽  
pp. 340 ◽  
Author(s):  
Andrew J. Scott ◽  
John W. Morgan
Keyword(s):  
Temperature Regime ◽  
Environmental Conditions ◽  
Seed Banks ◽  
Constant Darkness ◽  
Continuous Darkness ◽  
Soil Seed Banks ◽  
South Eastern ◽  
Single Temperature ◽  
Risk Spreading ◽  
Main Strategy

Germination is a key process driving the composition and dynamics of annual-forb communities and soil seed banks. We tested the germination biology of 20 annual forbs from semiarid grasslands in southern Australia, under a single temperature regime (20/10°C) in either constant darkness or 12-h diurnal light, to assess whether their laboratory germination responses are consistent with transient seed banks and rapid field emergence. Germination in the light was generally moderate to high, with most (70%) species achieving >35% final germination. Additionally, most (90%) species began germinating within 5 days, and all species achieved at least 50% of final germination within 10 days, suggesting that rapid and synchronous germination is the main strategy of annual forbs in this region. However, several species had seeds that continued to germinate for a prolonged period, and in most species, a fraction of seeds did not germinate, demonstrating risk-spreading strategies. Additionally, the germination of most (79%) species was significantly inhibited by continuous darkness. Despite the potential for the formation of large persistent seed banks through low germination in some species and dark inhibition in most, rapid germination and prevailing environmental conditions apparently prevent this in the field.

Germination asynchrony is increased by dual seed bank presence in two desert perennial halophytes

Botany ◽  
2019 ◽  
Vol 97 (11) ◽  
pp. 639-649 ◽  
Author(s):  
Arvind Bhatt ◽  
Narayana R. Bhat ◽  
Flavio Lozano-Isla ◽  
David Gallacher ◽  
Andrea Santo ◽  
...  
Keyword(s):  
Seed Bank ◽  
Environmental Conditions ◽  
Germination Rate ◽  
Soil Surface ◽  
Seed Banks ◽  
Viable Seed ◽  
Plant Recruitment ◽  
Soil Seed Banks ◽  
Desert Habitat

Maintaining a viable seed bank throughout the germination season is considered very important for plant recruitment in desert environments, where environmental conditions are unpredictable. Seeds from fully matured Seidlitzia rosmarinus Bunge ex Boiss and Halothamnus iraqensis Botsch. were collected in December 2016, then April, June, and September 2017 from both soil-surface and aerial seed banks. Both of the species were selected mainly by their capacity to rehabilitate saline coastal sites. Germination was analyzed under two photoperiods (0 or 12 h light per day), with winged or dewinged perianths. Seidlitzia rosmarinus had a shorter seasonal range in comparison with H. iraqensis (6 and 9 months, respectively), and the presence of a winged perianth reduced the germination rate of both species. A permanent winged perianth significantly inhibited the germination rate in both species. In the absence of perianth, the germination registered in December 2016 was mostly 100%, but declined to around 20% in September 2017. Seeds are thus more likely to germinate after scarification from wind mobilization, and do not require burial. Our results show that seeds of both the aerial and soil banks are transitory, and viable only during the winter months. Taken together, the combination of aerial and soil seed banks has greatly facilitated germination asynchrony in their environmentally unpredictable desert habitat.

Longevity and germination ecology of seeds of endemic Cactaceae species from high-altitude sites in south-eastern Brazil

2011 ◽  
Vol 22 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Ana Loureiro Cheib ◽  
Queila Souza Garcia
Keyword(s):  
Seedling Survival ◽  
Seed Banks ◽  
Ex Situ ◽  
Continuous Darkness ◽  
Soil Seed Banks ◽  
Eastern Brazil ◽  
High Germination ◽  
Absolute Requirement ◽  
Germination Behaviour ◽  
Germination Experiments

AbstractThe influence of light and temperature on germination behaviour and the longevity of seeds were evaluated in four taxa of the genusArthrocereus(Cactaceae). Germination experiments were conducted at six constant temperatures with a 12-h photoperiod and in continuous darkness. Forin situstorage tests, the seeds were buried in the soil where the species naturally occur, and germination experiments were performed for 14 months. Seeds were also stored dry at room temperature in the laboratory for 12 months. The results indicated that, in spite of the variations between the four taxa studied, there is a consistent pattern in their germination behaviour. The seeds are small, with an absolute requirement of light for germination. In the presence of light, we obtained high germinability at temperatures between 20 and 30°C and low germination percentages at 10, 15 and 35°C. This behaviour may represent an adaptive mechanism during seasons when environmental conditions in open rocky fields are not favourable for seedling survival. In general, germination was relatively slow, which would favour establishment during the rainy season. Dry storage did not significantly alter seed germination behaviour, and buried seeds, likewise, remained viable and retained high germination percentages. We can therefore infer that the seeds of the species studied here are able to form persistent soil seed-banks. All studied species are threatened with extinction, so their ability to form soil seed-banks, together with the possibility ofex situseed preservation, will possibly give support for future conservation efforts.

Comparative Germination Responses of 28 Temperate Grassland Species

1998 ◽  
Vol 46 (2) ◽  
pp. 209 ◽  
Author(s):  
J. W. Morgan
Keyword(s):  
Temperature Regime ◽  
Seed Weight ◽  
Life Form ◽  
Percentage Germination ◽  
Light Conditions ◽  
Continuous Darkness ◽  
Plant Family ◽  
Grassland Plants ◽  
Single Temperature ◽  
Germination Speed

The comparative germination biology of 28 perennial species native to the temperate grasslands of southern Victoria was tested using a single temperature regime (20/10˚C) in either constant darkness or 12 h diurnal white-light conditions. This temperature regime was chosen because it corresponds to the temperature found to produce substantial or optimal germination in other germination studies of grassland plants. Four germination attributes—time to the beginning of germination (germination lag), time taken to achieve 50% of final germination (germination speed –t50), percentage germination in diurnal light conditions and percentage germination in continuous darkness—were calculated for each species and correlated to three plant attributes: plant family, life form and seed weight. Germination lag was short for many species: 50% had a lag of less than 7 days, whilst 96% of species had begun germinating within 28 days. Germination speed was moderately fast for most species: 75% of species had a t50 of less than 28 days. Total percentage germination in diurnal light or continuous darkness was variable (0–98%), but many species (64%) germinated readily (> 50%) in at least one treatment. Twenty-four percent of species had germination substantially inhibited by darkness (i.e. Acaena echinata, Bulbine bulbosa, Eryngium ovinum, Podolepis sp. aff. jaceoides, Velleia paradoxa and Wahlenbergia luteola). No species had its germination promoted by darkness. Few correlations between plant and germination attributes were detected. Seed weight was not correlated with any of the three germination attributes, nor was life form or plant family correlated with germination speed or percentage germination in the light or dark. Germination lag, however, was significantly associated with plant family and, in a related way, with life form: species from the Liliaceae (geophytes) took longer to begin germination than species from the Asteraceae (hemicryptophytes). The ecological implications of the observed germination biology on the potential formation of persistent soil seed banks and seedling recruitment dynamics are discussed.

scholarly journals Storage and Composition of Soil Seed Banks of Different Degraded Karst Vegetation Types in South-Eastern Yunnan

2004 ◽  
Vol 28 (1) ◽  
pp. 101-106
Author(s):  
SHEN You-Xin ◽  
JIANG Jie ◽  
CHEN Sheng-Guo ◽  
CAI Guang-Li ◽  
ZHANG Ping
Keyword(s):  
Seed Banks ◽  
Vegetation Types ◽  
Soil Seed Banks ◽  
South Eastern

scholarly journals Classification of Post-Fire Responses of Woody Plants to include Pyrophobic Communities

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 15 ◽  
Author(s):  
Lynda D. Prior ◽  
David M. J. S. Bowman
Keyword(s):  
Woody Plants ◽  
Seed Banks ◽  
Classification Systems ◽  
Woody Vegetation ◽  
General Category ◽  
Conifer Species ◽  
Soil Seed Banks ◽  
Obligate Seeder ◽  
In Fire

Developing standardised classification of post-fire responses is essential for globally consistent comparisons of woody vegetation communities. Existing classification systems are based on responses of species growing in fire-prone environments. To accommodate species that occur in rarely burnt environments, we have suggested some important points of clarification to earlier schemes categorizing post-fire responses. We have illustrated this approach using several Australasian conifer species as examples of pyrophobic species. In particular, we suggest using the term “obligate seeder” for the general category of plants that rely on seed to reproduce, and qualifying this to “post-fire obligate seeder” for the narrower category of species with populations that recover from canopy fire only by seeding; the species are typically fire-cued, with large aerial or soil seed banks that germinate profusely following a fire, and grow and reproduce rapidly in order to renew the seed bank before the next fire.

Soil seed banks and the effects of meadow management on vegetation change in a 10-year meadow field trial

2002 ◽  
Vol 39 (2) ◽  
pp. 279-293 ◽  
Author(s):  
R.S. Smith ◽  
R.S. Shiel ◽  
D. Millward ◽  
P. Corkhill ◽  
R.A. Sanderson
Keyword(s):  
Field Trial ◽  
Vegetation Change ◽  
Seed Banks ◽  
Soil Seed Banks

scholarly journals Morphological variation in Leptorhynchos squamatus (Gnaphalieae: Asteraceae)

2002 ◽  
Vol 15 (2) ◽  
pp. 205 ◽  
Author(s):  
Christina Flann ◽  
Pauline Y. Ladiges ◽  
Neville G. Walsh
Keyword(s):  
High Altitude ◽  
Morphological Variation ◽  
Environmental Conditions ◽  
Leaf Size ◽  
Alpine Plants ◽  
The Other ◽  
Herbarium Specimens ◽  
South Eastern ◽  
Eastern Australia ◽  
Low Altitude

A study of morphological variation in Leptorhynchos squamatus (Labill.) Less. across its range in south-eastern Australia was undertaken to test the hypothesis that L. squamatus includes two taxa. Phenetic pattern analyses of both field-collected and herbarium specimens on the basis of morphology confirmed two major groups. Bract, cypsela, pappus bristle and leaf characters were particularly important in separating the two groups. The taxa are separated by altitude differences with one being a low-altitude plant found in many habitats and the other being a high-altitude taxon that is a major component of alpine meadows. Lowland plants have dark bract tips, fewer and wider pappus bristles than alpine plants, papillae on the cypselas and more linear leaves. A somewhat intermediate population from the Major Mitchell Plateau in the Grampians shows some alpine and some lowland characters but is included in the lowland taxon. Seeds from five populations (two alpine, two lowland and Major Mitchell) were germinated and plants grown for 18 weeks under four controlled sets of environmental conditions. The experiment showed that leaf size and some other characters are affected by environmental conditions, but that there are underlying genetic differences between the lowland and alpine forms. Leptorhynchos squamatus subsp. alpinus Flann is described here to accommodate the highland taxon.

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