Seed germination, seedling emergence, and seed bank ecology of sweet fern (Comptonia peregrina(L.) Coult.)

1999 ◽  
Vol 77 (9) ◽  
pp. 1378-1386
Author(s):  
Melissa A Dow ◽  
Christa R Schwintzer
Keyword(s):  
Seed Germination ◽  
Seed Bank ◽  
Temperature Fluctuation ◽  
Seedling Emergence ◽  
Chilling Temperature ◽  
Secondary Dormancy ◽  
Forest Sites ◽  
Moist Chilling ◽  
Adjacent Field ◽  
Dormancy Cycles

We examined seed-bank seeds of sweet fern (Comptonia peregrina (L.) Coult.), an actinorhizal nitrogen-fixing shrub, to determine their distribution in the soil and to identify the factors that stimulate them to germinate following removal of the vegetation. Seeds were extracted from the soil of adjacent field and forest sites currently lacking sweet fern in Orono, Maine. Both sites contained approximately 2000 seeds·m-2with the greatest concentration at a depth of 60-80 mm. The seeds were 4.0-5.5 mm long, enclosed by a pitted, woody pericarp, and 8% contained embryos. Many seedlings emerged in disturbed plots (vegetation removed and upper soil mixed) in May and June 1997, but none appeared after 24 July. Seeds collected in May and June germinated readily in a growth chamber (30-45% germination) whereas only 2-5% of July- and August-collected seeds germinated indicating induction of secondary dormancy. August-collected seeds showed strong germination after >=15 days of moist chilling at 4°C indicating relief of secondary dormancy by chilling. Temperature fluctuation with an amplitude of 10°C strongly stimulated germination. Presence of annual secondary dormancy cycles and stimulation by strong temperature fluctuation assures that seed-bank seeds germinate under conditions that allow the seedlings to become established.Key words: actinorhizal plants, Comptonia peregrina, germination ecophysiology, secondary dormancy, seed bank, seedling emergence.

Effects of heat and smoke on germination of soil-stored seed in a south-eastern Australian sand heathland

2002 ◽  
Vol 50 (2) ◽  
pp. 197 ◽  
Author(s):  
Timothy J. Wills ◽  
Jennifer Read
Keyword(s):  
Seed Germination ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Type Systems ◽  
Treated Soil ◽  
South Eastern ◽  
Heat Treated ◽  
Eastern Australia ◽  
And Control

Various fire-related agents, including heat, smoke, ash and charred wood, have been shown to break dormancy and promote germination of soil-stored seed in a broad range of species in mediterranean-type systems. However, relatively little work has been conducted in south-eastern Australian heathlands. This study examined the effects of heat and smoked water on germination of the soil seed bank in a mature sand heathland within the Gippsland Lakes Coastal Park, in south-eastern Australia. Heat was clearly the most successful treatment for promoting seed germination, followed by smoked water, then controls, with 55% of species present in the germinable soil seed bank requiring a heat or smoke stimulus to promote seed germination. Mean species richness of the germinable soil seed bank was found to be significantly higher in heat-treated soil than in smoke and control treatments. Seedling density of heat-treated soil was almost 10 times that of controls, while smoke-treated soil was almost five times that of controls. Seedling emergence was fastest in heat-treated soil, followed by smoke and control soils. Of the species found in the soil seed bank, 25% were absent from the extant vegetation, suggesting the existence of post-fire colonisers in the soil seed bank. The results have implications for the design of soil seed bank experiments and the use of fire as a tool in vegetation management.

Seed Germination Ecophysiology of Meadow Salsify (Tragopogon pratensis) and Western Salsify (T. dubius)

Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 362-368 ◽  
Author(s):  
Meiqin Qi ◽  
Mahesh K. Upadhyaya
Keyword(s):  
Seed Germination ◽  
Storage Temperature ◽  
Seedling Emergence ◽  
Separate Study ◽  
Optimum Temperature ◽  
Seedling Mortality ◽  
Secondary Dormancy ◽  
Persistence Strategies

To understand persistence strategies of meadow and western salsify, ecophysiological characteristics of their seed germination were studied. Anaerobiosis (immersion in deoxygenated water) induced secondary dormancy in seeds of both species. Dormancy could be induced in 86% of meadow salsify seeds and in 65% of western salsify seeds by a 1-d anaerobiosis treatment. The induced dormancy was gradually released during storage of air-dried secondary dormant meadow salsify seeds, and the rate of this release was influenced by storage temperature; 30 C was more effective than 10 or 20 C in releasing secondary dormancy. These results suggest that the two species may rely on induced dormancy as an option in their persistence strategy. The optimum temperature for germination of nondormant seeds of both species was 15 C. Maximum germination percentages for both species were established within 4 to 6 d of incubation at 15 C and within 14 to 28 d of incubation at 25 C. Nondormant seeds did not germinate below 10 or above 30 C. Stratification (at 5 C for 2 to 10 wk) stimulated germination of secondary dormant seeds of meadow salsify. This stratification requirement can be important in preventing germination of dormant salsify seeds in the fall, thereby avoiding high seedling mortality in the winter. Light (red and far-red) had no effect on germination of seeds in secondary dormancy. In a separate study, seeds of both species were planted in pots at depths of 2 to 14 cm and seedling emergence was observed. Maximum emergence occurred when seeds were buried 2 cm deep. Seeds planted 8 cm or deeper germinated but did not emerge.

scholarly journals Secondary dormancy of seeds in relation to the Bromus tectorum–Pyrenophora semeniperda pathosystem

2013 ◽  
Vol 49 (Special Issue) ◽  
pp. S11-S14 ◽  
Author(s):  
K.K. Hawkins ◽  
P. Allen ◽  
S. Meyer
Keyword(s):  
Seed Germination ◽  
Field Study ◽  
Seed Bank ◽  
Fungal Pathogen ◽  
Bromus Tectorum ◽  
Large Fraction ◽  
Annual Grass ◽  
Late Autumn ◽  
Secondary Dormancy ◽  
Laboratory Results

Bromus tectorum is a highly invasive annual grass. The fungal pathogen Pyrenophora semeniperda can kill a large fraction of B. tectorum seeds. Outcomes in this pathosystem are often determined by the speed of seed germination. In this paper we extend previous efforts to describe the pathosystem by characterising secondary dormancy acquisition of B. tectorum. In the laboratory approximately 80% of seeds incubated at –1.0 MPa became dormant. In the field, seeds were placed in the seed bank in late autumn, retrieved monthly and dormancy status determined. The field study confirmed the laboratory results; ungerminated seeds became increasingly dormant. Our data suggest that secondary dormancy is much more likely to occur at xeric sites.

Seedling emergence after maternal bentazon application to 10 cocklebur (Xanthium strumarium) populations

1994 ◽  
Vol 74 (4) ◽  
pp. 863-866 ◽  
Author(s):  
Jianhua Zhang ◽  
Paul B. Cavers
Keyword(s):  
Seed Germination ◽  
Key Words ◽  
Seed Bank ◽  
Seedling Emergence ◽  
Application Rate ◽  
Xanthium Strumarium ◽  
Cultivated Land ◽  
Mother Plants ◽  
Viable Seeds ◽  
Seedling Characteristics

Maternal environments have been reported to affect various seed and seedling characteristics in many plants. In this study, we examined the effect of bentazon application to the mother plants on seed germination and seedling emergence of 10 cocklebur populations from wetlands or cultivated land. The mortality or longevity of fully developed seeds was affected significantly by bentazon application. Rate of seedling emergence showed little response, whereas percentage seedling emergence and percentage viable seeds in the soil were reduced by bentazon treatment to the mother plants. Populations from wetlands produced seedlings earlier than those from cultivated land. Key words: Seedling emergence, seed bank, herbicide, bentazon, cocklebur, Xanthium strumarium

Seasonal dormancy cycles in the biennial Torilis japonica (Apiaceae), a species with morphophysiological dormancy

2008 ◽  
Vol 18 (3) ◽  
pp. 161-171 ◽  
Author(s):  
Filip Vandelook ◽  
Nele Bolle ◽  
Jozef A. Van Assche
Keyword(s):  
Western Europe ◽  
Light Stimulus ◽  
Seedling Emergence ◽  
Extensive Study ◽  
Temperate Climate ◽  
Morphophysiological Dormancy ◽  
Torilis Japonica ◽  
Moist Chilling ◽  
Cyclic Changes ◽  
Dormancy Cycles

AbstractTorilis japonica (Apiaceae) has a widespread distribution, extending from western Europe to eastern Asia. In Europe, it usually behaves as a spring-germinating biennial species. Ripe seeds of T. japonica have an underdeveloped embryo and can persist in the soil for several years. The aim of this research was to reveal the mechanisms regulating the seasonal emergence pattern of seedlings. Experiments in a natural environment were performed to study phenology of seedling emergence and embryo growth. Seasonal changes in the dormancy status of T. japonica seeds were examined by regularly exhuming buried seeds and incubating them in controlled conditions. The action of temperature and light in regulating dormancy, embryo growth and germination was studied in the laboratory. Results showed that seeds of T. japonica have non-deep, simple morphophysiological dormancy (MPD), whereby physiological dormancy is broken by moist chilling (5°C). Once MPD was broken, embryo growth and subsequent germination started in spring, when appropriate temperature and light conditions were present. Seeds buried at a depth where light could not reach them showed cyclic changes in their dormancy status; embryo growth in these seeds could not be initiated because of the lack of a light stimulus. As far as we know, this is the first extensive study of seasonal dormancy cycles in a spring-germinating species of the Apiaceae. T. japonica occurs in a temperate climate with cool winters and warm, moist summers. In this climate, spring is often the most favourable season for seedling establishment.

scholarly journals Effect of Environmental Factors on the Germination and Emergence of Drunken Horse Grass (Achnatherum inebrians)

Weed Science ◽  
2020 ◽  
pp. 1-29
Author(s):  
Yonghuan Yue ◽  
Guili Jin ◽  
Weihua Lu ◽  
Ke Gong ◽  
Wanqiang Han ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Abiotic Factors ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Germination Percentage ◽  
Western China ◽  
Burial Depth ◽  
Achnatherum Inebrians ◽  
Water Ph

Abstract Drunken horse grass [Achnatherum inebrians (Hance) Keng] is a perennial poisonous weed in western China. A comprehensive understanding of the ecological response of A. inebrians germination to environmental factors would facilitate the formulation of better management strategies for this weed. Experiments were conducted under laboratory conditions to assess the effects of various abiotic factors, including temperature, light, water, pH and burial depth, on the seed germination and seedling emergence of A. inebrians. The seeds germinated at constant temperatures of 15, 20, 25, 30, 35°C and in alternating-temperature regimes of 15/5, 20/10, 25/15, 30/20, 35/25, 40/30°C, and the seed germination percentages under constant and alternating temperatures ranged from 51% to 94% and 15% to 93%, respectively. Maximum germination occurred at a constant temperature of 25°C, and germination was prevented at 45/35°C. Light did not appear to affect seed germination. The germination percentage of seeds was more than 75% in the pH range of 5 to 10, with the highest germination percentage at pH 6. The seeds germinated at osmotic potentials of 0 MPa to -1.0 MPa, but decreasing osmotic potential inhibited germination, with no germination at -1.2MPa. After 21 d of low osmotic stress, the seeds that did not germinate after rehydration had not lost their vitality. The seedling emergence percentage was highest (90%) when seeds were buried at 1 cm but declined with increasing burial depth and no emergence at 9 cm. Deep tillage may be effective in limiting the seed germination and emergence of this species. The results of this study provide useful information on the conditions necessary for A. inebrians germination and provide a theoretical basis for science-based prediction, prevention and control of this species.

Embryo dormancy responses to temperature in capeweed (Arctotheca calendula) seeds

2002 ◽  
Vol 12 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Amanda J. Ellery
Keyword(s):  
Soil Temperature ◽  
Water Potential ◽  
Low Temperatures ◽  
Seasonal Changes ◽  
Temperature Fluctuation ◽  
Soil Surface ◽  
Seed Collection ◽  
Embryo Dormancy ◽  
Response To Temperature ◽  
Dormancy Cycles

Changes in embryo dormancy of capeweed [Arctotheca calendula (L.) Levyns.] seeds in response to temperature were investigated to determine the nature of seasonal dormancy cycles. Primary embryo dormancy persisted for 2–3 months after seed collection and was then rapidly relieved when seeds were maintained at temperatures simulating summer soil surface temperatures. Embryo dormancy was also rapidly relieved in seeds maintained at constant temperatures, indicating that a daily temperature fluctuation was not necessary for the relief of embryo dormancy in capeweed. Dormancy relief was maximal at 40°C. Secondary dormancy was induced when seeds were maintained at low temperatures and a water potential of –1.5 MPa, suggesting that the onset of winter may postpone germination until a subsequent autumn. These results indicate that the dormancy cycles observed in capeweed seeds maintained on the soil surface are probably driven by seasonal changes in soil temperature.

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