Interpopulation variation in germination response to fire-related cues and after-ripening in seeds of the evergreen perennial Anigozanthos flavidus (Haemodoraceae)

2020 ◽  
Vol 29 (10) ◽  
pp. 950
Author(s):  
Hongyuan Ma ◽  
Todd E. Erickson ◽  
Jeffrey L. Walck ◽  
David J. Merritt
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Mediterranean Environment ◽  
Species Persistence ◽  
Viability Loss ◽  
Interpopulation Variation ◽  
In Fire ◽  
Smoke Water ◽  
Germination Requirements

Variations in the degree of seed dormancy expressed among conspecific populations provide a basis for improving understanding of the mechanisms controlling species persistence, especially in fire-prone ecosystems. We investigated seed germination of 12 Anigozanthos flavidus populations in response to various fire-related cues that included exposure to karrikinolide, glyceronitrile and smoke water at five temperatures, and the effects of heat shock and its interaction with glyceronitrile. Seeds from populations with deep-degree dormancy (DD) and light-degree dormancy (LD) were subjected to 0–8 months of after-ripening, and the viability of the ungerminated seeds was tested. The degree of seed dormancy and responses to fire-related cues were highly variable among populations. Glyceronitrile and smoke water significantly improved germination in 12 and 8 populations respectively. Heat significantly enhanced germination in all populations, but was less effective when combined with glyceronitrile. After-ripening for 3 months increased germination, whereas ≥4 months led to secondary dormancy or loss of viability. Loss of viability was greater for DD than for LD seeds. Interpopulation variations in the degree of seed dormancy, seed germination requirements for fire-related cues and germination viability in response to after-ripening in A. flavidus contribute to persistence in the variable and unpredictable Mediterranean environment.

scholarly journals Heat shock and plant leachates regulate seed germination of the endangered carnivorous plant <i>Drosophyllum lusitanicum</i>

Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Susana Gómez-González ◽  
Maria Paniw ◽  
Kamila Antunes ◽  
Fernando Ojeda
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Fire Ecology ◽  
Germination Rate ◽  
Natural Populations ◽  
Seed Viability ◽  
Carnivorous Plant ◽  
In Fire

Abstract. In fire-prone ecosystems, many plant species have specialized mechanisms of seed dormancy that ensure a successful recruitment after fire. A well-documented mechanism is the germination stimulated by fire-related cues, such as heat shock and smoke. However, less is known about the role of inhibitory germination signals (e.g. allelopathy) in regulating post-fire recruitment. Plant leachates derived from the unburned vegetation can enforce dormancy by means of allelopathic compounds, acting as a signal of unfavourable (highly competitive) niche for germination in pyrophyte species. Here, we assessed the separate effects of heat shock and plant leachates on seed germination of Drosophyllum lusitanicum, an endangered carnivorous plant endemic to Mediterranean fire-prone heathlands. We performed a germination experiment in which seeds were subjected to three treatments: (1) 5 min at 100 ∘C, (2) watering with plant leachate, and (3) control. Germination rate and seed viability was determined after 63 days. Heat shock stimulated seed germination in D. lusitanicum while plant leachates had inhibitory germination effects without reducing seed viability. Thus, both positive and negative signals could be involved in its successful post-fire recruitment. Fire would break seed dormancy and stimulate seed germination of D. lusitanicum through high temperatures, but also by eliminating allelochemical compounds from the soil. These results help to understand the population dynamics patterns found for D. lusitanicum in natural populations, and highlight the role of fire in the ecology and conservation of this endangered species. Seed dormancy imposed by plant-derived leachates as an adaptive mechanism should be considered more in fire ecology theory.

scholarly journals Non-Deep Physiological Dormancy in Seed and Germination Requirements of Lysimachia coreana Nakai

Horticulturae ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 490
Author(s):  
Saeng Geul Baek ◽  
Jin Hyun Im ◽  
Myeong Ja Kwak ◽  
Cho Hee Park ◽  
Mi Hyun Lee ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Germination Rate ◽  
Seed Viability ◽  
Cold Stratification ◽  
Dormancy Breaking ◽  
Viability Test ◽  
Physiological Dormancy ◽  
Different Temperatures ◽  
Germination Requirements

This study aimed to determine the type of seed dormancy and to identify a suitable method of dormancy-breaking for an efficient seed viability test of Lysimachia coreana Nakai. To confirm the effect of gibberellic acid (GA3) on seed germination at different temperatures, germination tests were conducted at 5, 15, 20, 25, 20/10, and 25/15 °C (12/12 h, light/dark), using 1% agar with 100, 250, and 500 mg·L−1 GA3. Seeds were also stratified at 5 and 25/15 °C for 6 and 9 weeks, respectively, and then germinated at the same temperature. Seeds treated with GA3 demonstrated an increased germination rate (GR) at all temperatures except 5 °C. The highest GR was 82.0% at 25/15 °C and 250 mg·L−1 GA3 (4.8 times higher than the control (14.0%)). Additionally, GR increased after cold stratification, whereas seeds did not germinate after warm stratification at all temperatures. After cold stratification, the highest GR was 56.0% at 25/15 °C, which was lower than the GR observed after GA3 treatment. We hypothesized that L. coreana seeds have a non-deep physiological dormancy and concluded that 250 mg·L−1 GA3 treatment is more effective than cold stratification (9 weeks) for L. coreana seed-dormancy-breaking.

Population ecology of Cirsium pitcheri on Lake Huron sand dunes. III. Mechanisms of seed dormancy

1998 ◽  
Vol 76 (4) ◽  
pp. 575-586 ◽  
Author(s):  
Hua Chen ◽  
M A Maun
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Seed Coat ◽  
Threatened Species ◽  
Sand Dunes ◽  
Growth Chamber ◽  
Oenothera Biennis ◽  
Breaking Seed Dormancy ◽  
Cirsium Pitcheri ◽  
Germination Requirements

Growth chamber studies were conducted to examine seed dormancy and germination requirements of Pitcher's thistle (Cirsium pitcheri (Torr. ex Eaton) Torr. & Gray), a threatened species endemic to the shoreline sand dunes of the Great Lakes. We determined the effects of different environmental regimes on breaking seed dormancy of this monocarpic perennial. The data showed that seeds of C. pitcheri possessed innate dormancy that was caused by a hard seed coat as well as inhibitory compounds within the seed. Seed germination requirements were very specific. Exposure of seeds to different temperatures and photoperiods in a growth chamber had little effect on breaking seed dormancy unless the seeds had been pretreated. Pretreatment of seeds by cold stratification and its duration, scarification by sand paper or sulphuric acid, and application of gibberellic acid were also not very effective for breaking dormancy of C. pitcheri. High germination was obtained only when seeds were pretreated either by surgically removing the seed coat or by nicking the seed on the radicle or cotyledonary end. After this pretreatment seeds germinated over a temperature range of 15-30°C, but the highest proportion of seeds germinated when temperatures were above 20°C. Under natural conditions, germination of C. pitcheri seeds occurs in spring after they have overwintered and experienced the pretreatment of stratification and scarification through freezing and thawing of the substrate. Aqueous extract of C. pitcheri seeds had a strong inhibitory effect on germination of Oenothera biennis L. seeds indicating an allelopathic chemical in the seed. There was no relationship between the seed size of C. pitcheri and the germinability of seeds.Key words: Cirsium pitcheri, threatened species, seed dormancy, seed germination, scarification, stratification, nicking of seeds.

scholarly journals Roles of Reactive Oxygen Species and Mitochondria in Seed Germination

2021 ◽  
Vol 12 ◽  
Author(s):  
Muhammad Awais Farooq ◽  
Xiaomeng Zhang ◽  
Muhammad Mubashar Zafar ◽  
Wei Ma ◽  
Jianjun Zhao
Keyword(s):  
Reactive Oxygen Species ◽  
Heat Shock ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Energy Demand ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Reactive Oxygen ◽  
Dependent Manner ◽  
Oxygen Species

Seed germination is crucial for the life cycle of plants and maximum crop production. This critical developmental step is regulated by diverse endogenous [hormones, reactive oxygen species (ROS)] and exogenous (light, temperature) factors. Reactive oxygen species promote the release of seed dormancy by biomolecules oxidation, testa weakening and endosperm decay. Reactive oxygen species modulate metabolic and hormone signaling pathways that induce and maintain seed dormancy and germination. Endosperm provides nutrients and senses environmental signals to regulate the growth of the embryo by secreting timely signals. The growing energy demand of the developing embryo and endosperm is fulfilled by functional mitochondria. Mitochondrial matrix-localized heat shock protein GhHSP24.7 controls seed germination in a temperature-dependent manner. In this review, we summarize comprehensive view of biochemical and molecular mechanisms, which coordinately control seed germination. We also discuss that the accurate and optimized coordination of ROS, mitochondria, heat shock proteins is required to permit testa rupture and subsequent germination.

Seed ecology of Lepidosperma scabrum (Cyperaceae), a dryland sedge from Western Australia with physiological seed dormancy

2013 ◽  
Vol 61 (8) ◽  
pp. 643 ◽  
Author(s):  
S. R. Turner
Keyword(s):  
Heat Shock ◽  
Seed Dormancy ◽  
Large Scale ◽  
Winter Season ◽  
Additional Treatment ◽  
Scale Production ◽  
Large Scale Production ◽  
High Germination ◽  
Smoke Water

Lepidosperma scabrum is a common understorey species currently required for urban bushland restoration, although its propagation has been highly problematic. In this context, the overall aims of the present study were to (1) document key characteristics for seed-dormancy classification; (2) assess the effectiveness of different germination-promoting treatments; and (3) quantify changes in nutlet fill, dormancy and germination following soil storage under natural and nursery conditions. Initial investigations found that naturally shed nutlets (the natural germination unit) have high seed fill and viability (>90.0%) and a small (~468 µm) capitate embryo that readily grew (>95.0%) when extracted and cultured in vitro. Intact nutlets also imbibed moisture to a similar percentage (15.0 ± 1.4%) as nicked nutlets (18.0 ± 1.8%). Fresh nutlets germinated only in response to heat shock (100°C for 10 min), which was enhanced with additional treatment with 2.89 mM gibberellic acid (13.3%), 10% v/v smoke water (16. 6%) or a combination of both (23.3%). Nutlets placed into a burial trial maintained viability for 3 years and started to germinate (19.9 ± 9.5%) in response to smoke water by the third winter season. Heat shock was also found to significantly improve germination (81.1 ± 4.2%) for soil-aged nutlets. The present study is the first report of high germination from intact nutlets of any Lepidosperma spp. and provides practical techniques for the large-scale production of plants for horticulture and restoration.

Heat shock, smoke and darkness: partner cues in promoting seed germination in Epacris tasmanica (Epacridaceae)

2000 ◽  
Vol 48 (5) ◽  
pp. 603 ◽  
Author(s):  
Craig A. Gilmour ◽  
Ronald K. Crowden ◽  
Anthony Koutoulis
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Effective Treatment ◽  
Seed Dormancy ◽  
Inhibitory Effect ◽  
Dormancy Breaking ◽  
Seasonal Drought ◽  
Breaking Seed Dormancy ◽  
Tasmanian Endemic

The Epacridaceae is one of the families that dominate Australian heathlands, environments prone to disturbance events such as fire and seasonal drought. To investigate the role of fire-related cues in breaking seed-dormancy mechanisms in the Epacridaceae, the influences of heat shock, darkness, direct smoke and varying concentrations of aqueous smoke solutions (5, 10 and 100%) on seed germination of the Tasmanian endemic Epacris tasmanica were examined. A small fraction (5.3%) of non-dormant E. tasmanica seed could germinate in the absence of fire-related cues. The most effective treatment for promoting seed germination was direct smoke (74.67%); however, germination with direct smoke was delayed by about two weeks when compared to other significant treatments, suggesting an initial inhibitory effect. Significant interactions were recorded between all classes of treatments (heat shock, darkness and smoke solutions), with treatments acting sequentially and additively to promote germination. The most effective combinatory treatment tested was 5% smoked water (5%S) in conjunction with darkness (D) and heat-shock (H) treatments (5%SDH), which raised germination levels to 49%. In the absence of heat shock, darkness and various concentrations of smoked water had no significant effect on seed germination. The 5%SDH treatment promoted seed germination significantly also in two wet-heathland (E. lanuginosa (42.7%) and E. obtusifolia (64.7%)) and two dry-heathland Epacris species (the Tasmanian endemic E. apsleyensis (72.7%) and the rare mainland Australian E. purpurascens (75%)). The results of this study indicate that fire-related dormancy-breaking cues act synergistically in promoting seed germination in E. tasmanica and suggesting that their level of influence may reflect the ecology of Epacris species.

scholarly journals Practical Methods for Breaking Seed Dormancy in a Wild Ornamental Tulip Species Tulipa thianschanica Regel

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1765
Author(s):  
Wei Zhang ◽  
Lian-Wei Qu ◽  
Jun Zhao ◽  
Li Xue ◽  
Han-Ping Dai ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Combined Treatment ◽  
Individual Treatment ◽  
Cold Stratification ◽  
Slight Effect ◽  
Sowing Depth ◽  
Physiological Dormancy ◽  
Commercial Breeding ◽  
Breaking Seed Dormancy

The innate physiological dormancy of Tulipa thianschanica seeds ensures its survival and regeneration in the natural environment. However, the low percentage of germination restricts the establishment of its population and commercial breeding. To develop effective ways to break dormancy and improve germination, some important factors of seed germination of T. thianschanica were tested, including temperature, gibberellin (GA3) and/or kinetin (KT), cold stratification and sowing depth. The percentage of germination was as high as 80.7% at a constant temperature of 4 °C, followed by 55.6% at a fluctuating temperature of 4/16 °C, and almost no seeds germinated at 16 °C, 20 °C and 16/20 °C. Treatment with exogenous GA3 significantly improved the germination of seeds, but KT had a slight effect on the germination of T. thianschanica seeds. The combined treatment of GA3 and KT was more effective at enhancing seed germination than any individual treatment, and the optimal hormone concentration for the germination of T. thianschanica seeds was 100 mg/L GA3 + 10 mg/L KT. In addition, it took at least 20 days of cold stratification to break the seed dormancy of T. thianschanica. The emergence of T. thianschanica seedlings was the highest with 82.4% at a sowing depth of 1.5 cm, and it decreased significantly at a depth of >3.0 cm. This study provides information on methods to break dormancy and promote the germination of T. thianschanica seeds.

scholarly journals Regulation of Seed Dormancy and Germination Mechanisms in a Changing Environment

2021 ◽  
Vol 22 (3) ◽  
pp. 1357
Author(s):  
Ewelina A. Klupczyńska ◽  
Tomasz A. Pawłowski
Keyword(s):  
Climate Change ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Environmental Conditions ◽  
Global Climate ◽  
Plant Evolution ◽  
Suitable Habitat ◽  
Climate Change Scenarios ◽  
Adaptation Mechanism ◽  
Seed Dormancy And Germination

Environmental conditions are the basis of plant reproduction and are the critical factors controlling seed dormancy and germination. Global climate change is currently affecting environmental conditions and changing the reproduction of plants from seeds. Disturbances in germination will cause disturbances in the diversity of plant communities. Models developed for climate change scenarios show that some species will face a significant decrease in suitable habitat area. Dormancy is an adaptive mechanism that affects the probability of survival of a species. The ability of seeds of many plant species to survive until dormancy recedes and meet the requirements for germination is an adaptive strategy that can act as a buffer against the negative effects of environmental heterogeneity. The influence of temperature and humidity on seed dormancy status underlines the need to understand how changing environmental conditions will affect seed germination patterns. Knowledge of these processes is important for understanding plant evolution and adaptation to changes in the habitat. The network of genes controlling seed dormancy under the influence of environmental conditions is not fully characterized. Integrating research techniques from different disciplines of biology could aid understanding of the mechanisms of the processes controlling seed germination. Transcriptomics, proteomics, epigenetics, and other fields provide researchers with new opportunities to understand the many processes of plant life. This paper focuses on presenting the adaptation mechanism of seed dormancy and germination to the various environments, with emphasis on their prospective roles in adaptation to the changing climate.

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