Conditions de germination et rôle des herbivores dans la dispersion et le recrutement d'une espèce clonale : Juncus gerardi Lois.

2000 ◽  
Vol 78 (11) ◽  
pp. 1430-1439 ◽  
Author(s):  
Bernard Amiaud ◽  
Anne Bonis ◽  
Jan-Bernard Bouzillé
Keyword(s):  
Seedling Survival ◽  
Soil Seed Bank ◽  
Germination Rate ◽  
Rare Event ◽  
Clonal Plant ◽  
Seed Dispersion ◽  
Colonization Success ◽  
Juncus Gerardi ◽  
Favorable Conditions ◽  
Bovine Feces

The finding of new individuals of a clonal plant, Juncus gerardi, raised the question of modalities for the colonization of new sites by this species. Indeed, the existence of seedlings has not been observed in the field, nor reported in the literature for European marshes. Among the parameters limiting recruitment, we examined the soil seed bank, which appeared extremely small. Many seeds could be found in bovine feces but few were found in equine feces. Futhermore, bovines are not only important for seed dispersion, but also for the improvement of the germinative capacities: the seed germination rate of Juncus gerardi was doubled after digestive transit. Germination testing showed that this species is largely tolerant to salinity (from 0 to 26,4 mS·cm-1). The germination rate was maximal with a thermoperiod of 10-20°C but null for a 0-10°C thermoperiod. Germination was improved by immersion and was light dependent. The critical phase for colonization success in new habitats could be primarily seedling survival. Recruitment success in Juncus gerardi seems to be a rare event, requiring the combination of favorable conditions related to climate and gap openings in swards.Key words: germinative capacities, feces, clonal plant, grazers, endozoochory, pastures.

Seed-dispersal and seedling recruitment patterns by the last Neotropical megafaunal element in Amazonia, the tapir

2000 ◽  
Vol 16 (3) ◽  
pp. 369-385 ◽  
Author(s):  
José M. V. Fragoso ◽  
Jean M. Huffman
Keyword(s):  
Seedling Recruitment ◽  
Germination Rate ◽  
Seed Viability ◽  
Seed Rain ◽  
Dry Land ◽  
Forest Sites ◽  
Seed Dispersion ◽  
Tapirus Terrestris ◽  
Spatio Temporal ◽  
Seed Shadows

Tapirs (Tapiridae) are the last representatives of the Pleistocene megafauna of South and Central America. How they affect the ecology of plants was examined by studying the diversity, abundance, and condition of seeds defecated by the lowland tapir (Tapirus terrestris) in Amazonian Brazil. Additionally, the spatio-temporal pattern of the seed-rain and seed-shadows generated by tapirs was recorded. Three hundred and fifty-six tapir faeces were examined. Eleven per cent were found in water (n = 41), while 88% were located on dry land (n = 315). Of those found on dry land, 84% were located at sites that flood seasonally, while 14% of the total were encountered at forest sites that do not flood. In 127 faeces checked in the laboratory over 12 906 seeds of at least 39 species were found. Seed viability ranged from 65% for Maximiliana maripa to 98% for Enterolobium schomburgkii. Of nine seed species planted in the laboratory, seven germinated within 4 wk, with one species achieving an 89% germination rate. For many species recruitment to the seedling stage was also high under natural conditions, with 13 plant species occurring as seedlings in older faeces. Tapir generated seed-rain occurred throughout the year, with seeds defecated in all months. Two temporal patterns in species seed rain occurred: (1) contiguous monthly occurrence with peaks in abundance, and (2) discontinuous occurrence (time clumped) with small (a few months) to large (many months to more than a year) temporal gaps. The highest diversity of seeds appeared in April, at the end of the dry season. As the last of the Pleistocene megafauna of the region, tapirs may have particular importance as dispersers of large seeds and generators of unique seed dispersion patterns.

Effect of light on germination of seeds of Cactaceae from the Chihuahuan Desert, Mexico

2006 ◽  
Vol 16 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Joel Flores ◽  
Enrique Jurado ◽  
Alberto Arredondo
Keyword(s):  
At Risk ◽  
Chihuahuan Desert ◽  
Soil Seed Bank ◽  
Germination Rate ◽  
Ex Situ ◽  
Continuous Darkness ◽  
Secondary Dormancy ◽  
Large Numbers ◽  
Persistent Soil Seed Bank ◽  
Effect Of Light

In the Chihuahuan Desert, there are many cacti species considered to be at risk due to illegal extraction, land-use change and overgrazing. To reduce their illegal extraction,ex situplant propagation has been suggested. However, the literature regarding seed germination biology of these species is scarce. We investigated the effect of light on germination percentages and germination rate (t50) in seeds of 28 cactus species from the Chihuahuan Desert. Seeds were incubated at a 14-h daily photoperiod (light) and in continuous darkness at 25°C for 30 d, after which seeds failing to germinate in darkness were transferred to light for 30 d. Only 11 of the species had non-dormant seeds, germinating ≥70% in the light; thus an evaluation of the effect of light versus darkness on germination was confined to them. All species were positively photoblastic, and all of them had seeds weighing <1 mg. Ten species did not germinate in darkness, and one species had only 7% germination. From these 11 species, 8 did not germinate to a significantly higher percentage when the same set of seeds was transferred from dark to light, suggesting that darkness had triggered secondary dormancy (skotodormancy). To our knowledge, these results are the first to show that darkness triggers secondary dormancy in cacti. Implications of having a light requirement for germination and having small seeds to accumulate a persistent soil seed bank are discussed. These results contribute to understanding the germination biology of cactus species at risk, and could enhance the propagation of large numbers of cultivated individuals outside their habitats, promotingex situconservation.

scholarly journals Fecundity of Winged Euonymus Cultivars and Their Ability to Invade Various Natural Environments

HortScience ◽  
2012 ◽  
Vol 47 (8) ◽  
pp. 1029-1033 ◽  
Author(s):  
Mark H. Brand ◽  
Jessica D. Lubell ◽  
Jonathan M. Lehrer
Keyword(s):  
Seed Production ◽  
Seedling Survival ◽  
Germination Rate ◽  
Survival Rates ◽  
Natural Environments ◽  
Euonymus Alatus ◽  
Demographic Models ◽  
Non Invasive ◽  
Deciduous Woodland ◽  
Northern United States

Winged euonymus [Euonymus alatus (Thunb.)] is an important landscape shrub that has demonstrated its potential to be invasive in numerous states across the central and northern United States. Nine cultivars were evaluated for their potential to produce fruits and seeds in a randomized, replicated field planting. Seeds from all cultivars were evaluated for germination rate and initial survival in a deciduous woodland. Seeds collected from ‘Compactus’ were also sown in five natural environments (full sun meadow, edge of woods, moist woods, dry woods, pine woods) to determine which habitat types support its germination and establishment. Seed production for cultivars varied from 981 to 6090 seeds per plant. The dry deciduous woods and pine woods were the only environments that supported significant germination rates that could be as high as 37.8%. Seedling survival was at least 77% in the deciduous dry woods and at least 55% in the pine woods. In the first replication, establishment rates for cultivars in the dry deciduous woods ranged from a low of 6.5% for ‘Odom’ Little Moses™ to a high of 42.5% for ‘Monstrosus’. In the second replication, all cultivars achieved over 30% establishment and most exceeded 40% establishment. An estimate of the annual seedling contribution per plant per cultivar was calculated by combining seed production data with establishment data for each cultivar. This estimate was predicted to range from 588 to 3763 and therefore none of the nine cultivars evaluated should be considered non-invasive based on our findings. Our findings show that germination and seedling survival rates are high for E. alatus and because the species is long-lived, cultivars will likely have to be completely seed-sterile to be considered non-invasive according to demographic models.

scholarly journals A C2H2-Type Zinc-Finger Protein from Millettia pinnata, MpZFP1, Enhances Salt Tolerance in Transgenic Arabidopsis

2021 ◽  
Vol 22 (19) ◽  
pp. 10832
Author(s):  
Zhonghua Yu ◽  
Hao Yan ◽  
Ling Liang ◽  
Yi Zhang ◽  
Heng Yang ◽  
...  
Keyword(s):  
Salt Stress ◽  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Seedling Survival ◽  
Germination Rate ◽  
Biomass Accumulation ◽  
Plant Responses ◽  
Finger Protein ◽  
Millettia Pinnata ◽  
Mangrove Associate

C2H2 zinc finger proteins (ZFPs) play important roles in plant development and response to abiotic stresses, and have been studied extensively. However, there are few studies on ZFPs in mangroves and mangrove associates, which represent a unique plant community with robust stress tolerance. MpZFP1, which is highly induced by salt stress in the mangrove associate Millettia pinnata, was cloned and functionally characterized in this study. MpZFP1 protein contains two zinc finger domains with conserved QALGGH motifs and targets to the nucleus. The heterologous expression of MpZFP1 in Arabidopsis increased the seeds’ germination rate, seedling survival rate, and biomass accumulation under salt stress. The transgenic plants also increased the expression of stress-responsive genes, including RD22 and RD29A, and reduced the accumulation of reactive oxygen species (ROS). These results indicate that MpZFP1 is a positive regulator of plant responses to salt stress due to its activation of gene expression and efficient scavenging of ROS.

Fire can promote germination, recruitment and seed bank accumulation of the threatened annual grass Arthraxon hispidus

2020 ◽  
Vol 68 (6) ◽  
pp. 413
Author(s):  
Laura White ◽  
Claudia Catterall ◽  
Kathryn Taffs
Keyword(s):  
Seed Bank ◽  
Soil Seed Bank ◽  
Germination Rate ◽  
Life History Strategies ◽  
North Coast ◽  
Plant Recruitment ◽  
Chemical Mechanisms ◽  
Disturbance Regimes ◽  
Study Population ◽  
Persistent Seed Bank

Disturbance plays an important role in plant life history strategies and has been documented as both enhancing and threatening populations of the vulnerable grass Arthraxon hispidus (Thunb.) Makino (hairy jointgrass) on the NSW north coast. Mechanical disturbance (slashing) is often used in A. hispidus conservation management, but many Australian plants are adapted to fire-based disturbance regimes. In this study we undertook a field burning experiment, along with soil seed bank sampling and germination trials, to explore how fire influences A. hispidus population dynamics in terms of plant recruitment and seed bank fluctuations. We found that winter burning strongly promoted A. hispidus spring germination without entirely depleting the residual seedbank. Although drought affected our field study population, burning also led to increased adult cover and substantial seed bank replenishment the following autumn. Exposure to a smoke treatment almost doubled the germination rate of A. hispidus seeds in nursery trials. Our study suggests that appropriate burning regimes can help to maintain this species in the landscape, by both structural and chemical mechanisms, by enhancing plant recruitment and facilitating seed bank accumulation. However, some A. hispidus plants also successfully germinated, established, and reproduced in unburnt plots during our study, suggesting that populations of this species can persist without disturbance in some habitats, such as native wetland communities. We found that A. hispidus has a multi-year seed longevity and a persistent seed bank, providing the species a degree of resilience in the event of unpredictable disturbance regimes and climatic anomalies.

Ecological Studies of the Endangered Rutidosis Leptorrhynchoides .I. Seed Production, Soil Seed Bank Dynamics, Population Density and Their Effects on Recruitment

1995 ◽  
Vol 43 (1) ◽  
pp. 1 ◽  
Author(s):  
JW Morgan
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Seed Bank ◽  
Seedling Recruitment ◽  
Fire Regime ◽  
Seedling Survival ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Seed Bank Dynamics ◽  
The Impact

The seasonal dynamics of the soil seed bank of Rutidosis leptorrhynchoides F.Muell. were studied by the seedling emergence technique. Seed longevity in soil was quantified in a seed burial and retrieval experiment. The importance of annual seed production to recruitment was also determined over a 2-year-period, as was the impact of conspecific neighbour density on seed production per inflorescence. Rutidosis leptorrhynchoides appears to form a transient seed bank with little capacity to store germinable seeds in the soil from year to year. No seedlings were observed in soil sampled after the autumn germination pulse and no viable seed was present in the soil within 16 weeks of burial. The rate of seed loss was similar when seed was buried under all intact grassland canopy and in 0.25m2 canopy gaps. It appears that most seeds simply rot in moist soil or are predated by soil invertebrates. Seedling recruitment was at least 15 times greater in plots where natural seed input occurred than where it was curtailed. Less than 10% of seed shed resulted in seedling emergence. It is suggested that recruitment in the large populations studied was limited by germination rather than by microsite availability for seedling survival. Population density had an impact on seed production with sparsely distributed individuals producing fewer seeds per inflorescence than plants from denser colonies, although there was much variation. Sparse plants produced significantly fewer seeds per inflorescence than hand crosspollinated heads suggesting reduced pollinator efficacy in these colonies relative to larger colonies where there was no such difference. Rutidosis leptorrhynchoides is dependent on the maintenance of the standing population for recruitment. Any factors that influence flowering and subsequent seed production will limit the ability of the species to regenerate. Over sufficient time, this could lead to the localised extinction of the species and may explain why R. leptorrhynchoides has failed to reappear in remnants where a suitable fire regime has been re-implemented after a period of management unfavourable to the survival, flowering and regeneration of this species.

scholarly journals Evolutionary responses of a dominant plant along a successional gradient in a salt-marsh system

Plant Ecology ◽  
2021 ◽  
Author(s):  
Qingqing Chen
Keyword(s):  
Grazing Intensity ◽  
Clonal Plant ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Plant Populations ◽  
Genetic Changes ◽  
Successional Gradient ◽  
Number Of Leaves ◽  
Successional Stages ◽  
Favorable Conditions

AbstractThe ecological responses of plant populations along a successional gradient have been intensively examined; however, the evolutionary responses received much less attention. Here, I explored genetic changes of key phenotypic traits of a dominant clonal plant (Elytrigia atherica) along a saltmarsh successional gradient by collecting samples along the successional gradient in the high and low marsh and growing them in a common environment (greenhouse). Additionally, to explore whether changes in traits are driven by abiotic (e.g. clay thickness) and biotic (e.g. grazing intensity) variables along the successional gradient, I measured these two variables in the field. I found that clay thickness (a proxy of total nitrogen) increased along the successional gradient both in the high and low marsh; grazing intensity from hares (the most important herbivores) decreased along the successional gradient in the high marsh but did not change in the low marsh. Meanwhile, I found that growth in number of leaves and ramets decreased, while rhizome length increased, along the successional gradient for E. atherica collected from the high marsh. Opposite trends were found for E. atherica collected from the low marsh. Results suggest that, in the high marsh, herbivores may overrule nutrients to drive trait changes. That is, at the early successional stages, E. atherica had higher growth in number of leaves and ramets to compensate for high-intensity grazing. In the low marsh, nutrients may be the dominant driver for trait changes. That is, at the late successional stages, E. atherica had higher growth in number of leaves and ramets but shorter rhizomes to maximize its expansion under the favorable conditions (higher nutrient availability). Results suggest that ecologically important abiotic and biotic variables such as nutrients and herbivores may also have a substantial evolutionary impact on plant populations.

scholarly journals Pengaruh matriks kapsul terhadap perkecambahan benih sintetik teh (Camellia sinensis L.) Effect of capsule matrix on germination of synthetic seeds of tea (Camellia sinensis L.)

2016 ◽  
Vol 83 (2) ◽  
Author(s):  
. SUMARYONO ◽  
Rizka T SAPTARI
Keyword(s):  
Sodium Alginate ◽  
Camellia Sinensis ◽  
Somatic Embryos ◽  
Germination Rate ◽  
Clonal Plant ◽  
Physical Characteristics ◽  
Synthetic Seeds ◽  
Synthetic Seed ◽  
Plant Materials ◽  
Seed Technology

Abstract         Synthetic seed technology has been developed to combine the practical use of ordinary seeds and clonal plant materials. Single somatic embryos of tea (Camellia sinensis L.) clone GMB 9 were encap-sulated using sodium alginate and CaCl2 at different concentrations to produce synthetic seeds.  Encapsulating matrices with and without somatic embryos were made of WP medium and 20 g/L sucrose with   1, 2 or 3%  sodium alginate and 50 or 100 mM CaCl2. Encapsulating matrices without somatic embryos were then tested its physical characteristics, whereas the capsules with somatic embryos were observed its germination rate and secondary embryo formation every week up to six weeks. The results showed that the concentrations of sodium alginate and CaCl2 were affected significantly the physical characteristics of encap-sulating matrix produced. The sufficient level of hardness and highest germination rate was obtained from 2% sodium alginate and 50 mM CaCl2. Sodium alginate at 1% or less produced soft, leaky and oval encapsulating matrices which were not suitable for synthetic seeds. Sodium alginate 3% and 100 mM CaCl2  produced rounded and very hard encapsulating matrices and inhibited the germination of somatic embryos. Germination rates of tea synthetic seeds and somatic embryos without encapsulation were 5 to 20% after six weeks. Abstrak         Teknologi benih sintetik dikembangkan untuk memadukan kepraktisan penggunaan benih biasa dengan bahan tanam klonal. Embrio somatik tunggal dari tanaman teh (Camellia sinensis L.) klon GMB 9 dienkapsulasi menggunakan natrium alginat   dan CaCl2 untuk membuat benih sintetik. Matriks kapsul dengan dan tanpa embrio somatik dibuat dari medium WP dengan sukrosa 20 g/L dicampur dengan natrium alginat 1, 2, atau 3% dan CaCl2 50  atau 100 mM.  Matriks  kapsul  tanpa embrio somatik kemudian diuji sifat fisiknya, sedangkan matriks kapsul dengan embrio somatik diamati daya kecambah dan pembentukan embrio somatik sekunder setiap minggu sampai dengan enam minggu. Hasil penelitian menunjukkan bahwa konsentrasi natrium alginat dan CaCl2 sangat berpengaruh terhadap sifat fisik matriks kapsul yang dihasilkan. Tingkat kekerasan yang memadai dan menghasilkan persentase perkecambahan yang tinggi diperoleh dengan alginat 2% dan CaCl2 50 mM. Natrium alginat pada konsentrasi 1% atau kurang menghasilkan matriks kapsul yang  lunak, mudah bocor dan berbentuk lonjong sehingga tidak sesuai untuk benih sintetik. Natrium alginat konsentrasi 3% pada larutan CaCl2 100 mM menghasilkan benih sintetik yang bulat, sangat keras dan menghambat perkecambahan embrio somatik teh.  Daya kecambah benih sintetik dan embrio somatik teh tanpa enkapsulasi berkisar  5 - 20% setelah enam minggu. 

scholarly journals Protocol for ethyl methanesulphonate (EMS) mutagenesis application in rice

2021 ◽  
Vol 1 ◽  
pp. 19
Author(s):  
Rasim Unan ◽  
Ilyas Deligoz ◽  
Kassim Al-Khatib ◽  
Husrev Mennan
Keyword(s):  
Seedling Survival ◽  
Germination Rate ◽  
Lethal Dose ◽  
Point Mutations ◽  
Exposure Period ◽  
Optimum Number ◽  
Rice Seed ◽  
Standard Protocol ◽  
Ems Mutagenesis ◽  
Severe Mutation

Background: Non-transgenic chemical mutagen application, particularly ethyl methanesulfonate (EMS), is an important tool to create mutations and gain a new genetic makeup for plants. It is useful to obtain a sufficient number of mutant plants instead of working with a severe mutation in a few plants. EMS dose and exposure period have been previously studied in several crops; however, EMS used to create point mutations in presoaked rice seeds has not been sufficiently studied and there is no standard protocol for such treatment. The aim of this study is to establish a standard protocol for EMS mutagenesis application in rice. Methods: Two studies were conducted to evaluate the effect of four durations of rice seed presoaking (0, 6, 12, and 24 hours), four EMS concentration doses (0.0%, 0.5%, 1.0%, and 2.0%), and four EMS exposure periods (6, 12, 24, and 48 hours). Germination rate, plumula and radicle length, seedling survival, LD50 (Lethal Dose) determination, shoot length, root length and fresh seedling weight were evaluated. Results: Results showed that a 12-hour presoaking duration, 0.5% EMS dose, and six hours of EMS exposure were the best practices for the optimum number of mutant plants. Conclusions: In light of both this study and the literature, a standard application protocol was established. This application protocol, detailed in this article, contains the following guidelines: (1) Presoaking: 12 hours, (2) EMS application: 0.5% dose EMS and six hours, (3) Final washing: six hours, (4) Drying: 72 hours at 38°C. A user-friendly protocol has been presented for utilization by researchers.

scholarly journals The conflict between adaptation and dispersal for maintaining biodiversity in changing environments

2019 ◽  
Vol 116 (42) ◽  
pp. 21061-21067 ◽  
Author(s):  
Patrick L. Thompson ◽  
Emanuel A. Fronhofer
Keyword(s):  
Environmental Change ◽  
Biotic Interactions ◽  
Individual Species ◽  
Changing Environments ◽  
Contrast Adaptation ◽  
Evolutionary Rescue ◽  
Colonization Success ◽  
Population Sizes ◽  
Biodiversity Maintenance ◽  
Favorable Conditions

Dispersal and adaptation both allow species to persist in changing environments. Yet, we have limited understanding of how these processes interact to affect species persistence, especially in diverse communities where biotic interactions greatly complicate responses to environmental change. Here we use a stochastic metacommunity model to demonstrate how dispersal and adaptation to environmental change independently and interactively contribute to biodiversity maintenance. Dispersal provides spatial insurance, whereby species persist on the landscape by shifting their distributions to track favorable conditions. In contrast, adaptation allows species to persist by allowing for evolutionary rescue. But, when species both adapt and disperse, dispersal and adaptation do not combine positively to affect biodiversity maintenance, even if they do increase the persistence of individual species. This occurs because faster adapting species evolve to hold onto their initial ranges (i.e., monopolization effects), thus impeding slower adapting species from shifting their ranges and thereby causing extinctions. Importantly, these differences in adaptation speed emerge as the result of competition, which alters population sizes and colonization success. By demonstrating how dispersal and adaptation each independently and interactively contribute to the maintenance of biodiversity, we provide a framework that links the theories of spatial insurance, evolutionary rescue, and monopolization. This highlights the expectation that the maintenance of biodiversity in changing environments depends jointly on rates of dispersal and adaptation, and, critically, the interaction between these processes.

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