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1
Thompson, Ken, Roberta M. Ceriani, Jan P. Bakker e Renée M. Bekker. "Are seed dormancy and persistence in soil related?" Seed Science Research 13, n. 2 (giugno 2003): 97–100. http://dx.doi.org/10.1079/ssr2003128.
Testo completoAbstract (sommario):
AbstractThere is confusion in the ecological literature between seed dormancy and persistence in soil. Some ecologists seem to assume that dormancy is necessary for persistence, while others imply that dormancy and persistence are virtually synonymous. Here, we show that there is no close relationship between dormancy and persistence and, incidentally, that conventional methods of investigating soil seed banks underestimate the persistence of species with dormant seeds. The confusion appears to arise from the concept of ‘enforced dormancy’, which is not genuinely dormancy at all, and would be eliminated if ecologists adopted the definition of dormancy employed by physiologists. Dormancy is a characteristic of the seed, not of the environment, the degree of which defines the conditions required to make the seed germinate.
2
Steadman, Kathryn J., Amanda J. Ellery, Ross Chapman, Andrew Moore e Neil C. Turner. "Maturation temperature and rainfall influence seed dormancy characteristics of annual ryegrass (Lolium rigidum)". Australian Journal of Agricultural Research 55, n. 10 (2004): 1047. http://dx.doi.org/10.1071/ar04083.
Testo completoAbstract (sommario):
The role of temperature and rainfall during seed development in modulating subsequent seed dormancy status was studied for Lolium rigidum Gaud. (annual ryegrass). Climatic parameters relating to geographic origin were compared with annual ryegrass seed dormancy characteristics for seeds collected from 12 sites across the southern Western Australian cropping region. Seed germination was tested soon after collection and periodically during subsequent after-ripening. Temperature in the year of seed development and long-term rainfall patterns showed correlations with aspects of seed dormancy, particularly the proportion of seeds remaining dormant following 5 months of after-ripening. Consequently, for one population the temperature (warm/cool) and water supply (adequate/reduced) during seed development were manipulated to investigate the role of maternal environment in the quantity and dormancy characteristics of seeds produced. Seeds from plants grown at warm temperatures were fewer in number, weighed less, and were less dormant than those from plants grown at cool temperature. Seeds that developed under both cool temperature and reduced moisture conditions lost dormancy faster than seeds from well-watered plants. Seed maturation environment, particularly temperature, can have a significant effect on annual ryegrass seed numbers and seed dormancy characteristics.
3
Haile, Teketel A., e Steven J. Shirtliffe. "Effect of Harvest Timing on Dormancy Induction in Canola Seeds". Weed Science 62, n. 3 (settembre 2014): 548–54. http://dx.doi.org/10.1614/ws-d-13-00178.1.
Testo completoAbstract (sommario):
Seedbank persistence in canola seeds is related to their potential to develop secondary dormancy. This can result in volunteer weed problems many years after canola production. The potential to be induced into secondary dormancy is controlled by both the canola genetics and the environment of the mother plant. However, the effect of time of harvesting on secondary dormancy potential is not known. The objective of this study was to determine the effect of harvest timing on potential to develop seed dormancy in canola. Six harvest samples were collected weekly from two canola genotypes (5440 and 5020) starting from 10 to 20% seed color change on the main stem until they were fully ripened. Freshly harvested seeds of 5440 and 5020 showed 13 and 16% primary dormancy at 32 and 33 d after flowering (DAF), respectively, but dormancy decreased with harvest timings and no dormancy was observed when seeds were fully mature (78 DAF). After dormancy induction, 10% of 5440 seeds were dormant at 32 DAF, but 94% of seeds were dormant at 78 DAF. Similarly, 70% of 5020 seeds were dormant at 33 DAF, but 90% of seeds were dormant at 68 DAF. Thus, seeds had lower potential to secondary dormancy at early development but have a high potential to secondary dormancy induction at full maturity. This study suggests that windrowing these canola genotypes at the recommended time (60% seed color change on the main stem) may reduce ability of the seed to develop secondary dormancy and thus reduce the persistence of seeds in the soil seedbank.
4
Alvarado, Veria, e Kent J. Bradford. "Hydrothermal time analysis of seed dormancy in true (botanical) potato seeds". Seed Science Research 15, n. 2 (giugno 2005): 77–88. http://dx.doi.org/10.1079/ssr2005198.
Testo completoAbstract (sommario):
As seed dormancy is released within a seed population, both the rate and percentage of germination increase progressively with increasing dose of a dormancy-breaking treatment or condition. Population-based models can account for this behaviour on the basis of shifting response thresholds as dormancy is alleviated. In particular, hydrothermal time analysis of germination sensitivity to water potential (Ψ) and temperature (T) can describe these features of seed behaviour. We used the hydrothermal time model to analyse the effects of dormancy-breaking treatments on germination of dormant true (botanical) potato (Solanum tuberosumL.) seeds (TPS). After-ripening (37°C and 4% seed moisture content) of TPS for 7 or 30 days partially or fully alleviated primary dormancy. The median base water potential required to prevent germination [Ψb(50)] decreased from –0.25 MPa in control seeds to –0.87 MPa and –1.83 MPa after 7 and 30 days of after-ripening, respectively. In contrast, the base temperature for germination (Tb) was relatively unaffected (0–3.3°C). Fluridone (50 μM), an inhibitor of abscisic acid (ABA) biosynthesis, also promoted germination of dormant TPS and lowered Ψb(50), indicating a role forde novosynthesis of ABA during dormancy maintenance. Moist chilling (3 days at 4°C) or gibberellin (100 μM) alleviated secondary dormancy and lowered Ψb(50) values from –0.08 MPa to –0.36 and –0.87 MPa, respectively. The hydrothermal time model allows quantification of dormancy levels and explains why changes in germination speed and percentage are closely correlated during dormancy alleviation.
5
Buijs, Gonda. "A Perspective on Secondary Seed Dormancy in Arabidopsis thaliana". Plants 9, n. 6 (15 giugno 2020): 749. http://dx.doi.org/10.3390/plants9060749.
Testo completoAbstract (sommario):
Primary seed dormancy is the phenomenon whereby seeds newly shed by the mother plant are unable to germinate under otherwise favorable conditions for germination. Primary dormancy is released during dry seed storage (after-ripening), and the seeds acquire the capacity to germinate upon imbibition under favorable conditions, i.e., they become non-dormant. Primary dormancy can also be released from the seed by various treatments, for example, by cold imbibition (stratification). Non-dormant seeds can temporarily block their germination if exposed to unfavorable conditions upon seed imbibition until favorable conditions are available. Nevertheless, prolonged unfavorable conditions will re-induce dormancy, i.e., germination will be blocked upon exposure to favorable conditions. This phenomenon is referred to as secondary dormancy. Relative to primary dormancy, the mechanisms underlying secondary dormancy remain understudied in Arabidopsis thaliana and largely unknown. This is partly due to the experimental difficulty in observing secondary dormancy in the laboratory and the absence of established experimental protocols. Here, an overview is provided of the current knowledge on secondary dormancy focusing on A. thaliana, and a working model describing secondary dormancy is proposed, focusing on the interaction of primary and secondary dormancy.
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Seshu, D. V., e M. Dadlani. "Mechanism of seed dormancy in rice". Seed Science Research 1, n. 3 (settembre 1991): 187–94. http://dx.doi.org/10.1017/s0960258500000854.
Testo completoAbstract (sommario):
AbstractDormancy in rice (Oryza sativa L.) seed is imposed by certain physical and chemical factors associated with its covering structures, i.e.hull and pericarp. The nature of these germination blocks, their mode ofaction, and processes regulating the release of dormancy are not fully understood. Of nine rice cultivars studied, Ching-shi 15, Stejaree 45, PTB10, and Mahsuri are weakly dormant, and Bansphul, Benaful, Kataktara, Dular, and N22 are dormant. Release of seed dormancy in rice by various treatments, oxidative processes and enzymic changes associated with dormancy, and parallelism between natural and artificially imposed dormancy patterns were examined. The influence of the hull in imposing dormancy was stronger and more prolonged than that of the pericarp. Application of GA3 was effective in inducing germination only in weakly dormant cultivars. Dormancy was completely released in all cultivars by subjecting the seeds to moist heat treatment, by removing the hull and pericarp, and by applying GA3 after dehulling. Dormant cultivars had higher O2 uptake rate and peroxidase activity and lower amylase and dehydrogenase activities than the weakly dormant ones. Hull removal substantially decreased peroxidase activity but enhanced amylase and dehydrogenase activities. Nonanoic acid (C90), a short-chain saturated fatty acid (SCSFA), when exogenously applied to non-dormant seeds imposed dormancy. Dry heat treatment or presoaking in 0.01 m KNO3 or 0.1 m H2O2 was very effective in releasing SCSFA-imposed dormancy. Amylase activity was greatly reduced by treatments with nonanoic acid (C90) or ABA. Considering earlier reports and results of the present study, it is proposed that seed dormancy in rice is regulated both by the presence of SCSFAs and ABA in the hull and the pericarp. The relative significance of these substances in cultivars of tropical and temperate origins and its implications in terms of ecogeographic adaptability are discussed.
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Ismaturrahmi, Ismaturrahmi, Hasanuddin Hasanuddin e Agam Ihsan Hereri. "Teknik pematahan dormansi secara fisik dan kimia terhadap viabilitas benih aren (Arenga pinnata Merr.)". Jurnal Ilmiah Mahasiswa Pertanian 3, n. 4 (1 novembre 2018): 105–12. http://dx.doi.org/10.17969/jimfp.v3i4.9211.
Testo completoAbstract (sommario):
Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh teknik pematahan dormansi secara fisik dan kimia, serta nyata tidaknya interaksi antara pematahan dormansi secara fisik dengan pematahan dormansi secara kimia terhadap viabilitas benih aren. Penelitian ini dilaksanakan di Laboratorium Ilmu dan teknologi Benih, Fakultas Pertanian, Universitas Syiah Kuala, Darussalam, Banda Aceh, dari bulan juli sampai November 2017. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) Pola Faktorial 4 x 4 dengan 3 ulangan. Penelitian ini menggunakan 2 faktor yaitu: pematahan dormansi secara fisik (S), meliputi : (S0) = Tanpa perlakuan fisik, (S1) = Digosok dengan kertas amplas , (S2) = Digores dengan cutter sepanjang punggung benih, dan (S3) = Menghilangkan selaput gabus pada hilum, dan pematahan dormansi secara kimia (K), meliputi: (K0) = Konsentrasi 0% KNO3, (K1) = Konsentrasi 0,3% KNO3, (K2) = Konsentrasi 0,5% KNO3, (K3) = Konsentrasi 0,7% KNO3.Hasil penelitian yang telah dilakukan, dapat diambil kesimpulan bahwa : Kombinasi perlakuan secara fisik yang digores dengan cutter (S2) dengan konsentrasi KNO3 0,5% (K2) merupakan kombinasi perlakuan terbaik untuk pematahan dormanis pada benih aren.Dormancy Breaking Technique by Physical and Chemical Means on Viabitity of Palm Seed (Arenga pinnata Merr.)Abstract. This research aims to know the effect of physics and chemical dormancy breaking technique, and significant or not the interaction between physical dormancy breaking with chemical dormancy breaking on the viability of the palm seeds. This research was conducted in Science and Seed Technology Laboratory, Faculty of Agriculture, Syiah Kuala University, Darussalam, Banda Aceh, from July to November 2017. This research used Factorial Completely Randomize Design with 4 x 4 repeated 3 times. This research uses 2 factors, namely: physical dormancy breaking (S), including: (S0) = Without physical treatment, (S1) = Rubbed with sandpaper, (S2) = scratched with cutter along the back of seed, and (S3) = Eliminate the cork membrane on the hylum, and chemical dormancy breaking (K), namely: (K0) = Concentration 0% KNO3, (K1) = Concentration 0.3% KNO3, (K2) = Concentration 0.5% KNO3, (K3) = Concentration 0.7% KNO3. The results of research that has been done, it can be concluded that : The combination of physical treatment scratched with cutter (S2) with KNO3 concentration of 0.5% (K2) is the best treatment combination for dormanic breaking of palm seeds.
8
Tieu, Anle, e Louise M. Egerton-Warburton. "Contrasting seed morphology dynamics in relation to the alleviation of dormancy with soil storage". Canadian Journal of Botany 78, n. 9 (1 settembre 2000): 1187–98. http://dx.doi.org/10.1139/b00-093.
Testo completoAbstract (sommario):
We examined the effect of prolonged (up to 450 days) soil burial in the field on seed morphological traits (seed coat structure, permeability) to identify their potential roles in seed dormancy and release. Such traits were examined in species with seeds that demonstrated an obligate requirement for soil storage before germination: the dormant seeds of Anigozanthos manglesii D. Don, Conostylis neocymosa Hopper, Stylidium affine Sonder, and Stylidium crossocephalum F. Muell., and the deeply dormant fruits of Leucopogon conostephioides D.C. We detected species-specific and environmentally induced variation in seed morphology following soil burial. In A. manglesii and L. conostephioides, a significant deterioration of the seed coat or fruit wall and an increased permeability of the seed coat to water and solutes were correlated with germination responses. In these species, the seed coat and (or) fruit wall delayed germination until (morpho) physiological dormancy was broken. In C. neocymosa, S. affine, and S. crossocephalum, weathering of the seed coat, permeability, and germination were not correlated traits. These species appeared to possess physiological dormancy mechanisms and required environmental cues for dormancy release.Key words: physiological dormancy, soil burial, seed coat, morphology.
9
Liyanage, Ganesha S., e Mark K. J. Ooi. "Do dormancy-breaking temperature thresholds change as seeds age in the soil seed bank?" Seed Science Research 27, n. 1 (29 dicembre 2016): 1–11. http://dx.doi.org/10.1017/s0960258516000271.
Testo completoAbstract (sommario):
AbstractIn fire-prone ecosystems, many species regenerate after fire from persistent soil seed banks. Species with physically dormant (PY) seeds have dormancy broken by fire-related heat. The magnitude of post-fire recruitment, to predict response to varying fire severity, is commonly estimated by testing dormancy-breaking temperature thresholds of fresh PY seeds. However, seeds spend years in the soil during the inter-fire period, and determining whether dormancy-breaking thresholds change over time is essential to accurately predict population persistence. Germination of four south-eastern Australian PY species from the Fabaceae family (Acacia linifolia, Aotus ericoides, Bossiaea heterophylla and Viminaria juncea) were studied. Dormancy-breaking temperature thresholds vary inter-specifically and the species represented either high or low dormancy-breaking threshold classes. Freshly collected seeds, and seeds that had been buried in the field or stored in dry laboratory conditions for 6 and 18 months were subjected to a fire-related range of heat treatments (40–100°C). Seed ageing increased germination response to heat treatments, effectively lowering the dormancy-breaking thresholds of three species. The fourth species, A. linifolia, initially had a relatively large non-dormant fraction which was lost as seeds aged, with older seeds then displaying PY broadly similar to the other study species. Patterns of threshold decay were species-specific, with the thresholds and viability of low-threshold species declining more rapidly than high-threshold species. The non-dormant fraction did not increase over time for any of our study species. Instead of increasing their non-dormant fraction, as is common in other vegetation types, these fire-prone PY species displayed a change of dormancy-breaking temperature thresholds. This is an important distinction, as maintaining dormancy during the inter-fire period is essential for population persistence. While changes in sensitivity to dormancy-breaking treatments have previously been reported as seeds age, our study provides the first test of changes to temperature thresholds, which increases the range of germination response from the seed bank under varying fire severity.
10
Mira, Sara, Luciana Veiga-Barbosa e Félix Pérez-García. "Seed dormancy and longevity variability of Hirschfeldia incana L. during storage". Seed Science Research 29, n. 2 (9 maggio 2019): 97–103. http://dx.doi.org/10.1017/s0960258519000072.
Testo completoAbstract (sommario):
AbstractWe studied the variability of germination, dormancy and viability loss of Hirschfeldia incana seeds in relation to seed size. Seeds were stored at 35°C under humid [75% relative humidity (RH)] or dry (33% RH) conditions. Seed germination and electrolyte leakage were evaluated periodically. Small seeds had lower longevity at humid or dry storage conditions (5 or 407 days, respectively) than large or intermediate seeds (7–9 or 536–727 days, respectively). Moreover, H. incana shows variability in seed dormancy related to seed size within a population, with small seeds having lower dormancy (13%) than intermediate (50%) or large seeds (72%). Dormancy was partially released after a short storage at 35°C and humid conditions. Under dry storage conditions, endogenous dormancy cycles were observed for over a year, and longer times of storage had a dormancy-breaking effect through dry after-ripening. Results suggest a dual strategy producing non-dormant seeds with low longevity that will germinate immediately after dispersal, and seeds with greater longevity that will delay germination. Membrane permeability increased linearly with ageing at both humid and dry storage (R2 = 0.60). Small seeds showed greater conductivity than intermediate or large seeds (0.7, 0.4 or 0.3 mS g–1 dry weight, respectively, at the 80% germination). The conductivity test could be used to evaluate the quality of H. incana seeds and would allow us to identify dormant (non-germinating) seed lots as viable. However, the influence of storage conditions and variability within a seed population on seed longevity should be taken into account when evaluating seed quality.
11
Jin, Yea-Jung, Han-Jin Jeong, Soo-Young Kim, Seong-Hyun Cho, Jin-Hwan Lee e Du-Hyun Kim. "Pelleting of Physical Dormancy Small-Seeded Species in Astragalus sikokianus Nakai". Agronomy 13, n. 1 (10 gennaio 2023): 206. http://dx.doi.org/10.3390/agronomy13010206.
Testo completoAbstract (sommario):
Astragalus sikokianus is a rare Japanese perennial of the seashore that was reported to be extinct in the wild. The small seed size and deep dormancy of A. sikokianus make it difficult for direct seeding restoration in aspects of seed handling, transport, planting, and seedling establishment. For the large-scale economic restoration of dormant small-seeded species, seed pelleting combined with the breaking of dormancy was studied. Physiological (prechilling and plant hormones) and physical (hot water, hydrochloric acid, and sulfuric acid) seed dormancy break treatments were evaluated. The dormant broken seeds were used for pelleting. The effects of the substrate, pellet sizes, and their interactions on germination were measured. The scarification of five rubs of seeds placed between sandpapers completely broke the physical dormancy of A. sikokianus. Seed coat impermeability inhibited germination. Pelleted seeds ranging from 2.0 to 4.0 mm in diameter showed more than 90% germination on filter paper. The germination of the pelleted seeds was measured in commercial, field, and sand soil conditions. The highest germination was shown in sand (70–74% GP), regardless of the pellet size, whereas unpelleted scarified seeds germinated only 48%. These results suggest that small-seeded species with physical dormancy can be used for seed-based restoration after seed pelleting.
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Gill, GS, e WM Blacklow. "Variations in seed dormancy and rates of development of great brome, Bromus diandrus Roth., as adaptations to the climates of southern Australia and implications for weed control". Australian Journal of Agricultural Research 36, n. 2 (1985): 295. http://dx.doi.org/10.1071/ar9850295.
Testo completoAbstract (sommario):
Seeds of great brome, B. diandrus, were collected from 14 sites across southern Australia and sown at Perth, W.A. The duration of seed dormancy varied among the seed accessions when produced at the common field site of Perth, which suggested that variations in dormancy were genetically controlled. The environment of Perth shortened the duration of dormancy in all the accessions but did not affect their ranking, indicating a lack of genotype x environment interaction. The duration of dormancy was positively correlated (r = 0.78) with the duration of the rain-free summers of the site of collection. Dormancy was not due to hard-seededness and non-dormant seeds germinated within 40 h of wetting at 20�C. The seed dormancy was limited to about 5 months under the storage conditions examined. Dormant seed was stimulated to germinate by gibberellic acid (2.89 mM) and dormant seed of the accession from Geraldton also responded to removal of the lemma and palea or to leaching with water. The time taken for accessions to 'panicle peep' was positively correlated (r = 0.83) with the length of the rainy winters of the sites of collection. The results show great brome has adapted genetically to the climate of southern Australia. Cropping systems that exploit the lack of residual dormancy and the potential for rapid and complete germination s
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Ramos, Desirée M., Ana B. S. Liaffa, Pedro Diniz, Cássia B. R. Munhoz, Mark K. J. Ooi, Fabian Borghetti e José F. M. Valls. "Seed tolerance to heating is better predicted by seed dormancy than by habitat type in Neotropical savanna grasses". International Journal of Wildland Fire 25, n. 12 (2016): 1273. http://dx.doi.org/10.1071/wf16085.
Testo completoAbstract (sommario):
Open savannas and wet grasslands are present under the same seasonal macro-climate in central Brazil. However, in open savannas, temperatures during fires are higher than in wet grasslands. Grasses dominate both ecosystems and exhibit large variation in seed dormancy. We hypothesise that seeds of grass species from open savannas are more tolerant to heating than those of wet grasslands. Also, assuming that dormant seeds remain longer in the soil than non-dormant seeds – thus being more likely to burn – we expect that dormant seeds are more tolerant to heating than non-dormant seeds. We tested the effects of heating at 80 and 110°C for 2.5 and 5.0 min on the survival of seeds of 14 species, seven from each community, containing dormant and non-dormant species. Seeds of most species survived at 80°C, but seeds from open savannas maintained greater survival for 5 min than seeds from wet grasslands. Seeds of most species died at 110°C, but dormant seeds survived more than non-dormant seeds. We conclude that species with seed dormancy experience selection for covarying characteristics that allow tolerance to heating in hotter fires. Our findings suggest that both seed dormancy and habitat-specific fire temperatures may contribute to the evolution of seed fire tolerance in Neotropical savannas.
14
Kissing Kucek, L., M. D. Azevedo, S. S. Eagen, N. J. Ehlke, R. J. Hayes, S. B. Mirsky, C. Reberg-Horton et al. "Seed Dormancy in Hairy Vetch (Vicia villosa Roth) Is Influenced by Genotype and Environment". Agronomy 10, n. 11 (17 novembre 2020): 1804. http://dx.doi.org/10.3390/agronomy10111804.
Testo completoAbstract (sommario):
Seed dormancy complicates the agricultural use of many legume species. Understanding the genetic and environmental drivers of seed dormancy is necessary for advancing crop improvement for legumes, such as Vicia villosa. In this study, we quantify the magnitude of genetic and environmental effects on physical dormancy among 1488 maternal V. villosa plants from 18 diverse environments. Furthermore, we explore the relationship between physical dormancy and environmental conditions during seed development. Additive genetic variance (h2) accounted for 40% of the variance, while the growing environment explained 28% of the variance in physical dormancy. Maternal lines showed complete variance in physical dormancy, as one line was 100% dormant, and 56 lines were 0% dormant. Distributions of physical dormancy varied widely among seed production environments, with some site-years strongly skewed toward physically dormant seed, while other site-years exhibited little dormant seed. Twenty-three weather variables were associated with environmental and error effects of physical dormancy. High mean and minimum relative humidity, low mean and maximum temperature, and high precipitation weakly grouped with low physical dormancy. Weather variables calculated from fixed time windows approximating seed maturity to seed harvest at each site-year tended to be less predictive than biological seed drying windows calculated based on seed maturity of each maternal line. Overall, individual and cumulative effects of weather variables were poor predictors of physical dormancy. Moderate heritability indicates that breeding programs can select against physical dormancy and improve V. villosa for agricultural use. Marker-based approaches would maximize selection for physical dormancy by reducing the influence of unpredictable environmental effects.
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Schatral, A., J. M. Osborne e J. E. D. Fox. "Dormancy in seeds of Hibbertia cuneiformis and H. huegelii (Dilleniaceae)". Australian Journal of Botany 45, n. 6 (1997): 1045. http://dx.doi.org/10.1071/bt96056.
Testo completoAbstract (sommario):
Dormancy delays the germination of seeds in two species of the primitive angiosperm genus Hibbertia (H. cuneiformis and H. huegelii, family Dilleniaceae). After seed coat removal, germination increased in 18-month-old seeds of H. cuneiformis and 6- to 8-month-old seeds of H. huegelii. Hence, seeds of the two species exhibit seed coat dormancy. The removal of the seed coat may stimulate germination, as the result of increased water uptake, and/or the removal of mechanical and chemical inhibition. However, the occurrence of imbibitional injury and a reduced percentage of vigorous seedlings in decoated seeds suggest that embryo dormancy, as a second type of dormancy, impedes germination in H. cuneiformis. Embryo dormancy also delays the germination of seeds of H. huegelii, since a high percentage of seeds did not germinate after removal of the seed coat. Embryo dormancy appears to vary among individual seeds and between species. The germination experiments suggest a high percentage of non-dormant and weakly dormant embryos for 18-month-old seeds of H. cuneiformis. By contrast, many seeds of H. huegelii appear to contain deeply dormant embryos. In H. cuneiformis, the depth of the seed dormancy varied with the age of the seeds. Freshly harvested seeds did not germinate for 3 months. Treatment with gibberellic acid (GA3) (120 mg L-1) significantly enhanced germination of freshly harvested and 18-month-old, intact seeds of H. cuneiformis and the germination of decoated 18-month-old seeds of H. huegelii. The plant hormones kinetin and abscisic acid did not affect the final germination percentage in 18-month-old seeds of H. cuneiformis. For H. huegelii, germination was reduced in decoated seeds and seeds with cracked coats exposed to an 8 h day: 16 h night diurnal cycle compared with complete darkness.
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Molizane, Debora Manzano, Pricila Greyse dos Santos Julio, Sandra Maria Carmello-Guerreiro e Claudio José Barbedo. "Physical, physiological and anatomical changes in Erythrina speciosa Andrews seeds from different seasons related to the dormancy degree". Journal of Seed Science 40, n. 3 (settembre 2018): 331–41. http://dx.doi.org/10.1590/2317-1545v40n3199428.
Testo completoAbstract (sommario):
Abstract: Dormancy, a process that allows seeds to survive in adverse environments, needs to be broken for germination to start, for example, by the disruption of the impermeable layer of seeds. Mature seeds of Erythrina speciosa present seed coat impermeability, whose degree depends on the year of production. The objective of this study was to analyze the physical, physiological, anatomical, and ultrastructural seed coat modifications, according to the environmental conditions in which seeds were produced, as well as the seed sensitivity to treatments as for breaking dormancy. E. speciosa seeds were collected for six years in a row and were analyzed as for dormancy degree. Moreover, chemical scarifications by different immersion times were applied on seeds from two production years, as well as mechanical scarification, which was an efficient methodology to overcome dormancy. Different immersion times by acid scarification were necessary to break dormancy in each harvest year. It was possible to conclude that the climatic conditions under which the mother plant is submitted can influence the dormancy degree of E. speciosa seeds, but the expected anatomical changes between dormant and non-dormant seeds were not found in seeds from this species.
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Pawłowski, Tomasz A., Barbara Bujarska-Borkowska, Jan Suszka, Tadeusz Tylkowski, Paweł Chmielarz, Ewelina A. Klupczyńska e Aleksandra M. Staszak. "Temperature Regulation of Primary and Secondary Seed Dormancy in Rosa canina L.: Findings from Proteomic Analysis". International Journal of Molecular Sciences 21, n. 19 (23 settembre 2020): 7008. http://dx.doi.org/10.3390/ijms21197008.
Testo completoAbstract (sommario):
Temperature is a key environmental factor restricting seed germination. Rose (Rosa canina L.) seeds are characterized by physical/physiological dormancy, which is broken during warm, followed by cold stratification. Exposing pretreated seeds to 20 °C resulted in the induction of secondary dormancy. The aim of this study was to identify and functionally characterize the proteins associated with dormancy control of rose seeds. Proteins from primary dormant, after warm and cold stratification (nondormant), and secondary dormant seeds were analyzed using 2-D electrophoresis. Proteins that varied in abundance were identified by mass spectrometry. Results showed that cold stratifications affected the variability of the highest number of spots, and there were more common spots with secondary dormancy than with warm stratification. The increase of mitochondrial proteins and actin during dormancy breaking suggests changes in cell functioning and seed preparation to germination. Secondary dormant seeds were characterized by low levels of legumin, metabolic enzymes, and actin, suggesting the consumption of storage materials, a decrease in metabolic activity, and cell elongation. Breaking the dormancy of rose seeds increased the abundance of cellular and metabolic proteins that promote germination. Induction of secondary dormancy caused a decrease in these proteins and germination arrest.
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Chen, Shun-Ying, Ching-Te Chien, Jeng-Der Chung, Yuh-Shyong Yang e Shing-Rong Kuo. "Dormancy-break and germination in seeds of Prunus campanulata (Rosaceae): role of covering layers and changes in concentration of abscisic acid and gibberellins". Seed Science Research 17, n. 1 (marzo 2007): 21–32. http://dx.doi.org/10.1017/s0960258507383190.
Testo completoAbstract (sommario):
AbstractIntact seeds (seed+endocarp) from freshly harvested fruits of Prunus campanulata were dormant, and required 4–6 weeks of warm followed by 8 weeks of cold stratification for maximum germination percentage. Removing both endocarp and seed coat, however, promoted germination in a high percentage of non-stratified seeds. Treatment of intact, non-stratified seeds with gibberellic acid (GA3) was only partially effective in breaking dormancy. However, GA3 promoted germination of non-stratified seeds in which the endocarp (but not the seed coat) had been removed. The order of abscisic acid (ABA) concentration in fresh seeds was endocarp > seed coat > embryo, and its concentration in endocarp plus seed coat was about 6.2-fold higher than that in the embryo. Total ABA contents of seeds subjected to warm and/or cold moist stratification were reduced 6- to 12-fold. A higher concentration of GA4 was detected in embryos of non-dormant than in those of dormant seeds. Fluridone, a carotenoid biosynthesis inhibitor, was efficient in breaking dormancy of Prunus seeds. Paclobutrazol, a GA biosynthesis inhibitor, completely inhibited seed germination, and the inhibitory effect could be partially reversed by GA4, but not by GA3. Thus, dormancy in P. campanulata seeds is imposed by the covering layers. Dormancy break is accompanied by a decrease in ABA content of the covering layers and germination by an increase of embryonic GA4 content.
19
Visser, Marjolein, e Amaury Beaugendre. "Conditional dormancy of Stipa lagascae (Poaceae) bulk-harvested on seed increase plots in South Tunisia: a reassessment and a surprise". Plant Ecology and Evolution 152, n. 3 (28 novembre 2019): 450–59. http://dx.doi.org/10.5091/plecevo.2019.1575.
Testo completoAbstract (sommario):
Background and aims – With the perspective to reseed degraded drylands, grass seeds are often stocked for several years. This common practice overlooks conditional dormancy and the necessity to preserve it. This paper reports on the germination ecology of Stipa lagascae Roem. & Schult., which is a circum-Mediterranean winter-growing bunch grass of high grazing value. However, the published record on its germination ecology is scarce and inconsistent.Methods – This record was reassessed through a series of germination trials in combination with dormancy breaking treatments on seeds that were mainly harvested on a seed increase plot in South-Tunisia.Key results –The surprise finding was that Stipa lagascae exhibits a particular kind of conditional dormancy for many months after harvest. Whereas dormant seeds barely germinate at 10°C in classical Petri dishes or on germination tables, they germinate massively (but not fully) when allowed full contact with a water-saturated substrate at 7–10°C in boxes. Dehulling provokes fast germination of near 100% of the seeds, thus showing that the substrate effect at low temperatures breaks most but not all dormancy in a particular seed lot. This remaining or residual dormancy is not conditional, as it can only be broken through dehulling. There are thus two distinct germination windows: a very broad one for non-dormant seed and a narrow one for conditionally dormant seed.Conclusions – A pattern is suggested whereby each seed lot evolves through a continuum from full over conditional to non-dormancy and finally mortality. However, only the state of conditional dormancy times germination optimally with regard to the start of the winter growing season in South-Tunisia. Its ecological significance should be interpreted in combination with its trypanocarpy. Reseeding for restoration purposes and to render grazing value to depleted drylands should thus use conditionally dormant seed.
20
Hilhorst, Henk W. M. "Seed dormancy". Seed Science Research 7, n. 2 (giugno 1997): 221–23. http://dx.doi.org/10.1017/s096025850000355x.
Testo completo
21
Geneve, Robert L., Sharon T. Kester e Terriawkia A. Woods. "IS ETHYLENE ASSOCIATED WITH THE RELEASE FROM DORMANCY DURING CHILLING STRATIFICATION IN EASTERN REDBUD SEED (CERCIS CANADENSIS)?" HortScience 27, n. 6 (giugno 1992): 640d—640. http://dx.doi.org/10.21273/hortsci.27.6.640d.
Testo completoAbstract (sommario):
Ethephon and ethylene gas applied to intact Eastern redbud seed induced germination in 44 or 53% of dormant seed. However, endogenous ethylene production was not found to be correlated with the release from dormancy during chilling stratification (5°C). Seeds stratified in the presence of 6000 ppm 2.5-norbomadicne germinated at the same percentage as control seeds. Isolated embryos treated with 100 to 500 μM AOA or 1000 μM silver thiosulfate germinated at a slower rate than control seeds, but the release from dormancy during stratification was unaffected by either ethylene inhibitor. Ethylene evolution, ACC and MACC content remained at a low level throughout stratification. EFE activity was not detectable in hydrated dormant or non-dormant seed. All ethylene parameters measured increased sharply during germination with peak activity correlated with radicle emergence. These data indicated that ethylene production was linked to germination, but unrelated to dormancy release in Eastern redbud seed.
22
Sari, Maryati, Satriyas Ilyas, M. Rahmad Suhartanto e Abdul Qadir. "Perubahan Perilaku Dormansi selama Proses Desikasi pada Benih Kacang Bambara (Vigna subterranea L. Verdc.)". Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) 48, n. 1 (29 aprile 2020): 37–43. http://dx.doi.org/10.24831/jai.v48i1.29371.
Testo completoAbstract (sommario):
Bambara groundnut seeds often show unsynchronized and slow germination even though on newly harvested seeds. This might be due to the presence of seed dormancy. Therefore, the objective of this research was to obtain the information on seed dormancy and germination behaviour of bambara groundnut seeds during desiccation. The experiment was arranged in a nested design. Dormancy breaking treatments (untreated, mechanical scarification, soaking in 1% KNO3 for 2 hours, mechanical scarification followed by KNO3 soaking) were nested in each of the desiccation levels (fresh seeds with 54.7% moisture content (mc), desiccated seeds with 44.4%, 18.0%, 15.4%, and 12.1% mc). The results showed that newly harvested seeds were in dormant state. Seed desiccation did not increase the intensity of seed dormancy, even resulted in an increase in field emergence (at 30 days after planting) from 43.9% in fresh seeds to around 70% in dry seed (12-15% mc). Seed desiccation (from 44.4% mc to 12.1% mc) increased the field emergence, although it was inadequate to break the dormancy completely. Meanwhile, seed desiccation tended to increase the GA/ABA ratio, but the seed permeability was decreased. The fact showed that seed desiccation reduced the intensity of dormancy of bambara groundnut seed, therefore, it is suggested to modify the drying method in order to accelerate the increasing of GA/ABA ratio while keeping the testa permeable.
Keywords: after-ripening, GA/ABA ratio, hard seed, kacang bogor, permeability
23
Leon, Ramon G., Diane C. Bassham e Micheal D. K. Owen. "Inheritance of deep seed dormancy and stratification-mediated dormancy alleviation in Amaranthus tuberculatus". Seed Science Research 16, n. 3 (settembre 2006): 193–202. http://dx.doi.org/10.1079/ssr2006250.
Testo completoAbstract (sommario):
Amaranthus tuberculatusis a weed species that has shifted emergence patterns over the past few years, presumably due to changes in seed dormancy in response to selection in agricultural fields. Although it is recognized that the seed dormancy phenotype is greatly affected by the environment, it is also acknowledged that the genotype plays a significant role. However, the importance of the genotype in determining intra-population seed dormancy variability, and the effect on emergence patterns, is not well understood. The objective of the present study was to determine the importance of the genotype on deep dormancy and the stratification-mediated dormancy alleviation inA. tuberculatus. Wild populations differing in seed dormancy were crossed and F2families were generated. These families were used to determine narrow sense heritability of dormancy and stratification-mediated dormancy alleviation at the individual (hi2) and family (hf2) levels.hi2ranged from 0.13 to 0.4 and 0.04 to 0.06 for the dormancy and stratification response, respectively. In the case ofhf2, the values ranged from 0.76 to 0.91 for deep dormancy and from 0.33 to 0.58 for the stratification response. The genetic correlation between these two traits was below 0.075, indicating that different genes control them. High temperature strengthened the dormancy of deeply dormant seeds, making them less sensitive to stratification. However, high temperature promoted the germination of non-deeply dormant seeds. It is proposed that delayed weed emergence can be generated by selecting genes that control stratification response, and not necessarily only the genes that are directly responsible for deep dormancy.
24
Thusithana, Vidushi, Sean M. Bellairs e Christine S. Bach. "Seed germination of coastal monsoon vine forest species in the Northern Territory, Australia, and contrasts with evergreen rainforest". Australian Journal of Botany 66, n. 3 (2018): 218. http://dx.doi.org/10.1071/bt17243.
Testo completoAbstract (sommario):
Seed germination traits of seasonal rainforest species differ from permanently moist evergreen rainforest species due to the prolonged seasonal drought. We investigated whether seed germination traits used to categorise evergreen rainforest species into pioneer and climax guilds were applicable to seasonal rainforest species. Seed dormancy, light requirements for germination and seed storage types of five climax and thirteen pioneer species of a coastal vine thicket were studied. Results were compared with published studies of evergreen rainforest species. Evergreen rainforest pioneer species are typically dormant, require light to germinate and tolerate desiccation, whereas climax species are typically non-dormant, tolerate shade during germination and are sensitive to desiccation. In seasonal rainforest we found that a high proportion of pioneer species had seeds that were non-dormant (62%), and a high proportion of pioneer species germinated equally well in light and dark conditions. In seasonal rainforest, we found that the majority of climax species had desiccation tolerant seeds, whereas in evergreen rainforest the proportion of climax species producing desiccation sensitive seeds is equal to or greater than the proportion of species with desiccation tolerant seeds. In seasonal rainforest species physical, physiological and epicotyl dormancy types were found. Generally, for seasonal rainforest species, the prevalent form of dormancy in pioneer species was physical dormancy whereas physiological dormancy was most common in evergreen rainforest pioneer species with dormancy. Our results suggest that the contrasting seed biology traits that typically apply to pioneer and climax species of evergreen rainforest species don’t typically apply to seasonal rainforest species.
25
Auld, Tony D., David A. Keith e Ross A. Bradstock. "Patterns in longevity of soil seedbanks in fire-prone communities of south-eastern Australia". Australian Journal of Botany 48, n. 4 (2000): 539. http://dx.doi.org/10.1071/bt99046.
Testo completoAbstract (sommario):
Seed burial in nylon mesh bags over a 2-year period was used to examine seed longevity patterns in 12 shrub and two graminoid species in fire-prone habitats around Sydney, south-eastern Australia. Most species released a large fraction of their annual seed-crop in a dormant state and all species showed evidence for some form of persistent seedbank. However, regressions of seed persistence over time were in most cases poor predictors of seed decay (9 of 14 study species). Considerable variation in the degree and pattern of seed longevity was apparent in the study species. Three functional groupings of species are suggested. (1) Seed half-lives in the soil predicted to be greater than 2 years and evidence of imposed secondary dormancy (continuous, Kunzea spp. or seasonal, Grevillea caleyi). Only Kunzea capitata and G. caleyi showed significant seed decay in this group. (2) Seed half-lives in the soil predicted to be greater than 2 years and no evidence of secondary dormancy (nine species). Six species had high seed dormancy at release (only two of which showed significant seed decay). Three species had initial seed dormancy of 40–57%—two (Asterolasia elegans and Zieria involucrata) with significant decay only for the non-dormant seed fraction, and one (Comesperma ericinum) with significant decay of both the dormant and non-dormant seed fractions. (3) Two species (Darwinia biflora and Persoonia pinifolia) showed evidence of very short mean half-lives of seeds in the soil (0.4–1.0 years). The threatened species, D. biflora, had a rapid initial seed decay over 6 months followed by little decay for 18 months, and the half-life of seeds is likely to be a poor predictor of seed longevity. For P. pinifolia, maintenance of a soil seedbank is predicted to be dependent on continual inputs of seeds locally or dispersal of seeds from other sites.
26
Glison, Nicolás, Luis Viega e Pablo Speranza. "Differential incidence of the lemma on seed germination among different Paspalum dilatatum genotypes". Journal of Seed Science 39, n. 2 (giugno 2017): 133–41. http://dx.doi.org/10.1590/2317-1545v39n2169225.
Testo completoAbstract (sommario):
Abstract: Paspalum dilatatum Poir. is a promising perennial summer grass forage for temperate regions, but among other factors, slow stand establishment has hindered its adoption. One of the reasons may be seed dormancy. Intraspecific variability in seed dormancy has been reported in P. dilatatum, but the mechanisms underlying this variability remain unclear. In this paper, we focus on the role of seed external covering structures on germination, particularly the lemma. Seeds of apomictic and sexual biotypes of P. dilatatum were subjected to acid scarification and removal of the lemma to study their germination, imbibition rate and sensitivity to ABA. Seeds without lemma showed higher germination than other treatments in dormant genotypes. We found that the lemma delayed but did not prevent water uptake in any genotype. Comparing sexual biotypes, P. dilatatum subsp. flavescens showed higher lemma-imposed dormancy than P. dilatatum “Virasoro”, and also higher seed dormancy at the caryopsis level. The thickness of the lemma was not different between these biotypes, so this trait did not explain differences in dormancy. Intraspecific variability of seed dormancy in this species may be attributable to the lemma incidence, however differences in the caryopsis component of seed dormancy should be considered.
27
Dunbabin, Matthew T., e P. S. Cocks. "Ecotypic variation for seed dormancy contributes to the success of capeweed (Arctotheca calendula) in Western Australia". Australian Journal of Agricultural Research 50, n. 8 (1999): 1451. http://dx.doi.org/10.1071/ar99001.
Testo completoAbstract (sommario):
The seed dormancy characteristics of 2 capeweed [Arctotheca calendula (L.) Levyns] ecotypes from Western Australia were studied to determine aspects of seed dormancy that contribute to the success of this species in southern Australia. Short- and long-term dormancy pattern of buried and soil surface seed, effect of summer temperatures on afterripening, and effect of temperature on seed germination were investigated using seed produced in a common environment. There were large differences in the seed dormancy pattern of the 2 ecotypes studied. On the soil surface, >95% of seed of the Mt Barker ecotype became non-dormant and germinated in the first year, the remainder germinating the following season. In contrast, only 5% of Mullewa seed germinated in the first year, with 75% germinating in the second year and 20% of seed remaining dormant after 2 years. Cycling of dormancy was observed for buried seed of both ecotypes, with periods of non-dormancy corresponding with the likely timing of the break of the season. Dormancy cycling was also apparent in seed stored under constant conditions in the laboratory. Burial prevented germination of both ecotypes; however, the ability to resist germination while buried was lost in 30% of the Mt Barker seed in the second season. Differences in the duration of dormancy of soil surface and buried capeweed seed have evolved as an adaptation to the different environments likely to be experienced by plants at their site of collection. All seeds possessed primary dormancy at maturity, with any afterripening during the first year occurring by the end of summer. Afterripening was enhanced by exposure to typical soil surface temperatures, providing some protection against germination during early summer rainfall. Protection from late summer rains is insured by the inability of seed to germinate at temperatures >30°C and a relatively slow rate of germination. These features of capeweed seed dormancy, combined with the ability to evolve genetically distinct populations suited to particular environments, help explain why capeweed is so widespread and abundant across southern Australia.
28
Cao, Hong, Yi Han, Jingyi Li, Meng Ding, Yu Li, Xiaoying Li, Fengying Chen, Wim Jj Soppe e Yongxiu Liu. "Arabidopsis thaliana SEED DORMANCY 4-LIKE regulates dormancy and germination by mediating the gibberellin pathway". Journal of Experimental Botany 71, n. 3 (23 ottobre 2019): 919–33. http://dx.doi.org/10.1093/jxb/erz471.
Testo completoAbstract (sommario):
Abstract The molecular mechanisms underlying seed dormancy and germination are not fully understood. Here, we show that Arabidopsis thaliana SEED DORMANCY 4-LIKE (AtSdr4L) is a novel specific regulator of dormancy and germination. AtSdr4L encodes a protein with an unknown biochemical function that is localized in the nucleus and is expressed specifically in seeds. Loss of function of AtSdr4L results in increased seed dormancy. The germination of freshly harvested seeds of the Atsdr4l mutant is insensitive to gibberellin (GA). After-ripened mutant seeds are hypersensitive to the GA biosynthesis-inhibitor paclobutrazol but show unaltered sensitivity to abscisic acid. Several GA biosynthesis genes and GA-regulated cell wall remodeling genes are down-regulated in the mutant in both dormant and after-ripened seeds. These results suggest that the Atsdr4l mutation causes both decreased GA biosynthesis and reduced responses. In addition, a genetic analysis indicated that AtSdr4L is epistatic to DELAY OF GERMINATION1 (DOG1) for dormancy and acts upstream of RGA-LIKE 2 (RGL2) in the GA pathway. We propose that AtSdr4L regulates seed dormancy and germination by mediating both the DOG1 and GA pathways.
29
Xiong, Renci, Ying Wang, Hanwen Wu, Yan Ma, Weili Jiang e Xiaoyan Ma. "Seed treatments alleviate dormancy of field bindweed (Convolvulus arvensisL.)". Weed Technology 32, n. 5 (20 agosto 2018): 564–69. http://dx.doi.org/10.1017/wet.2018.46.
Testo completoAbstract (sommario):
AbstractField bindweed, a member of the Convolvulaceae family, is a problematic perennial weed in cotton fields and orchards in northwest China. The species exhibits strong seed dormancy, causing delayed germination. A clear understanding of the mechanisms involved in alleviating seed dormancy is important for effective plant propagation and successful management of field bindweed. Experiments were conducted to investigate seed germination and radicle growth of field bindweed by breaking seed dormancy using mechanical scarification, sulfuric acid, hot-water scarification, cold stratification, and chemical treatment. Chemical treatments (gibberellic acid or potassium nitrate) had no effect on breaking seed dormancy, whereas mechanical scarification (sandpaper and blade) resulted in 92% to 98% seed germination, indicating that seed dormancy of field bindweed was mainly due to the presence of a hard seed coat. Seeds pretreated with 80% sulfuric acid for 15 to 60 min or 98% sulfuric acid for 15 to 30 min had germination rates above 80%, and soaking seeds in 70 C water for 4 to 16 min or in boiling water for 5 to 20s were effective in breaking seed dormancy but had no effect on the radicle growth of field bindweed. Cold stratification at 5 C for 2 to 8wk partially accelerated seed dormancy release, resulting in 53% to 67% seed germination. Results indicated that field bindweed could potentially form a persistent soil seed bank with physically dormant seed; therefore, strategies for eliminating seed production should be adopted.
30
Silveira, Fernando A. O., Rafaella C. Ribeiro, Denise M. T. Oliveira, G. Wilson Fernandes e José P. Lemos-Filho. "Evolution of physiological dormancy multiple times in Melastomataceae from Neotropical montane vegetation". Seed Science Research 22, n. 1 (18 ottobre 2011): 37–44. http://dx.doi.org/10.1017/s0960258511000286.
Testo completoAbstract (sommario):
AbstractWe investigated seed dormancy among species of Melastomataceae from Neotropical montane vegetation of Brazil. Four out of 50 studied species had dormant seeds:Miconia corallina(Miconieae), Tibouchina cardinalis(Melastomeae), Comolia sertularia(Melastomeae) andChaetostoma armatum(Microlicieae). For these four species, germinability of seeds collected in different years was always < 10% and the percentages of embryoless seeds and non-viable embryos were both insufficient to explain low or null germinability. This is the first unequivocal report of seed dormancy in tropical Melastomataceae. The production of seeds with permeable seed coats and fully developed, differentiated embryos indicates the occurrence of physiological dormancy. The reconstructed phylogenetic tree of the 50 species suggests that physiological dormancy evolved multiple times during the evolutionary history of Melastomataceae in this vegetation. Physiological dormancy evolved in species and populations associated with xeric microhabitats, where seeds are dispersed in unfavourable conditions for establishment. Therefore, drought-induced mortality may have been a strong selective pressure favouring the evolution of physiological dormancy in Melastomataceae. We argue that dormancy may have been independently selected in other lineages of Cerrado plants colonizing xeric microhabitats and dispersing seeds at the end of the rainy season. The contributions of our data to the understanding of seed dormancy in tropical montane vegetation are discussed.
31
Baskin, Carol C., e Jerry M. Baskin. "Underdeveloped embryos in dwarf seeds and implications for assignment to dormancy class". Seed Science Research 15, n. 4 (dicembre 2005): 357–60. http://dx.doi.org/10.1079/ssr2005224.
Testo completoAbstract (sommario):
Studies were conducted to determine if small embryos (i.e. low embryo length:seed length ratio) in mature dwarf seeds (0.2–2 mm) are underdeveloped. In this case, they would grow (inside the seed) prior to germination, and seeds would have morphological or morphophysiological dormancy. Prior to radicle emergence, embryo length in seeds of Drosera anglica (Droseraceae), Campanula americana, Lobelia appendiculata, L. spicata (Campanulaceae) and Sabatia angularis (Gentianaceae) increased 0, 103, 182, 83 and 57%, respectively. Since embryo growth did not occur in seeds of D. anglica prior to germination, embryos, although small, are fully developed; seeds have only physiological dormancy. The underdeveloped embryo in seeds of C. americana has little or no physiological dormancy; thus, seeds have morphological dormancy. On the other hand, underdeveloped embryos in seeds of L. appendiculata, L. spicata and S. angularis are physiologically dormant, and seeds have morphophysiological dormancy. Therefore, since small embryos in dwarf seeds may or may not be underdeveloped, assignment of seeds to a dormancy class requires that studies be done to determine if embryos grow inside the seed before germination can occur. Such information is important in understanding the evolutionary relationship of the different kinds of seed dormancy.
32
Hou, J. Q., e G. M. Simpson. "Effects of immersing dry seeds in alkaline solutions on seed dormancy and water uptake in wild oat (Avena fatua)". Canadian Journal of Plant Science 74, n. 1 (1 gennaio 1994): 19–24. http://dx.doi.org/10.4141/cjps94-005.
Testo completoAbstract (sommario):
Effects of immersing dry seeds in KOH and NaOH solutions on seed dormancy and water uptake were studied in three dormant lines of wild oat (Avena fatua L.). KOH was more effective than NaOH in breaking dormancy. Maximum dormancy-breaking effect of 5.3 N KOH could be achieved with a 10- or 15-min treatment. Increase in treatment time did not necessarily increase germination; rather, it caused damage to the seeds. For 10-min treatment, 5.3 and 7.6 N KOH solutions were more effective than 3 and 9.8 N. Genetic lines responded differently to the KOH treatment. Initial rate and amount of water uptake by KOH-treated seed were significantly higher than by the untreated. It is believed that breaking dormancy by the alkaline treatment is related to removing the barrier to water uptake formed by the seed coat. Key words: Alkalis, Avena fatua, dormancy, seed coat, seedling growth
33
Baskin, Carol C., e Jerry M. Baskin. "Role of temperature and light in the germination ecology of buried seeds of weedy species of disturbed forests. II. Erechtites hieracifolia". Canadian Journal of Botany 74, n. 12 (1 dicembre 1996): 2002–5. http://dx.doi.org/10.1139/b96-240.
Testo completoAbstract (sommario):
At maturity in September, about half the seeds (achenes) of Erechtites hieracifolia (Asteraceae) collected in Kentucky were dormant (did not germinate at any test condition), whereas the others were conditionally dormant (germinated only at a narrow range of test conditions). Seeds sown on top of soil in an unheated greenhouse in September failed to germinate in autumn because temperatures were below those required for germination; however, they germinated at comparable temperatures the following spring. Seeds buried in soil in September 1987 and exposed to natural seasonal temperature changes were nondormant (germinated over full range of test conditions) by April 1988, but they entered conditional dormancy by October 1988. Each October through 1995, exhumed seeds exhibited conditional dormancy. Since 89% of the seeds were viable after 8 years of burial, it appears that although seeds of this species are wind dispersed, they also have the potential to form a long-lived seed bank. Thus, soil disturbance at any time from May to September could result in establishment of plants from seeds in the seed bank. Keywords: seed dormancy, Asteraceae, dormancy cycles, buried seeds, light.
34
Lefebvre, Maxime, Maryse L. Leblanc e Alan K. Watson. "Seed Dormancy and Seed Morphology Related to Weed Susceptibility to Biofumigation". Weed Science 66, n. 2 (7 novembre 2017): 199–214. http://dx.doi.org/10.1017/wsc.2017.66.
Testo completoAbstract (sommario):
Biofumigation is practiced to control soilborne pests and weeds in agronomic fields. The objectives of this research were to assess the dose response of weed seeds to Indian mustard biofumigation and associate responses to seed dormancy state, initial dormancy, and seed parameters. A petri dish biofumigation methodology was developed to expose seeds of common lambsquarters, bird vetch, wild carrot, common ragweed, green foxtail, velvetleaf, hairy galinsoga, and red clover to allelochemicals produced after rehydrating 0 (control), 1.94, 2.90, 5.81, 11.61, and 17.41 mg cm−2of dried mustard powder. Weed species expressed specific dose responses, estimated ED50, LD50, and maximal mortality. Hairy galinsoga and wild carrot were consistently the most affected by biofumigation, with maximal mortality reaching 97% and 95%, ED50values for germination were 1.91 and 2.68 mg cm−2, and LD50values were 3.31 and 3.69 mg cm−2of dried mustard tissue, respectively. Initial dormancy was assessed by germination and tetrazolium tests. Seed parameters such as testa thickness, relative weight of the testa, and seed size were measured directly by manual dissection, weighing seed structures, and stereomicroscopic imaging software measurements. Linear regression analyses revealed initial dormancy to be positively related to ED50and LD50values with a significant interaction with seed surface and seed width, respectively. Exposure to 5.81 mg cm−2of dried mustard powder increased common ragweed seed mortality for after-ripened seeds by 293% and by 58% for primary dormant seeds compared with untreated seeds. Mortality of common lambsquarters secondary and primary dormant seeds increased by 730% and 106%, respectively, and for wild carrot by 1,193 and 156%, respectively. Results underline the potential to incorporate biofumigation into weed management programs for repression of susceptible weed species.
35
Hawkins, K. K., P. Allen e S. Meyer. "Secondary dormancy of seeds in relation to the Bromus tectorum–Pyrenophora semeniperda pathosystem". Plant Protection Science 49, Special Issue (19 novembre 2013): S11—S14. http://dx.doi.org/10.17221/30/2013-pps.
Testo completoAbstract (sommario):
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.
36
Gallagher, Robert S., Kathryn J. Steadman e Andrew D. Crawford. "Alleviation of dormancy in annual ryegrass (Lolium rigidum) seeds by hydration and after-ripening". Weed Science 52, n. 6 (dicembre 2004): 968–75. http://dx.doi.org/10.1614/ws-04-075r.
Testo completoAbstract (sommario):
The effect of hydration (priming) treatment on dormancy release in annual ryegrass seeds from two populations was investigated. Hydration duration, number, and timing with respect to after-ripening were compared in an experiment involving 15 treatment regimens for 12 wk. Seeds were hydrated at 100% relative humidity for 0, 2, or 10 d at Weeks 1, 6, or 12 of after-ripening. Dormancy status was assessed after each hydration treatment by measuring seed germination at 12-hourly alternating 25/15 C (light/dark) periods using seeds directly from the hydration treatment and seeds subjected to 4 d postpriming desiccation. Seeds exposed to one or more hydration events during the 12 wk were less dormant than seeds that remained dry throughout after-ripening. The longer hydration of 10 d promoted greater dormancy loss than either a 2-d hydration or no hydration. For the seed lot that was most dormant at the start of the experiment, two or three rather than one hydration event or a hydration event earlier rather than later during after-ripening promoted greater dormancy release. These effects were not significant for the less-dormant seed lot. For both seed lots, the effect of a single hydration for 2 d at Week 1 or 6 of after-ripening was not manifested until the test at Week 12 of the experiment, suggesting that the hydration events alter the rate of dormancy release during subsequent after-ripening. A hydrothermal priming time model, usually used for modeling the effect of priming on germination rate of nondormant seeds, was successfully applied to dormancy release resulting from the hydration treatments.
37
Katsuya-Gaviria, Kai, Elena Caro, Néstor Carrillo-Barral e Raquel Iglesias-Fernández. "Reactive Oxygen Species (ROS) and Nucleic Acid Modifications during Seed Dormancy". Plants 9, n. 6 (27 maggio 2020): 679. http://dx.doi.org/10.3390/plants9060679.
Testo completoAbstract (sommario):
The seed is the propagule of higher plants and allows its dissemination and the survival of the species. Seed dormancy prevents premature germination under favourable conditions. Dormant seeds are only able to germinate in a narrow range of conditions. During after-ripening (AR), a mechanism of dormancy release, seeds gradually lose dormancy through a period of dry storage. This review is mainly focused on how chemical modifications of mRNA and genomic DNA, such as oxidation and methylation, affect gene expression during late stages of seed development, especially during dormancy. The oxidation of specific nucleotides produced by reactive oxygen species (ROS) alters the stability of the seed stored mRNAs, being finally degraded or translated into non-functional proteins. DNA methylation is a well-known epigenetic mechanism of controlling gene expression. In Arabidopsis thaliana, while there is a global increase in CHH-context methylation through embryogenesis, global DNA methylation levels remain stable during seed dormancy, decreasing when germination occurs. The biological significance of nucleic acid oxidation and methylation upon seed development is discussed.
38
Gonçalves, Edilma Pereira, Franklim Sales de Jesus Soares, Sérgio dos Santos Silva, Débora de Souza Tavares, Jeandson Silva Viana e Brenda Colleen Clifton Cardoso. "Dormancy Breaking inOrmosia arboreaSeeds". International Journal of Agronomy 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/524709.
Testo completoAbstract (sommario):
Ormosia arboreais a tree species planted in urban areas and used to restore degraded areas. Its seeds are dormant and propagation is difficult. This study compares different dormancy breaking methods and physiological seed quality and seedling production. The seeds were germinated in sand in the laboratory of the Universidade Estadual de Santa Cruz, Ilhéus, Bahia, Brazil. The following dormancy breaking treatments were applied: control (intact seeds), 100°C water immersion; boiling water immersion followed by 24 hours of soaking; scarification with number 100 and number 50 sandpaper opposite from root emergence; sulfuric acid immersion for 1 hour, 50, 45, and 30 minutes. Seed immersion in 100°C and boiling water did not break the dormancy. The study species showed a greater vigor of seedling when its seeds were submitted to treatments associated with tegument rupturing by sandpaper or sulfuric acid. On the other hand, seed scarification with sulfuric acid for 1 hour, 50, 45, and 30 minutes or sandpaper favored seed germination and vigor.
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Kitchen, Stanley G., e Susan E. Meyer. "Seed Germination of Intermountain Penstemons as Influenced by Stratification and GA3 Treatments". Journal of Environmental Horticulture 9, n. 1 (1 marzo 1991): 51–56. http://dx.doi.org/10.24266/0738-2898-9.1.51.
Testo completoAbstract (sommario):
Abstract Propagation of the genus Penstemon for use in landscape horticulture has been handicapped by a lack of understanding of seed dormancy and a practical method for breaking dormancy for numerous species. The extent of dormancy in seeds of 27 wild populations of Penstemon representing 16 Intermountain species was investigated by subjecting seeds to stratification (moist prechilling) of 2 to 16 weeks at 2°C (36°F) and varying concentrations of gibberellic acid (GA3). Germination varied from 0 to 88% for non-treated seeds and from 13 to 100% for seeds treated with 250 ppm GA3. Collections from 10 species required 12 or more weeks of stratification for complete germination. Three species exhibited reduced germination after stratification when compared to the non-chilled control. Gibberellic acid significantly reduced the stratification requirement of seeds for the more dormant species. Concentrations of 150, 250, and 500 ppm GA3 were equally effective in breaking dormancy for most species. The considerable variability in seed dormancy suggests that the most practical solution to penstemon propagation from seed may be the selection of species and ecotypes with minimal dormancy.
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Turner, S. R., D. J. Merritt, J. M. Baskin, C. C. Baskin e K. W. Dixon. "Combinational dormancy in seeds of the Western Australian endemic species Diplopeltis huegelii (Sapindaceae)". Australian Journal of Botany 54, n. 6 (2006): 565. http://dx.doi.org/10.1071/bt05156.
Testo completoAbstract (sommario):
Seeds of the endemic Western Australian species Diplopeltis huegelii Endl. were successfully germinated after the presence of combinational dormancy was identified, following the observation of selected seed characteristics. D. huegelii seeds were found to have large, fully developed, peripheral coiled embryos (with no endosperm) that are 7–8 mm long when uncoiled. Seed-coat dormancy was overcome by dipping seeds in hot water for ≥15 s, but seeds also required a period of after-ripening before they would germinate readily. After-ripening occurred while intact seeds were stored dry at ambient laboratory conditions for 13 months or when scarified (hot-water treated) seeds were stored at 13, 23 or 50% RH at 23°C for 6 weeks. Scarified 13-month-old seeds germinated readily at 7/18, 13/26 and 18/33°C in a 12-h photoperiod and in constant darkness, whereas scarified 1-month-old seeds germinated to ≤43%. Thus, seed dormancy in this species is caused by a water-impermeable seed coat (physical dormancy, PY) and a (non-deep) physiologically dormant embryo (PD), i.e. combinational dormancy (PY + PD). This is only the second report of combinational dormancy in seeds of Sapindaceae and the first report in this family of the PD component of (PY + PD) being broken during dry storage.
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Sautu, Adriana, Jerry M. Baskin, Carol C. Baskin, Jose Deago e Richard Condit. "Classification and ecological relationships of seed dormancy in a seasonal moist tropical forest, Panama, Central America". Seed Science Research 17, n. 2 (giugno 2007): 127–40. http://dx.doi.org/10.1017/s0960258507708127.
Testo completoAbstract (sommario):
AbstractThis is the first study to determine the class of seed dormancy (or non-dormancy) of a large number of native tree species in a tropical forest, the seasonal moist tropical forest of the Panama Canal Watershed (PCW), or to test the relationships between class of dormancy (or non-dormancy) and various seed and ecological characteristics of the constituent species. Fresh seeds of 49 of 94 tree species were non-dormant (ND), and 45 were dormant (D). Seeds of 23 species had physiological dormancy (PD), 13 physical dormancy (PY), two morphological dormancy (MD), 7 morphophysiological dormancy (MPD) and none combinational dormancy (PY+PD). Seeds with PY were significantly smaller ( < 0.1 g) and drier (moisture content < 16%) at maturity than those that were ND or in the other D classes. Seeds of 62, 42 and 53% of species dispersed in the early rainy, late rainy (LRS) and dry seasons, respectively, were ND. The majority (61%) of species with PD seeds, but only 17% of those with PY seeds, were dispersed in the LRS. The proportion of species with ND seeds was higher in large-size (63%) than in mid-size (35%) and understorey (17%) trees, but differed only slightly between non-pioneers (58%) and pioneers (54%). The proportion of species with D seeds increased only slightly through a precipitation gradient of about 3100 to 1900 mm in the PCW; however, PY increased from 19 to 32% and PD decreased from 63 to 44%.
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Schatral, A. "Dormancy in Seeds of Hibbertia hypericoides (Dilleniaceae)". Australian Journal of Botany 44, n. 2 (1996): 213. http://dx.doi.org/10.1071/bt9960213.
Testo completoAbstract (sommario):
Seeds of Hibbertia hypericoides (DC.) Benth. (Dilleniaceae), a shrub native to the south-west of Western Australia, exhibit both seed coat dormancy and embryo dormancy. Water uptake was passive and germination poor after an experimental time period of 3 months in mature, potentially viable seeds. After removal of the seed coat, imbibition occurred in three phases and resulted from passive hydration and active metabolic processes. In mature, potentially viable seeds low water uptake is due to the heavily cutinised cells of the endotesta, since immature, potentially viable seeds and non-viable seeds, which both have a weakly cutinised endotesta, imbibed water readily. Removal of the seed coat significantly increased the final germination percentage in potentially viable seeds. However, the low proportion of vigorous seedlings after seed coat removal suggests that the minute, underdeveloped embryo itself is dormant. Seed coat removal therefore appears to lead to the precocious germination of immature, presumably still partly dormant embryos. Gibberellic acid (GA3) did not affect the germination of seeds. Preliminary experiments do not suggest that the seed coat contains chemical inhibitors.
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Saputra, Jefi, Riska Audina Amir, Nur Mumin e Gusti Ayu Kade Sutariati. "PERSISTENSI DAN PEMATAHAN DORMANSI BENIH CABAI RAWIT LOKAL MENGGUNAKAN TEKNIK BIO-INVIGORASI BENIH". Jurnal Agrotek Tropika 8, n. 2 (26 giugno 2020): 391. http://dx.doi.org/10.23960/jat.v8i2.3194.
Testo completoAbstract (sommario):
Persistence and Breaking of Local Chilli Seed Dormancy Using Seed Bio-Invigoration Techniques. This study aims to evaluate the persistence of local chilli seed dormancy while evaluating seed bio-invigoration techniques that effectively break the dormancy of local chilli. The study consisted of two series of experiments, namely: the persistence test of local chilli. seed dormancy (Series 1) was observed descriptively using a germination indicator for several weeks to reach a germination percentage ≥ 80%. Testing of seed dormancy breakage by seed bio-invigoration technique (Series 2) using a randomized complete design with 3 replications and 7 treatments namely: no treatment (A0), matriconditioning of husk charcoal powder (SAS) + Bacillus sp. CKD061 (A1), matriconditioning SAS + Pseudomonas sp. TBT214 (A2), red brick powder matriconditioning (SBM) + Bacillus sp. CKD061 (A3), matriconditioning SBM + Pseudomonas sp. TBT214 (A4), matriconditioning SAS + Bacillus sp. CKD061 + Pseudomonas sp. TBT214 (A5), and matriconditioning SBM + Bacillus sp. CKD061 + Pseudomonas sp. TBT214 (A6). The results showed that the persistence of local chilli seed dormant cultivars Konsel 1 and Konsel 2 cultivars were 6 weeks. While the dormancy break test on the Konsel 1 cultivar was 2 weeks at A1 treatment with breaking dormancy of 90.00%. While in Konsel 2 cultivar which is 4 weeks in the A6 treatment with breaking dormancy 86.67% which is significantly different from the control. This study shows that A1 treatment can break dormancy of chilli seeds in Konsel 1 cultivar and A6 treatment in Konsel 2 cultivar.
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KHALADI, MOHAMED, MARC JARRY e MARTINE HOSSAERT-MCKEY. "A MODEL FOR ANNUAL PLANT DYNAMICS WITH SEED BANK AND DENSITY-DEPENDENT EFFECTS". Journal of Biological Systems 03, n. 02 (giugno 1995): 531–41. http://dx.doi.org/10.1142/s0218339095000496.
Testo completoAbstract (sommario):
A model is proposed for the population dynamics of an annual plant with a seed bank (i.e. in which a proportion of seeds remain dormant for at least one year). In this model, demographic parameters (dormancy and germination rate) of the seeds of the year are different from those of the seeds of the seed bank. First, a simple linear matrix model is deduced from the life cycle graph and a more complicated model is built by introducing density dependence effect. The obtained system, nonlinear with delay, can be simplified by a change of variables. A non-trivial fixed point of this system is obtained and the conditions of stability are studied. Under certain conditions (choice of exponential law for functional response of density dependence and absence of seed mortality before germination) we show that conditions of stability depend only on 3 parameters, the dormancy rate of the seeds of the year, dormancy rate of the seeds of the seed bank and the maximum potential fecundity of adults. Study of the behaviour of this model in the parameter space shows that the domain of demographic stability can be reduced if the dormancy rate of seeds of the year is low, even if the dormancy rate of seeds of the seed bank is high.
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Wei, Shouhui, Chaoxian Zhang, Xuezheng Chen, Xiangju Li, Biaofeng Sui, Hongjuan Huang, Hailan Cui, Yan Liu, Meng Zhang e Feng Guo. "Rapid and Effective Methods for Breaking Seed Dormancy in Buffalobur (Solanum rostratum)". Weed Science 58, n. 2 (giugno 2010): 141–46. http://dx.doi.org/10.1614/ws-d-09-00005.1.
Testo completoAbstract (sommario):
The spread of buffalobur in China poses a serious threat to existing ecosystems, and control and eradication of this species have become increasingly important. Studies were carried out to ascertain the seed production, morphological characterization, dormancy behavior, and methods for breaking dormancy of buffalobur. The results showed that a single buffalobur plant could produce 1,600 to 43,800 seeds with an average weight of 3.0 mg. Average seed length, width, and thickness were 2.5, 2.0, and 1.0 mm, respectively. Newly ripened buffalobur seeds were innately dormant and exhibited combinational dormancy, which involves a hard seed coat (physical dormancy, PY), a partial dormant embryo (physiological dormancy, PD), and a dark requirement to germinate. PY of buffalobur seeds could be broken by dehusking or acid scarification by 14 M H2SO4for 15 min, with germination rates of 55 or 50%, respectively. PD was effectively broken by KNO3or gibberellic acid (GA3). The optimum concentration for KNO3was between 20 and 40 mM, which resulted in over 70% seed germination. When presoaked with GA3at 30 C in dark for 24 h, maximum germination (> 98%) was obtained at 2.4 mM, the corresponding germination speed (85%) and germination index (16) were also highest at this concentration. Synergistic effects were observed in seed germination when H2SO4and GA3were combined. The most rapid and effective combination in breaking dormancy was when the seeds were immersed in H2SO4(14 M) for 20 min and presoaked with 2.4 mM GA3for 24 h. Germination index for this combination was over 35, and 95% of the seeds germinated within 7 d. Knowledge gained in this study will be useful in increasing germination of buffalobur and facilitating further laboratory studies.
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Barrero, Jose M., Marie M. Dorr, Mark J. Talbot, Shinnosuke Ishikawa, Taishi Umezawa, Rosemary G. White e Frank Gubler. "A role for PM19-Like 1 in seed dormancy in Arabidopsis". Seed Science Research 29, n. 3 (26 luglio 2019): 184–96. http://dx.doi.org/10.1017/s0960258519000151.
Testo completoAbstract (sommario):
AbstractThe understanding of the genetic basis of grain dormancy in wheat has rapidly improved in the last few years, and a number of genes have been identified related to that trait. We recently identified the wheat genes TaPM19-A1 and -A2 and we have now taken the first step towards understanding the role of this class of genes in seeds. By investigating the Arabidopsis homologous PM19-Like 1 (PM19L1) we have found that it has a seed-specific expression pattern and, while its expression is higher in dormant than in non-dormant seeds, knock-out mutations produced seeds with increased dormancy. Not only primary dormancy, but also secondary dormancy in response to high temperature was increased by the loss-of-function. We have also examined the function of PM19L1 by localizing the PM19 protein primarily to the cotyledon cells in seeds, possibly in membranes. By investigating the co-expression network of this gene we have found that it is connected to a small group of abscisic acid (ABA)-induced seed maturation and storage-related genes. The function of PM19L1 represents a good opportunity to explore the interactions of key factors that can influence seed dormancy such as ABA, temperature and membrane properties.
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Soltani, Elias, Sabine Gruber, Mostafa Oveisi, Nader Salehi, Iraj Alahdadi e Majid Ghorbani Javid. "Water stress, temperature regimes and light control induction, and loss of secondary dormancy in Brassica napus L. seeds". Seed Science Research 27, n. 3 (6 giugno 2017): 217–30. http://dx.doi.org/10.1017/s0960258517000186.
Testo completoAbstract (sommario):
AbstractThis study investigated the induction and loss of dormancy in oilseed rape (Brassica napus). Twenty genotypes were preliminary screened; from these, two genotypes, RGS003 and Hayola 308, which possess high potential for dormancy induction (HSD) and medium potential to induce secondary dormancy (MSD), were selected. The stratification of seeds at alternating temperatures of 5–30°C (in dark) significantly relieved secondary dormancy, but dormancy was not fully released. The ψb(50) values were −1.05 and −1.06 MPa for the MSD and the HSD before dormancy induction. After inducing dormancy, the ψb(50) values for the MSD and the HSD were increased to −0.59 and −0.01 on day 0 stratification at 20°C. The hydrothermal time (θHT) value was low for one-day stratification for HSD in comparison with other stratification treatments. Water stress can induce dormancy (if the seeds have the genetic potential for secondary dormancy) and warm stratification (in dark) can only reduce the intensity of dormancy. The seeds with a high potential of dormancy induction can overcome dormancy at alternating temperatures and in the presence of light. It can, therefore, be concluded that a portion of seeds can enter the cycle of dormancy ↔ non-dormancy. The secondary dormant seeds of B. napus cannot become non-dormant in darkness, but the level of dormancy may change from maximum (after water stress) to minimum (after warm stratification). It seems that the dormancy imposed by the conditions of deep burial (darkness in combination with water stress and more constant temperatures) might be more important to seed persistence than secondary dormancy induction and release. The dormancy cycle is an important pre-requisite in order to sense the depth of burial and the best time for seed germination.
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Rodrigues-Junior, Ailton G., José M. R. Faria, Tatiana A. A. Vaz, Adriana T. Nakamura e Anderson C. José. "Physical dormancy in Senna multijuga (Fabaceae: Caesalpinioideae) seeds: the role of seed structures in water uptake". Seed Science Research 24, n. 2 (9 maggio 2014): 147–57. http://dx.doi.org/10.1017/s0960258514000087.
Testo completoAbstract (sommario):
AbstractStructural studies in seeds with physical dormancy (PY) are important to better understand its causes and release when subjected to treatments for dormancy breaking. The aims of this study were to (1) characterize the PY break; (2) examine the role of different seed structures in water uptake; and (3) identify the water gap in Senna multijuga seeds. Imbibition patterns of dormant and non-dormant (subjected to dormancy breaking treatments) seeds and the morphological changes during dormancy breaking and germination were evaluated. To identify the water gap, the micropyle and lens were blocked separately, and the water absorption by seed parts was determined. Structural characteristics of the seed coat were also examined. Immersion in water at 80°C was efficient in breaking seed dormancy and imbibition occurred first at the hilar region, through the lens. Water was not absorbed through the micropyle or the extra-hilar region. S. multijuga seeds have a testa with a linearly aligned micropyle, hilum and lens. The seed coat consisted of a cuticle, macrosclereids, one (hilar region) or two (extra-hilar region) layer(s) of osteosclereids and parenchyma cell layers. The lens has typical parenchyma cells underneath it and two fragile regions comprised of shorter macrosclereids. Heat treatment stimulated the lens region, resulting in the opening of fragile regions at the lens, allowing water to enter the seeds. It is concluded that short-term exposure to a hot water treatment is sufficient for the formation of a water gap in S. multijuga seeds, and only the lens acts in the imbibition process.
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Maleki, Keyvan, Kourosh Maleki, Elias Soltani, Mostafa Oveisi e Jose L. Gonzalez-Andujar. "A Model for Changes in Germination Synchrony and Its Implements to Study Weed Population Dynamics: A Case Study of Brassicaceae". Plants 12, n. 2 (4 gennaio 2023): 233. http://dx.doi.org/10.3390/plants12020233.
Testo completoAbstract (sommario):
In every agricultural system, weed seeds can be found in every cubic centimeter of soil. Weed seeds, as a valuable trait underlying the fate of weed populations, exhibit differing levels of seed dormancy, ensuring their survival under uncertain conditions. Seed dormancy is considered as an innate mechanism that constrains germination under suitable conditions that would otherwise stimulate germination of nondormant seeds. This work provides new insight into changes in germination patterns along the dormant to nondormancy continuum in seeds with physiological dormancy. Notable findings are: (1) germination synchrony can act as a new parameter that quantitatively describes dormancy patterns and, subsequently, weed population dynamics, (2) germination synchrony is dynamic, suggesting that the more dormancy decreases, the more synchrony is obtainable, (3) after-ripening and stratification can function as a synchronizing agent that regulates germination behavior. Freshly harvested seeds of Brassica napus with type 3 of non-deep physiological dormancy showed the most synchronous germination, with a value of 3.14, while a lower level of germination asynchrony was found for newly harvested seeds of Sinapis arvensis with type 1 of non-deep physiological dormancy, with an asynchrony value of 2.25. After-ripening and stratification can act as a synchronizing factor through decreasing the asynchrony level and increasing synchrony. There is a firm relationship between seed dormancy cycling and germination synchrony patterns, ensuring their survival and reproductive strategies. By germinating in synchrony, which is accompanied by cycling mechanisms, weeds have more opportunities to persist. The synchrony model used in the present study predicts germination behavior and synchrony along the dormant to nondormancy continuum in weed seeds with physiological dormancy, suggesting a useful method for the quantification of germination strategies and weed population dynamics.
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Hradilová, Iveta, Martin Duchoslav, Jan Brus, Vilém Pechanec, Miroslav Hýbl, Pavel Kopecký, Lucie Smržová et al. "Variation in wild pea (Pisum sativumsubsp.elatius) seed dormancy and its relationship to the environment and seed coat traits". PeerJ 7 (14 gennaio 2019): e6263. http://dx.doi.org/10.7717/peerj.6263.
Testo completoAbstract (sommario):
BackgroundSeed germination is one of the earliest key events in the plant life cycle. The timing of transition from seed to seedling is an important developmental stage determining the survival of individuals that influences the status of populations and species. Because of wide geographical distribution and occurrence in diverse habitats, wild pea (Pisum sativumsubsp.elatius) offers an excellent model to study physical type of seed dormancy in an ecological context. This study addresses the gap in knowledge of association between the seed dormancy, seed properties and environmental factors, experimentally testing oscillating temperature as dormancy release clue.MethodsSeeds of 97 pea accessions were subjected to two germination treatments (oscillating temperatures of 25/15 °C and 35/15 °C) over 28 days. Germination pattern was described using B-spline coefficients that aggregate both final germination and germination speed. Relationships between germination pattern and environmental conditions at the site of origin (soil and bioclimatic variables extracted from WorldClim 2.0 and SoilGrids databases) were studied using principal component analysis, redundancy analysis and ecological niche modelling. Seeds were analyzed for the seed coat thickness, seed morphology, weight and content of proanthocyanidins (PA).ResultsSeed total germination ranged from 0% to 100%. Cluster analysis of germination patterns of seeds under two temperature treatments differentiated the accessions into three groups: (1) non-dormant (28 accessions, mean germination of 92%), (2) dormant at both treatments (29 acc., 15%) and (3) responsive to increasing temperature range (41 acc., with germination change from 15 to 80%). Seed coat thickness differed between groups with dormant and responsive accessions having thicker testa (median 138 and 140 µm) than non-dormant ones (median 84 mm). The total PA content showed to be higher in the seed coat of dormant (mean 2.18 mg g−1) than those of non-dormant (mean 1.77 mg g−1) and responsive accessions (mean 1.87 mg g−1). Each soil and bioclimatic variable and also germination responsivity (representing synthetic variable characterizing germination pattern of seeds) was spatially clustered. However, only one environmental variable (BIO7, i.e., annual temperature range) was significantly related to germination responsivity. Non-dormant and responsive accessions covered almost whole range of BIO7 while dormant accessions are found in the environment with higher annual temperature, smaller temperature variation, seasonality and milder winter. Ecological niche modelling showed a more localized potential distribution of dormant group. Seed dormancy in the wild pea might be part of a bet-hedging mechanism for areas of the Mediterranean basin with more unpredictable water availability in an otherwise seasonal environment. This study provides the framework for analysis of environmental aspects of physical seed dormancy.