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1.
Philip J. Kauth Michael E. Kane Wagner A. Vendrame 《In vitro cellular & developmental biology. Plant》2011,47(1):148-156
Seed responses to temperature are often essential to the study of germination ecology, but the ecological role of temperature
in orchid seed germination remains uncertain. The response of orchid seeds to cold stratification have been studied, but the
exact physiological role remains unclear. No studies exist that compare the effects of either cold stratification or temperature
on germination among distant populations of the same species. In two separate experiments, the role of temperature (25, 22/11,
27/15, 29/19, 33/24°C) and chilling at 10°C on in vitro seed germination were investigated using distant populations of Calopogon tuberosus var. tuberosus. Cooler temperatures promoted germination of Michigan seeds; warmer temperatures promoted germination of South Carolina and
north central Florida seeds. South Florida seed germination was highest under both warm and cool temperatures. More advanced
seedling development generally occurred at higher temperatures with the exception of south Florida seedlings, in which the
warmest temperature suppressed development. Fluctuating diurnal temperatures were more beneficial for germination compared
to constant temperatures. Cold stratification had a positive effect on germination among all populations, but South Carolina
seeds required the longest chilling treatments to obtain maximum germination. Results from the cold stratification experiment
indicate that a physiological dormancy is present, but the degree of dormancy varies across the species range. The variable
responses among populations may indicate ecotypic differentiation. 相似文献
2.
We analysed changes in AMP, ADP, and ATP concentrations and adenylate energy charge in Norway maple (Acer platanoides L.) and European beech (Fagus sylvatica L.) seeds during dormancy breaking (at 3 °C) and in the control variant at 15 °C. Values of the studied indicators in stratified
beech seeds were generally higher at 15 °C, at least until germination (+3 °C). By contrast, in maple seeds, the values recorded
during dormancy breaking by cold stratification were much higher than at 15 °C. Three peaks (usually in weeks 3, 6, and 8)
were observed in maple seeds at 3 °C, but not at 15 °C. Among adenine nucleotides, AMP reached the highest levels in both
species in both variants of the experiment. 相似文献
3.
Carex is a globally distributed genus with more than 2000 species worldwide and Carex species are the characteristic vegetation of sedge meadow wetlands. In the mid-continental United States, Carex species are dominant in natural freshwater wetlands yet are slow to recolonize hydrologically restored wetlands. To aid in
Carex revegetation efforts, we determined the dormancy breaking and temperature germination requirements of 12 Carex species. Seeds were cold stratified at 5/1°C for 0–6 months and then incubated in light at 5/1°C, 14/1°C, 22/8°C, 27/15°C,
or 35/30°C. We found that all Carex species produced conditionally dormant seeds. The optimal temperature for germination for all but three species was 27/15°C.
As is the case in other species with physiological dormancy, cold stratification increased germination percentages, broadened
the temperature range suitable for germination, and increased germination rates for most species, but the magnitude of the
effects varied among species. Many species germinated to 80% at 27/15°C without cold stratification and at 22/8°C with ≤1 month
of stratification but required much longer stratification (up to 6 months depending on the species) to germinate to 80% at
14/1°C and 35/30°C. Our findings illustrate how a stratification pretreatment can greatly benefit Carex seed sowing efforts by triggering rapid germination to higher percentages. We recommend that cold stratification be targeted
towards species with strong dormancy or used across a wider range of species when seed supplies for restoration are limiting.
For Carex revegetation, establishing Carex canopies rapidly may help to prevent the invasion of undesirable species such as Phalaris arundinacea. 相似文献
4.
Fluctuating temperature plays a critical role in determining the timing of seed germination in many plant species. However, the physiological and biochemical mechanisms underlying such a response have been paid little attention. The present study investigated the effect of plant growth regulators and cold stratification in regulating Leymus chinensis seed germination and dormancy response to temperature. Results showed that seed germination was less than 2 % at all constant temperatures while fluctuating temperature significantly increased germination percentage. The highest germination was 71 % at 20/30 °C. Removal of the embryo enclosing material of L. chinensis seed germinated to 74 %, and replaced the requirement for fluctuating temperature to germinate, by increasing embryo growth potential. Applications of GA4+7 significantly increased seed germination at constant temperature. Also, inhibition of GA biosynthesis significantly decreased seed germination at fluctuating temperatures depending upon paclobutrazol concentration. This implied GA was necessary for non-dormant seed germination and played an important role in regulating seed germination response to temperature. Inhibition of ABA biosynthesis during imbibition completely released seed dormancy at 20/30 °C, but showed no effect on seed germination at constant temperature, suggesting ABA biosynthesis was important for seed dormancy maintenance but may not involve in seed germination response to temperature. Cold stratification with water or GA3 induced seed into secondary dormancy, but this effect was reversed by exogenous FL, suggesting ABA biosynthesis during cold stratification was involved in secondary dormancy. Also, cold stratification with FL entirely replaced the requirement of fluctuating temperature for germination with seeds having 73 % germination at constant temperature. This appears to be attributed to inhibition of ABA biosynthesis and an increase of GA biosynthesis during cold stratification, leading to an increased embryo growth potential. We suggest that fluctuating temperature promotes seed germination by increasing embryo growth potential, mainly attributed to GA biosynthesis during imbibitions. ABA is important for seed dormancy maintenance and induction but showed less effect on non-dormant seed germination response to temperature. 相似文献
5.
Juan A. Delgado José M. Serrano Francisco López Francisco J. Acosta 《Plant Ecology》2008,197(2):269-276
The germination response of different sized seeds from individuals of a Mediterranean fire-prone shrub (Cistus ladanifer) was investigated in relation to pre-germination heating. A control (no heating), a low temperature during a short exposure
time (50°C during 5 min), a high temperature during a short exposure time (100°C during 5 min) and a high temperature during
a long exposure time (100°C during 15 min) were applied to seeds from different individual plants with different mean seed
weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire,
low intensity pasture fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Mean seed weight only showed
a marginally significant positive correlation with the proportion of germinated seeds whatever the pre-germination treatment.
These results suggest that seed dormancy is unrelated to seed size and that under the experimental conditions used in this
study, the effect of seed size on seed germination is low. Nevertheless, larger seeds could be favoured in natural conditions,
especially under the high competition scenario which arise after wildfires. Control seeds showed a negative correlation between
seed size and germination velocity suggesting that lighter seeds could take advantage from early germination in recruitment
events in the absence of wildfires. Nevertheless, even the lower pre-germination heating treatment turns this correlation
in not significant, suggesting a strong selection pressure (unrelated to seed size) for early germination after fire events.
In our study, different sized seeds of C. ladanifer seem to perform better under different germination scenarios suggesting that seed size variation could be maintained by the
alternation of recruitments without wildfires and recruitments after wildfire events. 相似文献
6.
Investigations on seeds of Scrophularia marilandica L. were undertaken to determine their germination requirements. Seeds were collected from three naturally occurring sites
and one greenhouse-grown population in London, Ontario in September and October of 1997. Some were set to germinate immediately
after collection; others were stored in or on soil outside and/or under controlled laboratory conditions before testing. Germination
was assessed under two light/temperature regimes (35°C 14 h light, 20°C 10 h dark and 25°C 14 h light, 10°C 10 h dark), in
continuous darkness, and in the presence of two germination-promoting chemicals (GA3 and KNO3). Fresh seeds germinated best at 35/20°C, while stored seeds germinated best at 25/10°C. No differences in percent germination
were found among three seed-maturity stages. All chemical treatments, except 0.01 M KNO3, increased percent germination. Significant differences were found both among and within sites for most chemical treatments,
but exposure to 3 × 10−4 M GA3 caused almost every seed to germinate. When compared to the control, both the gibberellic acid and the soil-storage treatments
contributed to faster germination. Exposure of seeds to naturally prevailing conditions on the soil surface followed by testing
under the 25/10°C regime produced the highest percent germination. No seeds germinated in the dark. In summary, seeds of S. marilandica exhibit physiological dormancy, which can be alleviated by exposure to light, after-ripening and/or cold stratification.
It is probable that the differences in germination response among sites can be attributed to differences in environmental
conditions during seed production. These experiments indicate that the seeds of S. marilandica must be buried shortly after dispersal in order to form a persistent seed bank. 相似文献
7.
The studies were carried out on Fagus sylvatica seeds during stratification and their germination. After imbibition beechnuts were subjected to cold (3 °C — temperature
which breaks dormancy) or warm (15 °C — temperature unable to break dormancy) stratification and alternatively were treated
with polyamine synthesis inhibitors: canavanine and DFMO (difluoromethylornithine). After cold stratification in embryo axes
we found (using 2-D electrophoresis) about 150 new proteins absent in dry seeds. Exogenous spermidine increased the protein
synthesis, percent of germinated seeds and accelerated breaking of dormancy. In contrast, canavanine and DFMO decreased dynamic
of protein synthesis, quantity of proteins probably synthesised de novo, and percent of germinated seeds. The maximum of polyamine content in embryo axes during cold stratification preceded such
the maximum during warm stratification. Irrespective of the influence of PAs and inhibitors of PA synthesis, the comparison
of electrophoregrams and autoradiograms showed that different groups synthesised de novo appeared after different periods of cold stratification. Probably the part of this protein is associated with Fagus sylvatica seeds dormancy breaking. 相似文献
8.
Aim of this study was to investigate the nature of dormancy in black henbane (Hyoscyamus niger) seeds which have low germination rate under normal laboratory conditions. To do this, before placing the seeds in Petri
dishes, they were soaked in 5,10 and 15 mg/L GA; 1,2 and 3% H2SO4, 15 mg/L GA + 1% H2SO4, 0.01 M KNO3 solutions, tap water, 40, 50 and 60°C hot water for 30 min. The study was performed under both continuous illumination and
darkness in growth chambers to evaluate the effect of light on germination rate. The results showed that H2SO4 and GA treatments were the most important factors affecting seed germination and their germination enhancing effects were
more evident in darkness. The results also suggested that black henbane seeds exhibit double dormancy involving a hard seed
coat and a partially dormant embryo and have a partial dark requirement to germinate. 相似文献
9.
Flixweed is one of the most abundant weeds in North America and China, and causes a reduction in crop yields. Dormancy of flixweed seeds is deep at maturity and is maintained in soil for several months. To identify regulators of seed dormancy and germination of flixweed, the effect of environmental and hormonal signals were examined using dormant and non-dormant seeds. The level of dormancy was decreased during after-ripening and stratification, but long imbibition (over 5 days) at 4 °C in the dark resulted in the introduction of secondary dormancy. The strict requirement of duration of cold treatment for the break of dormancy may play a role in the seasonal regulation of germination. The germination of non-dormant flixweed seeds was critically regulated by red (R) and far-red (FR) light in a photoreversible manner. Sodium nitroprusside, a donor of nitric oxide (NO), promoted germination of half-dormant seeds, suggesting that NO reduced the level of seed dormancy. As has been shown in other related species, light elevated sensitivity to GA4 in dark-imbibied flixweed seeds, but cold treatment did not affect GA4-sensitivity unlike in Arabidopsis. Taken together, our results indicate that seed germination in flixweed and its close relative Arabidopsis is controlled by similar as well as distinct mechanisms in response to various endogenous and environmental signals. 相似文献
10.
Konstantin V. Kiselev Anna V. Turlenko Yuri N. Zhuravlev 《Plant Cell, Tissue and Organ Culture》2009,99(2):141-149
A somatic embryogenesis protocol for plant regeneration of northern red oak (Quercus rubra) was established from immature cotyledon explants. Embryogenic callus cultures were induced on Murashige and Skoog medium
(MS) containing 3% sucrose, 0.24% Phytagel™, and various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-d) after 4 weeks of culture in darkness. A higher response (66%) of embryogenic callus was induced on 0.45 μM 2,4-d. Higher numbers of globular- (31), heart- (17), torpedo- (12), and cotyledon-stage (8) embryos per explant were obtained
by culturing embryogenic callus on MS with 3% sucrose, 0.24% Phytagel™, and devoid of growth regulators after 8 weeks culture
in darkness. Continuous sub-culturing of embryogenic callus on medium containing 2,4-d yielded only compact callus. Desiccation of embryos for 3 days in darkness at 25 ± 2°C followed by cold storage at 4°C in
darkness for 8 weeks favored embryo germination and development of plantlets. Cotyledon-stage embryos subjected to desiccation
and chilling treatment cultured on MS with 3% sucrose, 0.24 Phytagel™, 0.44 μM 6-benzylaminopurine (BA), and 0.29 μM gibberellic
acid germinated at a higher frequency (61%) than with 0.44 μM BA alone and control cultures. Germinated plantlets developed
a shoot and root, were acclimatized successfully, and maintained in a growth room for plantlet development. 相似文献
11.
Toshinari Godo Miho Komori Emi Nakaoki Tomohisa Yukawa Kazumitsu Miyoshi 《In vitro cellular & developmental biology. Plant》2010,46(3):323-328
The effects of culture conditions on the asymbiotic germination of mature seeds of Calanthe tricarinata Lindl., an endangered terrestrial cool-climate orchid, were examined. Specifically, conditions such as illumination, temperature,
and the addition of plant growth regulators to the medium were studied. Mature seeds were harvested from plants that had been
collected in Toyama Prefecture, Japan, and maintained at the Botanic Gardens of Toyama. Solidified “New Dogashima” medium
was used as the basal medium, and it was supplemented with 6-benzyladenopurine (BA) or α-naphthalene acetic acid (NAA). White
light at 40 μmol m−2 s−1, with a 16-h photoperiod, inhibited the germination of seeds by 53–80%, as compared to dark controls in genotypes examined.
The optimal temperature for the germination of seeds in darkness was 20°C and the germination frequency reached 60%, whereas
it was only 28% at 25°C. While both NAA and BA stimulated germination, BA was more effective than NAA. After storage for 18 mo
at 5°C, seeds incubated on medium that contained 0.2 mg l−1 BA germinated at a frequency of 36%, which was twice that of seeds grown without any plant growth regulators. The frequency
of subsequent germination decreased during storage of seeds at 5°C for approximately 2 yr, dropping from 61% to 13%. The protocorms
obtained in this study were developed to plantlets readily after transferring to fresh 1/2 MS medium without any plant growth
regulators. They were successfully acclimatized in green house after two to three subcultures in vitro. The significant role of a reproducible protocol for the germination of mature seeds is discussed in terms of the ex situ conservation of endangered orchid species. 相似文献
12.
Marcin Zarek 《In vitro cellular & developmental biology. Plant》2007,43(6):623-630
Conditions for obtaining an efficient mass propagation procedure to overcome isolated Taxus baccata embryo dormancy were investigated. The protocol herein described was efficient for overcoming the dormancy of T. baccata isolated embryos under in vitro conditions, enabling the conservation and propagation of this species. T. baccata seeds were unable to germinate directly after collection under in vitro conditions. Very good sterility and germination was achieved by soaking seeds in distilled water at a low temperature (+4°C)
at least for 48 h instead of leaching them for 7 d under running water, followed by maintaining isolated embryos on the Murashige
and Skoog medium (MS) supplemented with 5 g l−1 activated charcoal. That treatment allowed one to shorten the time of the experiment and gave almost 100% sterility. The
best germination was observed in darkness, but to obtain worthy seedlings, it was necessary to place cultures in a 16-h photoperiod
after a 2-wk incubation. There was no significant difference in germination between seeds collected from different populations
of Southern Poland. 相似文献
13.
K. Samuel D. Debashish B. Madhumita G. Padmaja Siva Ram Prasad V. Bhaskara Ramana Murthy P. S. Rao 《In vitro cellular & developmental biology. Plant》2009,45(4):466-473
The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken
to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for
micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds
when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA3). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts)
supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds
decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which
germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction
was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary
medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after
two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively. 相似文献
14.
Short or long-term ex situ conservation is becoming increasingly important in conservation of plants in today’s changing environments. One of the important steps in ex situ conservation is the collection and storage of seeds and the consequent establishment of seed germination protocols. Cerastium dinaricum (Caryophyllaceae) is an endemic, high elevation and rare species of European conservation concern. Because of its severely fragmented distribution along the Dinaric Alps, the populations are likely to undergo further shrinkage in the future, which addresses the need of a long-term effective conservation management. From the potential ex situ population management perspective, we focused our study on germination ecology of C. dinaricum. The study revealed that temperature considerably affected the germination of seeds, which germinate better at 20 °C rather than 10 °C. A period of cold-wet stratification also significantly improved the final germination percentage with more pronounced increase at 20 °C, while addition of GA3 increased the final germination percentage by breaking the dormancy of non-stratified seeds. Mechanical scarification did not improve germination; on the contrary, it resulted in the lowest germination success. Seeds grown in complete darkness germinated significantly better compared to control when they were exposed to cold-wet stratification. Contrary to previous studies on some alpine species, which germinate better when exposed to light, dark treatment resulted in the highest germination percentages with 70 and 90% germination success after 4 and 8 weeks of stratification, respectively. 相似文献
15.
The effect of smoke and smoke-derived butenolide in releasing dormancy of caryopses (referred to as seeds) of the economically
important weed Avena fatua L. was studied. Seeds of A. fatua are dormant after harvest. Both smoke-water and butenolide, applied continuously, removed dormancy in darkness at 15, 20
and 25°C and slightly at 30°C. Butenolide was very active at a concentration of 10−8 M. Butenolide at 10−8 M was also able to remove dormancy at 20°C when applied for 12 or 24 h at 4°C or for 3 to 24 h at 20°C. Sensitivity to butenolide
decreased with longer preincubation times in water. This compound was less effective in releasing dormancy in the light than
in darkness. Dormancy release by butenolide involves induction of cell-cycle activity just before coleorhiza protrusion. Stimulatory
effects of smoke-water and butenolide were also observed in respect of seedling growth and vigor. 相似文献
16.
We examined the response of seeds to heat in four geographically restricted and one widespread species of shrubby Darwinia from the fire-prone region of southeastern Australia. These shrubs are killed by fire and rely on seed germination after
a fire to maintain populations. We replicated the germination trials across several sites and several fruiting seasons for
most species. Seeds had a high level of viability and were largely dispersed in a dormant state, except in D. glaucophylla, where seed dormancy varied significantly across fruiting seasons. The indehiscent fruit of all species readily imbibes moisture
when wet and seeds are not considered to be ‘hard-seeded’. All species had increased seed germination in response to a limited
range of heating temperatures (generally 80–100°C). Higher temperatures killed increasing proportions of seeds. This pattern
was broadly consistent across species, population and seasons, although the proportion of seeds whose germination was promoted
by heat varied from high (D. diminuta, D. fascicularis, D. glaucophylla) to moderate (D. biflora, D. procera). Our work highlights the importance of heat as a mechanism for influencing germination in species that are not hard-seeded.
Consequently, soil temperatures during a fire should strongly influence post-fire germination levels in Darwinia. The roles of other cues that promote germination, i.e. smoke, seasonal temperatures and their interactions with heat, remain
to be investigated. 相似文献
17.
Sara Mira M. Elena González-Benito Ana M. Ibars Elena Estrelles 《Biodiversity and Conservation》2011,20(2):345-358
The influence of seed testa color, temperature and seed water content on dormancy release and seed viability loss in the endangered,
endemic species Silene diclinis (Lag.) M. Laínz was evaluated. Dormant heterogeneous seeds (black, red and grey colored) were exposed to three different
temperatures (5, 20, and 35°C) and two relative humidities (33 and 60%) in order to assay their dormancy release. Longevity
behavior was studied for the three colored seeds, storing samples at nine different combinations of temperature (5, 20 and
35°C) and relative humidities (33, 60 and 90%). According to our findings, seed heteromorphism was not related to neither
break of dormancy nor seed storage behavior. Silene diclinis seeds present dormancy after collection, and need an after-ripening period to germinate. Temperature and relative humidity
are positively correlated with dormancy release and seed ageing. Therefore, both factors must be carefully controlled during
seed manipulation in the laboratory for long term seed conservation purposes. When seeds are stored immediately after collection
(dormant), if the temperature of storage is above the base temperature for dormancy release found in this work (between 2.7
and 1.6°C), seeds may eventually overcome dormancy. On the other hand if seeds are stored after an after-ripening period,
storage at low temperature does not induce secondary dormancy. 相似文献
18.
Germination studies of Cymbopogon schoenanthus (Poaceae) distributed along southern Tunisia were carried out to assess the effects of salinity. A preliminary experiment
showed 30°C as the optimum germination temperature for seeds of this species. After that, seed germination was studied at
different salinity levels. Our results revealed a decrease in germination percentage with increasing salinity. Germination
rate, however, was maintained up to 200 mM NaCl and drastically declined at 300 mM NaCl. 相似文献
19.
Sanaz Zardari Farshid Ghaderi-Far Hamid R. Sadeghipour Ebrahim Zeinali Elias Soltani Carol C. Baskin 《Plant Species Biology》2019,34(3):85-94
We tested the hypothesis that seeds of the monocarpic perennial Ferula gummosa from the Mediterranean area and central Asia have deep complex morphophysiological dormancy. We determined the water permeability of seeds, embryo morphology, temperature requirements for embryo growth and seed germination and responses of seeds to warm and cold stratification and to different concentrations of GA3. The embryo has differentiated organs, but it is small (underdeveloped) and must grow inside the seed, reaching a critical embryo length, seed length ratio of 0.65–0.7, before the seed can germinate. Seeds required 9 weeks of cold stratification at <10°C for embryo growth, dormancy break and germination to occur. Thus, seeds have morphophysiological dormancy (MPD). Furthermore, GA3 improved the germination percentage and rate at 5°C and promoted 20 and 5% germination of seeds incubated at 15 and 20°C, respectively. Thus, about 20% of the seeds had intermediate complex MPD. For the other seeds in the seed lot, cold stratification (5°C) was the only requirement for dormancy break and germination and GA3 could not substitute for cold stratification. Thus, about 80% of the seeds had deep complex MPD. 相似文献
20.
Acacia gerrardii is the only native tree species of the Kuwaiti desert ecosystem. However, anthropogenic disturbances and harsh arid climate have contributed towards the disappearance of this keystone species from its habitat. In this study, effects of different seed pretreatments to break dormancy, water entry pathway, and ecology (seasonal timing) of dormancy loss and germination of A. gerrardii were investigated. Effects of mechanical scarification, hot water treatment (30 s, 1, 2, and 5 min), and concentrated acid scarification (10, 20, and 30 min) on germination percentage and rate (time to 50% germination and final germination) were also examined. Pretreatment with mechanical scarification produced the highest germination in the least time and 20 °C, 40% RH with 12 h of light (2370 Lux) were found to provide the best germination environment. Seeds were rapidly aged at 60% RH and 45 or 50 °C to determine longevity, and the results were analyzed using probit analysis. Times taken for viability of A. gerrardii seeds aged at 45 and 50 °C to fall to 50% (p50) were 38.6 and 9.3 days, respectively, and therefore the seeds can be considered to have medium longevity. Experiments to find the water entry pathway in A. gerrardii indicated that the micropyle region was the primary point of water entry into the seed. Seed burial experiments indicated that though seed retention decreased over time, there was no significant decrease in number of viable seeds after 31 weeks. The findings of this study are important to nursery managers, seed banks, and those involved in conservation and restoration activities. 相似文献