Factors controlling seed dormancy and germination response of Brachypodium hybridum growing in the hot arid mountains of the Arabian Desert

Botany ◽  
2019 ◽  
Vol 97 (7) ◽  
pp. 371-379 ◽  
Author(s):  
Masarra Elgabra ◽  
Ali El-Keblawy ◽  
Kareem A. Mosa ◽  
Sameh Soliman
Keyword(s):  
Seed Dormancy ◽  
Light Quality ◽  
Genetic Model ◽  
Germination Rate ◽  
Red Light ◽  
Germination Percentage ◽  
Light Conditions ◽  
One Year ◽  
Native And Introduced Ranges ◽  
Seed Dormancy And Germination

Seed dormancy and germination have been studied in the genetic model Brachypodium species complex in cooler, moist higher latitudes. Studying environmental factors in arid mountains affecting dormancy and germination in Brachypodium complex could determine the factors controlling these processes. This study assesses the impacts of temperature during seed maturation, seed after-ripening, drought, photoperiod, and thermoperiod on final germination and germination rate index of B. hybridum in the Arabian Desert. Seeds were germinated under dark or light conditions and under different ratios of red:far-red light, with three diurnal thermoperiods. The final germination percentage was significantly greater at 15/25 °C and 20/30 °C than at 25/35 °C and in light rather than in darkness. Seeds that reached maturity at 15/25 °C attained greater germination rates and faster germination than those that reached maturity at 20/30 °C. One-year after-ripening enhanced the final germination percentage and reduced photoperiod requirements. Light quality did not affect final germination percentage. The seeds tolerated drought of up to –0.8 MPa polyethylene glycol. The tolerance of B. hybridum seeds produced at higher thermoperiods to moderate levels of osmotic stress and their higher dormancy indicate that this species has the potential to survive the projected global warming in its native and introduced ranges.

The Effect of Light Quality on the Germination of Eight Species From Sandy Habitats in Western Australia.

1993 ◽  
Vol 41 (3) ◽  
pp. 321 ◽  
Author(s):  
DT Bell
Keyword(s):  
Western Australia ◽  
Light Quality ◽  
Red Light ◽  
Monochromatic Light ◽  
Coastal Dunes ◽  
High Energy ◽  
Germination Percentage ◽  
Light Conditions ◽  
Light Inhibition ◽  
Effect Of Light

The impacts of darkness and a range of monochromatic light conditions on germination was documented for eight native and naturalized species growing in sandy habitats in Western Australia. Four lake-margin species, Juncus articulatus, J. microcephalus, J. pallidus and Isolepis prolifera, germinated under red (c. 520-640 nm) light, but remained dormant in the dark or when illuminated with far-red (720 nm) or blue (430-490 nm) light. Sunlight-stimulated germination could be beneficial to these very small seeded species, which may not have sufficient reserves for seedlings to establish following deep burial. Oenothera stricta, a short-lived ruderal species, was also stimulated by red light, a response possibly related to germination following disturbance of overlying vegetation. Trachyandra divaricata, a dune inhabiting species, was inhibited by red light. Inhibition by the wavelengths of light dominant in full sunlight was thought to be a response beneficial to species of blowing sand habitats where germination on the dry surface could prove detrimental. Oenothera drummorndii , also a species of coastal dunes was inhibited under high energy light (430-490 nm) but showed no percentage gemination differences in light of wavelengths between 520 and 720 nm and under dark conditions. Asphodelus fistulosus, a species of similar life-fonn characteristics to Trachyarndra divaricata, showed no effect on germination percentage of varying light quality.

Seed dormancy in four Tibetan Plateau Vicia species and characterization of physiological changes in response of seeds to environmental factors

2013 ◽  
Vol 23 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Xiaowen Hu ◽  
Tingshan Li ◽  
Juan Wang ◽  
Yanrong Wang ◽  
Carol C. Baskin ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Seed Dormancy ◽  
Germination Rate ◽  
Soil Surface ◽  
The Tibetan Plateau ◽  
Physical Dormancy ◽  
High Germination ◽  
One Year ◽  
Hydrotime Model ◽  
Aba Biosynthesis

AbstractAlthough seed dormancy of temperate legumes is well understood, less is known about it in species that grow in subalpine/alpine areas. This study investigated dormancy and germination of four Vicia species from the Tibetan Plateau. Fresh seeds of V. sativa were permeable to water, whereas those of V. angustifolia, V. amoena and V. unijuga had physical dormancy (PY). One year of dry storage increased the proportion of impermeable seeds in V. angustifolia, but showed no effect on seed coat permeability in V. amoena or V. unijuga. Seeds of all four species also had non-deep physiological dormancy (PD), which was especially apparent in the two annuals at a high germination temperature (20°C). After 1 year of storage, PD had been lost. The hydrotime model showed that fresh seeds obtained a significantly higher median water potential [Ψb(50)] than stored seeds, implying that PD prevents germination in winter for seeds dispersed without PY when water availability is limited. After 6 months on the soil surface in the field, a high proportion of permeable seeds remained ungerminated, further suggesting that PD plays a key role in preventing germination after dispersal. Addition of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis, evened-out the differences in germination between fresh and stored seeds, which points to the key role of ABA biosynthesis in maintaining dormancy. Further, fresh seeds were more sensitive to exogenous ABA than stored seeds, indicating that storage decreased embryo sensitivity to ABA. On the other hand, the gibberellic acid GA3 increased germination rate, which implies that embryo sensitivity to GA is also involved in seed dormancy regulation. This study showed that PY, PD or their combination (PY+PD) plays a key role in timing germination after dispersal, and that different intensities of dormancy occur among these four Vicia species from the Tibetan Plateau.

Morphophysiological dormancy and germination ecology in diaspores of the subtropical palm Phoenix canariensis Chabaud

Botany ◽  
2021 ◽  
Author(s):  
Lanlan He ◽  
Ganesh K. Jaganathan ◽  
Baolin Liu
Keyword(s):  
Seed Dormancy ◽  
Seedling Emergence ◽  
Primary Root ◽  
Germination Percentage ◽  
Early Summer ◽  
Germination Ecology ◽  
Phoenix Canariensis ◽  
Morphophysiological Dormancy ◽  
Cotyledonary Petiole ◽  
Seed Dormancy And Germination

The timing of germination is a crucial event in a plant’s life cycle. Seed dormancy and germination mechanisms are important factors regulating seedling emergence. Since detailed experimental evidence for germination pattern of Phoenix canariensis colonizing sub-tropical climate is scarce, we investigated seed dormancy and germination ecology of P. canariensis. We found that the embryo is underdeveloped at the time of dispersal and doubles in size before the cotyledonary petiole (CP) protrudes through the operculum. The primary root and plumule emerge from the elongated CP outside the seed. In light/dark at 30/25°C, the CP emerged from 8% of the diaspores within 30 days and from 76% within 14 weeks. Thus, 8% of the diaspores have MD and the others MPD. Removal of the pericarp and operculum resulted in 100% germination within 5 days in light/dark at 30/25°C. Cold and warm stratification as well as treatment with GA3 significantly increased the germination speed, but the final germination percentage was not significantly increased. Seed germination was synchronized in early summer when seed dormancy was released by cold stratification in the soil over winter. A remote-tubular germination type and intricate root system provide an ecological advantage to the seedling establishment.

scholarly journals Interactive Effects of Light Quality and Temperature on Arabidopsis Growth and Immunity

2020 ◽  
Vol 61 (5) ◽  
pp. 933-941
Author(s):  
Xiaoying Liu ◽  
Chunmei Xue ◽  
Le Kong ◽  
Ruining Li ◽  
Zhigang Xu ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Blue Light ◽  
Light Quality ◽  
Red Light ◽  
Complex Interaction ◽  
Hypocotyl Elongation ◽  
Interactive Effects ◽  
Phytochrome B ◽  
Light Conditions ◽  
Effects Of Temperature

Abstract We report here the interactive effects of three light qualities (white, red and blue) and three growth temperatures (16�C, 22�C and 28�C) on rosette growth, hypocotyl elongation and disease resistance in Arabidopsis thaliana. While an increase in temperature promotes hypocotyl elongation irrespective of light quality, the effects of temperature on rosette growth and disease resistance are dependent on light quality. Maximum rosette growth rate under white, red and blue light are observed at 28�C, 16�C and 22�C, respectively. The highest disease resistance is observed at 16�C under all three light conditions, but the highest susceptibility is observed at 28�C for white light and 22�C for red and blue light. Interestingly, rosette growth is inhibited by phytochrome B (PHYB) under blue light at 28�C and by cryptochromes (CRYs) under red light at 16�C. In addition, disease resistance is inhibited by PHYB under blue light and promoted by CRYs under red light. Therefore, this study reveals a complex interaction between light and temperature in modulating rosette growth and disease resistance as well as the contribution of PHYB and CRY to disease resistance.

scholarly journals A Novel Method to Overcome Coat-Imposed Seed Dormancy in Lupinus albus L. and Trifolium pratense L.

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Iskender Tiryaki ◽  
Mustafa Topu
Keyword(s):  
Seed Dormancy ◽  
Trifolium Pratense ◽  
Germination Rate ◽  
Lupinus Albus ◽  
Red Clover ◽  
Treatment Method ◽  
Germination Percentage ◽  
Hot Water ◽  
White Lupin ◽  
Novel Method

We have developed a novel method to overcome coat-imposed seed dormancy in legume plants. Seeds of Lupinus albus L. and Trifolium pratense L. were stored in a freezer at −80°C for a period of time and then immediately treated with or without hot water at 90°C for 5 seconds. Germination tests were carried out in darkness at 20±1.0°C with four replications in a completely randomized design. Final germination percentage (FGP), germination rate, and synchrony of seeds were evaluated. The results showed that new approach of freeze-thaw scarification provided high percentage of germinations in white lupin (84.16%) and red clover (74.50%) seeds while control seeds had FGPs of 3.3% and 26.0%, respectively. The immediate thawing of frozen seeds in hot water for 5 seconds was found not only an effective and reliable but also the quickest seed treatment method to prevail against coat-imposed seed dormancy in legume species and may become operationally applicable to other plant species.

scholarly journals The Effect of Sodium Hypochlorite (NaOCl) and Heat Treatments on Seed Germination of Rice: An Approach to Restore Seed Viability

2021 ◽  
pp. 49-53
Author(s):  
Monoj Sutradhar ◽  
Subhasis Samanta ◽  
Brijesh Kumar Singh ◽  
Md. Nasim Ali ◽  
Nirmal Mandal
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Sodium Hypochlorite ◽  
Seed Viability ◽  
Germination Percentage ◽  
Heat Treated ◽  
Mother Plants ◽  
Breaking Seed Dormancy ◽  
One Year

Dormancy in rice serves as a mechanism of survival by protecting the seed from germinating in the mother plants; however, it becomes a problem in germination during sowing in soil or under in vitro conditions. This study was conducted to determine the effect of heat treatment and sodium hypochlorite (NaOCl) treatment of seeds on dormancy alleviation. The seeds included both freshly harvested seeds and one-year-old stored seeds, which were tested for germination after different types of seed treatments. Both the treatments increased the germination percentage in seeds, however, it was lesser in the case of old seeds. The best results were obtained from 2% NaOCl treatment for 24 hrs in new seeds, i.e. 92.84±0.103 % germination percentage (GP). However, the higher GP in old seeds were obtained from 48 hrs of heat-treated seeds i.e. 82.9±0.509 % GP. The results of the experiment revealed that rice seeds start to lose viability within a year due to seed dormancy, but this can be reversed with proper measures. These methods of breaking seed dormancy can be considered effective to break seed dormancy and improve seed germination in rice.

scholarly journals The Role of Leaves in Photocontrol of Flower Bud Abscission in Hibiscus rosa-sinensis L. `Nairobi'

2000 ◽  
Vol 125 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Uulke van Meeteren ◽  
Annie van Gelder
Keyword(s):  
Light Quality ◽  
Light Exposure ◽  
Red Light ◽  
Light Conditions ◽  
Flower Bud ◽  
Light Emitting ◽  
Hibiscus Rosa Sinensis ◽  
Number Of Leaves ◽  
Whole Plants

When compared with exposure to darkness, exposing Hibiscus rosa-sinensis L. `Nairobi' plants to red light (635 to 685 nm, 2.9 μmol·m-2·s-1) delayed flower bud abscission, while exposure to far-red light (705 to 755 nm, 1.7 μmol·m-2·s-1) accelerated this process. Flower bud abscission in response to light quality appears to be controlled partly by the presence of leaves. The delay of bud abscission was positively correlated to the number of leaves being exposed to red light. Excluding the flower buds from exposure to red or far-red light, while exposing the remaining parts of the plants to these light conditions, did not influence the effects of the light exposure on bud abscission. Exposing only the buds to red light by the use of red light-emitting diodes (0.8 μmol·m-2·s-1) did not prevent dark-induced flower bud abscission. Exposing the whole plants, darkness or far-red light could only induce flower bud abscission when leaves were present; bud abscission was totally absent when all leaves were removed. To prevent flower bud abscission, leaves had to be removed before, or at the start of, the far-red light treatment. These results suggest that in darkness or far-red light, a flower bud abscission-promoting signal from the leaves may be involved.

Variation of Seed Dormancy and Germination Ecology of Cowcockle (Vaccaria hispanica)

Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Hema S. N. Duddu ◽  
Steven J. Shirtliffe
Keyword(s):  
Seed Dormancy ◽  
Great Plains ◽  
Northern Great Plains ◽  
Light Conditions ◽  
Primary Dormancy ◽  
Local Environments ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Two Temperature ◽  
Seed Dormancy And Germination

Cowcockle, an introduced summer annual weed of the Northern Great Plains, is being considered for domestication because of its high quality starch, cyclopeptides, and saponins. Loss of seed dormancy is one of the key desirable traits for domestication. To determine the potential for domestication of this species, an understanding of the seed dormancy and germination patterns is required. The objectives of this study were to evaluate seed dormancy in cowcockle ecotypes and determine how temperature and light affect seed dormancy. We evaluated 15 populations of cowcockle for primary dormancy by exposing them to five temperatures (5, 7.5, 10, 15, and 20 C) under two temperature regimes (constant and alternating) in both dark and light conditions. Freshly matured seeds of all the populations showed high levels of primary dormancy except ‘Mongolia’. Lower levels of dormancy at medium temperatures (10 and 15 C) and greater dormancy at low and high temperatures suggest conditional dormancy, a state at which seeds germinate over a narrower range of conditions compared to nondormant seeds. The effects of temperature regime, light, and their interaction was significant only at suboptimal (5 and 7.5 C) and supraoptimal (20 C) temperatures. Under these conditions, alternating temperatures were more effective in breaking the conditional dormancy, followed by light. The variation in optimum temperature, light, and their interactions among the cowcockle populations may be due to the plants evolving to adapt to their local environments. From a domestication perspective, the conditional dormancy in cowcockle can be observed as an evolutionary mechanism that prevents untimely germination following maturity and may not be a major obstacle for its domestication.

scholarly journals Ecophysiology of seed germination in Mediterranean geophytes. 1. Muscari spp

2002 ◽  
Vol 12 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Maria A. Doussi ◽  
Costas A. Thanos
Keyword(s):  
Seed Germination ◽  
White Light ◽  
Mediterranean Climate ◽  
Germination Rate ◽  
Red Light ◽  
Rainfall Regime ◽  
Light Conditions ◽  
Rainy Period ◽  
Germination Characteristics ◽  
The Mediterranean

Ecophysiological aspects of seed germination were investigated in four Mediterranean geophytes of the genus Muscari (Liliaceae): M. comosum (tassel hyacinth), M. neglectum (common grape hyacinth), M. commutatum and M. weissii. Experiments were performed at constant temperatures in the dark and under temperature and light conditions simulating those prevailing in nature during November–January, i.e. well into the rainy season of the Mediterranean climate. In all species, no primary dormancy was revealed, and germination occurred in a rather narrow range of cool temperatures (optimum at 10 or 15°C) and at a remarkably slow rate; both germination characteristics seem to be associated with autumn/winter seed germination and seedling establishment. Such a postulated strategy is ecologically advantageous within an unpredictable rainfall regime, known to prevail during the start of the rainy period of the Mediterranean climate. This strategy may also explain the spread of germination of M. comosum seeds over two consecutive years, observed by Theophrastus. Far-red light, simulating light conditions under a dense canopy, resulted in only a slight delay of germination compared to dark controls. Diurnal white light, qualitatively simulating natural daylight, caused a significant decrease of the germination rate in all four species studied. Moreover, white light was found to suppress considerably final seed germination (photoinhibition) in M. weissii and M. neglectum; in the latter species, prolonged imbibition under white light also led to the induction of secondary dormancy.

scholarly journals (205) Germination of Echinacea Species Is Enhanced by ACC

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1069C-1069
Author(s):  
Laura A. Wood ◽  
Sharon Kester ◽  
Robert L. Geneve
Keyword(s):  
Seed Dormancy ◽  
North American ◽  
Germination Rate ◽  
Germination Percentage ◽  
Additional Work ◽  
Germination Speed ◽  
Viable Method

Echinacea are North American members of the Asteraceae, and all can show some degree of endogenous physiological seed dormancy that is alleviated by chilling stratification. In some species, ethephon has been shown to substitute for chilling stratification to relieve dormancy. The objective of this research was to investigate the effect of ACC on dormancy and germination in five Echinacea species. Germination for each species was 90%, 59%, 99%, 81%, and 21%, respectively. Germination on 5 mM ACC improved germination in E. tennesseensis, E. paradoxa, and E. simulata to 82%, 99%, and 82%, respectively, but there was no change for E. purpurea and E. angustifolia. Germination rate was dramatically accelerated in all species in the presence of ACC. On average, there were 57% more seeds germinated on ACC after 3 days compared to untreated seeds. Exposing E. purpurea and E. tennesseensis seeds to 1 or 2 days of 5 mM ACC before drying and subsequently re-hydrating the seeds did not have the same effect as continual exposure to ACC. Similarly, there was no clear enhancement of adding ACC during stratification over the improvement gained by chilling stratification alone. Seeds produced more ethylene upon germination following both stratification and ACC treatment. However, significantly more ethylene is produced during germination in ACC-treated seeds. It was clear that ACC-treated seeds showed improvement for enhanced germination speed and in some cases germination percentage. Unfortunately, this enhanced germination was not retained in seeds treated with ACC and dried prior to germination. Additional work is required to develop a commercially viable method of loading ACC into seeds for germination enhancement.

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