Seed Dormancy Breaking Research Articles

Germination of dimorphic seeds of Suaeda aralocaspica in response to light and salinity conditions during and after cold stratification.

Cold stratification is a requirement for seed dormancy breaking in many species, and thus it is one of the important factors for the regulation of timing of germination. However, few studies have examined the influence of various environmental conditions during cold stratification on subsequent germination, and no study has compared such effects on the performance of dormant versus non-dormant seeds. Seeds of halophytes in the cold desert might experience different light and salinity conditions during and after cold stratification. As such, dimorphic seeds (non-dormant brown seeds and black seeds with non-deep physiological dormancy) of Suaeda aralocaspica were cold stratified under different light (12 h light–12 h darkness photoperiod or continuous darkness) or salinity (0, 200 or 1,000 mmol L-1 NaCl) conditions for 20 or 40 days. Then stratified seeds were incubated under different light or salinity conditions at daily (12/12 h) temperature regime of 10:25 °C for 20 days. For brown seeds, cold stratification was also part of the germination period. In contrast, almost no black seeds germinated during cold stratification. The longer the cold stratification, the better the subsequent germination of black seeds, regardless of light or salinity conditions. Light did not influence germination of brown seeds. Germination of cold-stratified black seeds was inhibited by darkness, especially when they were stratified in darkness. With an increase in salinity at the stage of cold stratification or germination, germination percentages of both seed morphs decreased. Combinational pre-treatments of cold stratification and salinity did not increase salt tolerance of dimorphic seeds in germination phase. Thus, light and salinity conditions during cold stratification partly interact with these conditions during germination stage and differentially affect germination of dimorphic seeds of S. aralocaspica.

Carbonylated protein changes between active germinated embryos and quiescent embryos give insights into rice seed germination regulation

Rice seed germination is the determining physiological event during establishment of a new plant. Although numerous researches have focused on this complicated process, studies that disclose the carbonylated protein differences between active and quiescent rice embryos related with seed germination remain deficient. Here, protein carbonylation in rice seed embryo has been analyzed by two-dimensional electrophoresis (2-DE), anti-2,4-dinitrophenyl (DNP) immunoassay, and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) methods. As expected, varieties of carbonylated proteins were observed to increase along with rice seed germination. Certain proteins like catalase, IAA-amino acid hydrolase, cell structural proteins, and 26S protease regulatory subunit were specifically carbonylated in 48 h embryos. We speculate that ROS directly participate in cell wall loosening, cell expansion, and radicle elongation, which are facilitated by the carbonylation damage of antioxidant enzyme catalase upon imbibition. Carbonylation degradation of IAA conjugates hydrolase and cell structural proteins were necessary for hormone regulation and materials providing in seedling establishment. We also provided evidence that Dnak-type molecular chaperone hsp70, enzymes involved in glycolysis pathway, and actins were always carbonylated in 0 and 48 h embryos. Of note, glycolytic enzymes were the most prominent carbonylated proteins. Furthermore, embryo specific cupin family proteins were intensively carbonylated in 0 h embryos thus helping in reserves mobilization to facilitate germination. These results indicate that protein carbonylation in seed embryo proteins do not occur randomly, and ROS directly or indirectly participate in rice seed dormancy breakage and seedling establishment.

Seed Dormancy Break and Germination for Restoration of Three Globally Important Wetland Bulrushes

Limited knowledge of seed dormancy break, germination requirements, and intraspecific variation of these traits hinders revegetation of many species targeted for restoration. We evaluated the importance of cold stratification and chemical scarification for breaking seed dormancy and the impact of soaking in water on germination for three globally distributed bulrush species. These species, Bolboschoenus maritimus (alkali bulrush), Schoenoplectus acutus (hardstem bulrush), and S. americanus (threesquare bulrush), form critical habitat in Great Salt Lake wetlands. For B. maritimus and S. acutus , we also evaluated variation in response to seed dormancy breaking treatments among geographically-distant seed sources. We found that both 180 days of cold, moist stratification or 48 hours of bleach scarification were effective for breaking seed dormancy for most seed sources of B. maritimus . For S. acutus , longer stratification lengths may result in consistently higher germination percentages, but 30 days of stratification may be of sufficient length for some source sites. For S. americanus , stratification improved germination in one experiment, but 20–60 percent of viable seed did not germinate in each experiment potentially due to a poor understanding of germination requirements. Soaking seeds in water under greenhouse conditions, improved the germination of all species when done after dormancy breaking treatments. Importantly, response to dormancy breaking treatment varied among source sites; intraspecific variation may account for unpredictable responses to dormancy breaking treatments. These findings can assist practitioners in crafting strategies to effectively break dormancy and germinate seeds of B. maritimus, S. acutus , and S. americanus .

Seed dormancy and germination of the medicinal holoparasitic plant Cistanche deserticola from the cold desert of northwest China

Cistanche deserticola is a holoparasitic plant with high medicinal value that reproduces only by seeds. However, the requirements for seed dormancy break and germination of this species remain unclear. The freshly matured dust-like seeds consist of a water-permeable seed coat and an undifferentiated oval-shaped embryo embedded in endosperm. No fresh seeds germinated in water or a 10−5 M fluridone solution at any incubation temperature within 60 days. Length of embryos in seeds incubated in warm- and cold-started stratification sequences had increased 10.4 and 11.7% after 50 and 40 weeks, respectively. After 6 months, length of embryos in seeds stratified at 5 °C had increased by 12%. Germination of fresh seeds and of seeds stratified at 5 °C for 6 months and then incubated in mixed fluridone/gibberellic acid 3 (GA3) solutions at 30/20 °C germinated to only 2.6 and 11.7%, respectively. Embryos of fresh seeds and of cold-stratified seeds had increased 29.4 and 15.8% in length, respectively, at the time of germination, but they never differentiated into organs. The highest germination (54.4%) was for seeds incubated in a 10−5 M solution of fluridone in darkness in spring that had overwinter on the soil surface in the natural habitat. Our study indicates that breaking of physiological dormancy (PD) occurs first and then the embryo grows to a critical length (0.44 mm) without differentiation into organs prior to seed germination. Seeds for which PD had been broken were induced to germinate by fluridone and GA3 at high temperature. Taken together, these results suggest that C. deserticola seeds have a specialized kind of morphophysiological dormancy. This study reveals possible ways to release seed dormancy that will be useful in propagating this medicinal species.

Fruit Description and Evaluation of Five Treatments to Break Seed Dormancy of Brownlowia peltata Benth.

<p class="Els-Abstract-text"><em>Brownlowia peltata </em>Benth. is a native tree from Borneo, in its germination problem was physical dormancy due to the hard pericarp of the fruit. The study aimed to evaluate five treatments for breaking the seed physical dormancy and the fruit description. The experiment was using Randomized Complete Block Design (RCBD) with four different temperatures of water immersion, a scarification, and control. The fruit of <em>B. peltata</em> was a woody follicle; belong to yellow green group 148 A in color; 29.64 mm in long; 21.62 mm in thickness; 29.86 mm in wide, with an average weight of 12.05 g. Hot water immersion treatment of 40 °C for 60 s; 60 °C for 60 s and 80 °C for 30 s could raise the fruit moisture content of 0.92 % to 1.04 %. There was a significant difference on germination rate coefficient and coefficient of uniformity of germination among treatments. The mature seed does not have a physical dormancy once the carpel splits and create a slit (fruit opening).</p><div><p class="Els-keywords"><strong>Keywords:</strong> <em>Brownlowia pellata </em>Benth; dormancy; fruit; seed; viability.</p></div>

Seed dormancy-breaking in a cold desert shrub in relation to sand temperature and moisture.

Seasonal periodicity of seed germination and its relationship to seasonal changes in temperature and soil moisture have been well studied in seeds of species with physiological dormancy. However, relatively little information is available on the role of these environmental factors in controlling germination of seeds with physical dormancy (PY). Our primary aim was to determine if seeds of the cold desert sand dune semi-shrub Eremosparton songoricum exhibits seasonal periodicity of seed germination and the relationship between seed dormancy break and soil temperature and moisture. In the laboratory, seeds incubated on dry, wet, wet-dry and dry-wet sand were exposed to a 1-year sequence of temperature regimes simulating those in the field. In the field, seeds were buried at different depths on a sand dune, and germination of periodically exhumed seeds was tested at five temperature regimes during a 2-year period. In the one-year sequence of simulated natural temperature regimes, breaking of PY was more effective under constantly wet than under constantly dry conditions, and germination percentage was significantly higher under dry-wet than under wet-dry conditions. Seeds buried in the field exhibited a distinct peak of germination in spring and little or no germination in other seasons. The final (two-year) monthly cumulative germination percentage differed among burial depths and temperature, and it was highest (47%) in seeds buried at 3 cm and tested at 25/10 °C. A seed cohort of E. songoricum likely exhibits a long-term annual periodicity of spring germination in the field, and dormancy break appears to be driven by low (winter) temperatures and relatively high sand moisture content. To our knowledge this is the first study to document seasonal periodicity in seed germination in a cold desert species with PY and to identify the mechanism (at the whole-seed level) of its occurrence.

Effects of Hot Water on Breaking Seed Dormancy of Senna obtusifolia from Bichi, Nigeria, in Green House Conditions.

Effects of Hot Water on Breaking Seed Dormancy of Senna obtusifolia from Bichi, Nigeria, in Green House Conditions.

Effects of Gibberellic Acid and Alternating Temperature on Breaking Seed Dormancy of Panax ginseng C. A. Meyer

Effects of Gibberellic Acid and Alternating Temperature on Breaking Seed Dormancy of Panax ginseng C. A. Meyer

Water absorption and improvement of methods for electrical conductivity test in acacia seeds

Acacia is an important forest species of rapid growth whose seeds have tegument dormancy. In this work it was intended to characterize water absorption pattern after seed dormancy break, and to determine the amount of water, container size and the need of breaking the tegument dormancy, as to perform electrical conductivity test in small and large seeds of Acacia mangium (Fabaceae). The seeds were collected from 10, 8 and 6 years old trees established in poor yielding-capacity soils on savannah areas of Roraima, Brazil; seeds were classified in six lots concerning to seed size and tree age. Germination tests (50 seeds and four replications per lot) were carried out on germitest® paper maintained on gerbox at 25 °C. Imbibition was verified by seed weighing at different times (0, 2, 5, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96 and 120 hours). The electrical conductivity test consisted of three experiments, distinguished by the amount of water used and by the container size in which seeds were immersed. Seeds of A. mangium coming from 10 years old trees presented increased germination percent and germination speed than seeds of six-year old trees. Small seeds presented increased in electrical conductivity and water absorption until 120 hours when compared to large seeds. The immersion of seeds of A. mangium in 40 mL of distilled water into 180 mL plastic containers, after dormancy break, it is indicated for the determination of electrical conductivity test. The ratio of electrolytes by seed mass, after 24 hours of immersion in water, turns electrical conductivity test more accurate concerning A. mangium seeds.

Breaking seed dormancy in a forest plant: <em>Grewia damine</em> Gaertn

Seeds of Grewia damine are dormant and vegetative propagation is difficult which act as an obstacle for the introduction of this species for commercial or conservation processes. Therefore, the present study was conducted to identify the seed dormancy breaking treatments to improve seed germination of G. damine . The following dormancy breaking treatments were applied: control (intact seeds); scarified seeds with sand paper; hot water treatment (100 0 C) for 5, 10 and 15 minutes; refrigeration at 2-5 0 C for 1, 2 and 3 weeks; Conc. H 2 SO 4 or HNO 3 immersion for 5, 10 and 15 minutes. Germination parameters were measured and the data were subjected to ANOVA in Minitab 15. A significantly high (p 50% = 5.447) were recorded in the treatment of scarification with a sand paper followed by the treatments with Conc. H 2 SO 4 for 15 minutes and boiling water for 5 minutes where germination was 55 %. While significantly low germination of 22 % was recorded with Conc. HNO 3 for 15 minutes. The results suggests that seeds of G. damine possess a physical dormancy. None of the untreated seeds of G. damine germinated within the study period and scarification with a sand paper proved to be the most effective method of breaking seed dormancy. Hence seeds could be used by the nurserymen after breaking dormancy to produce plant material at large scale.

Analysis of the embryo proteome of sycamore (Acer pseudoplatanus L.) seeds reveals a distinct class of proteins regulating dormancy release

Acer pseudoplatanus seeds are characterized by a deep physiological embryo dormancy that requires a few weeks of cold stratification in order to promote germination. Understanding the function of proteins and their related metabolic pathways, in conjunction with the plant hormones implicated in the breaking of seed dormancy, would expand our knowledge pertaining to this process. In this study, a proteomic approach was used to analyze the changes occurring in seeds in response to cold stratification, which leads to dormancy release. In addition, the involvement of abscisic (ABA) and gibberellic acids (GA) was also examined. Fifty-three proteins showing significant changes were identified by mass spectrometry. An effect of ABA on protein variation was observed at the beginning of stratification, while the influence of GA on protein abundance was observed during the middle phase of stratification. The majority of proteins associated with dormancy breaking in the presence of only water, and also ABA or GA, were classified as being involved in metabolism and genetic information processing. For metabolic-related proteins, the effect of ABA on protein abundance was stimulatory for half of the proteins and inhibitory for half of the proteins. On the other hand, the effect on genetic information processing related proteins was stimulatory. GA was found to upregulate both metabolic-related and genetic information processing-related proteins. While seed dormancy breaking depends on proteins involved in a variety of processes, proteins associated with methionine metabolism (adenosine kinase, methionine synthase) and glycine-rich RNA binding proteins appear to be of particular importance.

Role of short-term cold stratification on seed dormancy break and germination of alien species in southeastern China

Do short periods of relatively low temperatures during winter in subtropical zones promote seed dormancy break and germination of alien species and thus facilitate their spread? To help answer this question, we tested the germination responses to moist storage at low temperatures of seeds of 21 alien species from southeastern China. For each species, fresh seeds and seeds stored dry at room temperature and wet at 15 °C and wet at 4 °C for 30 days were tested for germination at 25 and 25/15 °C in a 12-h daily photoperiod. Fresh seeds of Bidens pilosa,Eclipta prostrata, Hyptis suaveolens, and Talinum paniculatum germinated to 89–96.7 % at both test temperatures, those of Ageratum conyzoides, Mikania micrantha, and Wedelia trilobata to 53–83 % at one or both temperatures, and those of the other 14 species to 0–39 % at one or both temperatures. A 30-day cold stratification pretreatment at 4 °C increased the germination percentage of seeds of Lantana camara and Solanum torvum, but they germinated to only 10.7–21.3 % and 2–30.7 %, respectively. However, germination speed of seeds of five species increased following moist storage at 4 °C, and that of four species increased following storage at 15 °C. Seeds of 14 species began germinating during wet storage at 15 and/or 4 °C. B. pilosa germinated to 87.3 and 57 % at 15 and 4 °C, respectively, and the other 13 species to 0.3–22.3 % at 15 °C. Thus, the short periods at 4 and/or 15 °C increased germination percentages of two species and the rate of six species and permitted early germination of 14 species, leading to the conclusion that the short cool periods during winter in the subtropical zone of China may contribute to the success of alien plant species in this region.

Effects of Different Treatments on Physiological Characteristics of <i>Cephalotaxus sinensis</i> Seeds

Cephalotaxus sinensis seeds can’t germinate even in the appropriate environment. However, numerous studies have showed that cold stratification and gibberellin acid (GA) can break the seed dormancy and promote seed germination effectively. To investigate the effect of cold stratification and different concentrations of exogenous GA3 on dormancy breaking in seeds of Cephalotaxus sinensis, we monitored germination rates and changes in soluble sugar, starch, amylase, soluble protein, free amino acid during cold stratification. The results showed that seeds stratified for 5 months germinated to 12.7%, while those disposed with 200, 400, 600 mg/L of GA3 germinated to 29.2%, 21.7%, and 18.4%, respectively. Free amino acid content was enhanced significantly, whereas soluble sugar content decreased during 45 days and then increased constantly. Additionally, the main reserves such as starch, protein decreased significantly during cold stratification, and cold stratification induced increases in the activities of α-amylase, (α + β)-amylase. The preliminary results show that the combination of GA3 and cold stratification has better effect to break seed dormancy.

Standardizing the Methods for Breaking Seed Dormancy to Enhance Germination of Gloriosa superba Seeds

Standardizing the Methods for Breaking Seed Dormancy to Enhance Germination of Gloriosa superba Seeds Studies on imposing seed germination in glory lily revealed that the seeds scarifies by GA3 treatment method was recorded to be the best treatment with maximum germination of 17.6 ± 1.2 seeds within a minimum time interval. Treatments of GA3 not only break the seed dormancy, but also promote the growth of plant. So, the seed treatment can be recommended as a nursery practice. The aim of this study was to enhance the germination rate of G. superba seeds which have a very low germination rate under normal conditions. Chemical scarification was very efficient in breaking dormancy and promoting germination.

帰化アサガオ類5種の種子の硬実打破と生死に及ぼす低温の影響

帰化アサガオ類5種の種子の硬実打破と生死に及ぼす低温の影響

Effect of pre-chilling and environmental factors on breaking seed dormancy and germination of three foxtail species

The effect of wet and dry pre-chilling duration, pH, osmotic stress, salt stress and planting depth on seed germination and seedling emergence of three foxtail species (Setaria glauca, S. verticillata and S. viridis) was investigated in a series of laboratory and greenhouse experiments. Both wet and dry pre-chilling for 45 days promoted seed germination of S. glauca compared with the control. Pre-chilling was not significantly effective in seed dormancy breaking of S. viridis and S. verticillata. The maximum germination of foxtails (S. verticillata, S. viridis) was obtained when seeds were treated with pH 7 buffer solution. Increasing of osmotic and salt stress decreased seed germination of foxtails. Setaria verticillata seed germination was more tolerant than those of S. glauca and S. viridis to high water stress condition. Setaria glauca and S. verticillata seed germination were more tolerant to high salinity stress than S. viridis. Seedling emergence decreased with increasing the burial depth and no germination observed at 8 cm soil depth.

Effect of ultrasonic waves on seed germination of Atriplex lentiformis, Cuminum cyminum, and Zygophyllum eurypterum

Dormancy breaking and germination stimulation of seeds are important for proliferation and early production of rangeland plants. Some important plant seeds are barely germinating in usual natural conditions. Thus, research on novel, safe and healthy methods of germination stimulation of such plants seeds is important and helpful in many different aspects of plant studies. In this study, we assessed the effects of exposure to ultrasonic waves on germination of seeds of three important rangeland plants including Atriplex lentiformis, Cuminum cyminum and Zygophyllum eurypterum. These plants seeds have great importance in different aspects of plant utilizations such as medicinal, aromatic and agricultural uses and in rangeland/pasture rehabilitation, soil conservation and animal husbandry. Seeds were treated with ultrasonic waves for 1, 3, 5, 7, and 9min. The study was performed in Shahrood (northeast Iran) under laboratorial conditions. The percentage of germination of each culture revealed a significant positive effect of ultrasonic wave exposures. The statistical analyses were done by MSTATC software at probability level of 1% and the results were significant for all of the plants. Treatments of 5 and 7min of exposure had the highest seed germination percentage, but 9min of exposure had negative influence on germination in comparison with other treatments.

Effects of moist cold stratification on germination, plant growth regulators, metabolites and embryo ultrastructure in seeds of Acer morrisonense (Sapindaceae)

Breaking of seed dormancy by moist cold stratification involves complex interactions in cells. To assess the effect of moist cold stratification on dormancy break in seeds of Acer morrisonense, we monitored percentages and rates of germination and changes in plant growth regulators, sugars, amino acids and embryo ultrastructure after various periods of cold stratification. Fresh seeds incubated at 25/15 °C for 24 weeks germinated to 61%, while those cold stratified at 5 °C for 12 weeks germinated to 87% in 1 week. Neither exogenous GA3 nor GA4 pretreatment significantly increased final seed germination percentage. Total ABA content of seeds cold stratified for 12 weeks was reduced about 3.3-fold, to a concentration similar to that in germinated seeds (radicle emergence). Endogenous GA3 and GA7 were detected in 8-week and 12-week cold stratified seeds but not in fresh seeds. Numerous protein and lipid bodies were present in the plumule, first true leaves and cotyledons of fresh seeds. Protein and lipid bodies decreased greatly during cold stratification, and concentrations of total soluble sugars and amino acids increased. The major non-polar sugars in fresh seeds were sucrose and fructose, but sucrose increased and fructose decreased significantly during cold stratification. The major free amino acids were proline and tryptophan in fresh seeds, and proline increased and tryptophan decreased during cold stratification. Thus, as dormancy break occurs during cold stratification seeds of A. morrisonense undergo changes in plant growth regulators, proteins, lipids, sugars, amino acids and cell ultrastructure.

Germination and Dormancy in Seeds of Sorghum halepense and Sorghum arundinaceum

Light, temperature and dormancy are factors that influence the germination of seeds and are strictly linked to the emergence of weeds. The objective of this work was to assess the germination of Sorghum arundinaceum and Sorghum halepense subjected to different conditions of temperature and luminosity, as well as assessing seed dormancy breaking mechanisms. For this, two experiments were conducted, both arranged in a completely randomized design. Experiment 1 was installed in a 2 x 5 double factorial design. The first factor was the absence or presence of light for 12 hours, and the other was composed of five constant temperatures: 15, 20, 30, 40 and 45 oC. In experiment 2, the efficiency of nine treatments used for breaking dormancy of seeds was assessed. The variables analyzed for both experiments were germination percentage and germination speed index (GSI). For the statistical analysis were performed an analysis of variance (ANOVA) and all the necessary consequences, as well as regression, when relevant. In experiment 1 for both species greater germination occurred in the presence of light. For S. arundinaceum the temperatures at which there was the highest percentage of germination were 33.13 and 31.24 oC for presence and absence of light respectively. As for S. halepense these temperatures were 31.98 and 29.75 oC for presence and absence of light respectively. As for the treatments for breaking dormancy, the mechanical scarification of seeds with sandpaper presented the highest germination and GSI. It is concluded that the Sorghum species studied are neutral photoblastic seeds and present mechanical type dormancy.

Physiological and biochemical change of Paris seed in after-ripening during variable temperature stratification

In order to explore the dormancy physiological and biochemical mechanism of Paris seeds, the seed embryo growth courses, and the dynamic change of 5 enzymes, include SOD, POD, CAT, MDH, G-6-PDH were measured during variable temperature stratification. The results indicated that Paris seeds embryo grew quickly after 40 d in warm-stratification (18 ± 1) °C, at the meantime the metabolic activity was significantly strengthened. These facts showed that Paris seeds turned into physiological after-ripening process. After 60-80 d, the morphological embryo after-ripping process basically completed, and the following cold-stratification (4 ± 1) °C furthered Paris seed to finish physiological after-ripening. After 40 d, the activity of MDH decreased while G-6-PDH increased significantly. This showed that the main respiratory pathway of seed changed from TCA to PPP, which benifited breaking seed dormancy. In the whole period of stratification process, the activity variation of SOD and CAT was insignificantly and the activity of POD was enhanced significantly after shifting the seed in cold stratification process. This showed that SOD, CAT had no direct effects on breaking Paris seed dormancy but keeping the seed vigor, while the POD might involve in the process of Paris seed dormancy breaking.