Non-stratified Seeds Research Articles

Vernalization affects the germination performance of the wetland endangered species Eleocharis carniolica

AbstractEleocharis carniolica W.D.J. Koch (Cyperaceae) is an endangered wetland spike rush mainly threatened by habitat loss and fragmentation. Understanding the germination ecology of this species is essential to perform successful conservation and restoration actions. In this study, we investigated the effect of vernalization (i.e. cold stratification), gibberellic acid (GA3) and chemical scarification on seed germination of E. carniolica from wild populations in northern Italy. The results showed that vernalization (i.e. 8-weeks at 4 °C) significantly improved germination probability, speed, and uniformity compared to non-stratified seeds. Gibberellic acid treatment alone or in combination with vernalization did not show a significant improvement in germination. Chemical scarification using sodium hypochlorite increased germination probability, with 8 h of scarification showing the highest success rate. However, 24-h scarification had a negative impact on germination. Overall, vernalization was found to be the most effective method to enhance germination in E. carniolica. These findings provide valuable insights into the seed germination ecology of this endangered species, aiding in its exsitu conservation, propagation, and in-situ restoration efforts. Moreover, they have important implications on future germination dynamics of this endangered species, especially with predicted climate change scenarios.

PHYSICAL CHARACTERISTICS, VIABILITY, AND SANITARY ANALYSIS OF Ilex paraguariensis SEEDS AND SEEDLING EMERGENCE FROM DIFFERENT MOTHER TREES

The present study aimed to analyze the physical characteristics, seed health, and seedling emergence of nine Ilex paraguariensis mother trees. Physical characterization included determining the thousand-seed weight, number of seeds per kilogram, and moisture content. Viability and embryonic development were determined by the tetrazolium test, using five replications of 20 seeds for each mother tree. Seedling emergence was evaluated under three treatments: non-stratified seeds, seeds stored for 70 days, and seeds stratified for 180 days, using three replications of 2 g, being sown in a commercial substrate. Sanitary analysis was conducted by Blotter-test, using five repetitions of 20 non-disinfested seeds. Significant results were observed among the mother trees for physical and biometric variables. The initial seed viability was 52%, with embryos in the heart and post-heart stages. The most prevalent fungal genera in yerba mate seeds were Trichoderma sp., Aspergillus sp., and Penicillium sp.

Do Not Keep It in the Dark: How Shading and Other On-farm Management Decisions Influence Seed Production and Quality of Asclepias tuberosa L.

Demand for butterfly milkweed (Asclepias tuberosa L.) has increased in recent years. However, seed production practices are not well-defined. We partnered with a wildflower seed producer to investigate the effects of weed barrier cloth, plot shading, mature follicle harvest timing, and dry–cold stratification on seed production and germination. Weed cloth had no impact on seed production. However, shading decreased the number of seeds produced by 1.2- to 9.6-fold. Seeds harvested in July and August showed 2.9- and 2.3-fold improvements in total germination and more uniform and rapid germination compared with September-collected seeds. Conversely, seeds exposed to dry–cold stratification displayed a 3.0-fold reduction in the germination rate compared with nonstratified seeds. Our results indicate that the production system significantly impacts seed production and quality of A. tuberosa. Seed producers can use weed barrier cloth to facilitate seed collection from shattering follicles and suppress weeds without a considerable loss of seed production. However, plants should not be grown under conditions of additional shade. Furthermore, high-quality A. tuberosa seeds can be collected earlier in the year, but they should not be subjected to dry–cold stratification.

Seed germination variability: Why do genetically identical seeds not germinate at the same moment?

For survival in the wild environment, plants prefer a bet-hedging strategy where individual variation is high and also produce a range of phenotypes. When faced with unpredictable environmental conditions, fluctuation in seed behaviour is a beneficial trait that allows the survival of plants, particularly if seedlings from early germinated seeds don't survive. However, this is not a desired trait when agriculture is concerned, where a set of uniformly grown seedlings are required. Even though variability in seed behaviour is unavoidable, over the centuries, humans might have selected seeds with minimum variability for agricultural use. In the model plant Arabidopsis, non-stratified seeds even in the same silique germinate variably. How this variability is manifested from genes to a physiological outcome and what molecular mechanism of bet-hedging facilitates this diversity remains elusive. Will the reintroduction of valuable wild alleles in domesticated crops contribute to this variability between individual seeds by promotion of bet-hedging? Recent advances have shed light on possible molecular pathways of germination that are impacted at the level of single seeds and single cells. Here, we review the hormonal, molecular and cellular mechanisms that may impact the germination outcome of individual genetically identical seeds.

Statistical indicators of seed reproduction of apple <i>(MALUS MİL L.)</i> species introduced on apsheron

We have studied effective methods of seed reproduction of some species of apple trees in the condition of Apsheron. The newly introduced and available in the collection of the Central Botanical Garden of ANAS 23 species of wild apples were taken as research material. Experiments were carried out with both stratified and non-stratified seeds. The germination rate of the studied species was different. As a result, it turned out that in order to obtain good germination of seeds of apple varieties introduced in Absheron, they should be sown either early autumn, or for various reasons (climate, lack of time, etc.), it is better to stratify the seeds and to shorten the germination time it is advisable to sow in spring. Statistical analysis was carried out on the basis of the obtained results. In the course of statistical processing, the statistical programs PAST, SPSS 16. were used. Cluster analysis of samples was carried out using the Ward method based on the Evklid index of genetic distance. According to morphometric and mass parameters, the seeds of the studied species were divided into 3 main groups with 5 values of the genetic distance. The values of statistical indicators were also determined for other studied characteristics of seeds in apple species. The parametrs include minimum and maximum values, mean, standard error, standard deviation, coefficient of variation. And the studied characters are the width, length, and weight of the seeds. This indicates that among the three traits studied between species, the mass trait has greater variability, in other words, higher genetic diversity. That is, the trait of the seed mass of the studied species makes it possible to distinguish more species. It is known that by crossing genetically distant species, a hybrid with new traits can be obtained, i.e. with a high effect of heterosis. From this point of view, high-quality species are selected from the species included in the clusters, and by crossing them with species from other clusters, a hybrid with a high heterosis effect can be obtained. With this method of selection, it is possible to gradually obtain new varieties of high quality.

Impact of seed cold stratification on apricot germination and subsequent seedling growth as well as chemical constituents of seeds during stratification

Freshly harvested seeds of apricot varieties "Balady (Amar)" and "Hamawy" were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. 5°C cold stratification was found to be the best for breaking seed dormancy, germination and seedling growth. Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds. Apricot seeds required a cold stratification of about 12-15 days for "Balady variety (Amar)" and15-18 days for "Hamawy" variety "to reach maximum germination and normal seedling growth. Chemical constituents of apricot seeds (total and reducing sugars, total free amino acids and total indoles were increased while that of free phenols and total soluble phenols were decreased) when stratification period prolonged. Therefore, it can be suggested that breaking of dormancy is coincided with several changes in different chemical constituents of seeds. Some of these materials increased and other materials which decreased at seed germinations.

THE CONTROL OF APRICOT SEED DORMANCY AND GERMINATION BY LOW TEMPERATURE TREATMENTS

Objective: Freshly harvested seeds of “Local” apricot variety were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C cold stratification (CS). Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds.
 Methods: For stratification treatments, the seeds with removed endocarp were mixed with moistened sand. Afterward, they were subjected to a period of stratification at 5°C. Seeds were stratified in pots of 30 cm×40 cm. Stratified seeds were regularly irrigated once per week. To prevent the water loss during stratification upper surface of pots was covered by a sack. The following stratification was applied for apricot variety: CS for 0, 3, 6, 9, 12, and15 days in 1998 and 1999 years for “Local” variety.
 Results: Apricot seeds required a CS of about 15 days for “Local” variety to reach maximum germination and normal seedling growth. Moreover, when stratification period was prolonged, some of the chemical constituents of apricot seeds were increased and other was decreased. Therefore, it can be suggested that breaking of dormancy is coincided with several changes in different chemical constituents of seeds. Some of these materials increased (total, reducing and non-reducing sugars, total free amino acids, total indoles, and total and conjugated phenols) and other materials such as free phenols which decreased at seed germinations.
 Conclusion: The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C CS. Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds.

Initial stages of ontomorphogenesis of Ginkgo biloba L. seedlings in the conditions of the National Dendrological Park “Sofiyivka” of NAS of Ukraine

Aim. The study of the initial stages of ontomorphogenesis of Ginkgo biloba is determined by the need for conservation, mass reproduction and introduction of this valuable plant in different regions of Ukraine. Methods. To periodize the ontogenesis of G. biloba, the classification of age states of plants developed by T. O. Rabotnov (Rabotnov, 1950) with the additions of O. O. Uranov (Uranov, 1975) was used. The description of plants in different ontogenetic states was carried out on the basis of the recommendations given in the “Ontogenetic Atlas of Plants” (Ontogenetic Atlas…, 2007). Results. As a result of studies of the initial stages of ontomorphogenesis of G. biloba seedlings, it was found that the appearance of seedlings is observed at 38 days after non-stratified seeds sowing in autumn. After 5–7 days the seedlings become mass sprouting. Seeds of the studied species have a high germination (50–85%). G. biloba plants are able to produce part of the teratological seeds, which may be the result of the preservation of the signs of ancestral forms. G. biloba seedlings are characterized by an underground type of seed germination. It is found that in the initial stages of ontomorphogenesis, the leaves of G. biloba, compared with the leaves of adult plants, differ in size, texture and dissection of the leaf blade. Conclusions. In the conditions of the National Dendrological Park “Sofiyivka” of NAS of Ukraine G. biloba plants successfully pass three life periods of development and corresponding age states (from seed (sm) to early-generative state (g1)) with characteristic diagnostic signs of each of them.

Seed dormancy removal treatments and germnaton characterstcs of Acer trautvetteri Medvedev seeds

In this study, seed dormancy removal and germination characteristics of Acer trautvetteri Medvedev, is one of the major maple species of the eastern Black Sea region, were studied. To do that, the seeds were collected in 2008 three times with aproximately 15-days intervals. In order to remove dormancy, several germination treatments were applied. The treatments were (1) different seed collection time, (2) soaking in water, (3) cold-moist stratification and (4) GA3 (gibberellic acid) application. The treated seeds were germinated in growing chamber at 5 0C and in greenhouse conditions. This research indicated that seeds of Acer trautvetteri exhibit physiological dormancy and require stratification period to remove seed dormancy. The highest germination percentage in the growing chamber subjected to GA3 application after eight weeks of stratification treatment was 66 % for Acer trautvetteri seeds. The highest germination percentage in greenhouse was obtained with cold stratification after eight weeks (81 %). Although GA3 treatment had a positive effect on germination in growth chamber + 5 0C, GA3 treatment had a negative effect on germination in greenhouse conditions. Soaking in water of nonstratified seeds wasn’t any significant difference on seed germination. There was a positive correlation between seed collection time and germination (r=0.59). As a result, the third collection time (in october) should be preferred as seed collection time in Acer trautvetteri seeds, considering that it may vary according to the climatic conditions of the year.

From Embryo to Adult: Low Temperatures Affect Phase Transitions of Allium sativum L. from Germination to Flowering

Juvenile and vegetative adult shoot apical meristems (SAM) are actively involved in acquisition of flowering competence, while the embryonic SAM is regarded as “responsible” only for germination. Comparative analyses of imbibed and stratified seeds of garlic Allium sativum show that only stratified seedlings produced bulbs and flower stems at the end of the season. Since the seed morphology of stratified and non-stratified seeds prior to sowing was similar, the differences are attributed to the molecular alterations in the embryonic SAM. Functional annotation analysis of 3000 differentially expressed genes suggests that seed imbibition reactivates the embryonic cell cycle, initiates the metabolism, and primes garlic seed germination. Stratification enhances DNA modifications, biosynthesis, cellular transport, and tissue development. Similar to vernalization of the vegetative buds, stratification of the embryonic SAM resulted in altered expression of meristem-identity and flowering homologs. Phase transitions from seed germination to flowering and bulbing in A. sativum are tightly connected, and possibly associated with downregulation of specific flowering repressor(s). The embryonic SAM plays an important role not only in seed germination, but in the entire plant life cycle, providing the foundation for the genetic regulation of major functional shifts in metabolism and development.

Germinative capacity and energy of critically endangered Ojców birch (Betula oycoviensis Besser) in the Czech Republic

Ojców birch (Betula oycoviensis Besser) is a rare and critically endangered taxon of the genus Betula. Its distribution is limited to few countries in Europe. In the Czech Republic, this taxon, characterized by typical shrubby habitus, has been found in fewer than 70 tree individuals, prevailingly in the studied locality Volyně, West Bohemia. This study was focused on the germinative capacity and germinative energy of this taxon, as it is an important indicator of possible regeneration of the trees in nature and for conservation. Non-stratified seeds (2 200 pcs) and stratified ones (2 200 pcs) were compared to each other and in relation to dendrometric tree parameters. The results showed no significant (P > 0.1) differences between stratification variants in total germination (higher by 0.8% in stratified), though stratification improved germinative energy. Germination was in 1st week higher by 6.0% in stratified variant, respectively marginally (P < 0.1) higher in 2nd week in non-stratified variant. However, both germinative capacity and germinative energy were significantly (P < 0.01) variable between individual trees. The germinative capacity was significantly (P < 0.05) positively correlated with tree defoliation. Tiny seeds and triploid trees exhibited very low and zero germinative capacity and energy, respectively. Totally, seeds exhibited sufficient germinative capacity and germinative energy of 23.1% (0.0–62.5%). This suggests that the trees can be potentially used for this type of Ojców birch regeneration i.e. generatively from seeds, although rather in controlled artificial conditions.

Germination Traits in the Threatened Southeastern Grassland Endemic, Marshallia mohrii (Asteraceae)

Marshallia mohrii (Asteraceae) is a perennial forb endemic to grasslands in the southeastern United States. Despite having been listed as federally threatened for three decades, little is known about its biology and life history. In this study, we examined the role of light, temperature, seed age, and cold stratification on seed dormancy break and germination in M. mohrii. We also quantified soil temperatures in a Ketona glade population of M. mohrii to infer dormancy breaking and germination phenologies under natural conditions. Relatively high proportions (>65%) of cold stratified seeds germinated across a range of temperature regimes in both light and darkness, whereas nonstratified seeds only germinated to high proportions in light at high temperatures. Germination proportions of laboratory stored seeds were slightly greater than freshly matured seeds, but remained much lower than those of cold stratified seeds. According to laboratory experiments, both autumn and spring germination phenologies are possible depending on the temperature and light conditions seeds experience after dispersal. Seeds of M. mohrii exhibited type 3 non-deep conditional physiological dormancy, which has been found in other members of Asteraceae from temperate grasslands. Overall, the germination niche of M. mohrii is defined by conditional seed dormancy, reduced dormancy levels following cold stratification, dark germination after dormancy loss, seasonal germination cueing, and seed traits consistent with short-term persistence in soil. Results from our study are useful for future conservation and recovery actions with M. mohrii and represent the first known published report of germination traits in this genus, which contains several other rare and range-restricted species.

Differential protein analysis of Heracleum moellendorffii Hance seeds during stratification

Heracleum moellendorffii Hance is a medicinal vegetable species, and the seed dormancy of this species has caused many agricultural problems. One stratification technique involves alternating layers of seeds and substrate to allow post-ripening of dormant seeds under appropriate environmental conditions and to release dormancy. Non-stratified seeds (NS), cotyledon-stage-embryo seeds (CS) and germinated seeds (GS) represent key stages of H. moellendorffii seeds during stratification. To better understand the breaking of dormancy caused by stratification, tandem mass tag (TMT) mass spectrometry (MS)/MS was used to detect proteins among NS, CS and GS. A total of 876 proteins were identified, which were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The results showed that carbohydrate metabolic processes, responses to stress and ribosome biogenesis were the main biological processes. The changes in protein accumulation were validated by qRT-PCR. The results showed that starch, sucrose, pyruvate and fatty acid metabolism played significant roles and that the contents of stored substances were gradually degraded during stratification. This study provides a theoretical basis in terms of proteomics for exploring the post-ripening and germination of H. moellendorffii seeds.

Seed Treatment Techniques to Improve Germination of Wild Asparagus (Asparagus acutifolius L.), a Potential New Crop

Pre-sowing seed treatment techniques of stratification and scarification were used in order to find the most appropriate method to overcome dormancy of wild asparagus (Asparagus acutifolius L.) seeds. An indoor and an outdoor experiment were carried out at the Agricultural University of Athens. For the indoor experiment, the pre-sowing treatments of stratification (fresh and stratified seeds) and scarification (non-scarified, mechanical scarification and chemical scarification with sulfuric acid) were used as the main treatments, and three different temperatures (15, 20 and 25 °C) as sub-treatments. For the outdoor experiment, there were only the treatments of stratification and scarification. The stratification of asparagus seeds was found to have a positive effect on germination and vigor indices compared to non-stratified (fresh) seeds. The highest germination percentage, vigor index I and II were recorded with the stratified seeds that had been mechanically scarified in both indoor and outdoor conditions. The results indicate that just the scarification cannot improve germination of fresh collected seeds of wild asparagus. Stratification increased the germination percentage from 2.7-6.6% to 45.1-75.3%. The mechanical and the chemical scarification had a positive effect on the root length compared to the non-scarified seeds that have been stratified. These pre-sowing treatments can increase the germination percentage and produce vigorous seedlings that can be used to establish plantations of this potential new crop.

Alleviation of morphophysiological dormancy in seeds of the Australian arid-zone endemic shrub, Hibbertia glaberrima F. Muell. (Dilleniaceae)

AbstractMorphophysiological dormancy (MPD) is predominantly found in seeds of temperate regions and is uncommon in arid biomes. MPD has been reported in a number of Hibbertia (Dilleniaceae) species of temperate Australia, and in a single species of the arid zone, H. glaberrima. This study aimed to examine the dormancy and germination ecology of seeds of H. glaberrima. Seeds were subjected to temperature stratification treatments designed to mimic summer and autumn conditions in the Pilbara region of Western Australia. Seed germination and embryo growth were measured. We also tested the interaction between temperature stratification and cycles of drying and wetting designed to mimic sporadic rainfall events. All temperature and moisture treatments were tested in combination (+/–) with the smoke-derived chemical karrikinolide (KAR1). Exposing dormant seeds to temperatures suitable for warm stratification (35°C) for ≥ 8 weeks, followed by incubation at 25°C, resulted in significantly higher germination compared with non-stratified seeds. Exposing seeds to dry/wet cycling in conjunction with temperature stratification did not significantly increase germination. Exposure to KAR1 increased germination under most conditions. Once seeds are shed during October to December, they are exposed to hot and sporadically wet conditions over summer, allowing MPD to be overcome in a proportion of the seed population. Seeds may germinate in autumn (March to April), in conjunction with cooler temperatures. More deeply dormant individuals may require more than one summer to overcome dormancy. Similar to other species occurring in fire-prone ecosystems, fire also plays a crucial role in the germination ecology of H. glaberrima.

Seed dormancy and germination of the rare, high elevation Balkan endemic Cerastium dinaricum (Caryophyllaceae)

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.

Effects of pretreatments on seed dormancy and germination in endemic Uludağ flax (Linum olympicum Boiss.) (Linaceae)

Linum olympicum Boiss. (Linaceae) is an endemic species to Turkey, and has both medicinal and ornamental properties. In this study, we investigated the effects of GA3 and cold stratification (1 or 4 months) on the germination and mean germination time in relation to breaking dormancy in this species under darkness (20 °C) and light (20/10 °C, 12/12 h) conditions. Seeds were collected from specimens that spread on limestone or granite screes, ledges of rocky or turfy slopes, and hilltops of the alpine belt from Uludag Mt. (Bursa, Turkey, 2200–2300 m). We show that a combination of hormone and cold stratification treatments promoted seed germination under darkness and light conditions. Non-stratified seeds germinated to 73% following 1000 mg L−1 GA3 treatment and also it was 83% after 1 month cold stratification. After 4 months of cold stratification treatment, 10% and 53.3% of seeds successfully germinated after incubation in light and dark conditions, respectively. Hormone and cold stratification treatments also reduced mean germination time. Our results revealed that seeds of L. olympicum have physiological dormancy and require prolonged time for cold stratification and darkness for germination, rather than responding to the photoperiod. Germination requirements of L. olympicum have not been studied previously, and the data obtained could be used for the ex situ protection of this alpine species.

Germination niche breadth varies inconsistently among three Asclepias congeners along a latitudinal gradient.

Species responses to climate change will be primarily driven by their environmental tolerance range, or niche breadth, with the expectation that broad niches will increase resilience. Niche breadth is expected to be larger in more heterogeneous environments and moderated by life history. Niche breadth also varies across life stages. Therefore, the life stage with the narrowest niche may serve as the best predictor of climatic vulnerability. To investigate the relationship between niche breadth, climate and life stage we identify germination niche breadth for dormant and non-dormant seeds in multiple populations of three milkweed (Asclepias) species. Complementary trials evaluated germination under conditions simulating historic and predicted future climate by varying cold-moist stratification temperature, length and incubation temperature. Germination niche breadth was derived from germination evenness across treatments (Levins Bn ), with stratified seeds considered less dormant than non-stratified seeds. Germination response varies significantly among species, populations and treatments. Cold-moist stratification ≥4weeks (1-3°C) followed by incubation at 25/15°C+ achieves peak germination for most populations. Germination niche breadth significantly expands following stratification and interacts significantly with latitude of origin. Interestingly, two species display a positive relationship between niche breadth and latitude, while the third presents a concave quadratic relationship. Germination niche breadth significantly varies by species, latitude and population, suggesting an interaction between source climate, life history and site-specific factors. Results contribute to our understanding of inter- and intraspecific variation in germination, underscore the role of dormancy in germination niche breadth, and have implications for prioritising and conserving species under climate change.

Effect of cold stratification and gibberellic acid on in vitro germination ofActinidia argutaandActinidia chinensis

The effect of cold stratification (CS) and gibberellic acid (GA3) alone and in combination on in vitro germination of Actinidia arguta and Actinidia chinensis seeds was studied. Sterile seeds of the two plant species were stratified at 4°C for 28 and 42 days. Batches of stratified and non-stratified (control) seeds from both plant species were germinated on plant growth regulator-free Murashige and Skoog (MS) media and also on sterile filter paper bridges moistened with dH2O and GA3 concentrations of 500, 1000, 1500, 2000 and 2500 ppm. In the two plant species, seeds from the control and the CS treatments alone did not germinate on MS medium. However on filter paper bridges, seeds cold stratified for 28 days yielded only 8 and 20% germination percentage (GP) in A. arguta and A. chinensis, respectively, whereas CS for 42 days did not promote germination. In A. arguta, treatments of non-stratified seeds with GA3 resulted in 91% optimum GP at 1572 ppm GA3 and optimum 29 days mean germination time (MGT) at 1678 ppm GA3. In A. chinensis, 48% optimum GP and 24 days optimum MGT were achieved at 2225 and 2033 ppm GA3 concentrations, respectively. Cold stratification (28 days) followed by GA3 treatments of A. arguta resulted in optimum GP of 88% and 23 days optimum MGT at GA3 concentrations of 1435 and 1610 ppm, respectively. The same combined treatment of A. chinensis seeds yielded optimum GP of 80% and optimum 25 days MGT at GA3 concentrations of 1565 and 2050 ppm, respectively. In contrast, CS (42 days) followed by GA3 in A. arguta resulted in optimum GP of 99% and 27 days optimum MGT at GA3 concentrations of 1563 and 2120 ppm, respectively. Similar treatments in A. chinensis seeds yielded optimum GP of 45% and optimum 23 days MGT at GA3 of 998 and 1629 ppm, respectively. In conclusion, CS alone had little effect on germination, whereas CS (28 days) followed by GA3 significantly (p≤0.05) improved GP in both plant species. Treatments with GA3 alone and CS (42 days) followed by GA3 were more effective on germination of A. arguta than A. chinensis. Germinated seeds on moist filter paper can produce seedlings when sub-cultured on MS medium for seedling development.

Contribution to seed ecology of Sequoiadendron giganteum (Lindl.) Buchholz growing in the Central European conditions

The properties of Giant Sequoia (Sequoiadendron giganteum (Lindley) Buchholz) seeds originating from a single cultivated Sequoia tree in the second gene strain in the Czech Republic were examined. The maximum germination level was set at 1.8%. This type is a pyrophyte, but nonetheless the short-term effects of a temperature of 100°C simulating a natural fire are still lethal. The seeds were planted with the same success in one case using a fungicide, which is routine practice in nurseries, and in another case using a “biological method” relying on the positive effect of soil microflora. Both stratified and non-stratified seeds can germinate, but stratification increases the number of germinating individual trees to at least double.