seed viability
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Seed quality is routinely assessed by direct tests, e.g, the germination test, or indirect tests like the tetrazolium test, which has shoown to be promising in the determine viability and vigor, allowing the diagnosis of the main problems that may affect seed quality, such as mechanic damages, field deterioration and storage. In this respect, this study was conducted to develop a tetrazolium test protocol to evaluate the viability and vigor of Tamarindus indica L. seeds. Before exposing the seeds to the tetrazolium solution, seed preconditioning studies were carried out in which seven soaking times were tested. The soaking time that did not cause damage to the seed embryo and allowed the removal of the seed coat to expose the seed structures to the tetrazolium salt was selected. Then, an experiment was set up in a completely randomized design with a 2x3x3 factorial arrangement involving two seed lots, three soaking times in tetrazolium salt (6, 12 and 16 h) and three salt concentrations (0.075, 0.1 and 0.5%), totaling 18 treatments with four replicates of 25 seeds, evaluated at 40 ºC. For each treatment, the seeds were divided into three classes, namely, viable and vigorous embryos (class 1); viable embryos (class 2) and non-viable or dead embryos (class 3). For a comparison with the tetrazolium test results, the two seed lots were analyzed for water content, germination, emergence, first count, germination speed index, emergence speed index, growth and seedling dry weight. The viability and vigor of T. indica seeds can be evaluated after a soaking period of 48 h and immersion for 6h in tetrazolium salt at the concentration of 0.1%, at 40°C, with provides results similar to conventional seed viability tests. The tetrazolium test proved to be adequate to differentiate T. indica seed lots in terms of viability.

Relevance. Biological features (morphometric indicators, viability and germinating power) of Poterium polygamum seeds found in natural communites of the Stavropol Territory have been studied. The conservation of wild-growing plant species in the natural population and the rational use of their potential are relevant.Methods. Years of study — 2013–2021. The subject of the study is Poterium polygamum seeds. Seeds were collected in 2013. Studies were carried out according to the methods of studying seed material. Freshly harvested seeds and seeds of different shelf life were germinated in petri dishes at a temperature of 18–20 °C.Results. The collected seeds of Poterium polygamum are quite large. The length of the seeds is 4–5 mm, the width is about 2.5 mm. The mass of 1000 pieces of seeds on average was 10.59 grams. Complete absence of viability of freshly harvested Poterium polygamum seeds was revealed. After three months, seed viability was 97%. This is a shallow physiological rest associated with the post-harvest maturation period. During the storage of seeds, their high germination was established — from 70 to 100%. The duration of seed storage is 8 years. The largest number of germinated seeds and their germinating power were noted in the third year of their storage (100%). Seeds germinated on the third or fourth day. The differences between the viability of seeds and their germinating power are not great. In the eighth year of storage of Poterium polygamum seeds, viability and germinating power were slightly reduced. The storage period of seeds, in which they retain the ability to germinate and the germinating power, is long. It has been found that the wild species Poterium polygamum belongs to plants with a high (70 to 100%) viability. This species is regularly resumed in the natural population. The revealed biological features of Poterium polygamum seeds can become the scientific basis during the reconstruction of degraded natural grass stand and in selection work.

Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (Ficaria verna, Ranunculus auricomus, R. bulbosus, R. cassubicus, R. lanuginosus) and the endangered R. illyricus. The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application). Additionally, the pistil morphology was documented for R. bulbosus, R. illyricus and R. cassubicus using SEM techniques. It was demonstrated that the reproductive efficiency, expressed as the production of viable seeds able to germinate, was significantly higher in the species reproducing sexually (especially in R. lanuginosus) compared to the clonal ones. However, the complexity observed leads to separation of an additional group (cluster) of apomictic species: R. auricomus and R. cassubicus, distinguished by the lowest pollen viability and a low ability of the seeds to germinate. In the vegetatively reproducing R. illyricus, the seed formation efficiency was just 13.2% despite the having highest number of pistils in its flowers. The developed seeds of this species observed in our experiment were viable, but in general effective methods to stimulate their germination have not been proposed yet. Here, the first comparative study concerning the biology of sexual reproduction of R. illyricus is presented in the context of its decreasing distribution in natural habitats.

Abstract Cycnoches haagii Barb. Rodr. is an epiphytic orchid very targeted by collectors, but no reference was found in the literature about its reproductive biology. Thus, the purpose of this study was to obtain initial information regarding pollination types and its influence on seed viability of this native orchid of the Brazilian Cerrado, in order to enable future propagation and preservation programs. Pollination among flowers of the same plant (geitonogamy) or different plants (xenogamy) were carried out. Seeds extracted from the capsules were sown in B&G medium, with full and half strength. Seeds from geitonogamic resulted in 25% of albino protocorms and consequently in albino seedlings. This phenomenon did not occur in seedlings derived from xenogamic pollination. Pigment analysis showed that even the albino seedlings presented chlorophylls and carotenoids, however, in significantly minor concentrations, 16% and 37% respectively, in relation to green seedlings. Geitonogamic and xenogamic pollinations resulted in C. haagii viable seeds with high germination percentage (90%) under in vitro conditions. The germination of seeds from xenogamic pollination resulted in chlorophyll or normal seedlings only, and can be recommended at conservation programs. On the other hand, although geitonogamic pollination should be avoided at conservation programs of this orchid species as it leads to albino seedlings, it showed a very interesting system to obtain seedlings with this phenotype, an interesting plant material to future investigation.

Sorghum bicolor var. Samurai 2 can be used as raw material in silage production for ruminant feed. The problem encountered is the difficulty of obtaining certified seeds for commercial sorghum production. So that is necessary to do this research to investigate potential sorghum seed production and its quality of Sorghum bicolor var. Samurai 2. The study was conducted at University Research Station-Jonggol Animal Education and Research Unit, Bogor Agricultural University. The experimental design used was a randomized block design with 4 treatments and 5 replicates. Five individual plants were taken to measure the variables at each treatment set. The treatments consisted of different harvesting times, namely P95 (harvested 95 days after planting), P100, P105 and P110. The variables observed were dry weight of shelled seeds, seed weight per panicle, weight of panicle stalk, panicle weight, seed production per ha, seed moisture content, seed viability test, and shoot biomass production per ha. The results showed that seed production per ha, panicle dry matter weight, fresh seed moisture content, panicle stalk dry weight was not significantly different. Dry weight of shelled seeds, dry weight of seeds per panicle, panicle dry weight, seed viability, weight of biomass per ha were significantly different (p<0.05). The potential for the production of shelled seeds, dry matter of seeds per panicle was the best in the P105 and P110, the viability of the seeds in the P105 and shoot biomass production per ha in the P105. The potential for shelled seed production (4038 kg ha-1), seed dry weight per panicle (54.87 g panicle-1), seed viability (92.8%) and the best biomass production (55.88 tons ha-1) were in treatment P105. Key words:        seed production, shoot biomass, Sorghum bicolor, viability

Utilization of seeds storage results in decreased plant productivity. The increase can be used by treating seeds before planting through the technique of invigoration. This purpose of the study is to assess the effectiveness of invigoration methods using polyethylene glycol (PEG 6000) and ultrafine bubbles (UFB) to improve viability and vigor of sengon seeds (Falcataria moluccana). Seed agieng using 96 % ethanol was carried out to obtain the diversity of seedlot viability as the materials for testing the effectiveness of invigoration treatments. A complete random design was used to test the effectiveness of 5 invigoration treatments, i.e., seed without invigoration treatment, soaking in PEG 6000 -0.8 Mpa, soaking in PEG 6000 -1.2 Mpa, soaking in UFB water injected by environmental air, and soaking in UFB water injected by oxygen 99 %, with soaking time is 24 hours for each treatment. Seed agieng resulted three classes of seed viability, i.e. 62 % (initial seed), 83 % (seed agieng for 30 minutes) and 57 % (seed agieng for 60 minutes). In the condition of seed germination before treatment (DBA) 57 % and DBA 62%, invigoration treatments were significantly affected on seed germination capacity, but not significantly different in DBA 83 %. The soaking treatment of UFB injected by oxigen 99 % was able to improve the germination parameters (germination capacity, germination rate, and vigor index) on the sengon seeds with DBA 57 %. For seeds with DBA 62 %, the soaking treatment in UFB injected by environmental air was provided the best germination capacity, T50, and vigor index. The treatment of UFB injected by oxygen 99 % was more effective to improve the seed with very low viability and vigor (DBA 57 %). In general, improving of seed viability and vigor is more effective by using UFB than PEG 6000.

Marrubium friwaldskyanum Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of M. friwaldskyanum was different from that of the other Marrubium species reported in the literature. The main EO constituents of M. friwaldskyanum were (E)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the harvest stage was significant only on α-copaene, (E)-caryophyllene, caryophyllene oxide, and τ-muurolol. The concentration of α-copaene (1.26–1.83% range of the total oil), (E)-caryophyllene (31–41%), caryophyllene oxide (6.4–11.8%), and τ-muurolol (1.3–2.8%) were the highest at 2–3 pair of leaves or before flowering and lower at flowering. The harvest stage did not significantly affect the concentrations of the other six identified EO compounds β-bourbonene (1.1%), α-humulene (2.8%), germacrene D (23.3%), bicyclogermacrene (2.85%), δ-cadinene (1.1%), and spathulenol (2.8%). In a separate experiment, grinding of the biomass prior to EO extraction had a significant effect only on the concentrations of D-limonene (0.24–3.3%) and bicyclogermacrene (3.6–9.1%). Grinding in water or without water, maceration, and addition of Tween®20 had rather small effects on the EO profile. The identified EO constituents and their mean concentrations in this experiment were (E)-caryophyllene (25.4%), germacrene D (17.6%), caryophyllene oxide (9.1%), spathulenol (6.5%), τ-muurolol (5.0%), carvacrol (3.9%), α-copaene (2.5%), β-bourbonene (2.5%), δ-cadinene (2.4%), α-humulene (1.8%), and Z-β-farnesene (1.3%). Embryological studies observed anther and the development of the male gametophyte and ovule and development of the female gametophyte of M. friwaldskyanum. Furthermore, pollen and seed viability assays were conducted, and mass spectrometry-based metabolomics analysis of an extract from shoots revealed the presence of 45 natural products, identified as flavonoids, phenolic acids, and (tri)terpenoids. Overall, the phytochemistry and some of the microscopic analyses distinguished this endemic species from other species in Marrubium.

Gingerbread or Elongated Sedge Carex elongata L. is a rare plant in eastern England and the Yorkshire populations are isolated from the main distribution. It has only ever naturally occurred at five sites and is extant at two of them, one of which probably results from a recent colonisation event. It has been re-introduced near another of its historic sites. At its principal site, Askham Bog near York, the plant has expanded its population considerably over the last 40 years. Its local distribution appears to be strictly limited by topography and winter flooding. Its ability to colonise new sites and to expand populations show that earlier concern about seed viability was misplaced.

The caper (Capparis spinosa L.) is a perennial plant characteristic of the Mediterranean region that presents difficulties in its propagation, both vegetatively and by seeds. The main aim of this study is to provide collection guidelines to achieve a viable caper commercial propagation, for which three experiments were undertaken to determine the viability and germination in different seed lots. In the first experiment, commercial and own produced seeds (collected with the same criteria as commercial seeds) were analysed; the commercial seeds presented the lowest viability and germination. The second experiment analysed the effect of the fruit (from which the seeds were extracted) at its maturation stage, obtaining the lowest seed viability and germination in the seeds extracted from the dry fruits. In the third experiment, seed viability and germination were analysed immediately after collection, following a short drying period (3 d), and after six storage months. Viability and germination decreased with seed storage. Overall, it can be stated that caper seeds are sensitive to desiccation; consequently, a general rule of thumb is to collect the fruits once a week, to extract the seeds, and to plant them immediately for germination.