Seeds, Volume 2, Issue 4 (December 2023) – 7 articles

The genus Alstroemeria originates from South America, and Chile is one of the countries showing the highest number of taxa (49), of which 40 are endemic. However, anthropogenic and environmental factors are affecting the survival of these species; therefore, the conservation of their genetic variability is of great importance, and can be achieved through seed propagation. Seeds of this genus normally show dormancy, which prevents their germination under favorable conditions. The objective of this work was to understand the pre-germinative barriers to develop a seed propagation protocol for native alstroemerias and to determine the best method to break their dormancy. Seeds from 10 Alstroemeria species native to Chile were collected from the Coquimbo Region to Maule Region, and 5 pre-germination treatments combining scarification and stratification methods were evaluated. Moreover, a morphological and biochemical evaluation of the seeds was performed. The results showed a positive and significant effect on the percentage of emergence using seed soaking in water and cold stratification at 13 °C, obtaining the best results in A. pelegrina and A. angustifolia subsp. angustifolia (98.33% and 91.67%, respectively) after 30 days. The morphological characterization of seeds showed a wide range of size (diameter), from 2.18 mm (A. pulchra subsp. pulchra) up to 3.43 mm (A. pelegrina), and different shapes (pseudospherical and angular) and textures (rough and smooth). The highest phenol and tannin concentrations were observed in A. hookeri subsp. maculata with values of 4.71 and 30.95 mg g⁻¹ of seeds, respectively. A bigger size of the seed and a higher concentration of phenols could be related to a higher % of emergence of alstroemeria seeds. Full article

The elongation of the mesocotyl and the coleoptile and other seedling traits were analyzed from 16 hybrids of two seed sizes, five varieties and a control. Sowing was conducted in sand beds during the S-F 2020 cycle, where nine genotypes were identified that differed in the elongation of the mesocotyl: long (H-48, HS-2 and Promesa); medium (H-44-H-52 and H-70); and short (H-49 AE, H-40 and H-32). A total of 36 possible crosses were obtained between these nine parents, which were established in the S-S 2021 cycle, and on sand beds. Results show that seed size affected (p< 0.05) the speed and percentage of emergence, the elongation of mesocotyl–coleoptile, the biomass and the heterosis in parents and their crosses. The H-48 hybrid presented greater speed and percentage of emergence and elongation of the mesocotyl and the coleoptile with both seed sizes. The highest dry weight of mesocotyl, coleoptile, roots, and leaves was found in the hybrids Promesa and H-48. The crosses between parents with contrasting mesocotyl presented superior elongation and dry weight (p ≤ 0.05) compared to their parents, with the long × long (1 × 2, 1 × 3 and 2 × 3) crosses standing out for all the traits measured. A strong positive association was obtained (p ≤ 0.01) between the elongation of the mesocotyl–coleoptile, the percentage of emergence, and the production of total dry matter in parents and their crosses. Full article

Seaweeds are used in traditional agriculture practices because of their beneficial effects. Recently, the rising demand for organically grown foods has amplified the use of organic fertilizers such as seaweed extracts. Despite their beneficial effects, few studies have reported information about compounds in seaweed extracts that are responsible for these benefits. Thus, the aim of this study was to evaluate the potential relationships between the components and secondary metabolites in four seaweed liquid extracts from Eisenia arborea, Macrocystis pyrifera, Padina caulescens, and Sargassum horridum and their biostimulant activity through changes in the germination, growth, and protein content of tomato seedlings (Solanum lycopersicum). The E. arborea and S. horridum extracts showed similar compositions (ash, organic carbon, bicarbonates, and chlorides), minerals (Ca, Fe, and Cu) and secondary metabolites (triterpenes and saponins), albeit with different component concentrations. The chemical composition of the P. caulescens extract was significantly different from those of the other extracts; it was characterized by high levels of total nitrogen, phenols, and carbohydrates. Almost all seaweed extracts had beneficial effects on seed germination and seedling length, except the S. horridum extract that inhibits germination. The hierarchical clustering plots and principal component analysis indicated that germination and protein content are related to the presence of sterol. Shoot length was closely related to mineral levels (K, Zn, B, Na) and the C:N ratio, whereas radicle length was closely related to the content of nitrogen, carbohydrates, phenols, and flavonoids in the seaweed extracts. However, the underlying mechanisms are still unclear and require further studies. Full article

Ascorbic acid (AsA) is mainly known as an antioxidant. However, if the peculiar features of the AsA system in the different stages of seed development and germinationare taken into consideration, it can be concluded that the function of AsA goes far beyond its antioxidant properties. The possible involvement of AsA in the regulation of hormone synthesis and in the epigenetic control of gene expression opens new directions to further research. In recent years, seed priming with AsA has been successfully used as a strategy to improve germination and plant productivity. Beneficial effects of seed AsA priming could be observed in several crop species, but the underlying molecular mechanism(s) are still unclear. The available evidence suggests that AsA priming induces a wide range of coordinated responses allowing primed seeds to overcome adverse environmental conditions. Full article

Abiotic stresses, sometimes due to dramatic environmental changes, such as sudden and heavy rainfalls, or drought, increasing temperatures or soil salinization, deeply affect the growth and yield of plants. Progress in terms of improving the abiotic stress tolerance of plants can be obtained via classical breeding and genetic engineering, which can be slow, or by practice, such as acclimation and seed priming. The latter can improve seedling performance, and it can be considered a short-term approach. Seed priming with different agents and biopriming may offer the possibility to improve stress tolerance, even though its beneficial effect depends on crop species, dose, and time of application. The aim of this review is to highlight some of the current research trends that may ultimately lead to strategies for stress-proofing crop species. The focus is on those abiotic stresses, e.g., drought and soil salinity, that are most often associated with climate change and poor agricultural practices and those crops that are most important for human nutrition. Comments are provided on the challenges and pros and cons of this methodology. Full article

The pre-sowing treatment of seeds with an α static magnetic field has been reported in the literature as a means of enhancing plant development. In this work, we have designed, characterized, and constructed a setup for exposing small vegetable seeds to a static magnetic field. In a series of experiments, we have treated the seeds of vegetables that are important for the Mediterranean diet, i.e., tomato, lettuce, and salad rocket. The results show that tomato seedlings significantly benefit from a pre-sowing treatment with a magnetic flux density of 45 mT, for both an exposure time of 60 and 90 min compared to control, while the time of treatment that leads to improved growth is 90 min. In order to improve the growth of salad rocket seedlings the magnetic field had to be 150 mT, whereas the results for lettuce seeds were a bit inconsistent, i.e., it is not clear whether a lower (45 mT) or a higher (300 mT) magnetic flux density should be applied. Full article

Solanum paniculatum L. belongs to the Solanaceae family and has the ability to grow and develop under unfavorable environmental conditions such as drought and salt stress, acid soils and soils poor in nutrients. The present work aimed to analyze S. paniculatum seed transcriptome associated with induced tolerance to drought stress by osmopriming. Seeds subjected to osmopriming (−1.0 MPa) displayed a higher germination and normal seedling percentage under drought stress when compared with unprimed seeds. RNA-seq transcriptome profiles of osmoprimed and unprimed seeds were determined and the potential proteins involved in the drought tolerance of S. paniculatum were identified. From the 34,640 assembled transcripts for both osmoprimed and unprimed seeds, only 235 were differentially expressed and, among these, 23 (10%) transcripts were predicted to code for proteins potentially involved in response to stress, response to abiotic stimulus and response to chemical. The possible mechanisms by which these stress-associated genes may confer tolerance to osmoprimed Solanum paniculatum seeds to germinate under water deficit was discussed and may help to find markers for the selection of new materials belonging to the Solanaceae family that are more tolerant to stress during and following germination. Full article