Seed Storage Behaviour Research Articles

Storage behaviour and seed longevity of traditional African vegetables: a review

Effective management of seed collections in genebanks requires knowledge of seed storage behaviour and species-specific longevity under conventional air-dry storage. This knowledge is lacking for traditional African vegetable (TAV) crops compared to cereals and conventional vegetables. This review aimed to assess the published literature until December 2023. The findings will guide post-harvest seed processing (cleaning and drying), storage (containers, storage parameters), viability monitoring and regeneration intervals, and to identify further research gaps that will inform data needs from the genebanks conserving TAV seeds. Our findings show that, compared to cereals and legumes, there is limited information available on vegetable crops and more acutely on TAVs. While conventional vegetable seeds benefited from research on their storage behaviour and longevity, there was significant neglect of TAV crops, which represented only 17% of the studies reviewed. Overall, genebanks involved in TAV germplasm conservation should invest more time and resources to investigate seed physiology and generate data that will inform on the storage behaviour and longevity of these crops under medium and long-term storage conditions. Such data are important to establish crop-specific knowledge on optimal conditions for high post-harvest seed quality, and for genebanks to plan seed regeneration.

Evolutionary reversal of physical dormancy to nondormancy: evidence from comparative seed morphoanatomy of Argyreia species (Convolvulaceae).

Argyreia is the most recently evolved genus in the Convolvulaceae, and available information suggests that most species in this family produce seeds with physical dormancy (PY). Our aim was to understand the evolution of seed dormancy in this family via an investigation of dormancy, storage behaviour, morphology and anatomy of seeds of five Argyreia species from Sri Lanka. Imbibition, germination and dye tracking of fresh intact and manually scarified seeds were studied. Scanning electron micrographs and hand sections of the hilar area and the seed coat away from the hilar area were compared. Scarified and intact seeds of A. kleiniana, A. hirsuta and A. zeylanica imbibed water and germinated to a high percentage, but only scarified seeds of A. nervosa and A. osyrensis did so. Thus, seeds of the three former species are non-dormant (ND), while those of the latter two have physical dormancy (PY); this result was confirmed by dye-tracking experiments. Since >90% of A. kleiniana, A. hirsuta and A. zeylanica seeds survived desiccation to 10% moisture content (MC) and >90% of A. nervosa and A. osyrensis seeds with a dispersal MC of ~12% were viable, seeds of the five species were desiccation-tolerant. A. nervosa and A. osyrensis have a wide geographical distribution and PY, while A. kleiniana, A. hirsuta and A. zeylanica have a restricted distribution and ND. Although seeds of A. kleiniana are ND, their seed coat anatomy is similar to that of A. osyrensis with PY. These observations suggest that the ND of A. kleiniana, A. hirsuta and A. zeylanica seeds is the result of an evolutionary reversal from PY and that ND may be an adaptation of these species to the environmental conditions of their wet aseasonal habitats.

Selecting Suitable Tree Species for Direct Seeding to Restore Forest Ecosystems in Northern Thailand

To upscale restoration of tropical forest ecosystems, direct seeding—sowing seeds directly into the ground—is potentially a more cost-effective technique than tree planting. However, its success is limited by seed predation, the harshness of environmental conditions on restoration sites and particularly by a lack of information about suitable tree species. Therefore, this study tested the suitability of 23 native forest tree species for direct seeding, to restore a biodiversity-rich, upland, evergreen forest in northern Thailand. Three replicate seed batches of each species were sown randomly in two degraded sites and in a tree nursery under controlled conditions. Seed removal and germination were monitored weekly until no further germination had occurred for more than a month. Subsequently, seedling yield, growth and species performance score were also monitored at appropriate intervals. Nine months after sowing, seed removal differed significantly among species but was generally low, with a cross-species average of 3.4% (±0.5 SE). Seed size was negatively correlated with seed removal. Eight species failed to germinate. Seed germination percentage varied widely among species. Cross-species average germination of the 15 species that germinated was 25% (±6.2 SE). Two species (Adenanthera microsperma and Alangium kurzii) were ranked as having high germination (>50%), five species (Choerospondias axillaris, Spondias pinnata, Diospyros glandulosa, Melia azedarach and Phyllanthus emblica) had medium germination (20–50%) and eight species had low germination (<20%). Following the first dry season, two of the fifteen germinated species failed to establish. Germination and establishment were influenced by seed size, seed storage behavior and successional status. A. microsperma, S. pinnata and C. axillaris are recommended for direct seeding based on their high species performance index values. This study further concluded that selecting desiccation-tolerant seeds, particularly those with medium-to-large sizes, could increase the chances of successful seedling establishment.

Diversity of seed storage behavior of tree species from tropical lowland rainforests in Sri Lanka, a global biodiversity hotspot

AbstractTropical lowland rainforests are considered to be ecologically important refugia of national and global significance, yet wide‐scale deforestation and degradation of tropical lowland rainforests lead to losses in biodiversity. Seed storage behavior information is required for the effective restoration of these forests. Here, we studied the seed storage behavior of 42 selected tropical lowland rainforest tree species from Sri Lanka with the aim to test the reliability of current experimental methods and predictive models to predict the desiccation sensitivity of seeds. Seed storage behavior was experimentally determined through the 100 seed method and the results were compared with three predictive models; thousand seed weight–moisture content (TSW–MC), seed coat ratio–seed mass (SCR–SM), and phylogenetic affiliation models. Based on the 100 seed method, 28 species were identified as desiccation sensitive and 14 species were identified as desiccation tolerant. Compared to the 100 seed method, the predictability of the SCR–SM model was 70%, whereas the TSW–MC and phylogenetic affiliation models showed 52% and 58% predictability, respectively. Due to its higher predictability, the SCR–SM model has a high potential to be an effective predictive tool of seed storage behavior. This study revealed that tropical lowland rainforests are dominated by trees producing desiccation‐sensitive seeds. Further, species dispersing seeds in the peak rainy season have desiccation‐sensitive seeds, while those dispersing seeds in the normal wet season have desiccation‐tolerant seeds. Another key finding was that 100% of the subcanopy species produce nonorthodox, that is, desiccation‐sensitive seeds, which gradually decrease from subcanopy to understory.

Seed Desiccation Sensitivity Varies with Geographic Distribution in Two New Zealand Native Pittosporum Species

Ex situ conservation involves the maintenance and reproduction of species in areas outside their natural habitats. Seed banking is a well-established ex situ approach used for plant conservation. Seed banking consists of collecting, drying, and storing seeds to preserve genetic diversity. The main limitation of this technique is that the seed must be desiccation tolerant. Seed storage behaviour can vary among species, and for some species, drying without loss of viability is not possible, meaning storage under conventional seed banking conditions (sub-zero temperatures and low relative humidity) is not possible. Understanding seed storage behaviour is an essential prerequisite for establishing whether conventional seed banking is an option for seed conservation. This study investigated the desiccation tolerance and sensitivity of mature seeds of two native New Zealand species of Pittosporum (P. eugenioides and P. crassifolium) from two geographic locations (Palmerston North and Wellington), with the aim of understanding their seed storage behaviour and thereby improving conservation outcomes. The variables measured were seed moisture content, viability, germination, and desiccation responses. We developed sorption isotherm for both species to support the future development of storage protocols. Our results show that both P. eugenioides and P. crassifolium display non-orthodox behaviour, i.e., are desiccation sensitive and cannot be stored under conventional seed banking conditions, but also suggest that seed desiccation responses vary with the geographical origin of the seeds. This study highlights the importance of exploring seed storage behaviour using different populations to optimize ex situ conservation strategies aimed at preserving the genetic diversity of New Zealand’s threatened and endangered species.

Storage Behaviour of Groundnut (Arachis hypogaea L.) Seeds under Different Storage Condition

Background: Seed deterioration is an unavoidable process during seed storage resulting in declined germination and vigour of the seeds and the seeds have different storage potential under different storage condition. Maintenance of germination and vigour requires new alternative method of storage conditions viz., packaging material and temperature conditions. Storage potential of groundnut seeds cv. VRI 8 and the changes associated with the seeds stored under different storage conditions were investigated in this study. Methods: The efficiency of modified atmospheric storage with different combination of CO2, N2 and O2 and vacuum packaging under different storage temperature (25°C, 5°C and -5°C) for maintaining the storage behaviour of seeds up to 8 months were evaluated and the gas mixture was checked in gas analyzer at regular intervals. Result: The seeds stored under modified atmospheric storage (MAS) condition with a gas mixture of 0% CO2, 100% N2 and 0% O2 at -5°C temperature condition, maintained germination and seed vigour above 70% with a minimum increase in seed moisture content even after 8 months of storage and even when these seeds kept under ambient condition also maintained germination above 70% after 8 months of storage while the seeds stored under ambient condition registered less germination of below 70% by 6 months of storage itself. Down-regulation of antioxidant defence system viz., catalase and peroxidase activity and the minimum accumulation of malondialdehyde and H202 content in the embryo indicated the less oxidative damage in the seeds stored under MAS compared to ambient condition. Thus, the study highlighted that the seeds have better storage potential under modified atmospheric storage condition with low atmospheric temperature through maintaining the seed quality by reducing their metabolic activity and storing these seeds under ambient condition could be a cost-effective method.

Comparative Seed Cryopreservation of Indonesian and New Zealand Epiphytic And Terrestrial Orchids

Background: The atypical seed storage behaviour reported in several orchid species justifies cryopreservation as a complementary conservation strategy to conventional seed banking. Objective This study aimed to assess the seed cryopreservation potential of five orchid species; tropical epiphytic, Indonesian species (Dendrobium strebloceras, D. lineale), one temperate New Zealand species (D. cunninghamii) and two temperate terrestrial, New Zealand species banksii, Thelymitra nervosa). MATERIALS AND METHODS: Seeds were cryopreserved direct immersion in liquid nitrogen (LN) and through the application of a cryoprotectant method. For the latter, seeds were exposed to Plant Vitrification Solution 2 (PVS2) for 0, 50, and 70 min, at either room temperature or on ice, prior to immersion in LN. RESULTS: Seeds all the studied species germinated well following direct cooling in LN. There was no difference in seedling development capability between cryopreserved and non-cryopreserved seeds of both epiphytic species and direct immersion in LN enhanced seed germination and shoot formation both temperate terrestrials. CONCLUSION: Through a range of analyses of germination and post-growth, our study shows the potential for cryopreserving epiphytic or terrestrial orchids tropical and temperate regions.

Seed Dormancy and Germination Behaviour of Palmyrah: A Review

Palmyrah (Borassus flabellifer L.) is a slow growing, dioecious, drought resistant palm and considered to be native of Tropical Africa. It is cultivated as well as found growing in wild in the Indian subcontinent. It is distributed in India, Burma, Africa and Sri Lanka. Several problems are encountered in germination of seeds in palmyrah such as poor, protracted germination and prolonged nursery period. The main reasons for the failure of seeds to germinate in suitable conditions are either dead or dormant. The delayed germination of palmyrah might be due to the stony endocarp acting as a physical barrier to imbibition or imposing mechanical resistance to embryo enlargement. Against this backdrop, this review focuses on seed dormancy, pre-sowing seed treatment, nursery technology, and seed storage behaviour of palmyrah.Palmyrah (Borassus flabellifer L.) is a slow growing, dioecious, drought resistant palm and considered to be native of Tropical Africa. It is cultivated as well as found growing in wild in the Indian subcontinent. It is distributed in India, Burma, Africa and Sri Lanka. Several problems are encountered in germination of seeds in palmyrah such as poor, protracted germination and prolonged nursery period. The main reasons for the failure of seeds to germinate in suitable conditions are either dead or dormant. The delayed germination of palmyrah might be due to the stony endocarp acting as a physical barrier to imbibition or imposing mechanical resistance to embryo enlargement. Against this backdrop, this review focuses on seed dormancy, pre-sowing seed treatment, nursery technology, and seed storage behaviour of palmyrah.

Seed Storage, Dormancy, and Germination Behavior in Lithocarpus glaber (Fagaceae)

Abstract Knowledge of seed storage behavior and germination ecology of Fagaceae species is limited to the Quercus genus, prompting the need to investigate other genera. Using Lithocarpus glaber (Thunb.) Nakai acorns collected from China, storage behavior, dormancy type, and germination pattern were investigated by germination and desiccation experiments along with triphenyl tetrazolium chloride (TTC) staining and photomicrographs. The fairly large-sized acorns with a mass of 1,340 g per 1,000 acorns had a moisture content of 34.5% (fresh weight) at the time of dispersal. There were three distinctive regions: (1) scar (hilum), (2) apex, and (3) pericarp, with an embryonic axis located on the apex side. When tested for germination at 15/20°C, 76.6% of the acorns germinated within the first 3 weeks, indicating nondormancy. However, germination declined to 48% and 3% when dried in silica gel to 26% and 17% moisture content, respectively, confirming the acorns are recalcitrant. Germination was hypogeal. Nonetheless, the elongated cotyledonary petiole establishes an intumescent tubular structure at approximately 7–10 cm from acorns, from which taproots and leaves emerge. The nondormant recalcitrant acorns took 6–8 weeks to complete the germination process (from imbibition to leaf emergence), possibly indicating the presence of epicotyl dormancy. This is the first study on Lithocarpus showing intumescent tubular structure development during germination. The ecological significance of this structure requires further investigation.

Intra-Specific Variation in Desiccation Tolerance of Citrus sinensis 'bingtangcheng' (L.) Seeds under Different Environmental Conditions in China.

Intra-specific variation in seed storage behaviour observed in several species has been related to different maternal environments. However, the particular environmental conditions and molecular processes involved in intra-specific variation of desiccation tolerance remain unclear. We chose Citrus sinensis 'bingtangcheng' for the present study due to its known variability in desiccation tolerance amongst seed lots. Six seed lots of mature fruits were harvested across China and systematically compared for drying sensitivity. Annual sunshine hours and average temperature from December to May showed positive correlations with the level of seed survival of dehydration. Transcriptional analysis indicated significant variation in gene expression between relatively desiccation-tolerant (DT) and -sensitive (DS) seed lots after harvest. The major genes involved in late seed maturation, such as heat shock proteins, showed higher expression in the DT seed lot. Following the imposition of drying, 80% of stress-responsive genes in the DS seed lot changed to the stable levels seen in the DT seed lot prior to and post-desiccation. However, the changes in expression of stress-responsive genes in DS seeds did not improve their tolerance to desiccation. Thus, higher desiccation tolerance of Citrus sinensis 'bingtangcheng' seeds is modulated by the maternal environment (e.g., higher annual sunshine hours and seasonal temperature) during seed development and involves stable expression levels of stress-responsive genes.

Seed Longevity-The Evolution of Knowledge and a Conceptual Framework.

The lifespan or longevity of a seed is the time period over which it can remain viable. Seed longevity is a complex trait and varies greatly between species and even seed lots of the same species. Our scientific understanding of seed longevity has advanced from anecdotal 'Thumb Rules,' to empirically based models, biophysical explanations for why those models sometimes work or fail, and to the profound realisation that seeds are the model of the underexplored realm of biology when water is so limited that the cytoplasm solidifies. The environmental variables of moisture and temperature are essential factors that define survival or death, as well as the timescale to measure lifespan. There is an increasing understanding of how these factors induce cytoplasmic solidification and affect glassy properties. Cytoplasmic solidification slows down, but does not stop, the chemical reactions involved in ageing. Continued degradation of proteins, lipids and nucleic acids damage cell constituents and reduce the seed's metabolic capacity, eventually impairing the ability to germinate. This review captures the evolution of knowledge on seed longevity over the past five decades in relation to seed ageing mechanisms, technology development, including tools to predict seed storage behaviour and non-invasive techniques for seed longevity assessment. It is concluded that seed storage biology is a complex science covering seed physiology, biophysics, biochemistry and multi-omic technologies, and simultaneous knowledge advancement in these areas is necessary to improve seed storage efficacy for crops and wild species biodiversity conservation.

Embryo maturation, dormancy and seed storage behaviour of Gymnacranthera canarica (King) Warb., a threatened endemic tree species of Southern Western Ghats

Gymnacranthera canarica is a severely endangered endemic tree species found in the Myristica swamps of the Southern Western Ghats. Seed storage behaviour is an essential factor to consider when developing effective conservation methods for plant genetic resources whose ex-situ preservation is unclear. The seed storage behaviour, seed dormancy state, dormancy breaking treatments, germination, and phytohormonal analysis of G. canarica were explored in this work. G. canarica seed moisture at shedding was 28.86%, germinated to 34% at 25ºC, and had a low germination rate in natural conditions. Germination was considerably aided by Gibberellic acid pretreatment and drying stratification. G. canarica seeds may have non-deep simple morphophysiological dormancy, as evidenced by the fact that their embryos grew at temperatures between 20 and 25ºC (MPD). Seeds can be stored for up to 60 days at 20ºC after being desiccated to 19.37% suggest that G. canarica seeds are recalcitrant, with non-deep simple morphophysiological dormancy, and that seed pretreatment with Gibberellic acid prior to germination could be a viable approach for mass propagation and long term ex-situ conservation could be the potential storage of this critically endangered species.

Are current seed storage approaches suitable for Macrozamia fraseri (Cycadales), a temperate species used in restoration?

Abstract In this study, we focused on understanding key storage traits of seeds from Macrozamia fraseri, an unusual though important species that is impacted by mining. To support current restoration activities, large amounts of seed from M. fraseri have been regularly collected and stored for up to 8 years under standard seed banking conditions (5°C and 20% relative humidity), though in situ recruitment from directly sown seed is poor. To investigate the underlying constraints to germination on demand, we set out to assess the viability of M. fraseri seeds that had been stored in a restoration seed bank from 6 to 66 months. Seed moisture content (MC) (fresh weight basis) was also determined for seeds with different storage histories to ascertain whether M. fraseri seeds display traits (i.e. high MC) that might suggest non-orthodox seed storage behaviour. The youngest seed accession (6 months old) was found to have a high MC (45.8 ± 5.4%—fresh weight basis), and >50% viability. In comparison, older (>30 months old) accessions were observed to have a marked reduction in both seed MC (10–35% MC) and viability (0–29.4%). While preliminary, we conclude that M. fraseri seeds appear to lose viability during conventional storage with younger accessions displaying both a higher seed MC and viability, compared to accessions stored for longer. Given the significance of these results, future research activities are recommended to better understand the interplay between seed MC and storage environment and how this relates to the seasonally dry Mediterranean climate where this species naturally occurs. As well, storage and propagation approaches are proposed to increase success when using M. fraseri for conservation and restorative activities.

Effect of storage temperature and packing materials on seed germination and seed storage behavior of Schefflera abyssinica

Abstract. Bareke T, Addi A, Roba K, Kumsa T. 2022. Effect of storage temperature and packing materials on seed germination and seed storage behavior of Schefflera abyssinica. Nusantara Bioscience 14: 141-147. Knowledge of seed storage behavior is crucial for developing appropriate ex-situ conservation strategies. The main objective of this study was to determine the seed storage behavior of Schefflera abyssinica (Hochst. ex A. Rich.). A factorial combination of three temperatures (-10, 0, and 22°C) levels, two types of packing containers (polythene bag and aluminum bag), and eight periods of storage (0, 30, 60, 90, 120, 150, 180 days, and for a year) level was used to determine the germination capacity and storage behavior of the seeds. Accordingly, seed storage temperatures and storage period (up to 1 year) have a significant effect on the germination (p<0.01) of S. abyssinica. The highest average germination percentage of S. abyssinica seeds was obtained after 2 months of storage under all conditions. The seed storage period influences the germination of S. abyssinica by 47.8%. The germination percentages of S. abyssinica seeds have shown significant differences in storage temperatures. Seeds stored at -10°C showed the highest germination percentage in all storage periods compared to the two storage temperatures. Generally, the highest germination capacity of S. abyssinica seeds was between 7% and 9% moisture content after 60 and 90 days of storage. Packing materials have no significant difference in the survival of seeds. No stored seeds germinated after one year of storage at room temperature, 0°C, and -10°C. Based on the definition of seed storage behavior, we conclude that seeds of S. abyssinica have intermediate storage.

Impacts of Rapid Desiccation on Oxidative Status, Ultrastructure and Physiological Functions of Syzygium maire (Myrtaceae) Zygotic Embryos in Preparation for Cryopreservation.

Syzygium maire is a highly threatened Myrtaceae tree species endemic to New Zealand. Due to its recalcitrant seed storage behaviour, cryopreservation is the only viable long-term ex situ conservation option for this species. This study investigated viability, oxidative stress, thermal properties, and ultrastructure of zygotic embryo axes (EAs) desiccated to various moisture contents (MC). Fresh EAs had a MC of c. 1.9 g/g with 100% viability but rapid desiccation to MC < 0.3 g/g significantly reduced viability and decreased the activities of the enzymatic antioxidants superoxide dismutase, catalase and glutathione peroxidase, with a sevenfold increase in the production of protein carbonyls and lipid peroxides. Differential Scanning Calorimetry analysis showed no thermal events in EAs desiccated to a MC of <0.2 g/g, indicating that all freezable water had been removed, but this was lethal to both EAs and enzymatic antioxidants. The ultrastructure of desiccated EAs showed signs of plasmolysis, while fully hydrated EAs exposed to cryogenic temperature had ultrastructural disintegration and membrane damage. The decline in enzymatic antioxidant activities and the increase in lipid peroxidation suggest that S. maire EA viability loss is due to oxidative stress rather than structural impacts.

Myrtaceae in Australia: Use of Cryobiotechnologies for the Conservation of a Significant Plant Family under Threat.

The Myrtaceae is a very large and diverse family containing a number of economically and ecologically valuable species. In Australia, the family contains approximately 1700 species from 70 genera and is structurally and floristically dominant in many diverse ecosystems. In addition to threats from habitat fragmentation and increasing rates of natural disasters, infection by myrtle rust caused by Austropuccinia psidii is of significant concern to Australian Myrtaceae species. Repeated infections of new growth have caused host death and suppressed host populations by preventing seed set. Although most Myrtaceae species demonstrate orthodox seed storage behavior, exceptional species such as those with desiccation sensitive seed or from myrtle rust-suppressed populations require alternate conservation strategies such as those offered by cryobiotechnology. Targeting seven key Australian genera, we reviewed the available literature for examples of cryobiotechnology utilized for conservation of Myrtaceae. While there were only limited examples of successful cryopreservation for a few genera in this family, successful cryopreservation of both shoot tips and embryonic axes suggest that cryobiotechnology provides a viable alternative for the conservation of exceptional species and a potential safe storage method for the many Myrtaceae species under threat from A. psidii.

Seed traits and climate resilience in three Mesua species from Sri Lanka

To test the hypothesis that variations of seed traits are adaptations to their habitat conditions and to evaluate adaptability of species to climate change, we investigated variation in seed traits in three Mesua species from Sri Lanka. Seed traits of the dominant native tree M. ferrea sampled across a wide climatic range were compared to those of sub-dominant M. thwaitesii and critically restricted M. stylosa. Seed shape, size, mass, moisture content, seed coat ratio and germinability were studied. Seed storage behavior was evaluated using the hundred seed method and two predictive models: TSW-MC (Thousand seed weight – Moisture content) and SCR-SM (Seed Coat Ratio – Seed Mass). Mesua stylosa had larger seeds with higher MC than the other two species, which allow it to produce seedlings with high tolerance to harsh conditions. Further, M. stylosa seeds are dormant and desiccation sensitive in contrast to those of M. thwaitesii and M. ferrea, whose seeds are non-dormant and desiccation tolerant. These seed traits make M. stylosa seeds more adapted to its unique habitat (freshwater swamp forest in the wet zone), proving our hypothesis that seed trait variations are adaptations to environmental variability in the species’ habitats. Inter-population variation was observed in M. ferrea based on seed mass, MC and SCR. However, inter-annual variation was only observed in MC. When the seed traits were considered, M. ferrea and M. thwaitesii exhibit climate resilience aligned with more dry conditions predicted under climate change with low climate resilience in M. stylosa being desiccation sensitive and dormant.

A imersão em água e o armazenamento de um ano influenciam a germinação dos pirênios de Copernicia alba Morong, uma palmeira de um bioma alagado neotropical

ABSTRACT Palm seeds are known for displaying dormancy and a thick endocarp that delays germination and embryo growth, but water treatments may accelerate their germination process. Additionally, ex-situ conservation of arecaceae species may cause loss of seed viability over time. Data on seed dormancy and storage have been neglected for many native palm species in Brazil. Therefore, we investigated the effect of water treatments and one-year storage on the germination of Copernicia alba Morong, a palm tree from the Brazilian Pantanal wetland. Fresh and stored pyrenes were immersed in water (at room temperature for 24, 48, and 72h) and in hot water (~75°C for 5 and 10-min). Fresh pyrenes germinated up to 84% in control, reaching 100% after water immersion for 48 and 72h. One-year storage reduced germination by almost 50%, but water immersion slightly increased the germination of stored pyrenes. Hot water decreased germination for both fresh and stored pyrenes. Seeds of C. alba may be classified as orthodox seed storage behavior. Taken all together, water treatments at room temperature improved the germination of the pyrenes. In contrast, long-term seed storage and hot-water treatments may jeopardize germination.

Germination, viability and dormancy of 47 species from threatened tropical montane grassland in southeast Brazil: Implications for ex situ conservation.

To mitigate anthropogenic impacts on plant diversity in tropical montane grasslands, one of the most threatened ecosystems in Brazil, it will be essential to develop ex situ conservation strategies to preserve wild species. The lack of basic research on the seed storage behaviour of grassland species may, however, limit their use for reintroduction and restoration projects. We investigated seed storage behaviour at the community level by comparing the effects of cold-low RH (10 °C; 10% RH) and freezing-low RH (20 °C; 10% RH) conditions on seed viability, germination and dormancy of 47 species. Fresh seeds of 43% of the species showed primary dormancy. More than half of the species showed high seed survival responses (viability >60%) under both storage temperatures. Despite a variety of dormancy responses among the different species, the low RH storage conditions tested released dormancy for most species during 12- and 30-month storage times. Multivariate analysis of the best (freezing-low RH, 30 months) storage condition evidenced the formation of five distinct groups, three with species having high conservation potential in seed banks. Although further studies are needed to test dormancy-breaking treatments and improve seed conservation practices, this first approach to assessing seed banking techniques could contribute to demand for locally adapted seeds for ecological restoration projects in tropical montane grasslands.

Desiccation tolerance and sensitivity of selected tropical montane species in Sri Lanka

AbstractAlthough the level of seed desiccation sensitivity (LSDS) may have an impact on plant species conservation, information is available for &lt;10% of tropical angiosperms. A study was conducted to assess the LSDS of 28 tropical montane species in Sri Lanka. Seeds were extracted from freshly collected fruits. Initial weight was recorded, and thousand seed weight (TSW) was calculated. Seed moisture content (MC) was determined. LSDS was determined using seed desiccation experiments and predicted using the TSW–MC criterion. Seed storage behaviour was predicted using LSDS and storage data and using a model based on phylogenetic affiliation. The relationship between LSDS and seed dormancy, life form and forest strata was evaluated. Fresh seeds of only 12 species germinated to &gt;80%. Although seeds of the other species had &gt;80% viability, only 0–70% germinated due to dormancy. Seeds of five species had MC &lt;15%, indicating desiccation tolerance (DT). Seeds of 12 species lost viability after desiccation, indicating desiccation sensitivity (DS). Seeds of Ardisia missionis, Psychotria gartneri and Psychotria nigra remained viable after desiccation, showing DT. Seeds of 17 species were DS and those of 11 species DT. The TSW of four species was &gt;500 g. Thus, seeds of other species were predicted to be DT by the TSW–MC criterion. A relationship was identified between LSDS and the forest strata of the species. More canopy species produced DS than DT seeds. Since seeds of most of the studied species were DS, these species may be threatened due to prolonged droughts predicted for the region due to climate change.