Seed Storage Conditions Research Articles

Effect of different conditions of storage on seed viability and seedling growth of six European wild fruit woody plants

Key messageMalus sylvestris(L.) Mill.,Pyrus communis(L.),Sorbus aucuparia(L.),Prunus avium(L.),Prunus padus(L.), andCornus sanguinea(L.) are related, co-occurring species producingorthodoxseeds. However, we observed differences in their response to storage conditions, such as storage at different seed moisture contents (5%, 8%, and 11%) and/or temperatures (− 3 °C, − 18 °C, and − 196 °C). Severe desiccation to ca. 5% of MC negatively affected seeds ofM. sylvestris. Seeds ofP. aviumwere sensitive to storage in LN or at − 18 °C.S. aucupariaseeds are best stored at − 3 °C, whereasC. sanguineaseeds tolerate desiccation and storage in LN. In general, species with deeper physiological dormancy (S. aucuparia,P. padus, andC. sanguinea) tended to be more tolerant to desiccation and low temperatures. For all species, storage conditions did not affect seedling growth.ContextWild fruit woody species face many threats such as genetic loss, population fragmentation, and alien species; thus, their genetic variability should be preserved.AimsTo examine the effect of storage conditions on seed viability and the initial growth of seedlings of six European wild fruit species: Malus sylvestris (L.) Mill., Pyrus communis (L.), Sorbus aucuparia (L.), Prunus avium (L.), Prunus padus (L.), and Cornus sanguinea (L.).MethodsSeeds were desiccated to three different levels of moisture content (ca. 5, 8, or 11%) and stored at three different temperatures (− 3°, − 18°, or − 196 °C; liquid nitrogen, LN) for up to 3 years. Germination and seedling emergence tests were performed as well as measurement of seedling growth.ResultsDesiccation of M. sylvestris seeds from 10.7 to 4.9% significantly lowered germination from 91 to 77% and seedling emergence from 88 to 74%. In P. avium, LN storage significantly inhibited seedling emergence, both in the laboratory and the greenhouse, but did not affect total seed germination. In P. communis, P. padus, and C. sanguinea, neither germination nor seedling emergence was affected by seed storage conditions. There were small or no differences in stem height and root collar diameter in the first year of seedling growth of stored seeds.ConclusionSpecies with deeper physiological dormancy (S. aucuparia, P. padus, C. sanguinea) tended to be more tolerant of various storage conditions. Seeds of P. padus and C. sanguinea can be stored long term at − 18 °C or in LN at 5–8% MC without losing viability. M. sylvestris and P. avium seeds are sensitive to desiccation below 6% MC or low temperature of storage at − 18 °C or − 196 °C, respectively. We observed that storage conditions had significant influence on germination and seedling emergence but had no effect on seedling growth after the first growing season.

Seed Longevity of Enterolobium contortisiliquum (Vell.) Morong

Abstract: Seed storage under controlled temperature and humidity maintains the viability and the vigor of seeds for a long time while preserving their longevity. Ex situ conservation in a seed storage chamber is perfect for simulating the cool dry conditions that are associated with long-term seed storage. This helps to preserve the availability of seeds for the recovery of degraded areas and to ensure a supply of propagating material for various purposes in silvicultural production, or as raw materials for biotechnological use. The present work evaluated the physical and physiological quality of Enterolobium contortisiliquum (Vell.) Morong seeds from an ex situ collection that was kept in a seed storage chamber at 6 °C ± 3 °C and with 60% ± 5% of RH in waterproof packaging. The water content, the physical quality by X-ray tests, germination, electrical conductivity, and the integrity and quality of RNA that was extracted from the embryonic axes were all determined. It was possible to identify full, damaged, malformed, translucent, and empty seeds. The seeds that had been stored for 1, 5, 9, and 10 years presented 78, 82, 42, and 38% of normal seedlings, respectively, while the lots of 6 and 7 years presented 0 and 6%. The seed storage conditions were the same for all of the lots. A water content higher than 6% influenced the quality of the seeds. The E. contortisiliquum seeds demonstrated high longevity. They could be stored for up to 10 years under controlled conditions.

Optimal long-term seed storage conditions for the endangered seagrass Zostera japonica: implications for habitat conservation and restoration

BackgroundSeagrass meadows are recognized as critical and among the most vulnerable habitats on the planet. The alarming rates of decline in seagrass meadows have attracted the attention globally. There is an urgent need to develop techniques to restore and preserve these vital coastal ecosystems. So far little work has been done to develop effective long-term storage method for seagrass seeds. The seagrass Zostera japonica Asch. & Graebn is an endangered species in its native range. Here we utilized combinations of different storage times, salinities, and temperature to determine the most appropriate conditions for optimal seed storage.ResultsZostera japonica seeds were strongly desiccation sensitive, with a complete loss of viability after 24 h of desiccation. Therefore, long periods of exposure to air should be avoided to minimize seed mortality. In addition, Z. japonica seeds could not endure freezing conditions such as – 5 °C. However, our results indicated that reduced storage temperature to 0 °C could effectively prolong the duration of dormancy of Z. japonica seeds. Seeds stored at 0 °C under a salinity of 40–60 psu showed relatively low seed loss, high seed vigor and fast seed germination, suggesting these to be optimal seed storage conditions. For example, after storage for 540 days (ca. 600 days since the seed collection from reproductive shoots in early October, 2016) at 0 °C under a salinity of 50 psu, seeds still had a considerable vigor, i.e. 57.8 ± 16.8%.ConclusionOur experiments demonstrated that seeds stored at 0 °C under a salinity of 40–60 psu could effectively prolong the duration of dormancy of Z. japonica seeds. The proposed technique is a simple and effective long-term storage method for Z. japonica seeds, which can then be used to aid future conservation, restoration and management of these sensitive and ecologically important habitat formers. The findings may also serve as useful reference for seed storage of other threatened seagrass species and facilitate their ex situ conservation and habitat restoration.

Seed selection and storage with nano-silver and copper as potential antibacterial agents for the seagrass Zostera marina: implications for habitat restoration

Globally, seagrass meadows are extremely important marine ecosystems that are disappearing at an alarming rate. Therefore, research into seagrass restoration has become increasingly important. Various strategies have been used in Zostera marina L. (eelgrass) restoration, including planting seeds. To improve the efficiency of restoration by planting seeds, it is necessary to select high-quality seeds. In addition, a suitable antibacterial agent is necessary for wet storage of desiccation sensitive seeds to reduce or inhibit microorganism infection and seed decay. In the present study, an efficient method for selecting for high-quality eelgrass seeds using different specific gravities of salt water was developed, and potential antibacterial agents (nano-silver and copper sulfate) for seed storage were assessed. The results showed that the highest proportion of intact seeds (72.91 ± 0.50%) was recorded at specific gravities greater than 1.20. Therefore, specific gravities greater than 1.20 can be used for selecting high-quality eelgrass seeds. During seed storage at 0 °C, the proportion of intact seeds after storage with nano-silver agent was over 90%, and also higher than 80% with copper sulfate agent, which was significantly higher than control treatments. The findings revealed a potential selection method for high-quality seeds and long-term seed storage conditions for Z. marina, which could facilitate conservation and habitat restoration.

Seed Germination and Viability in African Teak, Milicia excelsa (Welw.) C.C. Berg- (Moraceae) - a promising timber tree

The occurrence of Milicia excelsa (Welw.) C.C. Berg, native to tropical Africa, commonly known as African Teak is reported in the forest plantation area of Alimukku, Punalur Forest Division, Kollam District, in Kerala (Sabu et al, 2018). An attempt is made to popularize and conserve this highly promising tree having multipurpose use, by raising seedlings through standardized seed germination protocols and evolving suitable seed storage conditions.

Effects of seed storage conditions on seed water uptake, germination and vigour in Pinus dabeshanensis, an endangered pine endemic to China

Effects of seed storage conditions on seed water uptake, germination and vigour in <i>Pinus dabeshanensis</i>, an endangered pine endemic to China

Abscisic acid-determined seed vigour differences do not influence redox regulation during ageing.

High seed quality is a key trait to achieve successful crop establishment required for optimum yield and sustainable production. Seed storage conditions greatly impact two key seed quality traits; seed viability (ability to germinate and produce normal seedlings) and vigour (germination performance). Accumulated oxidative damage accompanies the loss of seed vigour and viability during ageing, indicating that redox control is key to longevity. Here, we studied the effects of controlled deterioration at 40°C and 75% relative humidity (RH) ('ageing') under two different O2 concentrations (21 and 78% O2) in Brassica oleracea Two B. oleracea genotypes with allelic differences at two QTLs that result in differences in abscisic acid (ABA) signalling and seed vigour were compared. Ageing led to a similar loss in germination speed in both genotypes that was lost faster under elevated O2 In both genotypes, an equal oxidative shift in the glutathione redox state and a minor loss of α-tocopherol progressively occurred before seed viability was lost. In contrast, ABA levels were not affected by ageing. In conclusion, both ABA signalling and seed ageing impact seed vigour but not necessarily through the same biochemical mechanisms.

INFLUENCE OF SEED STORAGE CONDITIONS ON QUALITY OF Torresea acreana SEEDLINGS

ABSTRACT The plant vigor defined in the laboratory may not indicate the final quality of seedlings produced under nursery conditions, or even their survival in plantations. So, we evaluated the influence of the storage conditions of Torresea acreana seeds on its emergence, as well as, on the morphological quality of produced seedlings. Seeds were collected in October/2011, packed, transported, conditioned in closed glas pots and stored in three environments for a period of 462 days. The treatments consisted of seedlings produced from seeds: 1 - without storage (control), 2 - stored in a dry chamber, 3 - stored in a humid chamber, and 4 - stored in an uncontrolled environment (laboratory). Sowing was performed in 50 cm³ plastic tubes filled with decomposed pine bark and coconut fiber (50/50 v/v) which were packed in a glasshouse. The study analyzed the percentage of emergence, mean seedlings emergence time, stem diameter, total height, ratio between total height and stem diameter, shoot length, mean root length, total dry biomass, root dry biomass, shoot dry biomass, and Dickson quality index. Seed storage proved to be a negative factor for the emergence and vigor of T. acreana seedlings. The vigor of the seeds is a preponderant factor to increase the morphological quality of the seedlings.

Aflatoxin B1 (AFB1) production by Aspergillus flavus and Aspergillus parasiticus on ground Nyjer seeds: The effect of water activity and temperature

Nyjer oil seed cake supports high levels of aflatoxin B1 (AFB1) production. AFB1 is a secondary metabolite of Aspergillus flavus and A. parasiticus, classified as a Class 1A carcinogen. The aim of this study was to determine the effects of temperature (20, 27, and 35 °C) and water activity (0.82, 0.86, 0.90, 0.94, and 0.98 aw) on fungal growth and AFB1 production of A. flavus and A. parasiticus on ground Nyjer seeds over a 30-day incubation period.Linear regression models indicated that both fungal growth and AFB1 production were significantly influenced by water activity of Nyjer seeds and incubation temperature. The two fungi did not grow on Nyjer seeds at 0.82 aw at the three incubation temperatures. The most favorable growth conditions for both fungi were 0.90–0.98 aw at 27 °C or 0.90–0.94 aw at 35 °C. The optimum temperature for AFB1 production was 27 °C for both A. flavus and A. parasiticus (with regression coefficients of 6.01 and 9.11, respectively). Both fungi were likely to produce high levels of AFB1 at 0.90 aw (with regression coefficients of 3.56 for A. flavus and 7.17 for A. parasiticus). Aspergillus flavus only produced AFB1 on seeds with 0.90–0.98 aw at 27 °C (in the range of 203–282 μg/kg) and on seeds with 0.90 aw at 35 °C (212 μg/kg). No detectable AFB1 was produced by this fungus in any other culture conditions that were studied.Aspergillus parasiticus, in contrast, was able to produce AFB1 under all of the growth conditions. At 20 °C, this fungus produced the highest level of AFB1 (212 μg/kg) at high water activity (0.98 aw). At 27 °C, A. parasiticus produced high levels of AFB1 (in the range of 209–265 μg/kg) at a wide range of water activities (0.86–0.98 aw). In the entire study, the highest AFB1 concertation for A. parasiticus was detected on seeds incubated at high temperature (35 °C) and low water activity (0.86 aw). The findings of this study could help optimize the storage conditions of Nyjer oil seeds to reduce aflatoxin contamination.

저장온도 및 종자 처리가 봄파종 인삼 출아와 생장에 미치는 영향

Background: In Korea, seeds of Panax ginseng C. A. Meyer need to be stored under cold temperature and high humidity condition for months to break physiological dormancy, making storage difficult until spring-sowing. This study was conducted to test the effects of seed storage conditions and seed treatment on the emergence of seedling after spring-sowing in a nursery greenhouse. BR Methods and Results: After dehiscence, endocarp dried seeds in mild or completely, and wet seeds were stored in 2℃ and -3.5℃ during winter. Storage at -3.5℃ resulted in a lower emergence rate (ER) than that at 2℃, and additional cold (2℃) treatment before or after storage at -3.5℃ increased the ER. Endocarp dehydration prevented pre-germination at 2℃ storage and increased the ER of seeds stored at -3.5℃. ER was also dependent on the batch of seeds. However, seed treatments before sowing had only limited effects on ER. Root loss was the main reason for damping-off; prolonged cold storage of seeds increased damping-off, as the detection of pathogens was not high.BR Conclusions: This study showed that storage conditions such as temperature and moisture content of seeds, affect the ER after spring-sowing and vitality of seedlings, suggesting further attention on seed control for secure seedling stands after spring-sowing.

Seed storage behaviour of eight peatland pool specialists: Implications for restoration

Seed introduction is a current practice for the conservation and restoration of plant populations and communities. In many cases, however, seeds of target wild species must be collected from natural populations and then stored in proper conditions until re-introduction. Peatland pool margin specialists rarely recolonize their habitat once a peatland is restored following peat extraction and therefore must be actively reintroduced. However, little is known about the storage conditions promoting seed viability. In this context, we investigated the effects of four storage conditions on the seed viability of eight species collected from natural peatland pool margins of eastern Canada: 1) room temperature, dry conditions, 2) cold temperature, dry conditions, 3) cold temperature, moist conditions, and 4) cold temperature, submerged. Seeds stored for one year were periodically (3, 6, 12 months) tested for viability using 2,3,5-triphenyltetrazolium chloride staining. Seed viability decreased after storage for four of the eight species investigated (Carex echinata, C. magellanica, C. oligosperma, and C. pauciflora) and increased for Rhynchospora alba, but did not vary significantly following storage for C. limosa and Scheuchzeria palustris. Furthermore, the viability of Drosera intermedia and Rhynchospora alba seeds was higher when stored in dry conditions relative to moist or submerged conditions. Proper seed storage conditions are thus highly species-dependent. Direct sowing after collection should be preferred for most of the Carex species, while seeds of Scheuchzeria palustris, Drosera intermedia and Rhynchospora alba could be stored, preferably in dry conditions, without impacting introduction success due to reduced seed viability.

Extending Populus seed longevity by controlling seed moisture content and temperature.

The poplar species Populus davidiana and P. koreana are widely grown in plantations and as biofuel resources, but little is known about ex-situ seed conservation in poplar. To identify the optimal long-term seed storage conditions for these species, we evaluated the viability of seeds with different seed water contents (SWCs) at various storage temperatures and time periods. P. davidiana seeds with <6% SWC could be stored at room temperature (RT) for 4 weeks, while P. koreana seeds showed no storability at RT. P. davidiana seeds with 3% SWC showed 74% viability after 36 months of storage at 4°C, while those with 9–18% SWC showed >89% viability after 48 months of storage at -18°C. Long-term storage at -80°C was best for P. davidiana seeds with a wide range of SWCs (3–24%), with 91–98% of normal germination after 48 months of storage. However, the normal germination of P. koreana seeds with 3–24% SWC declined to <20% after 36 months of storage, even at -18°C and -80°C. No significant difference was observed between seeds immersed vs. not immersed in liquid nitrogen for both species. Our findings increase the possibility for long-term seed conservation for both Populus species.

Chemical Deterioration of Lotus Seeds During Storage

AbstractStarch, protein and lipids, the major components in lotus seeds, affected taste and cooking properties of the food. The chemical compositions, gelatinization properties, crystal structure of the starch, compositions of fatty acids and soluble protein of lotus seeds, stored for 24 months, 12 months and as fresh were studied. The overall starch, protein and lipid contents in lotus seeds remained unchanged during storage, but structural changes occurred. The contents of amylose and free fatty acid increased significantly during prolonged storage, but the solubility of protein decreased dramatically. The increases of onset temperature, peak temperature and gelatinization enthalpy of lotus seed starch were also studied by a differential scanning calorimetry. Its content especially for disulfide bonds, increased from 63.24 to 95.59 μ mol/g. All changes had significant correlation with storage time and ultimately denatured the sensory quality of selected aged lotus seeds. The study could be conductive to fresh lotus seed discrimination from stale seed, and dynamic monitoring of lotus seed, by determination chemical deterioration of lotus seeds during storage.Practical ApplicationsThis study is helpful to discriminate fresh lotus seed from stale seed, and explain aging mechanism, and put forward the improvement measures of lotus seed storage conditions.

Seed Source May Determine Field‐Specific Germination and Emergence: The Source by Planting Environment Interaction

ABSTRACTFarm environmental conditions and management practices can result in within‐cultivar differences in seed quality and lead to transgenerational plasticity (farm‐specific effects on offspring, or TGP) that affect germination and emergence in transplant fields. We used three perennial bunchgrasses, [green needlegrass (Nassella viridula) ‘Lodorm’, slender wheatgrass (Elymus trachycaulus) ‘Pryor’, and bluebunch wheatgrass (Pseudoregneria spicata) prevariety registered germplasm P‐7] to determine if seeds exhibited TGP. We also determined if TGP was affected by the interaction between production farms and planting environments (farm × environment interaction, or context‐dependent TGP), using four laboratory temperature regimes to test germination response and four field environments to test emergence response in 2013. We stored seeds in four different environments for 10 mo before repeating the experiment to test if recent seed storage conditions mitigated TGP. Context‐dependent TGP affected emergence for Pryor and Lodorm both years, however, only Pryor exhibited context‐dependent TGP for germination in 2013. Sources with low germination and emergence in the field were less likely to exhibit context‐dependent TGP. Some transplant fields did not show differences among sources, but in other transplant fields, emergence increased as much as 24% depending on farm source. The effect of recent seed storage conditions, significant only for Pryor, was opposite for germination and emergence, with room‐temperature stored seeds exhibiting the highest emergence and lowest germination. Context‐dependent TGP in emergence could not be predicted by our coarse information regarding seed production environments and storage conditions or by germination in the lab. Nonetheless, context‐dependent TGP significantly determined emergence in two of the three study species. Mechanisms underlying this phenomenon need further study to understand potential benefits and pitfalls for producers and seed buyers.

Rye seeds endurance for storage under model experiment

The aim and tasks of the study. Determination of the optimal seed storage conditions for rye seed samples after monitoring results under model experiment.Materials and methods. The material for the study were samples of seeds of rye: sterility maintainers L.1201 B L.961358 B L.90691 B L.120337 B; hybrid populations: Koroleva, Kharkiv'yanka and sterile line L.1201 A, L.90691A. Seeds were dried to moisture content 5, 6, 7% and kept in conditions of model experiment "accelerated aging" at 37 °C during 12 months. Monitoring of seed viability was performed after 4, 8 and 12 months of storage by seed germination test and length of seedlings.Results and discussions. In model terms "artificial aging for 12 months" conducted monitoring of the seed lines and varieties of rye with a moisture content of 5-7% in terms of vigor, germination and seedling length. The low humidity conditions can be traced decisive influence genotype than the variation of the moisture content in the investigated range.Seed germination after 4, 8, 12 months of seed storage under modeling conditions have lower indexes for lines L.1201 A, L.90691 A, compared with the majority of sterility maintainers and rye varieties. The length of the seedlings doesn’t always image the influence of storage conditions on the population status of seeds. There was advantages of the effect of genotype on seed moisture level in the range of 5-7% for the life of theConclusions. The most of the samples of rye in the conditions of model experiment show the benefits of endurance to store seeds with moisture content 5 and 6 %. There was a lower performance storage capacity for sterile lines L.1201 A, L.90691 A than majority- sterility maintainers and hybrids of rye. Seedling length does not always demonstrate the effect of storage conditions influence on the state of populations seeds.

Threatened Native Trees in Guam: Short-term Seed Storage and Shade Conditions Influence Emergence and Growth of Seedlings

Seedling emergence and growth traits of three rare and threatened tree species in the Mariana Islands were studied within a range of incident light levels and up to 9 months of seed storage. Seedling emergence percentage and velocity were maximized in moderate shade for Elaeocarpus joga Merr., deep shade for Serianthes nelsonii Merr., and full sunlight for Tabernaemontana rotensis (Kaneh.) P.T. Li. Seedling height was increased by shade for E. joga and S. nelsonii. Height of T. rotensis seedlings was not influenced by incident light from 25% to 100%. Nine months of seed storage at ambient temperature did not influence emergence percentage of E. joga or S. nelsonii seeds. In contrast, seeds of T. rotensis began declining in seedling emergence percentage between 2 and 3 months of storage, and seedling emergence was nil by 4 months. This study represents the first experimental approach to determining the influences of light and storage on seed and seedling behavior for any rare and threatened taxa from the Mariana Islands. Our findings that revealed highly contrasting responses among the species provide a valuable start to building the knowledge base needed to respond to formal recovery or conservation plans by defining horticultural protocols for managing a conservation nursery.

Germination of seeds of Avena fatua L. under different storage conditions

Storage conditions have a strong influence on the germination of seeds of &lt;em&gt;Avena fatua&lt;/em&gt; L, especially at variable conditions, the germination decreased. Seeds stored at a constant low temperature maintained the germination capability for 5 years. Under greenhouse conditions, seeds matured and germinated more rapidly comparing to field conditions, but individuals from these seeds were weaker and produced fewer seeds. The higher temperature in the greenhouse accelerated the development and maturing of plants. Field emergence varied depending on seed storage conditions, sample, further reproduction, and weather conditions. It was observed that individual specimens of &lt;em&gt;A. fatua&lt;/em&gt; were able to form ripe seeds with high thousand grain mass (TGM), regardless of the occurrence of fungal diseases. The knowledge of the biology of &lt;em&gt;A. fatua&lt;/em&gt; is very important due to its status as a restricted weed in certified seed of crop plants.

Impact of storage conditions on seed germination and seedling growth of wild oat (Avena fatua L.) at different temperatures

The influence of seed storage conditions and different temperatures (5?C, 10?C, 15?C, 20?C, 25?C, 30?C and 26?C/21?C) during germination and seedling development on seed germination, shoot length and germination rate of wild oat (Avena fatua L.) was examined. Germinated seeds were counted daily over a period of ten days and shoot length was measured on the last day, while germination rates were calculated from those measurements. The results showed that seed storage under controlled conditions (T1: temperature 24?1?C, humidity 40-50%; T2: temperature 26?1?C, humidity 70-80% and T3: temperature 4?C) for periods of 3 (t1) and 12 (t2) months had a significant influence on germination of wild oat seeds. The percentage of germinated seeds under all examined temperatures was higher when they were stored for 12 months under controlled temperature and humidity. The results also showed that temperature had a significant effect on the percentage of germination and germination rate of A. fatua seeds. The highest total germination occurred at 15?C temperature (T1: t1 - 41.25%, t2 - 44.37%; T2: t1 - 28.13%, t2 - 34.37%; T3: t1 - 10.63%, t2 - 12.50%). Germination percentage under an alternating day /night photoperiod at 26?C/21?C temperature was higher in all treatment variants (T1: t1 - 8.13%, t2 - 10.00%; T2: t1 - 11.87%, t2 - 13.13%; T3: t1 - 2.42%, t2 - 2.70%) than germination in the dark at 25?C, 30?C and 5?C.

ARMAZENAMENTO DE SEMENTES DE IPÊ-AMARELO-DO-BREJO (&lt;i&gt;Handroanthus umbellatus&lt;/i&gt; (Sond.) Mattos. Bignoniaceae)

http://dx.doi.org/10.5902/1980509815725A manutenção da viabilidade das sementes por meio do armazenamento, em condições de ambiente controlado, representa uma das linhas de pesquisa mais importantes para espécies florestais com sementes pouco longevas como as das espécies do gênero Handroanthus. Nesse trabalho procurou-se identificar o comportamento das sementes quanto à longevidade e à condição mais adequada para o armazenamento de sementes de Handroanthus umbellatus. As sementes foram secas até 6,3% de teor de água e submetidas aos seguintes tratamentos de armazenamento: acondicionamento em sacos de papel unifoliado (permeável) em condições não controladas de temperatura e umidade relativa de laboratório (testemunha) e multifoliados (semipermeável) nas temperaturas de -18ºC, 1ºC e 25oC. As sementes armazenadas foram avaliadas trimestralmente até 24 meses quanto ao teor de água, à porcentagem de germinação e ao vigor por meio do teste da primeira contagem. As sementes de Handroanthus umbellatus são ortodoxas, mas de baixa longevidade em condições naturais, pois se mantêm viáveis no ambiente por menos que 5 meses. A melhor condição para a conservação de sementes dessa espécie foi obtida com o armazenamento a -18ºC em sacos multifoliados, que manteve praticamente inalterada a qualidade fisiológica das sementes por 24 meses.

Environmental control of germination in semi-arid Mediterranean systems: the case of annuals on gypsum soils

AbstractWhether or not it is time for germination is a dilemma for annuals since they have only a single opportunity to reproduce successfully. This is critical for species living in stressful and unpredictable environments such as Mediterranean habitats. In order to clarify the environmental cues of germination, four annuals of different families, all of them occurring very frequently on gypsum soils, were selected and their germination observed under 14 climate scenarios, mimicking temperature and photoperiod conditions from autumn to spring, at two levels of water availability (continuous irrigation versus an initial single irrigation event followed by a progressive soil desiccation). In spring scenarios, two seed-storage conditions were compared: dry cold and room conditions. In the absence of water limitation, germination decreased from early autumn to late spring. Water scarcity always reduced germination, especially in early spring. Our results suggest a facultative winter germination behaviour and highlight the crucial role of dry cold storage in reducing spring germination. In conclusion, Mediterranean ephemerals showed a very plastic germination response that allows them to take advantage of favourable environmental conditions from autumn to spring. This environmental cueing is combined with the ability to dilute the risk through a variable rate of seed dormancy that, according to bet-hedging strategies, increases from secure autumn to riskier spring.