Ungerminated Seeds Research Articles

Seed germination and radicle development in six provenances of Pinus sylvestris L. under water stress

The effects of water stress of the substrate on seed germination and on the first stage of radicle growth were studied in six Pinus sylvestris provenances. Water potentials ranging from 0 to -0.8 MPa under 20 °C conditions were obtained by the use of 6000-Da polyethylene glycol. Decreases in water potential produced a marked reduction in germination percentage and germination value. Significant variations among the provenances were found, and provenances S5 (Culhali) and S6 (Pinarbasi), the southernmost ones, appeared to be less susceptible to water stress. No germination occurred at -0.8 MPa at all, and when the ungerminated seeds at -0.8 MPa were transferred to germinators with saturated filter paper, maximum germination occurred. The effect of water stress ranging from 0 to -0.3 MPa on radicle growth showed that the reaction to variations of the water potential was significantly different among the six provenances. The results were also discussed in relation to the climatic conditions of the zones of s...

Release of Seed Dormancy in Field Plantings of Eastern Gamagrass

Seed dormancy is a main factor limiting the use of eastern gamagrass (Tripsacum dactyloides L.) for forage and conservation purposes; however, there is little available information on the seed bank dynamics of eastern gamagrass plantings. Knowledge of the degree and rate of seed dormancy loss would improve decisions concerning eastern gamagrass plantings and provide a better understanding of the seed bank longevity for this species. In this study, cold, moist stratified seed or unstratified seed was planted at 2.5‐ and 5.0‐cm depths on 16 Aug. 1999, 1 Nov. 1999, 14 April 2000, 15 May 2000, and 16 June 2000 for the first year of the study and 15 Aug. 2000, 31 Oct. 2000, 17 April 2001, 15 May 2001, and 15 June 2001 in the second year. Plants and seeds were retrieved at 3, 6, 9, and 12 mo after planting of 50 seeds for each seed treatment and planting depth combination. Intact seeds were germinated for 28 d and the viability of ungerminated seeds was determined with a tetrazolium test. Seed dormancy of both stratified and unstratified eastern gamagrass seed was lost mostly between mid‐September and mid‐November. No more than 12% dormant seed remained after mid‐December and dormancy was completely lost by April and May. Seed dormancy in eastern gamagrass was substantially reduced with several weeks of soil temperatures below 15°C and adequate soil moisture.

Salinity tolerance during germination of seashore halophytes and salt-tolerant grass cultivars

Direct sowing is the simplest method of plant establishment for restoration and remediation purposes, but relatively few plants can establish under high salinity conditions. In this study, the ability of different seashore plants and grass cultivars to germinate in different dilutions of seawater (0–400 mM NaCl) was tested. Highest germination was found in distilled water or seawater dilutions up to 100 mM NaCl. When seawater concentrations were increased from 100 to 200 mM NaCl, a strong decline in germination percentage and rate was observed in less salt-tolerant species, such as Matricaria maritima and Achillea millefolium. The more salt-tolerant species, Plantago maritima, Juncus gerardii, Artemisia vulgaris, Agrostis spp. and Rumex spp., had a threshold salinity, where germination was significantly decreased in seawater dilutions between 200 and 400 mM NaCl. Even among the salt-tolerant species, only two, Agrostis stolonifera and Artemisia vulgaris, germinated at 400 mM. Variation in salinity response was observed among populations of Artemisia vulgaris and among cultivars of Festuca spp. Increasing salinity to 200 mM NaCl delayed germination in most species. Ungerminated seeds of most salinity-tolerant species were still viable after 21 d at the highest salinity (400 mM), and showed a rapid and high germination when transferred to distilled water. These species would be able to survive high salinity and germinate when the salinity of the sediments decreases through dilution or leaching of salts. The experiment revealed species and cultivars that will be of interest in further testing for restoration and remediation in saline habitats.

Germination of Leitneria floridana Seeds from Disjunct Populations

Attributes of Leitneria floridana Chapman have been recognized, but this North American shrub remains rare in commerce, and little information on propagation is available. We studied germination of seeds collected from several disjunct populations of L. floridana in 2002 and 2003. In 2002, ≤5% germination occurred when ripe drupes from Missouri and Florida were sown soon after collection. Effects of GA3 (750 mg·L-1 for 24 hours) were assessed on stored drupes leached with water and on seeds excised from stored drupes. Germination percentages were 21 and 32 for leached drupes and excised seeds from Florida, respectively, but ≤5% germination occurred among germplasm from Missouri and among untreated drupes from both provenances. Viability of ungerminated seeds among treatments ranged from 0% to 7%. In 2003, fleshy, apparently unripe drupes from Texas, which were scarified with H2SO4 and then treated with 1000 mg·L-1 GA3 showed 48% germination (germination value = 3.9). Up to 29% germination (germination value = 2.7) occurred when seeds were excised from unripe drupes from Arkansas and Missouri and then were treated for 24 hours with 750 or 1000 mg·L-1 GA3. We conclude that provenance, developmental stage of drupes when collected, storage, and pregermination treatments influence viability and germination of seeds of L. floridana. Barriers to germination may be avoided by collecting drupes when they are green and fleshy.

Soaking, moist-chilling, and temperature effects on germination of Acer pensylvanicum seeds

The effect on germination of soaking duration, moist-chilling time, and temperature was evaluated using five seed lots of Acer pensylvanicum L. Seeds were soaked for 0, 48, 72, or 96 h, then moist chilled at 4 °C for 16, 24, or 32 weeks. Two temperature regimes were used for germination: (i) 16 h dark at 5 °C : 8 h light at 15 °C (5:15 °C) and (ii) 16 h dark at 20 °C : 8 h light at 30 °C (20:30 °C). Soaking and chilling seeds significantly increased germination. Germination was highest at 5:15 °C, but the germination speed was slow. Germination at 20:30 °C was lower, but 94%–98% of ungerminated seeds appeared to be viable, suggesting that they were dormant. Overall results showed that soaking seeds for 48 h, moist chilling for 16 weeks, and germinating at 5:15 °C produced an average germination of 92%.

Utilization of protein concentrates from ungerminated and germinated fluted pumpkin (Telfairia occidentalis Hook) seeds in cookie formulations

AbstractCookies (soft type biscuits) were produced from blends of wheat flour containing graded levels (0–25%) of protein concentrates prepared from ungerminated and germinated fluted pumpkin (Telfairia occidentalis Hook) seeds and evaluated for nutritional, baking and sensory properties. Protein quality was investigated using weanling albino rats fed diets that were formulated to supply 10% protein using cookie samples, with casein as a control. Cookies produced from blends containing protein concentrates from germinated seeds had higher contents of crude protein and lower levels of polyphenol and phytic acid, compared with cookies supplemented with concentrates from ungerminated seeds. The use of up to 15% concentrate from ungerminated seeds in the blends produced cookies with spread ratio, hardness, colour and flavour similar to the 100% wheat flour (control) cookies. Cookies supplemented with concentrates from germinated seeds at 15–25% levels were nutritionally comparable to diets based on casein, but at the expense of acceptability. Copyright © 2004 Society of Chemical Industry

Effect of water stress on germination of beechnuts treated before and after storage

Beechnuts from two seedlots were pretreated, without medium, at a controlled moisture content (MC) of 30% before or after 1-year storage at –7 °C. Seeds treated with the two methods were germinated on substrates at decreasing osmotic potential down to –1.2 MPa. A moderate stress of –0.2 MPa caused a slight but significant decrease in germination percentage. Each further increment in water stress produced additional significant decreases in germination capacity. At –1.2 MPa, germination was almost prevented. Seeds pretreated before storage showed lower germination percentage and speed at all osmotic potentials, but this result was due to a marked effect of seed initial MC, rather than a lower resistance to water deficit. In fact, MC of beechnuts pretreated before storage was 8%, whereas beechnuts pretreated after storage started germination tests under water stress with an initial MC of 30%. Moreover, seeds at lower initial MC need more time to imbibe before the germination process can start. Seeds with higher initial MC were probably able to cope better with water deficit, at least during the 30-day germination test in the laboratory. A second experiment carried out on beechnuts treated only before storage but made to have different initial MC seemed to confirm this conclusion. Ungerminated seeds were not damaged, as revealed by a tetrazolium test performed at the end of each germination test. Advantages in nursery practice shown by dry, nondormant beechnuts (pretreated before storage) are discussed in relation to the possibility of sowing when water availability in the soil is not a limiting factor.

Six chemicals with animal repellent or insecticide properties are screened for phytotoxic effects on the germination and viability of ash, birch, Corsican pine and sycamore seeds

Summary As a prelude to direct sowing experiments, a laboratory study was carried out to determine whether six chemicals with insect and/or rodent repellent properties (Aaprotect, Capsaicin, Guardsman, Hallmark, Scuttle, Treeguard) affected the germination capacities and/or viability percentages of European ash (Fraxinus excelsior L.), silver birch (Betula pendula L.), Corsican pine (Pinus nigra ssp. laricio L.) and sycamore (Acer pseudoplatanus L.) seeds. None of the chemical repellents had a significant effect on either the germination capacity or viability of ash or birch seeds. One repellent (Guardsman) significantly reduced the germination capacity of sycamore from 49 to 32 per cent (P ≤ 0.01). Two repellents (Aaprotect and Scuttle) significantly reduced the germination capacity of Corsican pine from 74 to 62 per cent (P ≤ 0.05) and 11 per cent (P ≤ 0.001), respectively. Corsican pine was therefore the most sensitive of the species investigated to phytotoxic effects. Viability percentages (at the end of germination tests on repellent-treated seeds) showed that virtually all ungerminated seeds were dead. Greater phytotoxicity was observed for small-seeded species when they were incubated on a substrate of moist filter paper than when they were sown in moist peat + sand. One explanation is that the larger volume of peat + sand in the seed-tray allowed the chemicals to leach away from the seeds more quickly. Alternatively, perhaps the peat inactivated the chemicals through adsorption. The results are used to exclude certain chemical and tree seed combinations from future seed predation studies associated with direct sowing.

Effects of salinity, light, and temperature on seed germination in a Turkish endangered halophyte, Kalidiopsis wagenitzii (Chenopodiaceae)

Effects of salinity, light, and temperature on the seed germination of an endangered, endemic halophyte, Kalidiopsis wagenitzii Aellen (Chenopodiaceae), were examined. Germination tests were carried out at four salinity levels (0-400 mM) under various alternating temperature regimes and photoperiods. At 5-30 °C, percentage of germination was 99%, but at the highest temperature regime, 25-35 °C, percentage of germination was significantly inhibited. At 400 mM NaCl, few seeds germinated. While percentage of germination of K. wagenitzii seeds was greater in 24-h dark than in 12-h light/12-h dark treatment on salinities less than 200 mM NaCl, there were no differences between percentage germination in light- and dark-germinated seeds above 200 mM NaCl. Recovery of germination of K. wagenitzii seeds from NaCl salinity was studied under various temperature regimes and photo-periods. The percentage of ungerminated seeds that recovered when they were transferred to distilled water varied significantly with change...

Seed dispersal by the Florida box turtle (Terrapene carolina bauri) in pine rockland forests of the lower Florida Keys, United States.

Seed dispersal by animals is one of the most important plant-animal mutualisms, but saurochory, the dispersal of seeds by reptiles, has received little attention. We investigated the role of the Florida box turtle (Terrapene carolina bauri) as a seed dispersal agent in pine rockland forests of the lower Florida Keys and examined the effect of turtle digestion on seed germination. We obtained seeds of 11 species with fleshy fruits and 2 species with non-fleshy fruits (a grass and legume) from the feces of 145 box turtles collected on Key Deer National Wildlife Refuge from 1999 to 2000. We planted the seeds of nine species and germination percentage (percentage of seeds that germinated during the experiment) varied from 10% to 80%. Comparative germination experiments were conducted with Thrinax morrissii, Serenoa repens, and Byrsonima lucida. We compared the germination percentage and germination rate (number of days from planting to seedling emergence) of seeds from three treatments (seeds recovered from feces, control seeds with pulp, and control seeds without pulp) and continued these experiments for up to 2 years. Passage through the box turtle digestive tract greatly enhanced the germination percentage and germination rate of S. repens, but decreased the germination percentage of B. lucida and T. morrissii, and decreased germination rate for T. morrissii. Subsequent destructive seed viability tests revealed that many ungerminated T. morrissii seeds remained viable, suggesting long-term seed dormancy may occur, even after passage through the turtle digestive system. In addition, the proportion of ungerminated seeds which remained viable was greater for seeds recovered from turtle feces than from control seeds with pulp. Furthermore, removal of fleshy pulp either manually or by the turtle digestive system may allow T. morrissii to escape insect predation.

Salinity tolerance during germination in two arid-land varieties of wheat (Triticum aestivum L.)

Soil and water salinity can constrain agricultural production through impairment of germination and growth of early seedlings. Effects of salinity were investigated in two salt-tolerant wheat varieties, Cieta Serros and Maxipak, at germination and early seedling stages. Seeds were treated during germination with either distilled water or one of six concentrations of either NaCI or KCI. Both salts reduced final germination percentage, germination rate and increased the production of abnormal seedlings (i.e., where radicle and/or plumule structures were deformed, missing or incomplete). Low concentrations of either salt (0.05, 0.1 M) had no significant effect on final germination percentage and only slight effects on germination rate. High concentrations (0.2-0.4 M) had significant effects on all three parameters. No germination occurred during a germination recovery control (where ungerminated seeds were transferred to distilled water for recovery for 10 days). This suggests effects of NaCl and KCl may be due to ionic toxicity, rather than osmotic inhibition.

The interaction between salinity stress and seed vigour during germination of soyabean seeds

Seeds of six soyabean (Glycine max (L.) Merr.) cultivars were germinated between paper towels moistened with a range of solutions of both NaCI (32.2 to 421.1 mmolal NaCI) and polyethylene glycol (PEG, 5-30% w/v). The solutions of NaCI and PEG used had the same water potentials within the range -0.23 to -1.9 MPa. After 8d the ungerminated seeds were transferred to towels moistened with deionised water for 7d. Cultivars differed in their response to salinity and failure of seeds to recover from high salinity when transferred to deionised water, revealed the toxicity of NaCl. In contrast, the increase in germination during the recovery period after exposure to PEG suggested that PEG was not toxic. At the same external water potential, the lower mean germination time (MGT) and higher final germination in NaCl than in PEG could be explained by the more rapid imbibition in NaCl solutions and achievement of a moisture content that allowed germination. The influence of seed vigour on the response of soyabean to stress was examined using seeds having high percentage germination but a range of seed vigour, produced by rapid ageing at 15% moisture content (MC) and 45°C for up to 9h. The germination of aged seeds having reduced vigour fell with increased salinity (330, 421 mmolal NaCI) but there was no significant interaction between salinity and seed ageing. Transfer of unaged and aged seeds to 0 MPa after exposure to NaCI resulted in a greater increase in the germination of unaged seeds. The negative correlation of seed leachate conductivity and MGT with the increase percentage germination after transfer to 0 MPa suggested that seed vigour influences the ability of seeds to recover from saline conditions.

Effects of salinity on germination of six salt‐tolerant forage species and their recovery from saline conditions

Seed germination of six forage species under salt stress and their recovery response from saline conditions were studied. The forage species studied were Bromus inermis, Elytrigia elongata, Puccinellia tenuiflora, Hordeum brevisubulatum, Kalidium gracile, and Suaeda salsa. All of these plants are important forage plants in the inland areas of northern China. Seeds were germinated in solutions of 0, 21, 66, 110, 155, 200, 267, 334, 445 mmol/litre NaCl. After a 21‐day period, the ungerminated seeds were removed to Hoagland solution to observe the recovery germination, radicle, and shoot length. The percentage germination of all the species tested, except E. elongata, significantly decreased with increasing salinity (P < 0.01). The lengths of radicles and shoots were increased at 21 mmol/litre NaCl as compared with that in the control, except for S. salsa. Recovery germination and length of radicles and shoots in Hoagland solution increased with increasing salinity in treatment solutions. The recovery germination performances of the six species indicated that inhibition of germination under NaCl stress was induced by osmotic effects. Shoot growth of P. tenuiflora had the highest tolerance to NaCl stress, which suggests why it is the most widely used plant species for saline soil rehabilitation in northern China. The evaluation of salt tolerance in the early stage of growth should emphasise the response of germination and shoot or radicle growth under salt stress.

Germination responses of Sporobolus ioclados: a saline desert grass

Sporobolus ioclados (Nees ex Trin.) Nees (Poaceae), a halophytic grass distributed in coastal and inland regions of Pakistan, is a potential forage crop which could be grown in the degraded saline soils of the Indus plain and coastal areas. Greatest germination was obtained in non-saline control and it was linearly reduced with increases in salinity to 500 m M NaCl. Variation in temperature substantially affected germination in both the saline and non-saline treatments. At the optimal temperature regime of 20:30°C, S. ioclados seeds showed 93% germination at 0 m M NaCl and 18% germination at 500 m M NaCl, respectively. In all other temperature regimes, only 50% of the seeds germinated in 0 m M while none germinated at 500 m M NaCl. Rate of germination decreased with an increase in salinity at all temperature regimes but comparatively higher rates were obtained at 20:30°C. Seeds showed a low recovery response when transferred to distilled water after 20 days of exposure to salinity and tetrazolium viability test showed that most of the un-germinated seeds were dead. The present study showed that if the seed is protected from salinity and temperature stress during storage in the soil, it could germinate during monsoon rains.

Alfalfa Sprouts and Salmonella Kottbus Infection: A Multistate Outbreak following Inadequate Seed Disinfection with Heat and Chlorine

Raw sprouts have been implicated in a number of foodborne disease outbreaks. Because contaminated seeds are usually responsible, many sprout producers attempt to disinfect seeds before germination and detect sprout contamination during production. In March 2001, we detected an increased number of Salmonella serotype Kottbus isolates in California. Overall, we identified 31 cases from three western states. To identify the cause, we conducted a case-control study with the first 10 identified case-patients matched to 20 controls by age, sex, and residential area. Our case-control study found illness to be statistically associated with alfalfa sprout consumption. The traceback investigation implicated a single sprouter, where environmental studies yielded Salmonella Kottbus from ungerminated seeds and floor drains within the production facility. Pulsed-field gel electrophoresis patterns of all patient, seed, and floor drain Salmonella Kottbus isolates were indistinguishable. Most implicated sprouts were from seeds that underwent heat treatment and soaking with a 2,000-ppm sodium hypochlorite solution rather than the Food and Drug Administration (FDA)-recommended 20,000-ppm calcium hypochlorite soak. Other implicated seeds had been soaked in a calcium hypochlorite solution that, when tested, measured only 11,000 ppm. The outbreak might have been averted when screening tests of sprout irrigation water detected Salmonella in January; however, confirmatory testing of these samples was negative (but testing improperly utilized refrigerated irrigation water). Producers should use the enrichment broth of positive screening samples, not refrigerated irrigation water, for confirmatory testing. Until other effective disinfection technologies are developed, producers should adhere to FDA recommendations for sprout seed disinfection.

Some Properties of Proteolytic Enzymes and Storage Proteins in Recalcitrant and Orthodox Seeds of Araucaria

Araucaria bidwillii Hook. and Araucaria cunninghamii Don D. are two species of conifers whose seeds belong to different physiological categories: A. bidwillii seeds are recalcitrant, while A. cunninghamii seeds are orthodox. The extraction of enzymes and storage proteins was carried out from A. bidwillii and A. cunninghamii megagametophytes. The endopeptidase activities of both species were assayed with azocasein and with haemoglobin; the exopeptidase activities were detected by various N-carbobenzyloxy-dipeptides and L-leucine p-nitroanilide. The use of appropriate proteinase inhibitors, i.e. pepstatin A, ethylenediaminetetraacetic acid and trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane, showed the presence of aspartic and metallo proteinases and the absence of the cysteine ones both in A. bidwillii and in A. cunninghamii ungerminated seeds. Since the results do not show differences between the types of enzymes in the ungerminated araucarian seeds and those present in some ungerminated angiosperm seeds (barley, wheat, maize, rice, buckwheat), we conclude that their physiological role is similar. The electrophoretical analyses of soluble and insoluble storage proteins of A. cunninghamii showed patterns similar to those found in other gymnosperms, while the storage protein patterns of A. bidwillii seeds were rather atypical.

Les globoïdes dans les cotylédons d'Helianthus annuus L.: microanalyses, études cytochimiques et cytoenzymologiques dans les graines sèches et en début d'hydratation

One fine analysis (MET) of globoïds and their crystals has been effectuated in the protein bodies of two layers of palisade tissu in the cotyledons of Helianthus annuus. Their distribution (evaluated with the dimensions) had showed the presence of three classes of globoïds in the two layers of our study. The structure and composition of internal crystals could also be different, according to the globoïds of the groups. Those with small dimensions and their amorphous substances, often located in the periphery of cotyledons, have a little content of Al and Zn, comparatively with the great globoids, much frequent inside the cotyledon. Another way, the different crystals contain characteristic elements of phytin. Acid phosphatase activity exists during stage of ungerminated seeds, located either in the periphery of globoïds, or into their contents. In the same way, cytochemical methods were utilized, for the localization of insoluble phosphates, with cytochemical methods.

Light, temperature and burial depth effects on Rumex obtusifolius seed germination and emergence

Trials were carried out to investigate the effects of light and temperature on germination of Rumex obtusifolius L. After several months of storage, seeds gradually lost dormancy and became photosensitive. Thermal optima for germination were between 20 °C and 25 °C in light or in darkness. At lower temperatures there was a greater demand for light, so that the greatest differences in germination percentage (between low and high temperatures) were found within the 10–15 °C temperature range. The calculated thermal minima (x‐intercept method) in light and darkness were 8.3 °C and 6.1 °C respectively. Daily temperature fluctuation increased germination even after seed irradiation with far‐red light, suggesting a lower demand for the far‐red‐absorbing form of phytochrome. Seed burial inhibited germination in proportion to depth; however, germination inhibition was independent of seed phytochrome photo‐equilibrium, which had been diversified by seed pretreatment with light. Seedlings did not emerge when seeds were buried &gt;8 cm deep. Recovery of ungerminated seeds showed that excessive burial did not impede seedling emergence but rather prevented seed germination. However, this induction of dormancy was lost once germination processes were activated (24–48 h at 20 °C) that made germination irreversible. Temperature was also involved in inhibition, and low temperature (&lt;15 °C) induced the least inhibition. This is discussed in terms of processes of respiration and fermentation in buried seeds.

Persistent soil seed banks in Phacelia secunda (Hydrophyllaceae): experimental detection of variation along an altitudinal gradient in the Andes of central Chile (33 S)

Summary It is unclear whether soil seed banks in alpine environments are a result of selection for extended seed dormancy, of ideal conditions for seed preservation in the soil, or a combination of both. The nature of the soil seed bank was investigated in the perennial herb Phacelia secunda (Hydrophyllaceae) through reciprocal burial experiments using seeds obtained from populations growing at 1600, 2200, 2900 and 3400 m a.s.l. in the mediterranean Andes of central Chile. At the four elevations, six replicates of 50 seeds each, from each of the four elevational sources, were buried at 5 cm depth in mesh envelopes, placed in wire cages to protect against predation. Seeds were retrieved 1, 2 and 3 years after burial, and numbers of ungerminated seeds, and of those that remained viable, were determined. At all elevations of seed burial, increasing proportions of seeds remained ungerminated, and proportionately more of the ungerminated seeds remained viable, as elevation of source of seed increased. For seed from low elevation, more seeds remained viable in the soil at the higher burial sites. However, for the seeds from higher elevation sources, seeds remaining viable were similar in number at all sites for seed burial. Half‐lives of seed buried at the source elevation, calculated from the log‐logistic distribution, increased with elevation, and ranged from 188 days at 1600 m to 354 days at 3400 m. The results suggest that the propensity to form a persistent seed bank in P. secunda increases with elevation. Seeds from the highest elevations had the longest persistence, and this was largely unaffected by soil preservation conditions. Seeds from lower elevations survived for less time, and this was modifiable by preservation conditions. These results suggest that both selective effects and soil conditions may be involved in soil seed bank expression in the alpine environment.

Recovery of Germination from Different Osmotic Conditions by Four Halophytes from Southeastern Spain

Seeds of four halophytes from southeastern Spain (the perennials Halocnemum strobilaceum,Arthrocnemum macrostachyum and Sarcocornia fruticosa, and the annual Salicornia ramosissima) were exposed to iso-osmotic stress with NaCl, MgCl2, MgSO4and Na2SO4. The osmotic potential that enforced dormancy in the majority of seeds was determined. The percentage of ungerminated seeds that recovered when they were transferred to distilled water did not differ significantly from the percentage germination of seeds in distilled water controls, irrespective of the salt used to impose the stress. Therefore, the factor responsible for the dormancy of seeds seems to be the decrease in osmotic potential. Such osmotic pretreatments promoted an increase in the rate of recovery germination which, inArthrocnemum macrostachyum and Sarcocornia fruticosa, doubled their rates of germination compared to distilled water controls. The osmotic potentials of the soils where the four species occur naturally were more negative than those allowing seeds to germinate after osmotic stress.