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Worldwide, there is relatively little information on seed dormancy and germination of tropical montane species. Our aim was to help fill this knowledge gap by conducting seed dormancy/germination studies on woody species from this vegetation zone in Hawai'i. All species had water‐permeable seeds with a fully developed embryo. Seeds of 29 species (23 genera) were incubated in light/dark at 15/6, 20/10 and 25/15°C and germination monitored at 2‐week intervals for 16–128 weeks. Seeds of Chenopodium oahuense, Dubautia menziesii and Silene lanceolata were non‐dormant (ND) and those of 26 other species had physiological dormancy (PD); 10 of the 26 species had conditional PD. The optimum germination temperature regime(s) was (were) 25/15°C, 17 species; 25/10 and 20/10°C, 2; 20/10°C, 6; 20/10 and 15/6°C, 2; and 15/6°C, 2. Worldwide, PD in the woody genera included in our study is more common than ND. In addition to its contribution to the world biogeography of seed dormancy/germination, this study will be useful to conservation biologists who need to germinate seeds of tropical montane species. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that seeds of the monocarpic perennial Ferula gummosa from the Mediterranean area and central Asia have deep complex morphophysiological dormancy. We determined the water permeability of seeds, embryo morphology, temperature requirements for embryo growth and seed germination and responses of seeds to warm and cold stratification and to different concentrations of GA3. The embryo has differentiated organs, but it is small (underdeveloped) and must grow inside the seed, reaching a critical embryo length, seed length ratio of 0.65–0.7, before the seed can germinate. Seeds required 9 weeks of cold stratification at <10°C for embryo growth, dormancy break and germination to occur. Thus, seeds have morphophysiological dormancy (MPD). Furthermore, GA3 improved the germination percentage and rate at 5°C and promoted 20 and 5% germination of seeds incubated at 15 and 20°C, respectively. Thus, about 20% of the seeds had intermediate complex MPD. For the other seeds in the seed lot, cold stratification (5°C) was the only requirement for dormancy break and germination and GA3 could not substitute for cold stratification. Thus, about 80% of the seeds had deep complex MPD. The embryo has differentiated organs and must grow inside the seed. Seeds of Ferula gummosa have morphophysiological dormancy (MPD). [ABSTRACT FROM AUTHOR]

No study has yet been carried out on seed development in a cold desert sand dune papilionoid legume. Thus, our primary aims were to (i) monitor seed development in the cold desert sand dune species Eremosparton songoricum from the time of pollination to seed maturity, and (ii) compare seed development in this species with that in other species of papilionoid legumes. Fruit and seed size, mass and seed moisture content, and seed imbibition, germination, desiccation tolerance and water retention during development (pollination to seed maturity) were monitored in the papilionaceous shrub E. songoricum in the Gurbantunggut Desert of northwest China. The duration of seed development was 40 days. Seeds reached physiological maturity 28 days after pollination ( DAP), at which time 58% of them germinated and they had developed desiccation tolerance. Seeds became impermeable 36-40 DAP, when their moisture content was about 10%. The final stage of maturation drying occurred via loss of water through the hilum. The developmental stages and their timing ( DAP) in seeds of E. songoricum are generally similar to those reported for other papilionaceous legumes with a water-impermeable seed coat (physical dormancy). In general, the developmental features of seeds with water-impermeable coats at maturity do not appear to be specific to habitat or phylogeny. [ABSTRACT FROM AUTHOR]

Seeds with a water-impermeable seed coat and a physiologically dormant embryo are classified as having combinational dormancy. Seeds of Sicyos angulatus (burcucumber) have been clearly shown to have a water-impermeable seed coat (physical dormancy [PY]). The primary aim of the present study was to confirm (or not) that physiological dormancy (PD) is also present in seeds of S. angulatus. The highest germination of scarified fresh (38%) and 3-month dry-stored (36%) seeds occurred at 35/20°C. The rate (speed) of germination was faster in scarified dry-stored seeds than in scarified fresh seeds. Removal of the seed coat, but leaving the membrane surrounding the embryo intact, increased germination of both fresh and dry-stored seeds to > 85% at 35/20°C. Germination (80-100%) of excised embryos (both seed coat and membrane removed) occurred at 15/6, 25/15 and 35/20°C and reached 95-100% after 4 days of incubation at 25/15 and 35/20°C. Dry storage (after-ripening) caused an increase in the germination percentage of scarified and of decoated seeds at 25/15°C and in both germination percentage and rate of excised embryos at 15/6°C. Eight weeks of cold stratification resulted in a significant increase in the germination of scarified seeds at 25/15 and 35/20°C and of decoated seeds at 15/6 and 25/15°C. Based on the results of our study and on information reported in the literature, we conclude that seeds of S. angulatus not only have PY, but also non-deep PD, that is, combinational dormancy (PY + PD). [ABSTRACT FROM AUTHOR]

We determined the kind of seed dormancy in Schisandra arisanensis, an ANA grade ([A]mborellales [N]ymphaeales [A]ustrobaileyales) angiosperm with medicinal value. Seeds have small underdeveloped embryos, and following seed maturity their length increased approximately 360% before radicle emergence. Germination was delayed 6-8 weeks, and the percentage and rate were much higher at 15/6, 20/10 and 25/15°C than at 30/20°C. For seeds incubated at 5/5°C (8 weeks) → 15/6°C (4 weeks) → 20/10°C (8 weeks) → 25/15°C (12 weeks) → 20/10°C (5 weeks), embryos grew at 15/6°C → 20/10°C, and almost all seeds that germinated (89%) did so at 20/10°C → 25/15°C. When seeds were incubated in a complementary temperature sequence, 25/15°C (12 weeks) → 20/10°C (8 weeks) → 15/6°C (4 weeks) → 5/5°C (9 weeks) → 15/6°C (4 weeks), embryos grew at 25/15°C → 20/10°C. Nearly all seeds that germinated (93%) did so at 25/15°C → 20/10°C and at 15/6°C following 9 weeks at 5/5°C. Based on the temperature requirements for embryo growth and seed germination, seeds of this species have non-deep simple morphophysiological dormancy (CB). [ABSTRACT FROM AUTHOR]

Seeds of Agalinis fasciculata, a native eastern North American summer annual, were dormant at maturity in autumn and thus did not germinate in light or in darkness at 12/12 h daily temperatures of 15/6, 20/10, 25/15, 30/ 15 and 35/20°C. Buried seeds exposed to natural temperature changes in Lexington, Kentucky (USA) for 53 months came out of dormancy in late autumn and winter and re-entered it in late spring and early summer of each year. Nondormant seeds germinated to 60–100% in light at 20/10°C. Stratification at 5°C broke dormancy, and nondormant seeds entered dormancy during exposure to 25/15 or 30/15°C. Light was required for germination, but some seeds could be light-stimulated during stratification. Seeds stratified in light had a broader temperature range for germination than those stratified in darkness and tested in light. Buried seeds of 11 of the 12 previously-studied native eastern North American summer annuals exhibited seasonal changes in their dormancy states. As buried seeds of the 12 species began to come out of dormancy during winter, they germinated only at high temperatures, but with additional stratification the minimum temperature for germination decreased, which is a Type 2 temperature response pattern. As seeds of A. fasciculata began to come out of dormancy during stratification, they germinated at an intermediate temperature (20/10°C), but with additional stratification the maximum temperature for germination increased and the minimum temperature decreased, which is a Type 3 pattern. This is the first report of a Type 3 pattern in a summer annual and in the Scrophulariaceae. However, the ecological significance, if any, of Type 3 in A. fasciculata seeds is unknown and may reflect more about the past history of the species or its ancestors than it does about present-day ecological adaptations to the habitat. [ABSTRACT FROM AUTHOR]

Seeds of Polemonium reptans var. reptans, a perennial herb of mesic deciduous forests in eastern North America, mature in late May-early June, and a high percentage of them are dormant. Seeds afterripened (came out of dormancy) during summer when kept in a nylon bag under leaves in a nonheated greenhouse or on wet soil in a 30/15°C incubator. The optimum temperature for germination of nondormant seeds was a simulated October (20/10° C) regime. In germination phenology studies in the nonheated greenhouse, 20-30% of the seeds that eventually germinated did so in October, and the remainder germinated the following February and March. Since low (5°C) winter temperatures promote some afterripening (ca. 50%) and do not cause nondormant seeds to re-enter dormancy, seeds that fail to germinate in autumn may germinate in spring. Thus, the taxon has very little potential to form a persistent seed bank. The large spatulate embryos and ability of seeds to afterripen at high temperatures means that seeds of P. reptans var. reptans have nondeep physiological dormancy, unlike many herbaceous woodland species, which have morphophysiological dormancy. [ABSTRACT FROM AUTHOR]

Freshly-matured achenes of Krigia oppositifolia Raf. were buried in soil at near-natural temperatures for 0-35 months and then exhumed and tested in light and darkness at (12/12 hr) daily thermoperiods of 15/6, 20/10, 25/15, 30/15 and 35/20°C. Achenes required light for germination and exhibited an annual dormancy/nondormancy cycle, being dormant in spring and nondormant in autumn. High summer temperatures (30/15, 35/20°C) fully promoted afterripening, whereas low temperatures (5, 15/6°C) prevented it. As buried seeds came out of dormancy in summer, they first germinated at medium temperatures (20/10, 25/15°C), but with additional afterripening the maximum and minimum temperatures for germination increased and decreased, respectively. Thus, during afterripening, achenes exhibit type 3 temperature responses, which otherwise are known only in two perennial Asteraceae and one perennial Liliaceae. The physiological responses of achenes of K. oppositifolia are unlike those of most winter annuals, which have type 1 responses-i.e., the maximum temperature for germination increases during afterripening. Also, they are unlike the majority of Asteraceae, which have type 2 responses-i.e., the minimum temperature for germination decreases during afterripening. Type 1 responses, typical of most winter annuals, have yet to be reported in the Asteraceae. [ABSTRACT FROM AUTHOR]

Lesquerella stonensis (Brassicaceae) is an obligate winter annual endemic to a small portion of Rutherford County in the Central Basin of Tennessee, where it grows in disturbed habitats. This species forms a persistent seed bank, and seeds remain viable in the soil for at least 6 years. Seeds are dormant at maturity in May and are dispersed as soon as they ripen. Some of the seeds produced in the current year, as well as some of those in the persistent seed bank, afterripen during late spring and summer; others do not afterripen and thus remain dormant. Seeds require actual or simulated spring/summer temperatures to come out of dormancy. Germination occurs in September and October. Fully afterripened seeds germinate over a wide range of thermoperiods (15/6-35/20°C) and to a much higher percentage in light (14 h photoperiod) than in darkness. The optimum daily thermoperiod for germination was 30/15°C. Nondormant seeds that do not germinate in autumn are induced back into dormancy (secondary dormancy) by low temperatures (e.g., 5°C) during winter, and those that are dormant do not afterripen; thus seeds cannot germinate in spring. These seed dormancy/ germination characteristics of L. stonensis do not differ from those reported for some geographically widespread, weedy species of winter annuals and thus do not help account for the narrow endemism of this species. [ABSTRACT FROM AUTHOR]

Defining the seed dormancy profile (SDP) of plant communities may provide insight into species adaptive mechanisms, community structure, and dynamics. Golestan National Park (GNP) in Iran consists of different types of vegetation, namely deciduous temperate forest, matorral, and steppe in close proximity but with variability of environmental factors. Plant species, life forms, and kinds of seed dormancy were determined in the three vegetation types, and a SDP of types was generated and compared with corresponding ones in the world database. In all GNP vegetation types, 80%–82% and 2%–3% of the species had dormant (D), and nondormant (ND) seeds, respectively, but in 17% the class of dormancy was unknown. Physiological dormancy (PD) was the most abundant followed by physical dormancy (PY). The species percentage with ND seeds in GNP was significantly two or three times lower than that in the world database. The PD percentage in the matorral was significantly higher than that in the world database. The PY percentage was higher in the forests but lower in the matorral and steppe compared with the world database. The morphophysiological (MPD) dormancy percentage was significantly lower in the forests but higher in the matorral and steppe than in the global database. Seed dormancy profiles were not affected by the proximity of vegetation types in the GNP, but they differed from those of the world database for each vegetation type. The past climatic fluctuations associated with the present‐day seasonality of the region might be the selective pressure for the increased percentage of species with D seeds in the GNP. [ABSTRACT FROM AUTHOR]