Deep complex morphophysiological dormancy in Sanicula europaea (Apiaceae) fits a recurring pattern of dormancy types in genera with an Arcto-Tertiary distribution

Genus Sanicula encompasses about 40 species, mainly from temperate deciduous forests and exhibiting an Arcto-Tertiary relict distribution. It has previously been shown that stasis in physiological traits, such as seed dormancy, can occur in genera with an Arcto-Tertiary disjunct distribution. The aim of this study was to determine the requirements for dormancy break and seed germination in the Eurasian woodland herb Sanicula europaea L. Comparing our results with other Apiaceae in a phylogenetic and biogeographic framework enables us to determine whether stasis in seed dormancy has occurred in Sanicula. Experiments under natural conditions showed that the embryo elongates within the seed during winter, when temperatures are low. Seeds of S. europaea germinated immediately after growth of the embryo was completed, and seedlings subsequently emerged when temperatures had risen in spring. A series of tests under temperature-controlled conditions revealed that growth of the embryo and physiological dormancy break occur simultaneously at low temperatures (5 °C), irrespective of a pre-treatment at high temperatures. These results contrast with the dormancy traits of several eastern North American Sanicula species, which presumably require a high temperature pre-treatment before chilling becomes effective. This geographical distribution pattern of seed dormancy traits has also been established independently in several other Arcto-Tertiary relict genera.

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The great diversity in kinds of seed dormancy: a revision of the Nikolaeva–Baskin classification system for primary seed dormancy

Seed Science Research ◽

10.1017/s096025852100026x ◽

2021 ◽

pp. 1-29

Author(s):

Jerry M. Baskin ◽

Carol C. Baskin

Keyword(s):

Seed Dormancy ◽

Seed Coat ◽

Classification System ◽

Primary Dormancy ◽

Morphophysiological Dormancy ◽

Physiological Dormancy ◽

Whole Seed ◽

Dust Seeds ◽

Impermeable Seed Coat ◽

Morphological Dormancy

Abstract This review provides a revised and expanded word-formula system of whole-seed primary dormancy classification that integrates the scheme of Nikolaeva with that of Baskin and Baskin. Notable changes include the following. (1) The number of named tiers (layers) in the classification hierarchy is increased from three to seven. (2) Formulae are provided for the known kinds of dormancy. (3) Seven subclasses of class morphological dormancy are designated: ‘dust seeds’ of mycoheterotrophs, holoparasites and autotrophs; diaspores of palms; and seeds with cryptogeal germination are new to the system. (4) Level non-deep physiological dormancy (PD) has been divided into two sublevels, each containing three types, and Type 6 is new to the system. (5) Subclass epicotyl PD with two levels, each with three types, has been added to class PD. (6) Level deep (regular) PD is divided into two types. (7) The simple and complex levels of class morphophysiological dormancy (MPD) have been expanded to 12 subclasses, 24 levels and 16 types. (8) Level non-deep simple epicotyl MPD with four types is added to the system. (9) Level deep simple regular epicotyl MPD is divided into four types. (10) Level deep simple double MPD is divided into two types. (11) Seeds with a water-impermeable seed coat in which the embryo-haustorium grows after germination (Canna) has been added to the class combinational dormancy. The hierarchical division of primary seed dormancy into many distinct categories highlights its great diversity and complexity at the whole-seed level, which can be expressed most accurately by dormancy formulae.

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Classification and ecological relationships of seed dormancy in a seasonal moist tropical forest, Panama, Central America

Seed Science Research ◽

10.1017/s0960258507708127 ◽

2007 ◽

Vol 17 (2) ◽

pp. 127-140 ◽

Cited By ~ 33

Author(s):

Adriana Sautu ◽

Jerry M. Baskin ◽

Carol C. Baskin ◽

Jose Deago ◽

Richard Condit

Keyword(s):

Tropical Forest ◽

Seed Dormancy ◽

Tree Species ◽

Panama Canal ◽

Physical Dormancy ◽

Ecological Relationships ◽

Morphophysiological Dormancy ◽

Large Size ◽

Physiological Dormancy ◽

Dry Seasons

AbstractThis is the first study to determine the class of seed dormancy (or non-dormancy) of a large number of native tree species in a tropical forest, the seasonal moist tropical forest of the Panama Canal Watershed (PCW), or to test the relationships between class of dormancy (or non-dormancy) and various seed and ecological characteristics of the constituent species. Fresh seeds of 49 of 94 tree species were non-dormant (ND), and 45 were dormant (D). Seeds of 23 species had physiological dormancy (PD), 13 physical dormancy (PY), two morphological dormancy (MD), 7 morphophysiological dormancy (MPD) and none combinational dormancy (PY+PD). Seeds with PY were significantly smaller ( < 0.1 g) and drier (moisture content < 16%) at maturity than those that were ND or in the other D classes. Seeds of 62, 42 and 53% of species dispersed in the early rainy, late rainy (LRS) and dry seasons, respectively, were ND. The majority (61%) of species with PD seeds, but only 17% of those with PY seeds, were dispersed in the LRS. The proportion of species with ND seeds was higher in large-size (63%) than in mid-size (35%) and understorey (17%) trees, but differed only slightly between non-pioneers (58%) and pioneers (54%). The proportion of species with D seeds increased only slightly through a precipitation gradient of about 3100 to 1900 mm in the PCW; however, PY increased from 19 to 32% and PD decreased from 63 to 44%.

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Underdeveloped embryos in dwarf seeds and implications for assignment to dormancy class

Seed Science Research ◽

10.1079/ssr2005224 ◽

2005 ◽

Vol 15 (4) ◽

pp. 357-360 ◽

Cited By ~ 21

Author(s):

Carol C. Baskin ◽

Jerry M. Baskin

Keyword(s):

Seed Dormancy ◽

Evolutionary Relationship ◽

The Other ◽

Length Ratio ◽

Morphophysiological Dormancy ◽

Physiological Dormancy ◽

Radicle Emergence ◽

Relationship Of ◽

Embryo Length ◽

Morphological Dormancy

Studies were conducted to determine if small embryos (i.e. low embryo length:seed length ratio) in mature dwarf seeds (0.2–2 mm) are underdeveloped. In this case, they would grow (inside the seed) prior to germination, and seeds would have morphological or morphophysiological dormancy. Prior to radicle emergence, embryo length in seeds of Drosera anglica (Droseraceae), Campanula americana, Lobelia appendiculata, L. spicata (Campanulaceae) and Sabatia angularis (Gentianaceae) increased 0, 103, 182, 83 and 57%, respectively. Since embryo growth did not occur in seeds of D. anglica prior to germination, embryos, although small, are fully developed; seeds have only physiological dormancy. The underdeveloped embryo in seeds of C. americana has little or no physiological dormancy; thus, seeds have morphological dormancy. On the other hand, underdeveloped embryos in seeds of L. appendiculata, L. spicata and S. angularis are physiologically dormant, and seeds have morphophysiological dormancy. Therefore, since small embryos in dwarf seeds may or may not be underdeveloped, assignment of seeds to a dormancy class requires that studies be done to determine if embryos grow inside the seed before germination can occur. Such information is important in understanding the evolutionary relationship of the different kinds of seed dormancy.

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A classification system for seed dormancy

Seed Science Research ◽

10.1079/ssr2003150 ◽

2004 ◽

Vol 14 (1) ◽

pp. 1-16 ◽

Cited By ~ 851

Author(s):

Jerry M. Baskin ◽

Carol C. Baskin

Keyword(s):

Seed Dormancy ◽

Deep Level ◽

Basic Mechanism ◽

Model Species ◽

Physical Dormancy ◽

Genetic Studies ◽

Morphophysiological Dormancy ◽

Class Level ◽

Physiological Dormancy

The proposal is made that seed scientists need an internationally acceptable hierarchical system of classification for seed dormancy. Further, we suggest that a modified version of the scheme of the Russian seed physiologist Marianna G. Nikolaeva be adopted. The modified system includes three hierarchical layers – class, level and type; thus, a class may contain levels and types, and a level may contain only types. The system includes five classes of dormancy: physiological dormancy (PD), morphological dormancy (MD), morphophysiological dormancy (MPD), physical dormancy (PY) and combinational dormancy (PY + PD). The most extensive classification schemes are for PD, which contains three levels and five types (in the non-deep level), and MPD, which contains eight levels but no types. PY is not subdivided at all but probably should be, for reasons given. Justifications are presented for not including mechanical dormancy or chemical dormancy in the modified scheme. PD (non-deep level) is the most common kind of dormancy, and occurs in gymnosperms (Coniferales,Gnetales) and in all major clades of angiosperms. Since, first, this is the class and level of dormancy in seeds of wild populations ofArabidopsis thalianaand, secondly, Type 1 (to which seeds ofA. thalianabelong) is also common, and geographically and phylogenetically widespread, it seems that biochemical, molecular and genetic studies on seed dormancy in this model species might have rather broad application in explaining the basic mechanism(s) of physiological dormancy in seeds.

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Dormancy-breaking and germination requirements for seeds of Diervilla lonicera (Caprifoliaceae), a species with underdeveloped linear embryos

Canadian Journal of Botany ◽

10.1139/b00-094 ◽

2000 ◽

Vol 78 (9) ◽

pp. 1199-1205 ◽

Cited By ~ 5

Author(s):

Siti N Hidayati ◽

Jerry M Baskin ◽

Carol C Baskin

Keyword(s):

Seed Dormancy ◽

Constant Darkness ◽

Cold Stratification ◽

Dormancy Breaking ◽

Morphophysiological Dormancy ◽

Germination Phenology ◽

Physiological Dormancy ◽

Temperature Controlled ◽

Germination Requirements ◽

Morphological Dormancy

Dormancy-breaking requirements and type of dormancy were determined for seeds of Diervilla lonicera Mill. Seeds have an underdeveloped linear embryo that is about 35% of the length of the seed at maturity. Embryos (in intact seeds) grew at 25:15°C but not at 5°C. Up to 85% of the freshly matured seeds had morphological dormancy (MD), and thus, they germinated within about 30 days on a moist substrate in light at 30:15°C; a maximum of 3% of the seeds germinated in constant darkness. The other portion of fresh seeds had nondeep simple morphophysiological dormancy (MPD) and required a period of warm stratification or treatment with GA3 to break dormancy. These seeds also required light to germinate. In contrast, cold stratification induced dormancy, and dry storage for up to 1 year did not effectively break dormancy. Seeds with MD germinated to significantly higher percentages on soil than on filter paper or on sand. Seeds sown on soil in a non-temperature-controlled greenhouse in mid-November germinated mostly in late May, whereas those sown in mid-April germinated in early May. Apparently, embryos of November-sown seeds were induced into physiological dormancy during winter. Thus, seeds had MPD in spring and needed several weeks of warm temperatures for dormancy break, embryo growth, and germination. This is the first report on seed dormancy in the genus Diervilla.Key words: embryo growth, germination phenology, Diervilla lonicera, morphological seed dormancy, morphophysiological seed dormancy, underdeveloped linear embryo.

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Practical Methods for Breaking Seed Dormancy in a Wild Ornamental Tulip Species Tulipa thianschanica Regel

Agronomy ◽

10.3390/agronomy10111765 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1765

Author(s):

Wei Zhang ◽

Lian-Wei Qu ◽

Jun Zhao ◽

Li Xue ◽

Han-Ping Dai ◽

...

Keyword(s):

Seed Germination ◽

Seed Dormancy ◽

Combined Treatment ◽

Individual Treatment ◽

Cold Stratification ◽

Slight Effect ◽

Sowing Depth ◽

Physiological Dormancy ◽

Commercial Breeding ◽

Breaking Seed Dormancy

The innate physiological dormancy of Tulipa thianschanica seeds ensures its survival and regeneration in the natural environment. However, the low percentage of germination restricts the establishment of its population and commercial breeding. To develop effective ways to break dormancy and improve germination, some important factors of seed germination of T. thianschanica were tested, including temperature, gibberellin (GA3) and/or kinetin (KT), cold stratification and sowing depth. The percentage of germination was as high as 80.7% at a constant temperature of 4 °C, followed by 55.6% at a fluctuating temperature of 4/16 °C, and almost no seeds germinated at 16 °C, 20 °C and 16/20 °C. Treatment with exogenous GA3 significantly improved the germination of seeds, but KT had a slight effect on the germination of T. thianschanica seeds. The combined treatment of GA3 and KT was more effective at enhancing seed germination than any individual treatment, and the optimal hormone concentration for the germination of T. thianschanica seeds was 100 mg/L GA3 + 10 mg/L KT. In addition, it took at least 20 days of cold stratification to break the seed dormancy of T. thianschanica. The emergence of T. thianschanica seedlings was the highest with 82.4% at a sowing depth of 1.5 cm, and it decreased significantly at a depth of >3.0 cm. This study provides information on methods to break dormancy and promote the germination of T. thianschanica seeds.

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