Abstract:& Key message Dormancy in Arecaceae diaspores is due to underdeveloped embryos, therefore, morphological dormancy or morphophysiological dormancy. Consequently, claims such as external seed structures inhibit germination, embryos are fully developed at maturity, and underdeveloped embryo is not a form of dormancy are rejected, because embryo size of the diaspore at the time of dispersal was not taken into consideration. The re-classification proposal for moving morphological dormancy into non-dormancy is also … Show more
“…MD refers to the dormancy due to the small embryo size, incomplete development, or lack of differentiation after seed maturation. The morphology of the seed embryo is generally spatulate, rudimentary, or linear; in some species, it occupies ≤1% of the seed volume (Jaganathan, 2020;Liu et al, 2020). For example, the Lamprocapnos spectabilis seed endosperm comprises the entire internal tissue of the seed, and the embryo is almost invisible (Cho et al, 2020).…”
Section: Dormancy Class and Potential Factorsmentioning
Seed dormancy is a complex adaptive trait of plants that are influenced by several physiological and environmental factors. The endangered plant Cinnamomum migao is also known to exhibit seed dormancy and low germination, which may influence its regeneration; however, these characteristics remain unexplored. To our knowledge, this study is the first to examine the type of dormancy and improve the germination percentage of C. migao seeds. We evaluated the structure and characteristics of the embryo and endocarp of C. migao seeds as well as the effects of endogenous inhibitors. Furthermore, we assessed the effects of light, stratification, alternating temperature, and gibberellic acid 3 (GA3) on the dormancy release of these seeds. The embryo was well developed the endocarp was water-permeable, and no obvious mechanical hindrance to germination was observed. However, the endocarp and embryo contained phenols and other germination inhibitors. The seed extracts of C. migao delayed the germination of cabbage and ryegrass seeds, which indicates the presence of endogenous inhibitors. These findings suggest that C. migao seeds exhibit physiological dormancy. Light and an alternating temperature (15/20°C) did not influence germination. However, GA3 pretreatment, alternating temperatures, and warm stratification relieved dormancy. GA3 pretreatment combined with the 15°C stratification treatment was most effective in rapidly releasing the C. migao seed dormancy. Our findings may facilitate the storage and conservation of this endangered plant, which is currently underrepresented in ex situ collections.
“…MD refers to the dormancy due to the small embryo size, incomplete development, or lack of differentiation after seed maturation. The morphology of the seed embryo is generally spatulate, rudimentary, or linear; in some species, it occupies ≤1% of the seed volume (Jaganathan, 2020;Liu et al, 2020). For example, the Lamprocapnos spectabilis seed endosperm comprises the entire internal tissue of the seed, and the embryo is almost invisible (Cho et al, 2020).…”
Section: Dormancy Class and Potential Factorsmentioning
Seed dormancy is a complex adaptive trait of plants that are influenced by several physiological and environmental factors. The endangered plant Cinnamomum migao is also known to exhibit seed dormancy and low germination, which may influence its regeneration; however, these characteristics remain unexplored. To our knowledge, this study is the first to examine the type of dormancy and improve the germination percentage of C. migao seeds. We evaluated the structure and characteristics of the embryo and endocarp of C. migao seeds as well as the effects of endogenous inhibitors. Furthermore, we assessed the effects of light, stratification, alternating temperature, and gibberellic acid 3 (GA3) on the dormancy release of these seeds. The embryo was well developed the endocarp was water-permeable, and no obvious mechanical hindrance to germination was observed. However, the endocarp and embryo contained phenols and other germination inhibitors. The seed extracts of C. migao delayed the germination of cabbage and ryegrass seeds, which indicates the presence of endogenous inhibitors. These findings suggest that C. migao seeds exhibit physiological dormancy. Light and an alternating temperature (15/20°C) did not influence germination. However, GA3 pretreatment, alternating temperatures, and warm stratification relieved dormancy. GA3 pretreatment combined with the 15°C stratification treatment was most effective in rapidly releasing the C. migao seed dormancy. Our findings may facilitate the storage and conservation of this endangered plant, which is currently underrepresented in ex situ collections.
“…1 D) may also delay root formation and development. Our previous work (yet to be published) revealed that D. involucrata seeds have physical dormancy + deep physiological dormancy based on a recent description by Jaganathan (2020) . Fig.…”
“…They have both a morphological, that is, embryo not fully grown (underdeveloped) at seed maturity, and a physiological, that is, require a period of afterripening or warm stratification to germinate, component of dormancy. Thus, the diaspores have some kind of MPD (Perez et al, 2008;Baskin and Baskin, 2014b;Rajapakshe et al, 2017;Jaganathan, 2020Jaganathan, , 2021Jaganathan et al, 2021). For palms with the remote tubular and remote ligular types of seedling formation (see Baskin and Baskin, 2014b) For B (rs) ′ b ′ , B indicates an underdeveloped embryo (i.e.…”
Section: Seed Dormancy Classification With Particular Reference To the Monocots Palms And Cannamentioning
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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