Sensitivity cycling and its ecological role in seeds with physical dormancy

2009 ◽  
Vol 19 (1) ◽  
pp. 3-13 ◽  
Author(s):  
K.M.G. Gehan Jayasuriya ◽  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Life Cycle ◽  
Environmental Conditions ◽  
Common Phenomenon ◽  
Ecological Role ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Physiological Dormancy ◽  
Seed Coats

AbstractCycling of physically dormant (PY) seeds between states insensitive and sensitive to dormancy-breaking factors in the environment has recently been demonstrated inFabaceaeandConvolvulaceae, and it may be a common phenomenon in seeds with water-impermeable seed coats. In contrast to seeds of many species with physiological dormancy (PD), those with PY cannot cycle between dormancy and non-dormancy (ND). In this paper, we evaluate the role of sensitivity cycling in controlling the timing of germination of seeds with PY in nature, and show that sensitivity cycling in seeds with PY serves the same ecological role as dormancy cycling in seeds with PD. Thus, sensitivity cycling in seeds with PY ensures that germination in nature occurs only at (a) time(s) of the year when environmental conditions for growth are, and are likely to remain, suitable long enough for the plant to complete its life cycle or to form a perennating structure. Further, we describe the experimental procedures necessary to determine whether sensitivity cycling is occurring, and discuss briefly the possible relevance of sensitivity cycling to dormancy classification.

scholarly journals Ecological role of physical dormancy in seeds of Oxytropis racemosa in a semiarid sandland with unpredictable rainfall

2017 ◽  
Vol 11 (4) ◽  
pp. 542-552 ◽  
Author(s):  
Dandan Hu ◽  
Jerry M Baskin ◽  
Carol C Baskin ◽  
Xuejun Yang ◽  
Zhenying Huang
Keyword(s):  
Ecological Role ◽  
Physical Dormancy

Overcoming physiological dormancy in Prostanthera eurybioides (Lamiaceae), a nationally endangered Australian shrub species

2008 ◽  
Vol 56 (3) ◽  
pp. 214 ◽  
Author(s):  
P. J. Ainsley ◽  
M. K. Jones ◽  
T. E. Erickson
Keyword(s):  
South Australia ◽  
Physical Dormancy ◽  
Shrub Species ◽  
Dry Heat ◽  
Pulse Heat ◽  
Germination Process ◽  
Physiological Dormancy ◽  
Continuous Application ◽  
Persistent Calyx

Prostanthera eurybioides (Lamiaceae) is an endangered shrub endemic to South Australia. Fruits consist of four mericarps enclosed by a persistent calyx, with each seed characterised by the presence of what we are defining as a mericarp plug. Research focussed on understanding the role of the mericarp plug in the germination process, determining seed dormancy classification and germination cues. Treatments tested included combinations of pulse dry heat (60–120°C) for up to 60 min, continuous application of gibberellic acid (100 mg L–1), smoked water (10% (v/v)) and excision of the mericarp plug. Seed imbibition experiments dispelled the presence of physical dormancy. The mericarp plug was found to be acting as a mechanical barrier preventing germination. Pulse dry heat (80°C) significantly improved germination, as did removal of the mericarp plug. Smoked water inhibited germination. Based on germination response, seeds have been classified as having non-deep physiological dormancy, with maximum germination (86%) observed following a pulse heat treatment (80°C, 10 min) and removal of the mericarp plug. Natural mechanisms for overcoming dormancy are proposed.

Intermediate morphophysiological dormancy allows for life-cycle diversity in the annual weed, Turgenia latifolia (Apiaceae)

2014 ◽  
Vol 62 (8) ◽  
pp. 630 ◽  
Author(s):  
Miregul Nurulla ◽  
Carol C. Baskin ◽  
Juan J. Lu ◽  
Dun Y. Tan ◽  
Jerry M. Baskin
Keyword(s):  
Life Cycle ◽  
Low Temperatures ◽  
Western China ◽  
Intermediate Complex ◽  
Dormancy Breaking ◽  
Morphophysiological Dormancy ◽  
Temperature Regimes ◽  
Germination Phenology ◽  
Physiological Dormancy ◽  
Winter Annual

Our aim was to determine the seed dormancy-breaking requirements and type of life cycle of Turgenia latifolia in north-western China. At dispersal in July, only 0–9% of the seeds germinated at 5/2°C, 15/2°C, 20/10°C and 25/15°C; thus, 91% of the seeds exhibited physiological dormancy (PD) and 9% were non-dormant. Also, the embryo was underdeveloped and embryo length : seed length ratio increased from 0.38 in fresh seeds to 0.79 at germination. Seeds buried in dry soil at the four temperature regimes for 12 weeks germinated to ≥50% when tested in darkness at 5/2°C, and those buried at 15/2°C and 20/10°C germinated to ≥50% when tested at 15/2°C. Seeds have intermediate complex morphophysiological dormancy (MPD). PD was broken at high and/or low temperatures, but embryo growth was completed only at low temperatures; gibberellic acid (GA3) promoted germination. Seeds buried under natural conditions during summer germinated to ~70% and ~55% at 5/2°C and 15/2°C, respectively, in darkness in autumn. In a germination-phenology study, cumulative germination was ~20% and ~80% in autumn and spring, respectively. Intermediate complex MPD allows the species to behave as a winter annual and as a short-lived summer annual.

Seed germination of six coastal plant species of the Baltic region: effect of salinity and dormancy-breaking treatments

2008 ◽  
Vol 18 (3) ◽  
pp. 173-177 ◽  
Author(s):  
Jevgenija Necajeva ◽  
Gederts Ievinsh
Keyword(s):  
Salinity Tolerance ◽  
Sea Water ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Physiological Dormancy ◽  
Nacl Concentration ◽  
Gulf Of Riga ◽  
Coastal Plant ◽  
Germination Behaviour ◽  
The Baltic

AbstractSeed salinity tolerance and dormancy play important roles in germination behaviour. The effects of NaCl concentration and different dormancy-breaking treatments on germination were determined for six species growing on the coasts of the Baltic Sea or the Gulf of Riga: Juncus balticus, Triglochin maritima, Triglochin palustre, Anthyllis maritima, Linaria vulgaris and Linaria loeselii. Germination percentages were significantly reduced at NaCl concentrations >100 mM. Germination of J. balticus, T. maritima and T. palustre, but not that of A. maritima and L. vulgaris, recovered after seeds were rinsed with distilled water. Seeds of J. balticus were non-dormant; those of A. maritima had physical dormancy; and those of T. palustre, T. maritima, L. loeselii and L. vulgaris had non-deep to intermediate physiological dormancy, which was broken by cold stratification or gibberellic acid. The seeds of plants growing in habitats periodically exposed to sea water (coastal meadows) were characterized by greater salinity tolerance than seeds of plants growing in habitats less exposed to sea water (dunes).

Physical dormancy in Senna multijuga (Fabaceae: Caesalpinioideae) seeds: the role of seed structures in water uptake

2014 ◽  
Vol 24 (2) ◽  
pp. 147-157 ◽  
Author(s):  
Ailton G. Rodrigues-Junior ◽  
José M.R. Faria ◽  
Tatiana A.A. Vaz ◽  
Adriana T. Nakamura ◽  
Anderson C. José
Keyword(s):  
Water Uptake ◽  
Seed Coat ◽  
Parenchyma Cell ◽  
Hot Water ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Short Term Exposure ◽  
Hilar Region ◽  
Senna Multijuga

AbstractStructural studies in seeds with physical dormancy (PY) are important to better understand its causes and release when subjected to treatments for dormancy breaking. The aims of this study were to (1) characterize the PY break; (2) examine the role of different seed structures in water uptake; and (3) identify the water gap in Senna multijuga seeds. Imbibition patterns of dormant and non-dormant (subjected to dormancy breaking treatments) seeds and the morphological changes during dormancy breaking and germination were evaluated. To identify the water gap, the micropyle and lens were blocked separately, and the water absorption by seed parts was determined. Structural characteristics of the seed coat were also examined. Immersion in water at 80°C was efficient in breaking seed dormancy and imbibition occurred first at the hilar region, through the lens. Water was not absorbed through the micropyle or the extra-hilar region. S. multijuga seeds have a testa with a linearly aligned micropyle, hilum and lens. The seed coat consisted of a cuticle, macrosclereids, one (hilar region) or two (extra-hilar region) layer(s) of osteosclereids and parenchyma cell layers. The lens has typical parenchyma cells underneath it and two fragile regions comprised of shorter macrosclereids. Heat treatment stimulated the lens region, resulting in the opening of fragile regions at the lens, allowing water to enter the seeds. It is concluded that short-term exposure to a hot water treatment is sufficient for the formation of a water gap in S. multijuga seeds, and only the lens acts in the imbibition process.

A meta-analysis of the effects of treatments used to break dormancy in seeds of the megagenus Astragalus (Fabaceae)

2020 ◽  
Vol 30 (3) ◽  
pp. 224-233
Author(s):  
Elias Soltani ◽  
Jerry M. Baskin ◽  
Carol C. Baskin ◽  
Fatemeh Benakashani
Keyword(s):  
Life Cycle ◽  
Sulphuric Acid ◽  
Life Form ◽  
Meta Analysis ◽  
Seed Plants ◽  
Physical Dormancy ◽  
Edaphic Conditions ◽  
Geographic Boundaries ◽  
Physiological Dormancy ◽  
Breaking Seed Dormancy

AbstractAstragalus is the largest genus of seed plants with 3000 or more species that occurs naturally on several continents. The genus has some use as a forage and medicine and in industry, and many of the species are rare endemics threatened with extinction. The seeds are reported to be dormant at maturity, and various treatments have been used in an attempt to germinate them. Our primary aim was to determine via a meta-analysis the most effective way(s) to break dormancy in seeds of this species-rich genus. Mechanical and chemical (conc. sulphuric acid) scarification were by far the best of 12 treatments for breaking seed dormancy of the 40 species included in our meta-analysis, whereas prechilling, gibberellin and smoke were ineffective. These results along with those of imbibition tests confirm that seeds of the examined Astragalus species have physical dormancy (PY). Further, PY in these 40 species and (its documented occurrence) in 118 species that could not be included in our meta-analysis transcends climatic and geographic boundaries, edaphic conditions, life cycle/life form types and infrageneric phylogeny. Thus, it seems likely that most species of Astragalus have PY. However, in addition to PY, physiological dormancy (PD), that is, combinational dormancy (PY + PD), has been reported in a few species of Astragalus. This study should be useful to both basic and applied scientists who want to germinate seeds of Astragalus.

Role of the lens in physical dormancy in seeds of Sophora alopecuroides L. (Fabaceae) from north-west China

2008 ◽  
Vol 59 (6) ◽  
pp. 491 ◽  
Author(s):  
X. W. Hu ◽  
Y. R. Wang ◽  
Y. P. Wu ◽  
Z. B. Nan ◽  
C. C. Baskin
Keyword(s):  
Sulfuric Acid ◽  
Water Entry ◽  
Primary Site ◽  
Hot Water ◽  
Field Conditions ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Field Exposure ◽  
Sophora Alopecuroides

Abstract Although many studies have been done on seeds with physical dormancy, i.e. water-impermeable seed or fruit coat, the primary site of water entry into seeds after dormancy-breaking treatments is still controversial. In this work, the role of the lens in physical dormancy breaking was examined. The present study investigated the primary site of water entry and changes in seed-surface features for seeds of Sophora alopecuroides L. following various periods of scarification with sulfuric acid, hot-water treatments, and exposure to field conditions. Most seed coats first cracked in the hilum when pre-treated with sulfuric acid and after field exposure, but they cracked in both the hilum and extrahilar regions when treated with hot water. After pre-treatment, seeds first became slowly permeable in the hilum or extrahilar region and not in the lens. Acid scarification for 35 or 50 min caused the lens to crack, thus causing seeds to enter a fast imbibition stage. Seeds exposed to field conditions had further damage to the hilum, causing them to enter a fast imbibition stage. Imbibition time is a key point that determines the primary site of water entry into seed, and at least in part explains various results and interpretations about the role of the lens in physical dormancy in previous research.

Role of the lens in controlling water uptake in seeds of twoFabaceae(Papilionoideae) species treated with sulphuric acid and hot water

2009 ◽  
Vol 19 (2) ◽  
pp. 73-80 ◽  
Author(s):  
Xiao Wen Hu ◽  
Yan Rong Wang ◽  
Yan Pei Wu ◽  
Carol C. Baskin
Keyword(s):  
Sulphuric Acid ◽  
Water Uptake ◽  
Water Entry ◽  
Primary Site ◽  
Hot Water ◽  
Sesbania Sesban ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Water Treatments

AbstractAlthough many studies have been conducted on seeds with a water-impermeable seed or fruit coat (physical dormancy), the primary site of water entry into these seeds after dormancy-breaking treatments is still controversial. Thus, the role of lens, hilum, micropyle and extrahilar regions in water uptake of seeds treated to break physical dormancy was examined inVigna oblongifoliaandSesbania sesban(Fabaceae) following pretreatment with sulphuric acid and hot water. Morphology of seed surfaces in treated versus non-treated seeds of both species was examined with scanning electron microscopy. Most seeds ofV. oblongifoliafirst cracked in the hilum when pretreated with sulphuric acid, but they cracked in both the hilum and extrahilar regions when pretreated with hot water. However, inS. sesbanseeds, a crack formed only in the lens following either acid scarification or hot-water treatments, and the seeds imbibed water only through the lens. These results indicate that the primary site of water entry into seeds following physical dormancy break can vary with species and treatments. Slow, early imbibitionviathe hilum, and subsequent rapid imbibitionviathe lens, may not be detected unless seeds are monitored for several days. Time allowed for imbibition studies may, at least in part, explain various interpretations about the role of the lens in physical dormancy reported in the literature.

scholarly journals Water absorption and dormancy-breaking requirements of physically dormant seeds of Sophora tomentosa L. and Erythrina speciosa Andr. (Fabaceae-Faboideae)

2014 ◽  
Vol 63 (1) ◽  
pp. 285 ◽  
Author(s):  
Carolina Maria Luzia Delgado ◽  
Alexandre Souza de Paula ◽  
Marisa Santos ◽  
Maria Terezinha Silveira Paulilo
Keyword(s):  
Water Absorption ◽  
Atlantic Forest ◽  
Seed Coat ◽  
Temperature Fluctuation ◽  
Hot Water ◽  
Epifluorescence Microscopy ◽  
Maximum Temperature ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Seed Coats

<p>The physical dormancy of seeds has been poorly studied in species from tropical forests, such as the Atlantic Forest. This study aimed to examine the effect of moderate alternating temperatures on breaking the physical dormancy of seeds, the morphoanatomy and histochemistry of seed coats, and to locate the structure/region responsible for water entrance into the seed, after breaking the physical dormancy of seeds of two woody Fabaceae (subfamily Faboideae) species that occur in the Brazilian Atlantic Forest: <em>Sophora tomentosa </em>and<em> Erythrina speciosa</em>. To assess temperature effect, seeds were incubated in several temperature values that occur in the Atlantic Forest. For morphological and histochemical studies, sections of fixed seeds were subjected to different reagents, and were observed using light or epifluorescence microscopy, to analyze the anatomy and histochemistry of the seed coat. Treated and non-treated seeds were also analyzed using a scanning electron microscope (SEM) to observe the morphology of the seed coat. To localize the specific site of water entrance, the seeds were blocked with glue in different regions and also immersed in ink. In the present work a maximum temperature fluctuation of 15ºC was applied during a period of 20 days and these conditions did not increase the germination of <em>S.</em> <em>tomentosa</em> or <em>E. speciosa</em>. These results may indicate that these seeds require larger fluctuation of temperature than the applied or/and longer period of exposition to the temperature fluctuation. Blocking experiments water inlet combined with SEM analysis of the structures of seed coat for both species showed that besides the lens, the hilum and micropyle are involved in water absorption in seeds scarified with hot water. In seeds of <em>E. speciosa</em> the immersion of scarified seeds into an aniline aqueous solution showed that the solution first entered the seed through the hilum. Both species showed seed morphological and anatomical features for seed coats of the subfamily Faboideae. Lignin and callose were found around all palisade layers and the water impermeability and ecological role of these substances are discussed in the work.</p>

scholarly journals Ecological role of physical dormancy in seeds of Oxytropis racemosa in a semiarid sandland with unpredictable rainfall

2018 ◽  
Vol 12 (2) ◽  
pp. 393-393
Author(s):  
Dandan Hu ◽  
Jerry M Baskin ◽  
Carol C Baskin ◽  
Xuejun Yang ◽  
Zhenying Huang
Keyword(s):  
Ecological Role ◽  
Physical Dormancy
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