Pericarp structure of Glebionis coronaria (L.) Cass. ex Spach (Asteraceae) cypselae controls water uptake during germination

2015 ◽  
Vol 25 (3) ◽  
pp. 255-266 ◽  
Author(s):  
Giuseppe Puglia ◽  
Simona Grimaldi ◽  
Angelino Carta ◽  
Pietro Pavone ◽  
Peter Toorop
Keyword(s):  
Water Uptake ◽  
Complete Removal ◽  
Water Entry ◽  
Cold Stratification ◽  
Palisade Layer ◽  
Physical Dormancy ◽  
Vessel Elements ◽  
Reduced Water ◽  
Seeds Germination ◽  
Mechanical Constraint

AbstractGlebionis coronaria (L.) Cass. ex Spach is a common Mediterranean weed producing distinctive central and peripheral dormant cypselae with a hard fruit coat, which was previously hypothesized to impose physical dormancy. Analysis of water uptake in cypselae and in naked seeds showed that it preferentially takes place at the basal end of the fruit; however, seeds within an intact pericarp do not fully imbibe when compared with naked seeds. Germination was not significantly different between the two heteromorphs, and afterripening or cold stratification did not increase germination, while warm stratification at 35/20°C, as revealed by logistic regression, resulted in a significant improvement. However, loss of viability was also rapid at these high temperatures. Central and peripheral cypselae generally showed very low germination. In both heteromorphs, faster and higher germination (60–70%) was reached only after extensive scarification of pericarp tissue, and full germination was observed only after complete removal of pericarp tissue. Although the pericarp significantly reduced water uptake, no palisade layer(s) of macrosclereids could be observed. Xylem-vessel elements were found running through the basal end of the pericarp and forming the main point of water entry. We reject the hypothesis that G. coronaria cypselae have physical dormancy. Instead, water uptake and germination are impeded by: (1) directed water uptake, mainly through a pericarp-spanning channel-like structure; and (2) mechanical constraint on embryo growth exerted by the hard pericarp. The channel-like structure forms the principal system for controlling seed germination.

scholarly journals Seed anatomy and water uptake and their relation to seed dormancy of Ormosia paraensis Ducke

2018 ◽  
Vol 40 (3) ◽  
pp. 237-245
Author(s):  
Breno Marques da Silva e Silva ◽  
Camila de Oliveira e Silva ◽  
Fabiola Vitti Môro ◽  
Roberval Daiton Vieira
Keyword(s):  
Sulfuric Acid ◽  
Seed Dormancy ◽  
Water Uptake ◽  
Furniture Industry ◽  
Palisade Layer ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Seed Physiology ◽  
Breaking Dormancy ◽  
Hydrophobic Substances

Abstract: Ormosia paraensis Ducke has ornamental seeds widely used in the manufacture of bio-jewels and wood used in the furniture industry. For seedling production, the information on its seed physiology is scarce. Thus, the aim of this study was to assess methods for breaking dormancy and relate them to integument structure and water uptake by O. paraensis seeds. Seed dormancy-breaking was performed by mechanical scarification and soaking in sulfuric acid for 0, 15, 30, 60, 120, and 240 minutes. Dormancy‐broken seeds were compared with intact seeds. Seed integument is formed by a cuticle (hydrophobic substances), epidermis (macroesclereids of the palisade layer,), hypodermis (osteosclereids), and parenchyma cells. Intact seeds did not absorb water after 72 hours of soaking. The highest percentages and rates of seed germination were observed in treatments with mechanical scarification and soaking in sulfuric acid for 60 or 120 minutes. Seed soaking in sulfuric acid (H2SO4 p.a. 98.08%) for 60 or 120 minutes or mechanical scarification are adequate to overcome physical dormancy associated with O. paraensis seed integument impermeability to water or gases.

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 permeability/impermeability in seeds of 15 species of Caragana (Fabaceae)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6870 ◽  
Author(s):  
Dali Chen ◽  
Rui Zhang ◽  
Carol C. Baskin ◽  
Xiaowen Hu
Keyword(s):  
Seed Coat ◽  
Water Permeability ◽  
Water Entry ◽  
The Other ◽  
Palisade Layer ◽  
Physical Dormancy ◽  
Dry Storage

Majority legumes in the temperate and arctic zones have water-impermeable seeds (physical dormancy, PY). However, various authors have reported that seeds of some Caragana species are water-permeable and thus non-dormant. We (1) tested seeds of 15 species of Caragana matured in the same site in 2014, 2016 and/or 2017 for presence of PY, (2) determined if dry storage decreased or increased the percentage of seeds with PY and (3) located the site on the seed coat of 11 species where water enters the seed. Sixty-three percent and 45% of the seeds of C. roborovskyi had PY in 2016 and 2017, respectively, but only 0–14% of the seeds of the other 14 species had PY. The palisade layer in the seed coat of water impermeable seeds had no cracks in it, whereas cracks were present in the palisade layer of water-permeable seeds. Year of collection and dry storage had significant effects on imbibition of two species (C. acanthophylla and C. roborovskyi). In two (C. acanthophylla and C. roborovskyi) of the 11 species tested, the hilum was the site of water entry into seeds (control seeds, not any dormant broken treatments), but for the other nine species tested water entered through all parts of the seed coat.

scholarly journals Effects of Different Pretreatments and Seed Coat on Dormancy and Germination of Seeds of Senna obtusifolia (L.) H.S. Irwin & Barneby (Fabaceae)

2016 ◽  
Vol 8 (2) ◽  
pp. 77
Author(s):  
Stephen I. Mensah ◽  
Chimezie Ekeke
Keyword(s):  
Sulfuric Acid ◽  
Seed Dormancy ◽  
Water Uptake ◽  
Seed Coat ◽  
Critical Factor ◽  
Potassium Nitrate ◽  
Ex Situ ◽  
Mechanical Resistance ◽  
Physical Dormancy ◽  
Senna Obtusifolia

<p class="1Body">The seed dormancy of <em>Senna obtusifolia</em> was investigated through various methods, namely pretreatments in concentrated sulfuric acid, 2% potassium nitrate (KNO<sub>3</sub>), 99% ethanol, 99% methanol, and in hydrogen perioxide; examination of the seed coverings; and the determination of water uptake by the seeds in order to ascertain the most effective technique for breaking dormancy and also determine the dormancy type. The results showed that sulfuric acid treatment recorded the highest germination (100%); followed by 2% hydrogen peroxide treatment (24%) in 15minutes immersion. The methanol and ethanol pretreatments gave 18.33% and 16.5% germinations respectively. Pretreatment in 2% potassium nitrate gave the lowest germination (8.50%), while the intact seeds of <em>S. obtusifiolia</em> (control) gave 0% germination. The anatomy of the seed coat indicated the presence of hard, thickened and specialized cells of cuticle, macrosclereids, osteoscereids, and disintegrated parenchyma layers. The water uptake of intact seeds was low (13.5%) after 24 hr imbibitions. These findings revealed that the seed coat acts as barrier to germination by preventing water absorption, possibly gaseous diffusion in and out of the seed and conferring mechanical resistance to the protrusion of embryo. Pretreatments, such as immersion in H<sub>2</sub>SO<sub>4 </sub>will soften the seed coat and permit germination. Seed dormancy in <em>S. obtusifolia </em>can be considered of physical nature and classified as physical dormancy. The results obtained in this study may serve as useful information in the production and improvement of <em>S. obtusifolia </em>seedlings, as knowledge on seed dormancy and germination is a critical factor and requirements to the understanding of the propagation of this plant either in situ or ex-situ, in view of the economic potentials/attributes of this species.</p>

Functional morpho-anatomy of water-gap complexes in physically dormant seed

2018 ◽  
Vol 28 (3) ◽  
pp. 186-191 ◽  
Author(s):  
Robert L. Geneve ◽  
Carol C. Baskin ◽  
Jerry M. Baskin ◽  
K.M.G. Gehan Jayasuriya ◽  
Nalin S. Gama-Arachchige
Keyword(s):  
Water Entry ◽  
Type I ◽  
Type Ii ◽  
Physical Dormancy ◽  
Type Iii ◽  
Distinct Area ◽  
Primary Water ◽  
Plant Families ◽  
Palisade Cells ◽  
Gap Structure

AbstractPhysical dormancy (PY) occurs in at least 18 angiosperm plant families and is caused by water-impermeable palisade cells in seed (or fruit) coats. Breaking of PY involves disruption or dislodgement of water-gap structures causing the seeds/fruits to become water permeable (non-dormant). The water-gap region is a morphologically distinct area of the seed or fruit coat that forms a water-gap complex. The location, anatomy, morphology and origin of water-gaps can differ between and even within families and genera. Water-gap structures sense environmental conditions that allow seeds with PY to become permeable just prior to the commencement of conditions favourable for germination and plant establishment. There are three basic water-gap morpho-anatomies characterized by the way the water-gap opens: Type-I, Type-II and Type-III. In Type-I water-gaps, specific kinds of cells pull apart to form a surface opening, while in Type-II a portion of the surface structure is pulled away from adjacent cells, opening the water-gap. Type-III is the least common type and has a circular, plug-like structure that is dislodged, whereby water entry occurs. In addition, water-gap complexes are either simple or compound, depending on whether only a single primary water-gap structure is involved in dormancy release or an additional secondary water-gap structure opens, permitting water entry.

scholarly journals Cool–Warm Temperature Stratification and Simulated Bird Digestion Optimize Removal of Dormancy in Rosa rugosa Seeds

2022 ◽  
Vol 12 ◽  
Author(s):  
Peng Gao ◽  
Jie Dong ◽  
Sihan Wang ◽  
Wuhua Zhang ◽  
Tao Yang ◽  
...  
Keyword(s):  
Water Absorption ◽  
Seed Dormancy ◽  
Global Climate ◽  
Natural Populations ◽  
Suitable Condition ◽  
Growth Potential ◽  
Cold Stratification ◽  
Rosa Rugosa ◽  
Physiological Dormancy ◽  
Mechanical Constraint

Rosa rugosa Thunb. has been explored multi-function in medicinal, edible, cosmetic, ornamental and ecological etc. However, R. rugosa natural populations have recently declined substantially in China, besides of global climate change, this species also has the defect of limiting the reproduction of itself such as the hard-to-release seed dormancy. In this study, only 30% of R. rugosa seeds were viable, and the others were incompletely developed or diseased seeds. Without stratification, morphologically complete viable seeds imbibed water but those seeds could not germinate even after seed husk removal under suitable condition to exhibit a physiological dormancy. After cold (4°C) and warm (18 ± 2°C) stratification, macromolecular substances containing carbon or nitrogen accumulated, and respiration, antioxidant enzyme activity, and gibberellin (GA3) /abscisic acid (ABA) and auxin (IAA)/ABA ratios increased significantly in seeds. Water absorption also increased as endocarps softened. Thus, physiological dormancy of seed was broken. Although warm and cold stratification increased separation between endocarp and embryo, the endocarp binding force was removed insufficiently, because only 10.20% of seeds germinated. Therefore, stratified seeds were treated with simulated bird digestion. Then, folds and cracks in loosened endocarps increased permeability, and water absorption rate increased to 64.43% compare to 21.14% in cold and warm stratification treatment. With simulated digestion, 24.20% of radicles broke through the endocarp with plumules and cambiums to develop into seedlings. Thus, the seed dormancy type of R. rugosa is physiological as seeds imbibed water and possessed fully developed embryos with a low growth potential in combination with a mechanical constraint from the endocarp. Cold stratification helped remove physiological dormancy, and additional warm stratification accelerated the process. The optimal stratification treatment was 4°C for 45 days followed by 18 ± 2°C for 15 days. After warm and cold stratification, simulated bird digestion broke the mechanical constraint from the seed covering layers. Based on this research, production of R. rugosa seedlings can be greatly increased to help protect the species from further declines.

scholarly journals Water Uptake and Germination of Caper (Capparis spinosa L.) Seeds

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 838
Author(s):  
María Laura Foschi ◽  
Mariano Juan ◽  
Bernardo Pascual ◽  
Núria Pascual-Seva
Keyword(s):  
Moisture Content ◽  
Water Uptake ◽  
Sensu Stricto ◽  
Physical Dormancy ◽  
Seed Moisture Content ◽  
Mediterranean Countries ◽  
Capparis Spinosa ◽  
Viable Seeds ◽  
Two Phases ◽  
Almost All

Caper is a perennial deciduous sub-shrub that grows in almost all circum-Mediterranean countries. The specialized literature presents three possible dormancy types that can cause low germination of caper seeds: Physiological dormancy (PD), physical dormancy (PY), and combinational dormancy (PY + PD). We conducted three experiments to analyze the imbibition, viability, and germination of seeds of different ages, provenances, and the level of deterioration of the seed cover. None of the commercialized lots of standard seeds tested exceeded 6% germination, nor 35% viability, while the owned seeds reached 90% in both parameters, indicating that all viable seeds germinated. The seed moisture content along the soaking period followed the first two phases of the typical triphasic model of water uptake in seed germination: The imbibition and lag phases (phase I and II of germination, respectively). Seed hydration began through the hilar region. The fact that all viable owned seeds germinated, together with their moisture content being lower than that of standard seeds, indicated that caper seeds do not have a water-impermeable coat sensu stricto, i.e., they do not show PY; nevertheless, the need to use gibberellic acid to obtain high germination percentages, demonstrated the presence of PD.

Etude cytologique de l'embryon du Pin d'Alep lors de la germination : influence d'un traitement stimulant par administration successive d'ions mercure et chlore

1978 ◽  
Vol 56 (23) ◽  
pp. 2931-2936 ◽  
Author(s):  
J. C. Pargney ◽  
P. Thalouarn
Keyword(s):  
Water Uptake ◽  
Filter Paper ◽  
Cytological Study ◽  
Distilled Water ◽  
Seeds Germination

Since it is known that successive applications of Hg2+ and Cl− ions accelerates Apel pine seeds germination, a cytological study of the treated embryo was made during the first 6 days of imbibition. In comparison with control seeds germinating on filter paper imbibed with distilled water, treated seeds show precocious mitoses and an acceleration of lipolysis and proteolysis as well as synthesis of organelles. These phenomena are particularly evident in the radicle. Since water uptake occurs especially in the radicular pole of the seed, this result suggests a determining role of imbibition in the process of germination in the Alep pine. No abnormal ultrastructures are observed in treated seeds.not available

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