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.

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.

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.

Water absorption and dormancy-breaking requirements of physically dormant seeds of Schizolobium parahyba (Fabaceae – Caesalpinioideae)

2012 ◽  
Vol 22 (3) ◽  
pp. 169-176 ◽  
Author(s):  
Thaysi Ventura de Souza ◽  
Caroline Heinig Voltolini ◽  
Marisa Santos ◽  
Maria Terezinha Silveira Paulilo
Keyword(s):  
Water Absorption ◽  
Atlantic Forest ◽  
High Temperatures ◽  
Hot Water ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Maximum Percentage ◽  
Schizolobium Parahyba ◽  
Inhibited Water

AbstractPhysical dormancy refers to seeds that are water impermeable. Within the Fabaceae, the structure associated with the breaking of dormancy is usually the lens. This study verified the role of the lens in physical dormancy of seeds of Schizolobium parahyba, a gap species of Fabaceae from the Atlantic Forest of Brazil. The lens in S. parahyba seeds appeared as a subtle depression near the hilum and opposite the micropyle. After treatment of the seeds with hot water, the lens detached from the coat. Blocking water from contacting the lens inhibited water absorption in hot-water-treated seeds. High constant (30°C) and alternating (20/30°C) temperatures promoted the breaking of physical dormancy and germination in non-scarified seeds. Maximum percentage of germination occurred earlier for seeds incubated at 20/30°C than for those incubated at 30°C. Seeds with a blocked lens did not germinate at alternating or high temperatures. This study suggests that alternating temperatures are probably the cause of physical dormancy break of seeds of S. parahyba in gaps in the forest.

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 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.

scholarly journals Chemical Applications, Scarification and Stratification Effects on Seed Germination of Rare Endemic Verbascum calycosum Hausskn. ex Murb. (Scrophulariaceae)

2018 ◽  
Vol 46 (2) ◽  
pp. 376-380 ◽  
Author(s):  
Muhip HİLOOĞLU ◽  
Emel SÖZEN ◽  
Ersin YÜCEL ◽  
Ali KANDEMİR
Keyword(s):  
Hot Water ◽  
Ex Situ ◽  
Cold Stratification ◽  
Endemic Plant ◽  
Physical Dormancy ◽  
Hard Seed ◽  
Physiological Dormancy ◽  
Endemic Plant Species ◽  
Water Treatments ◽  
Rare Endemic

Verbascum calycosum is an endemic plant species having considerable narrow distribution in Erzincan (Turkey) region. This species is known from only a single population and its habitats are highly threatened due to intensive human activities and soil erosion. In this study, the germination behavior of V. calycosum under different concentrations of NaCl, HCl, KNO3, GA3 (100 and 200 μM), hot-cold stratification and mechanical scarification were investigated. Seeds were exposed to a photoperiod of 8 h light/16 h dark with a 23/18 °C thermoperiod. Germination rates increased with GA3-100 µM (39%), GA3-200 µM (54.5%), mechanical scarification (34.5%) and cold stratification treatments (+4 °C, 23.25%; -20 °C, 18.25%) on the other hand, KNO3, NaCl, HCl and stratification with hot water treatments have decreased germination rates significantly when compared to the control (12.25%). Increased germination after GA3 application and mechanical scarification indicated that seeds of V. calycosum exhibited both non-deep and intermediate physiological dormancy as well as physical dormancy due to its hard seed coat. The highest speed of germination index was obtained at cold stratification of +4 °C and -20 °C (10.3). This study represents first report about seed dormancy and germination characteristics of V. calycosum. Overall, these results will provide valuable data for ex situ conservation of this rare endemic plant.

ROLE OF THE SEED COAT IN GERMINATION OF CISTUS POPULIFOLIUS L.

1997 ◽  
Vol 45 (4) ◽  
pp. 329-331 ◽  
Author(s):  
Félix Pérez-García ◽  
Adrian Escudero
Keyword(s):  
Sulphuric Acid ◽  
Seed Coat ◽  
Hot Water ◽  
Thermal Treatments ◽  
Distilled Water ◽  
Acid Pretreatment ◽  
Dry Heat

Effect of mechanical scarification, dry heat, hot water, and sulphuric acid on the germination behavior ofCistus populifoliusL. (rockrose) was studied. Untreated seeds after 60 days of incubation germinated less than 7%. After thermal treatments, 90% germination was achieved, and sulphuric acid pretreatment gave 61% germination. Soaking in distilled water did not increase germination, but scarification of the seed coat gave 57%. Hardness and impermeability of the seed coat appear to cause deep dormancy inC. populifoliusseeds.

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>

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.

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