Effect of salinity on seed germination of five mangroves from Sri Lanka: use of hydrotime modelling for mangrove germination

2018 ◽  
Vol 29 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Malaka M. Wijayasinghe ◽  
K.M.G. Gehan Jayasuriya ◽  
C.V.S. Gunatilleke ◽  
I.A.U.N. Gunatilleke ◽  
Jeffrey L. Walck
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Osmotic Potential ◽  
Germination Percentage ◽  
Mangrove Species ◽  
Sonneratia Caseolaris ◽  
Acanthus Ilicifolius ◽  
Time Courses ◽  
Hydrotime Model ◽  
The Relationship

AbstractMangroves are highly adapted to extreme environmental conditions that occur at the interface of salt and fresh water. Adaptations to the saline environment during germination are a key to mangrove survival, and thereby, its distribution. The main objective of this research was to study the effect of salinity on seed germination of selected mangrove species and the application of a hydrotime model to explain the relationship between water potential of the medium and rate of seed germination. Germination of seeds was examined at 15, 25 and 35°C in light/dark over a NaCl gradient. Germination time courses were prepared, and germination data were used to investigate whether these species behave according to the principles of the hydrotime model. The model was fitted for the germination of Acanthus ilicifolius seeds at 25°C. Final germination percentage was significantly influenced by species, osmotic potential and their interaction at 25°C. Moreover, temperature had a clear effect on seed germination (Sonneratia caseolaris and Pemphis acidula) which interacted with osmotic potential. Only A. ilicifolius seeds behaved according to the hydrotime principles and thus its threshold water potential was –1.8 MPa. Optimum germination rates for seeds of the other species occurred at osmotic potentials other than 0 MPa. The descending order of salinity tolerance of the tested species was Aegiceras corniculatum > Sonneratia caseolaris > Acanthus ilicifolius > Pemphis acidula > Allophylus cobbe, suggesting that the viviparous species (A. corniculatum) is highly salt tolerant compared with the non-viviparous species. The results revealed that seeds of the study species exhibited facultative halophytic behaviour in which they can germinate over a broad range of saline environments. Use of a hydrotime model for mangroves was limited as germination of their seeds did not meet model criteria.

Hydrothermal time analysis of tomato seed germination at suboptimal temperature and reduced water potential

1994 ◽  
Vol 4 (2) ◽  
pp. 71-80 ◽  
Author(s):  
Peetambar Dahal ◽  
Kent J. Bradford
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Time Course ◽  
Hydrothermal Time ◽  
Tomato Seed ◽  
Time Model ◽  
Germination Time ◽  
Radicle Emergence ◽  
Time Courses ◽  
Hydrotime Model

AbstractBoth temperature (T) and water potential (ψ) have consistent and quantifiable effects on the rate and extent of seed germination (radicle emergence). Germination at suboptimal T can be characterized on the basis of thermal time, or the T in excess of a base (Tb) multiplied by the time to a given percentage germination (tg). Similarly, germination at reduced ψ can be characterized on a hydrotime basis, or the ψ in excess of a base (ψb) multiplied by tg. Within a seed population, the variation in thermal times to germination for a specific percentage (g) is based upon the normal distribution of ψb values among seeds (ψb(g)). Germination responses across a range of suboptimal T and ψ might be accounted for by a general hydrothermal time model incorporating both T and ψ components. We tested this hypothesis for tomato (Lycopersicon esculentum Mill.) seeds of two genotypes differing in germination rates and tolerance of suboptimal T and ψ. For combinations of T (10−25°C) and ψ (0 to −0.9 MPa), a general hydrothermal time model accounted for approximately 75% of the variation in times to germination within the seed populations of both genotypes, and over 96% of the variation in median germination rates. However, ψb(g) distributions were sensitive to both the T and ψ of imbibition, resulting in a poor fit of the model to specific time course data. Analysis of germination timing separately for low and high ψ ranges within a given T resulted in specific models accounting for 88−99% of the variation in individual germination times and >99% of the variation in madian germination rates. Thus, for a given T and ψ range, the hydrotime model closely matched tomato seed germination time courses. Accumulated hydrothermal time accounted well for germination rates at ψ> −0.5 MPa across suboptimal T if ψb(g) was allowed to vary with T. Germination did not show a consistent response to T at ψ < −0.5 MPa, and estimated Tb values varied over different T ranges. Generalization of the hydrothermal time model across the entire range of suboptimal T and ψ was limited by physiological adjustments of the seeds to their current environment. The hydrothermal time model detected and quantified these adjustment processes that would otherwise not be evident from inspection of germination time courses. Temperature and water potential influence the time to germination via physiological mechanisms that reciprocally interact.

Incubation under fluctuating temperatures reduces mean base water potential for seed germination in several non-cultivated species

2005 ◽  
Vol 15 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Roberto Huarte ◽  
Roberto L. Benech-Arnold
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Osmotic Potential ◽  
Quantitative Description ◽  
Maximum Temperature ◽  
The Mean ◽  
Hydrotime Model ◽  
Total Seed ◽  
Base Water Potential ◽  
Fluctuating Temperatures

Seeds ofCarduus acanthoides,Cynara cardunculus,Cirsium vulgare,Brassica campestris, andSisymbrium altissimumwere incubated at a range of decreasing osmotic potentials (Ψo) under fluctuating temperatures or the median temperature of the fluctuation cycle. Fluctuating temperatures promoted total seed germination in water and at reduced osmotic potential. Total germination was reduced as the Ψodecreased. However, this trend was smallest under fluctuating temperatures, signalling a higher tolerance of seeds to reduced osmotic potential. Effects of osmoticum and temperature were modelled with the hydrotime model. The parameters estimated from the model, the hydrotime constant (θH), the mean base water potential Ψb(50) and its standard deviation (σΨb) gave good descriptions of germination time courses. For all species, incubation under fluctuating temperatures shifted Ψb(50) values downwards without modifying their distribution substantially. This accounted for the greater tolerance of germination to reduced Ψounder fluctuating temperatures. To confirm that these effects were mediated by temperature fluctuationsper se, the behaviour ofC. acanthoidesandC. cardunculusincubated at the minimum, the mean and the maximum temperature of the fluctuation cycle was also analysed. Constant maximum and minimum temperatures of the cycle did not stimulate germination, nor did they shift Ψb(50) towards more negative values. The hydrotime model provides a physiologically based quantitative description for germination promotion due to fluctuating temperature.

Moisture Stress and Hydration-Dehydration Effects on Hemp Sesbania (Sesbania exaltata) Seed Germination

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 487-492 ◽  
Author(s):  
Robert D. Williams
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Moisture Stress ◽  
Germination Percentage ◽  
Moisture Uptake ◽  
Sesbania Exaltata ◽  
Hemp Sesbania ◽  
Number Of Cycles

Increased osmotic potential from 0 to −14 bars decreased the moisture uptake and germination of mechanically scarified hemp sesbania [Sesbania exaltata(Raf.) Cory] seed. Germination percentage for osmotic potential of 0, −2, −4, −6, and −8 bars was 86%, 86%, 70%, 19%, and 1%, respectively. This response to moisture stress was modified by imbibition, or hydration-dehydration, of the seed prior to the moisture stress. Imbibing the seed for as little as 2 h significantly increased its subsequent germination against moisture stress. One hydration-dehydration cycle had little or no effect on germination, but as the number of cycles increased, the germination percentage decreased. Prolonged hydration of 3 and 7 days followed by dehydration greatly reduced subsequent seed germination.

scholarly journals Osmotic Priming or Chilling Stratification Improves Seed Germination of Purple Coneflower

HortScience ◽  
1994 ◽  
Vol 29 (12) ◽  
pp. 1445-1448 ◽  
Author(s):  
N. Wartidiningsih ◽  
R.L. Geneve ◽  
S.T. Kester
Keyword(s):  
Polyethylene Glycol ◽  
Seed Germination ◽  
Osmotic Potential ◽  
Echinacea Purpurea ◽  
Germination Percentage ◽  
Polyethylene Glycol 4000 ◽  
Purple Coneflower ◽  
High Germination

High germination seed lots of purple coneflower [Echinacea purpurea (L.) Moench] were evaluated for laboratory germination following osmotic priming or chilling stratification. Compared to nontreated seeds, osmotic priming at 25C in salts (KNO3 + K3PO4; 1:1, w/w) or polyethylene glycol 4000 (PEG) increased early (3-day) germination percentage at 27C of all seed lots, and improved total (10-day) germination percentage of low-germination seed lots. Total germination percentage was unaffected or increased by priming for 4 days compared to 8 days, and by priming at –1.0 MPa compared to –0.5 MPa (except for one low-germination seed lot). Chilling stratification in water at 5 or 10C increased early and total germination of all seed lots, except for that same lot, compared to nontreated seeds. Total germination percentage was unaffected or increased by stratification at 10C rather than at 5C. Neither extending stratification ≥20 days nor lowering osmotic potential with PEG during stratification improved total germination percentage.

scholarly journals Predicting Seed Germination of Safflower (Carthamus Tinctorius) Cultivars Using Hydrotime Model

2017 ◽  
Vol 50 (1) ◽  
pp. 79-87
Author(s):  
S.A. Tabatabae ◽  
O. Ansari
Keyword(s):  
Seed Germination ◽  
Water Availability ◽  
Germination Percentage ◽  
Carthamus Tinctorius ◽  
Safflower Seed ◽  
Arid Environments ◽  
Crop Establishment ◽  
Hydrotime Model ◽  
Short Time ◽  
Peg 600

Abstract Safflower (Carthamus tinctorius) is a highly branched, herbaceous, thistle-like annual plant. It is commercially cultivated for vegetable oil extracted from the seeds, which is cultivated under arid environments. In such environments, the water needed for germination is available for only a short time and, consequently, successful crop establishment depends not only on rapid and uniform germination of the seedlot, but also on its ability to germinate under low water availability. All of these attributes can be analyzed through the hydrotime model (HT). Safflower seeds were germinated in various polyethylene glycol (PEG 600) solutions to obtain water potentials of 0, -0.2, -0.4, -0.6, and -0.8 Mpa. Results indicated that germination of safflower cultivars decreased significantly with reduction of osmotic potential. The highest germination percentage for Sina (93.06 and 94.02%), Faraman (93.52 and 95.33%), Talaei (94.98 and 93.98%) and Kouseh (93.58 and 95.55%) cultivars were attained from distilled water (0 MPa) and -0.2 MPa, respectively. The hydrotime constant (θH) for Sina, Faraman, Talaei and Kouseh cultivars were 0.93, 0.84, 0.78 and 0.72 MPa d, and the water potential (Ψb(50)) for Sina, Faraman, Talaei and Kouseh cultivars were -0.56, -0.67, -0.64 and -0.77 MPa, respectively. Cumulative germination of safflower seed was higher in Kouseh cultivar, than in Sina, Faraman and Talaei cultivars. Results showed that, hydrotime model is suited to predicting seed germination of safflower seeds. In addition, the information gathered with this work allows us to build mathematical models to predict germination of safflower cultivars in the field under various environments.

scholarly journals Influence of priming on Eucalyptus spp seeds' tolerance to salt stress

2016 ◽  
Vol 38 (4) ◽  
pp. 329-334 ◽  
Author(s):  
Anderson Cleiton José ◽  
Natália Cristina Nogueira Silva ◽  
José Marcio Rocha Faria ◽  
Wilson Vicente Souza Pereira
Keyword(s):  
Salt Stress ◽  
Seed Germination ◽  
Water Potential ◽  
Salt Solution ◽  
Germination Percentage ◽  
Eucalyptus Urophylla ◽  
Nacl Solution ◽  
Peg 6000 ◽  
Germination Speed ◽  
Osmotic Potentials

Abstract: The objective of this experiment was to evaluate the effect of priming on the germination of Eucalyptus urophylla and of hybrid E. urophylla × E. grandis seeds under salt stress. Two osmotic potentials (-1.0 and -1.5 MPa) were tested, using PEG 6000 for 1 and 3 days. After priming, seeds were germinated under salt stress in a NaCl solution at 0.0 (control), -0.5, -0.75 and -1.0 MPa potentials, at 25 °C. Seed germination and germination speed index decreased as the water potential of the germination medium decreased. However, E. urophylla was more tolerant to salt stress; it showed a higher germination percentage under all tested potentials, when compared to the hybrid. The osmotic conditioning at -1.0 MPa for three days was more effective when E. urophylla x E. grandis was germinated in a salt solution at -1.0 MPa, indicating that this treatment was more effective in inducing tolerance to salt stress.

Response of highbush blueberry seed germination to gibberellin A3 and 6N-benzyladenine

1989 ◽  
Vol 67 (11) ◽  
pp. 3391-3393 ◽  
Author(s):  
I. M. Dweikat ◽  
P. M. Lyrene
Keyword(s):  
Seed Germination ◽  
Gibberellic Acid ◽  
Acid Concentration ◽  
Growth Regulators ◽  
Vaccinium Corymbosum ◽  
Germination Percentage ◽  
Highbush Blueberry ◽  
Gibberellin A3 ◽  
The Relationship ◽  
Germinated Seeds

Open-pollinated highbush blueberry (Vaccinium corymbosum L.) seeds were treated with 0, 2.6, 5.2, 10.4, or 20.8 mM gibberellic acid, 0, 0.4, 2.2, or 4.4 mM 6N-benzyladenine, or the two growth regulators in combination. Seeds were treated for 24 h, then germinated under intermittent mist during summer with temperatures fluctuating between 21 and 40 °C. Germinated seeds were counted weekly from day 15 to day 30, using hypocotyl exposure to indicate germination. Treatment with gibberellic acid at 10.4 mM in combination with 6N-benzyladenine at 0.4 to 2.2 mM gave the highest germination percentage. The relationship between gibberellic acid concentration and seed germination was cubic. Seedlings from the germinated seed flowered and fruited the following spring, making it possible for highbush blueberry to complete a generation in 1 year.

scholarly journals Modeling the influence of temperature and water potential on seed germination of Allium tenuissimum L.

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8866
Author(s):  
Hong Xiao ◽  
Helong Yang ◽  
Thomas Monaco ◽  
Qian Song ◽  
Yuping Rong
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Crop Production ◽  
Soil Water Potential ◽  
Germination Percentage ◽  
Cold Environments ◽  
Drought Tolerant ◽  
Temperature Regimes ◽  
Desert Steppes ◽  
Base Water Potential

Allium tenuissimum L. is a widely distributed perennial herbaceous species in temperate and desert steppes. Relative to other wild Allium species, it produces unique sweet flavors, more biomass in arid and cold environments, and has generated greater interest for crop production. Successful crop establishment, however, will depend on rapid and uniform seed germination. Our study aimed to characterize seed germination of A. tenuissimum under various temperature regimes (11, 15, 20, 24 and 28 °C) and water potential levels (0, −0.2, −0.4 and −0.6 MPa), and model germination by hydrotime (HT) and hydrothermal time (HTT) analysis. Final germination percentage (FGP) increased within the range of 11 to 20 °C, yet it declined within the range of 24 to 28 °C and generally decreased as water potential became more negative within each temperature setting. Maximum FGP was observed at 20 °C at all water potential settings and ranged from 55.0 ± 5.3 to 94.8 ± 1.4%. According to HT and HTT models, the base (Tb) and optimum temperatures (To) for seed germination were 7.0 and 20.5 °C, respectively. In addition, base water potential for the fraction of germination within the seed lot (Ψb(g)) shifted to 0 MPa as temperature increased from Tb to ceiling temperature (Tc). For obtaining 50 % seed germination, Ψb(50) and Tc(50) were estimated to be −0.67 MPa and 27.2 °C, respectively. These values for Tb and Ψb(50) suggest seed germination of A. tenuissimum is both cold and drought tolerant and suitable for production in semi-arid regions. Our characterization of the ideal sowing conditions for A. tenuissimum, i.e., 20.5 °C and soil water potential less negative than −0.67 MPa offers information to forecast suitable settings to enhance crop production.

scholarly journals Mobilization of reserves and germination of seeds of Erythrina velutina Willd. (Leguminosae - Papilionoideae) under different osmotic potentials

2012 ◽  
Vol 34 (4) ◽  
pp. 580-588 ◽  
Author(s):  
Renata Conduru Ribeiro Reis ◽  
Bárbara França Dantas ◽  
Claudinéia Regina Pelacani
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Germination Percentage ◽  
Uniformity Coefficient ◽  
Carbon And Nitrogen ◽  
Germination Process ◽  
Mean Time ◽  
Osmotic Potentials

Some environmental factors, including water availability, may influence seed germination. This study investigated the germination of E. velutina seeds submitted to different osmotic potentials and mobilization of reserves during water-stress. Scarified seeds were arranged in paper rolls and soaked in solutions of Polyethylene Glycol (PEG) prepared in osmotic potentials 0.0, -0.2, -0.4, -0.6, and -0.8 MPa and kept into a seed germinator, at 25 °C, and 12/12 h photoperiod (L/D), during 10 days. The percentage, mean time, mean speed, germination speed index; as well as the germination uniformity coefficient were assessed. During germination process the total soluble sugars, reducing sugars, soluble protein, and total amino acids were quantified in the cotyledon, hypocotyl and radicle of soaked seeds and cotyledons of quiescent seeds (control). There was influence of osmotic potential on E. velutina seed germination. The germination percentage remained at high levels until -0.6 MPa and above this osmotic potential there has been no germination. The mobilization of stored reserves of carbon and nitrogen in E. velutina seeds was also influenced by water-stress. There was sensitiveness between -0.2 and -0.6 MPa; however, the degradation and the mobilization of reserves was slower when the osmotic potential decreased.

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