Alleviation of dormancy in annual ryegrass (Lolium rigidum) seeds by hydration and after-ripening

Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 968-975 ◽  
Author(s):  
Robert S. Gallagher ◽  
Kathryn J. Steadman ◽  
Andrew D. Crawford
Keyword(s):  
Seed Germination ◽  
Relative Humidity ◽  
Germination Rate ◽  
Dormancy Release ◽  
Annual Ryegrass ◽  
Dormant Seed ◽  
Lolium Rigidum ◽  
Time Model ◽  
Treatment Regimens ◽  
Two Populations

The effect of hydration (priming) treatment on dormancy release in annual ryegrass seeds from two populations was investigated. Hydration duration, number, and timing with respect to after-ripening were compared in an experiment involving 15 treatment regimens for 12 wk. Seeds were hydrated at 100% relative humidity for 0, 2, or 10 d at Weeks 1, 6, or 12 of after-ripening. Dormancy status was assessed after each hydration treatment by measuring seed germination at 12-hourly alternating 25/15 C (light/dark) periods using seeds directly from the hydration treatment and seeds subjected to 4 d postpriming desiccation. Seeds exposed to one or more hydration events during the 12 wk were less dormant than seeds that remained dry throughout after-ripening. The longer hydration of 10 d promoted greater dormancy loss than either a 2-d hydration or no hydration. For the seed lot that was most dormant at the start of the experiment, two or three rather than one hydration event or a hydration event earlier rather than later during after-ripening promoted greater dormancy release. These effects were not significant for the less-dormant seed lot. For both seed lots, the effect of a single hydration for 2 d at Week 1 or 6 of after-ripening was not manifested until the test at Week 12 of the experiment, suggesting that the hydration events alter the rate of dormancy release during subsequent after-ripening. A hydrothermal priming time model, usually used for modeling the effect of priming on germination rate of nondormant seeds, was successfully applied to dormancy release resulting from the hydration treatments.

The occurrence of herbicide cross-resistance in a population of annual ryegrass, Lolium rigidum, resistant to diclofop-methyl

1986 ◽  
Vol 37 (2) ◽  
pp. 149 ◽  
Author(s):  
I Heap ◽  
R Knight
Keyword(s):  
Cross Resistance ◽  
Annual Ryegrass ◽  
Lolium Rigidum ◽  
Leaf Stage ◽  
Two Populations

A population of L. rigidum, which is known to have developed resistance to one of the diphenyl-ethertype of herbicides, diclofop-methyl, was tested for cross-resistance to three other herbicides of the same type, namely fluazifop-butyl, oxyfluorfen and the experimental herbicide CGA 82725. The population was also tested for cross-resistance to two sulfonylurea-type herbicides - chlorsulfuron and the experimental herbicide DPX-T6376. A population susceptible to diclofop-methyl was used as the controls in the tests. The two populations were treated with various rates of the herbicides during germination and at the two-leaf stage. The results show that the diclofop-methyl-resistant biotype was cross-resistant to fluazifop-butyl, CGA 82725, chlorsulfuron and DPX-T6376 but not to oxyfluorfen.

Germination of annual ryegrass seeds (Lolium rigidum Gaud.) as influenced by temperature, light, storage environment, and age

1972 ◽  
Vol 23 (5) ◽  
pp. 779 ◽  
Author(s):  
D Gramshaw
Keyword(s):  
Germination Rate ◽  
Soil Surface ◽  
Day Length ◽  
Annual Ryegrass ◽  
Lolium Rigidum ◽  
Light Storage ◽  
Seed Age ◽  
Germination Behaviour ◽  
Alternating Temperature ◽  
The Relationship

Germination of Lolium rigidum seeds, in the light (12 hr day length) and in the dark, at constant temperatures of 12, 18, and 24°C and an alternating temperature of 24/12° (12 / 12 hr), was studied in freshly harvested seeds and in seeds stored for 18 weeks. In freshly harvested seeds the highest germinability (80%) was recorded at 12° in either light or dark and at 24/12° in the light. After 18 weeks' storage, a germinability of between 95 and 100% was observed at 12° and 24/12° in the dark and at 24° and 24/12° in the light. In another experiment in which seeds from a different source were used, seeds kept in six different environments and recovered at 3-weekly intervals during a 21 week post-harvest period were examined for germinability and germination rate. The six environments were: storage in a room, storage in a 60/15°C temperature cabinet, and four field treatments in which seeds were buried 0.2 and 1.0 cm under both a bare and a mulched soil surface. Germination was tested in the light and in the dark at an alternating temperature of 24/12°. Major increases in seed germinability with age occurred during the first 9 weeks after harvest. The different environments influenced the relationship between seed age and germinability only during the first 9 weeks. Seeds located 0.2 cm beneath either a bare or a mulched soil surface during summer germinated at a faster rate than seeds kept in the other environments. These findings are discussed in relation to the germination behaviour of seeds in the field.

Dormancy release in Lolium rigidum seeds is a function of thermal after-ripening time and seed water content

2003 ◽  
Vol 30 (3) ◽  
pp. 345 ◽  
Author(s):  
Kathryn J. Steadman ◽  
Andrew D. Crawford ◽  
Robert S. Gallagher
Keyword(s):  
Water Content ◽  
Dry Weight ◽  
Base Temperature ◽  
Dormancy Release ◽  
Lolium Rigidum ◽  
Time Model ◽  
Ripening Time ◽  
Seed Moisture ◽  
Water Contents ◽  
Seed Water Content

Dormancy release in seeds of Lolium rigidum Gaud. (annual ryegrass) was investigated in relation to temperature and seed water content. Freshly matured seeds were collected from cropping fields at Wongan Hills and Merredin, Western Australia. Seeds from Wongan Hills were equilibrated to water contents between 6 and 18% dry weight and after-ripened at constant temperatures between 9 and 50°C for up to 23 weeks. Wongan Hills and Merredin seeds at water contents between 7 and 17% were also after-ripened in full sun or shade conditions. Dormancy was tested at regular intervals during after-ripening by germinating seeds on agar at 12-h alternating 15°C (dark) and 25°C (light) periods.Rate of dormancy release for Wongan Hills seeds was a positive linear function of after-ripening temperature above a base temperature (Tb) of 5.4°C. A thermal after-ripening time model for dormancy loss accounting for seed moisture in the range 6–18% was developed using germination data for Wongan Hills seeds after-ripened at constant temperatures. The model accurately predicted dormancy release for Wongan Hills seeds after-ripened under naturally fluctuating temperatures. Seeds from Merredin responded similarly but had lower dormancy at collection and a faster rate of dormancy release in seeds below 9% water content.

Estimation of base and optimum temperatures for seed germination in common crupina (Crupina vulgaris)

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 529-533 ◽  
Author(s):  
Cindy Talbott Roché ◽  
Donald C. Thill ◽  
Bahman Shafii
Keyword(s):  
Seed Germination ◽  
Time Course ◽  
Germination Rate ◽  
Logistic Growth ◽  
Base Temperature ◽  
Bootstrap Confidence Intervals ◽  
Significant Difference ◽  
Winter Annual ◽  
Best Fit ◽  
Two Populations

Thermal time models for predicting phenological development require an estimate of base temperature, an attribute not previously defined for common crupina, a Mediterranean winter annual introduced in western North America. The stage of seed germination was selected for estimating base temperature, because facilities were available for experiments over a range of constant temperatures and base temperature is relatively constant throughout the life cycle in other species. Achenes from three populations of common crupina, including two varieties,typicaandbrachypappa, were produced under uniform conditions. Cumulative germination was recorded at 12 h intervals for achenes in darkness and optimum moisture at 23 constant temperatures from 4 to 17 C. The time course of germination was best described by a logistic growth curve from which time to 50% germination was estimated. A parabolic model provided the best fit in a regression of germination rate (reciprocal of time to 50%) against the temperature gradient, yielding base and optimum temperatures of 1 and 10.5 C, respectively. Bootstrap confidence intervals indicated no significant difference in base and optimum temperatures in germination between the two varieties nor between two populations of var.typicaof common crupina introduced in the northwestern United States.

scholarly journals Using hydrothermal time concepts to model seed germination response to temperature, dormancy loss, and priming effects in Elymus elymoides

2000 ◽  
Vol 10 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Susan E. Meyer ◽  
Susan B. Debaene-Gill ◽  
Phil S. Allen
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Time Course ◽  
Germination Rate ◽  
Base Temperature ◽  
Hydrothermal Time ◽  
Time Model ◽  
Priming Effects ◽  
Elymus Elymoides ◽  
Temperature Regimes

AbstractHydrothermal time (HTT) describes progress toward seed germination under various combinations of incubation water potential ( ) and temperature (T). To examine changes in HTT parameters during dormancy loss, seeds from two populations of the bunchgrass Elymus elymoides were incubated under seven temperature regimes following dry storage at 10, 20 and 30°C for intervals from 0 to 16 weeks. Fully after-ripened seeds were primed for 1 week at a range of s. Data on germination rate during priming were used to obtain a HTT equation for each seed population, while data obtained following transfer to water were used to calculate HTT accumulation during priming. HTT equations accurately predicted germination time course curves if mean base water potential, b(50), was allowed to vary with temperature. b(50) values increased linearly with temperature, explaining why germination rate does not increase with temperature in this species. b(50) showed a linear decrease as a function of thermal time in storage. Slopes for the T × b(50) relationship did not change during after-ripening. This thermal after-ripening time model was characterized by a single base temperature and a constant slope across temperatures for each collection. Because the difference between initial and final b(50)s was uniform across tempera-tures, the thermal after-ripening requirement was also a constant. When seeds were primed for 1 week at −4 to −20 MPa, accumulation of HTT was a uniform 20% of the total HTT requirement. When primed at 0 to −4 MPa, HTT accumulation decreased linearly with decreasing priming potential, and a hydrothermal priming time model using a constant minimum priming potential adequately described priming effects. Use of these simple HTT relationships will facilitate modelling of germination phenology in the field.

Survival of annual ryegrass (Lolium rigidum Gaud.) seed in a Mediterranean type environment. II.* Effects of short-term burial on persistence of viable seed

1977 ◽  
Vol 28 (1) ◽  
pp. 93 ◽  
Author(s):  
D Gramshaw ◽  
WR Stern
Keyword(s):  
Soil Disturbance ◽  
Burial Depth ◽  
Annual Ryegrass ◽  
Dormant Seed ◽  
Lolium Rigidum ◽  
Short Term ◽  
Gaseous Environment ◽  
Seed Population ◽  
Total Seed ◽  
Soil Temperature And Moisture

Two seed components, dark dormant and non-dark dormant, were identified in experiments in which germination and survival of seeds buried in soil were examined. These comprised c. 10–20% and 80–90% of the seed population respectively. About 12% of the dark dormant seeds (1–2% of total seed population) germinated when first buried between 0 and 2 cm depth, and subsequent disturbance of the soil on two occasions caused further germinations. In contrast, all non-dark dormant seed rapidly germinated when buried at 2 cm; however, germination of non-dark dormant seeds decreased progressively as burial depth increased, until at 11 and 14 cm no seed germinated. In one experiment, seed that failed to germinate when buried at 14 cm was found to germinate readily if transferred to a depth of 2 cm without soil disturbance. This indicated that dormancy was enforced, rather than induced, in seeds buried relatively deeply for short periods. In these experiments soil temperature and moisture were favourable for germination, and it is suggested that an unfavourable gaseous environment around deeply buried seeds is the factor enforcing dormancy. The implication of these findings for the persistence of annual ryegrass in the pasture-crop rotation is discussed. _____________________ *Part I, Aust. J. Agric. Res., 28: 81 (1977).

scholarly journals Using mathematical models to evaluate germination rate and seedlings length of chickpea seed (Cicer arietinum L.) to osmotic stress at cardinal temperatures

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260990
Author(s):  
Sikandar Shah ◽  
Sami Ullah ◽  
Sajjad Ali ◽  
Ajmal Khan ◽  
Muhammad Ali ◽  
...  
Keyword(s):  
Seed Germination ◽  
Cicer Arietinum ◽  
Time Constant ◽  
Germination Rate ◽  
Interactive Effect ◽  
Germination Percentage ◽  
Hydrothermal Time ◽  
Time Model ◽  
Water Potentials ◽  
Cardinal Temperatures

Cicer arietinum is the 3rd most important cool season legume crop growing in vast arid and semi-arid regions of the world. A lab experiment was designed using hydrothermal time model (HTT) to investigate the chickpea seed germination (SG) behavior, cardinal temperatures and germination responses across fluctuating temperatures (Ts) and water potentials (Ψs). Seeds of chickpea var. NIFA 1995 were germinated at six constant Ts (7, 14, 21, 28, 35 and 42°C) each having the following five water potentials: 0, -0.2, -0.4–0.6 and -0.8 MPa. Germination percentage (G%) decreased significantly at (*P ≤ 0.05) from 86.7% at 28°C in -0.2 MPa to 10% in -0.2 MPa at 7°C. The germination rate (GR = 1/t50) against different T percentiles exhibited that linear increase was observed in the GR pattern above and below the To. Based on the confidence intervals of the model coefficients and (R2: 0.96), the average cardinal temperatures were 4.7, 23 and 44.2°C for the base (Tb), optimal (To) and ceiling (Tc) temperatures respectively. θT1 value was observed maximum at 28°C in -0.2 MPa and decreases with decreasing Ψ (-0.8 MPa). In comparison with control, the θT2 value was also highest in -0.2 MPa at 28°C. The thermal time (TT) concept is well fitted to germination fraction data in distilled water with an R2 value increasing 0.972. The hydro time constant (θH) increased with an increase in T to To and then decreased when T>To. The ѱb(50) irregularly varied with increasing T, σΨb was also recorded lowest (0.166 MPa) at 28°C and highest (0.457 MPa) at 7°C. Based on the statistical analysis, cardinal temperatures, hydrothermal time constant (θHTT) and germination findings the HTT gives an insight into the interactive effect of T and Ψ on seed germination time courses under varying environmental conditions.

Stimulating dormancy release and emergence of annual ryegrass (Lolium rigidum) seeds using short-term hydrated storage in darkness

2004 ◽  
Vol 55 (7) ◽  
pp. 787 ◽  
Author(s):  
Kathryn J. Steadman ◽  
Gavin P. Bignell ◽  
Pippa J. Michael
Keyword(s):  
Effective Means ◽  
Soil Surface ◽  
Dormancy Release ◽  
Annual Ryegrass ◽  
Moist Soil ◽  
Lolium Rigidum ◽  
Short Term ◽  
Water Conditions ◽  
Buried Seeds ◽  
Diurnal Temperatures

Experiments were performed to determine whether the dormancy release effect of hydrated storage in darkness (dark-stratification) is common amongst annual ryegrass populations and has the potential to occur under field conditions. Dormant seeds from all populations tested (22) became sensitive to light during dark-stratification, enabling them to germinate when subsequently exposed to light. Under controlled temperature (25/15°C), light (12-h photoperiod), and hydration (solidified agar-water) conditions, more seeds germinated by 28 days if the first 14 days were in darkness followed by exposure to light for 12 h per day than if they were exposed to light throughout or darkness throughout. Constraint over the conditions imposed during dark-stratification and germination was gradually reduced to investigate whether the dormancy release effect was diminished. Dark-stratification was effective in promoting germination when performed under natural diurnal temperatures, and burial in moist soil provided suitable conditions for dark-stratification to occur. The surface of moist soil, with natural diurnal temperatures and sunlight, was suitable for germination of dark-stratified seeds. Dark-stratification is a quick and effective means to enhance the sensitivity of dormant annual ryegrass seeds to light, enabling the majority of the population to germinate. However, large quantities of light are required to promote germination of dark-stratified seeds, so buried seeds must be moved to the soil surface to allow exposure to adequate light for germination.

scholarly journals Influence of Storage Conditions on the Quality of Cotton Seeds in Benin Republic

2020 ◽  
Author(s):  
Roger IDOSSOU ◽  
Razack ABOUDOU
Keyword(s):  
Seed Germination ◽  
Relative Humidity ◽  
Germination Rate ◽  
Storage Conditions ◽  
Germination Capacity ◽  
Sampling Sequence ◽  
Significant Difference ◽  
Cotton Seeds ◽  
Benin Republic

Abstract Background The availability of good quality seeds is synonymous with improved farming, especially cash crops such as cotton. However, serious problems with seed germination have been reported recently by cotton farmers in Benin Republic. The assumptions formulated at the base with regard to this situation remain to be verified technically. Thus, this study aims to evaluate the influence of storage conditions on the quality of cotton seeds in Northern Benin. Temperature and relative humidity were assessed followed by a seed sampling sequence in seven (07) cotton seeds stores according to three main periods, ranging from the establishment in conservation to the following seasonal production. Germination tests were then carried out on each sample followed by data analysis using R and Minitab17 software.Results There is a large variation in the germination rate of cotton seed during their storage period. The probabilities values ​​(Pvalue1 = 0.023, Pvalue2 = 0.001 and Pvalue3 = 0.038) respectively associated with the three samples and the various coefficient of variation (CV) between stores (CV1 = 2.42%, CV2 = 7.1% and CV3 = 8.88%) explain a significant difference not only between the stores but also from one sample to another with regard to sampling periods. There is a strong progressive decrease in seed germination (Germination rate 1 > Germination rate2 > Germination rate3), which is responsible for the failure observed by the growers during sowing. Thus, seeds lose an average of 15% of their initial germination capacity already at one month of storage. This is generally negative due to all the storage conditions and system in the stores.Conclusions The excessive increase in temperature and the considerable decrease in relative humidity in stores are the main factors of significant loss of germination capacity of cotton seeds. In view of this situation, it is desirable that technical measures be taken in this direction in order to better preserve the quality of the seeds made available to producers for an optimization of the cotton sector in Benin.

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