scholarly journals Seed dormancy and germination of Shaggy soldier (Galinsoga ciliata Blake.) and Common lambsquarter (Chenopodium album L.)

2011 ◽  
Vol 49 (No. 11) ◽  
pp. 511-518 ◽  
Author(s):  
M. Jursík ◽  
J. Soukup ◽  
V. Venclová ◽  
J. Holec
Keyword(s):  
Temperature Interval ◽  
Laboratory Experiments ◽  
Chenopodium Album ◽  
Germination Test ◽  
Primary Dormancy ◽  
Germination Energy ◽  
High Germination ◽  
Galinsoga Ciliata ◽  
Very High ◽  
Seed Dormancy And Germination

Laboratory experiments were carried out with seeds of Galinsoga ciliata and Chenopodium album in 1998, 2000 and 2001. The study involved germination of non-dormant seeds in the light and the dark at 5–30°C, the germination energy at 15, 24, and 33°C, and the primary dormancy of seeds matured during the period from July to October. Both weeds germinated better in the light compared to the dark. Seeds of G. ciliata germinated at 10–33°C. Germination exceeding 85% was recorded at 12–28°C. Ch. album germinated in a wider temperature interval (5–33°C). Maximum germination (75%) was obtained at 18°C. A very high germination energy of G. ciliata seeds was found at 24°C. At this temperature, 89% of seeds germinated during the second and third day of the germination test. Seeds of Ch. album had a low germination energy at 15 and 24°C. The germination energy was high only at 33°C, however, the total germination reached at this temperature was only 26.5%. Both G. ciliata and Ch. album formed primary dormant seeds during all three testing years. The length of primary dormancy varied from 10 to 100 days depending on the date of ripening and on the year. The longest primary dormancy was found with early ripened seeds (July and August).

Halosulfuron and 2,4-D Mixtures' Effects on Common Lambsquarters (Chenopodium album)

2006 ◽  
Vol 20 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Mark A. Isaacs ◽  
Kriton K. Hatzios ◽  
Henry P. Wilson ◽  
Joe Toler
Keyword(s):  
Laboratory Experiments ◽  
Chenopodium Album ◽  
Independent Action ◽  
Common Lambsquarters ◽  
Synergistic Response

Greenhouse and laboratory experiments were conducted to investigate the response of common lambsquarters to POST applications of halosulfuron–methyl plus 2,4-D admixtures and to investigate the effects of 2,4-D on the absorption, translocation, and metabolism of halosulfuron. In the greenhouse, halosulfuron at 0, 4.5, 9, 18, and 36 g ai/ha was applied alone and mixed with 2,4-D at 0, 17, 35, and 70 g ai/ha POST to 7.5- to 9-cm seedlings, and plant fresh weights were determined 4 wk after treatment (WAT). Halosulfuron alone did not control this weed, while fresh weights of common lambsquarters treated with 2,4-D declined hyperbolically as rates increased. A synergistic response for mixtures of these herbicides occurred, as observed fresh weights for all combinations were less than expected based on independent action and the calibrated marginal responses. In the laboratory, 7.5- to 9-cm seedlings were treated POST with commercially formulated halosulfuron at 9 and 18 g/ha and 2,4-D at 0, 70, and 140 g/ha, respectively, followed by foliar-applied14C-halosulfuron. Absorption of14C-halosulfuron increased with time, and absorption and translocation were not influenced by the addition of 2,4-D. Results from these studies inferred that halosulfuron and 2,4-D were generally synergistic on common lambsquarters and that mechanisms other than absorption, translocation, and metabolism may explain this response.

scholarly journals Seasonal emergence of selected summer annual weed species in dependence on soil temperature

2010 ◽  
Vol 56 (No. 9) ◽  
pp. 444-450 ◽  
Author(s):  
M. Jursík ◽  
J. Holec ◽  
J. Soukup ◽  
V. Venclová
Keyword(s):  
Chenopodium Album ◽  
Soil Surface ◽  
Main Field ◽  
Weed Species ◽  
Soil Temperatures ◽  
Field Emergence ◽  
The Relationship ◽  
Galinsoga Ciliata ◽  
Surface Layer Temperature ◽  
Mass Field

This study aimed to describe emergence cycles of selected weed species under Central European conditions in relation to cumulative soil temperatures from the start of the vegetation season. Emergence of Chenopodium album, Echinochloa crus-galli, Galinsoga ciliata, and Abutilon theophrasti was observed from March to October during the period 2001–2006 at two locations. The beginning of main field emergence was determined as the day when the sum of effective hour temperatures was achieved, and was detected from the second decade of April to early May for C. album, in the second decade of May for E. crus-galli, from late April to the beginning of May for G. ciliata, and from the end of April to mid-May for A. theophrasti. The relationship between cumulative soil surface layer temperature and weed mass field emergence at the beginning of the growing season is very direct (differences ±7 days) – but only when soil moisture is sufficient. In a drier spring, the beginning of mass field emergence occurs with 1–4 weeks of delay and field emergence is usually slower and protracted.

The effect of humic substances on germination and early growth of Lamb’s Quarters (Chenopodium album agg.)

Biologia ◽  
2011 ◽  
Vol 66 (3) ◽  
Author(s):  
Božena Šerá ◽  
František Novák
Keyword(s):  
Seed Germination ◽  
Humic Substances ◽  
Seed Development ◽  
Initial Phase ◽  
Chenopodium Album ◽  
Early Growth ◽  
Germination Test ◽  
Diverse Origin ◽  
Lamb’S Quarters ◽  
Germination And Growth

AbstractIn order to understand the biological activity of humic substances (HS), the effect of four humic acids (HA) and one fulvic acid (FA) on seed germination and early growth of cosmopolitan weed Chenopodium album agg. were tested. Humic substances of diverse origin were used, namely purified commercial HA, HA isolated from lignite, cambisol and podzol, and FA from mountain spruce forest soil. Data processing by two-way ANOVA has shown that type of the tested substances was a more important factor on seed development than used concentration. The major differences in germination and length of shoots were found in the first days of the experiment. Commercial and lignite HA stimulated the seed germination and growth, while podzol HA inhibited them. After this initial phase, all humic substances stimulated the seed development, but these stimulations were not significant (P < 0.05). At the end of germination test, the greatest stimulation effect (up to 20%) was achieved with the lignite HA.

scholarly journals Effect of Packaging Materials and Storage Periods on the Vigor Parameters of Some Selected Varieties of Soybeans in Makurdi, Benue State, Nigeria

2019 ◽  
pp. 1-14
Author(s):  
J. O. Obute ◽  
S. V. Irtwange ◽  
T. Vange
Keyword(s):  
Storage Period ◽  
Packaging Material ◽  
Packaging Materials ◽  
Seedling Vigor ◽  
Storage Material ◽  
Germination Test ◽  
Plastic Container ◽  
Seedling Length ◽  
And Storage ◽  
Very High

This study was carried out in 2017 at the Federal University of Agriculture, Makurdi Nigeria. The study was aimed at evaluating the effect of packaging materials and storage period on the vigor parameters of some selected varieties of soybeans in Makurdi. The experimental design was 3x5x6 factorial CRD comprising 3 varieties, 5 storage periods and 6 packaging materials by 3 replicates. Samples were collected from National Cereal Research Institute, Yandev sub-station. The soybeans were cleaned, dried and the moisture content noted. Five hundred grams was measured into the various packaging material stored and at Strategic Grains Reserve, Federal Ministry of Agriculture Makurdi. The seeds in storage was sampled periodically (2, 4, 6 and 8 months) to determine quality by conducting standard germination test with 100 seeds (100 seeds/rep). The investigation revealed that V3 (TGx 1448-2E) stored for 2 months had the highest Shoot seedling length while V1 (TGx 923-3F) stored for 8 months had the least shoot seedling length. Soybeans stored in cloth had a very high Shoot seedling length at 2 months but dropped thereafter and turned out to be the lowest at the end of the storage period. V2 (TGx 1904-6F) stored in laminate paper produced the longest Shoot seedling length and also produced the shortest with V1. The seedling root length was longest in V3 stored for 2 months and least in V1 stored for 8months.Soybeans stored in cloth for 2 months produced very high SRL 2 months but dropped to 0.00 at the end of the storage period. V2 did better in LDPE than all the packaging materials. V1 had the shortest SRL in soybeans stored in bottle. The highest seedling vigor was recorded in V3 stored for 2 months while the lowest seedling vigor was recorded in V1 stored for 8 months. V2 in plastic container had the highest seedling vigor whileV1 in plastic had the lowest. However, significant differences were observed at (P< 0.05) in the interaction effect. In the present study, LDPE proved to be the best packaging material and the variety that had more resistance to deterioration was V2 (TGx 1904-6F). Soybeans that are stored at ambient should be in storage material that are impervious to air and moisture otherwise the seeds will lose viability and vigor. In addition, varieties that are prone to fast deterioration should not be stored longer.

scholarly journals Cognitive Biases: Mistakes or Missing Stakes?

2021 ◽  
pp. 1-45
Author(s):  
Benjamin Enke ◽  
Uri Gneezy ◽  
Brian Hall ◽  
David Martin ◽  
Vadim Nelidov ◽  
...  
Keyword(s):  
College Students ◽  
Laboratory Experiments ◽  
Cognitive Biases ◽  
Response Times ◽  
Heuristics And Biases ◽  
Intuitive Reasoning ◽  
Improve Performance ◽  
High Stakes ◽  
Base Rate Neglect ◽  
Very High

Abstract Despite decades of research on heuristics and biases, evidence on the effect of large incentives on cognitive biases is scant. We test the effect of incentives on four widely documented biases: base-rate neglect, anchoring, failure of contingent thinking, and intuitive reasoning. In laboratory experiments with 1,236 college students in Nairobi, we implement three incentive levels: no incentives, standard lab payments, and very high incentives. We find that very high stakes increase response times by 40% but improve performance only very mildly or not at all. In none of the tasks do very high stakes come close to de-biasing participants.

Non-commutative quantum gravity phenomenology in underground experiments

2019 ◽  
Vol 34 (29) ◽  
pp. 1950236 ◽  
Author(s):  
Andrea Addazi ◽  
Rita Bernabei
Keyword(s):  
Laboratory Experiments ◽  
Planck Scale ◽  
Pauli Exclusion Principle ◽  
Energy Scale ◽  
Exclusion Principle ◽  
Atomic Systems ◽  
Quantum Gravity Phenomenology ◽  
Nuclear Transitions ◽  
Moyal Plane ◽  
Very High

We show how non-commutative spacetime models can induce Pauli Exclusion Principle (PEP) forbidden nuclear and atomic transitions. We focalize our analysis on one of the most popular instantiations of non-commutativeness: [Formula: see text]-Poincaré model, based on the Groenewold–Moyal plane algebra. We show that PEP violating transitions induced by [Formula: see text]-Poincaré have an energy scale and angular emission dependence. PEP violating transitions in nuclear and atomic systems can be tested with very high accuracy in underground laboratory experiments such as DAMA/LIBRA and VIP(2). We derive that the Equivalence Principle assumed [Formula: see text]-Poincaré model can be already ruled-out until the Planck scale, from nuclear transitions tests by DAMA/LIBRA experiment.

Variation of Seed Dormancy and Germination Ecology of Cowcockle (Vaccaria hispanica)

Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Hema S. N. Duddu ◽  
Steven J. Shirtliffe
Keyword(s):  
Seed Dormancy ◽  
Great Plains ◽  
Northern Great Plains ◽  
Light Conditions ◽  
Primary Dormancy ◽  
Local Environments ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Two Temperature ◽  
Seed Dormancy And Germination

Cowcockle, an introduced summer annual weed of the Northern Great Plains, is being considered for domestication because of its high quality starch, cyclopeptides, and saponins. Loss of seed dormancy is one of the key desirable traits for domestication. To determine the potential for domestication of this species, an understanding of the seed dormancy and germination patterns is required. The objectives of this study were to evaluate seed dormancy in cowcockle ecotypes and determine how temperature and light affect seed dormancy. We evaluated 15 populations of cowcockle for primary dormancy by exposing them to five temperatures (5, 7.5, 10, 15, and 20 C) under two temperature regimes (constant and alternating) in both dark and light conditions. Freshly matured seeds of all the populations showed high levels of primary dormancy except ‘Mongolia’. Lower levels of dormancy at medium temperatures (10 and 15 C) and greater dormancy at low and high temperatures suggest conditional dormancy, a state at which seeds germinate over a narrower range of conditions compared to nondormant seeds. The effects of temperature regime, light, and their interaction was significant only at suboptimal (5 and 7.5 C) and supraoptimal (20 C) temperatures. Under these conditions, alternating temperatures were more effective in breaking the conditional dormancy, followed by light. The variation in optimum temperature, light, and their interactions among the cowcockle populations may be due to the plants evolving to adapt to their local environments. From a domestication perspective, the conditional dormancy in cowcockle can be observed as an evolutionary mechanism that prevents untimely germination following maturity and may not be a major obstacle for its domestication.

Study on Characteristics and Oil Displacement Characteristics of High Concentration Polymer System

2011 ◽  
Vol 391-392 ◽  
pp. 255-259
Author(s):  
Yan Chang Su ◽  
Wen Xiang Wu
Keyword(s):  
Polymer Solution ◽  
Laboratory Experiments ◽  
Polymer System ◽  
Resistance Coefficient ◽  
Chemical Flooding ◽  
High Concentration ◽  
Residual Resistance ◽  
Large Improvement ◽  
Very High ◽  
Viscosity Stability

Through laboratory experiments, viscosity stability of high concentration polymer solution was studied. Viscoelasticity of high concentration polymer was measured by HAAKE RS-150 Rheometer. The flow tests of high concentration polymer solution were carried out by utilizing artificial homogeneity cores, while the influence of injection time on displacement characteristics of high concentration polymer were studied on artificial heterogeneous cores. The results showed that high concentration polymer solution had a good stability within 15 days, but decreased significantly after 30 days. Both viscosity and elasticity of high concentration polymer are higher than the lower ones’. Because the high viscoelasticity of high concentration polymer made the flow resistance increase, resistance coefficient and residual resistance coefficient were very high. Therefore viscoelasticity of high concentration polymer could make a large improvement on chemical flooding recovery.

Behaviour and Feeding of the Nassariid GastropodCyclope Neritea, Abundant at Hydrothermal Brine Seeps off Milos (Aegean Sea)

1997 ◽  
Vol 77 (3) ◽  
pp. 753-771 ◽  
Author(s):  
A.J. Southward ◽  
E.C. Southward ◽  
P.R. Dando ◽  
J.A. Hughes ◽  
M.C. Kennicutt ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Interstitial Water ◽  
Aegean Sea ◽  
Fine Sand ◽  
Behaviour Pattern ◽  
Extreme Conditions ◽  
Field Observations ◽  
Elevated Salinity ◽  
Bacterial Mats ◽  
Very High

Field observations and laboratory experiments were made onCyclope neritea, a small (~10 mm diameter) burrowing stenoglossan gastropod with a flattened shell found in very high densities (>200 m2) in Paleohori Bay on the south coast of Milos (Aegean Sea).Cyclope neriteaforms a high proportion of the biomass at seeps in this bay, where the medium to fine sand overlies hot, sulphidic brines. About half the animals were found on the surface in the daytime, an exception to the normal habit of this species which usually emerges from the sediment only at night. TheC. neriteawere aggregated on the thinner bacterial mats over the seeps. In the laboratory,C. neritearemained active for 3 h at sulphide concentrations up to 1 mM, the highest concentration in the interstitial water in the upper 25 mm of sediment at the seeps. Although the species can tolerate elevated salinity and temperature, it shows little adaptation for sulphide detoxification by oxidative pathways. It may survive at the seeps by its behaviour pattern, especially the use of the extensible siphon to access oxic water above the sediment boundary layer, and perhaps by exclusion of sulphide from the tissues.Cyclope neriteaingests large quantities of sand together with adhering bacteria and diatoms, but also scavenges on other animals killed by the extreme conditions of the seeps.

Seed dormancy and germination in Rhexia mariana var. interior (Melastomataceae) and eco-evolutionary implications

1999 ◽  
Vol 77 (4) ◽  
pp. 488-493 ◽  
Author(s):  
Carol C Baskin ◽  
Jerry M Baskin ◽  
Edward W Chester
Keyword(s):  
Seed Dormancy ◽  
Climatic Conditions ◽  
Eastern North America ◽  
Temperate Region ◽  
High Germination ◽  
Germination Characteristics ◽  
Physiological Dormancy ◽  
Plant Families ◽  
Dormancy Cycles ◽  
Seed Dormancy And Germination

Ninety-seven percent of the Rhexia mariana L. seeds collected in Tennessee were physiologically dormant at maturity in autumn, and they became nondormant during stratification. Light was required for germination, and seeds germinated to higher percentages on filter paper than on sand. Seeds buried in soil in October 1992 and 1994 and exposed to natural seasonal temperatures were exhumed and tested for germination at monthly or bimonthly intervals for 30 and 32 months, respectively. Seeds gained the ability to germinate to 80% or more at 30:15 and 35:20°C during the first winter of burial and also at 25:15°C during the second winter, but they did not re-enter dormancy. In contrast, seeds incubated at 20:10°C exhibited an annual cycle of moderate to high germination percentages in winter-spring and low germination percentages in summer-autumn. Thus, germination can occur at habitat temperatures in Tennessee from April to September. This is the first report of physiological dormancy in seeds of the Melastomataceae in the temperate region. Like members of many plant families in temperate eastern North America, seeds of R. mariana (i) show a decrease in the minimum temperature for germination as they come out of dormancy and (ii) exhibit some seasonal variation in the temperature range for germination. Thus, these dormancy or germination characteristics appear to be adaptations of species to the climatic conditions in temperate eastern North America.Key words: seed dormancy, seed germination, dormancy cycles, buried seeds, Melastomataceae, Rhexia.

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