Modeling weed emergence as influenced by burial depth using the Fermi-Dirac distribution function

Research was conducted to determine the suitability of the Fermi-Dirac distribution function for modeling the seedling emergence of downy brome, johnsongrass, and round-leaved mallow, as influenced by burial depth. Six sets of previously published emergence data were used to formulate the model and test its adequacy. Two independent johnsongrass emergence data sets were used to validate the model. Constant temperature growth chamber studies were conducted to evaluate the effects of temperature and moisture on the model parameters. The Fermi-Dirac distribution function was found to adequately describe the seedling emergence of downy brome, johnsongrass, and round-leaved mallow as indicated by a good visual data fit, narrow confidence intervals for the model parameters, and regression analysis of observed vs. modeled data. Although this function is a model used in physical science, its parameters can be related to abiotic factors such as soil texture, temperature, and moisture.

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Effect of Environmental Factors on the Germination and Emergence of Drunken Horse Grass (Achnatherum inebrians)

Weed Science ◽

10.1017/wsc.2020.81 ◽

2020 ◽

pp. 1-29

Author(s):

Yonghuan Yue ◽

Guili Jin ◽

Weihua Lu ◽

Ke Gong ◽

Wanqiang Han ◽

...

Keyword(s):

Seed Germination ◽

Environmental Factors ◽

Abiotic Factors ◽

Seedling Emergence ◽

Management Strategies ◽

Germination Percentage ◽

Western China ◽

Burial Depth ◽

Achnatherum Inebrians ◽

Water Ph

Abstract Drunken horse grass [Achnatherum inebrians (Hance) Keng] is a perennial poisonous weed in western China. A comprehensive understanding of the ecological response of A. inebrians germination to environmental factors would facilitate the formulation of better management strategies for this weed. Experiments were conducted under laboratory conditions to assess the effects of various abiotic factors, including temperature, light, water, pH and burial depth, on the seed germination and seedling emergence of A. inebrians. The seeds germinated at constant temperatures of 15, 20, 25, 30, 35°C and in alternating-temperature regimes of 15/5, 20/10, 25/15, 30/20, 35/25, 40/30°C, and the seed germination percentages under constant and alternating temperatures ranged from 51% to 94% and 15% to 93%, respectively. Maximum germination occurred at a constant temperature of 25°C, and germination was prevented at 45/35°C. Light did not appear to affect seed germination. The germination percentage of seeds was more than 75% in the pH range of 5 to 10, with the highest germination percentage at pH 6. The seeds germinated at osmotic potentials of 0 MPa to -1.0 MPa, but decreasing osmotic potential inhibited germination, with no germination at -1.2MPa. After 21 d of low osmotic stress, the seeds that did not germinate after rehydration had not lost their vitality. The seedling emergence percentage was highest (90%) when seeds were buried at 1 cm but declined with increasing burial depth and no emergence at 9 cm. Deep tillage may be effective in limiting the seed germination and emergence of this species. The results of this study provide useful information on the conditions necessary for A. inebrians germination and provide a theoretical basis for science-based prediction, prevention and control of this species.

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Effect of Environmental Factors on Germination and Emergence of Shortawn Foxtail (Alopecurus aequalis)

Weed Science ◽

10.1017/wsc.2017.42 ◽

2017 ◽

Vol 66 (1) ◽

pp. 47-56 ◽

Cited By ~ 12

Author(s):

Ning Zhao ◽

Qi Li ◽

Wenlei Guo ◽

Lele Zhang ◽

Lu’an Ge ◽

...

Keyword(s):

Seed Germination ◽

Osmotic Potential ◽

Control Strategies ◽

Abiotic Factors ◽

Germination Rate ◽

Seedling Emergence ◽

Soil Surface ◽

Burial Depth ◽

Effective Measure ◽

Wide Range

Shortawn foxtail is an invasive grass weed infesting winter wheat and canola production in China. A better understanding of the germination ecology of shortawn foxtail would help to develop better control strategies for this weed. Experiments were conducted under laboratory conditions to evaluate the effects of various abiotic factors, including temperature, light, pH, osmotic stress, salt concentration, and planting depth, on seed germination and seedling emergence of shortawn foxtail. The results showed that the seed germination rate was greater than 90% over a wide range of constant (5 to 25C) and alternating (15/5 to 35/25C) temperatures. Maximum germination occurred at 20C or 25/15C, and no germination occurred at 35C. Light did not appear to have any effect on seed germination. Shortawn foxtail germination was 27% to 99% over a pH range of 4 to 10, and higher germination was obtained at alkaline pH values ranging from 7 to 10. Seed germination was sensitive to osmotic potential and completely inhibited at an osmotic potential of −0.6 MPa, but it was tolerant to salinity: germination even occurred at 200 mM NaCl (5%). Seedling emergence was highest (98%) when seeds were placed on the soil surface but declined with the increasing burial depth. No seedlings emerged when seeds were buried 6-cm deep. Deep tillage could be an effective measure to limit seed germination from increased burial depth. The results of this study will lead to a better understanding of the requirements for shortawn foxtail germination and emergence and will provide information that could contribute to its control.

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Stimulation of Common Cocklebur (Xanthium pensylvanicum) and Redroot Pigweed (Amaranthus retroflexus) Seed Germination by Injections of Ethylene into Soil

Weed Science ◽

10.1017/s0043174500061129 ◽

1980 ◽

Vol 28 (5) ◽

pp. 510-514 ◽

Cited By ~ 18

Author(s):

G. H. Egley

Keyword(s):

Seed Germination ◽

Laboratory Tests ◽

Seedling Emergence ◽

Amaranthus Retroflexus ◽

Redroot Pigweed ◽

Plastic Bags ◽

Viable Seeds ◽

Chamber Studies ◽

Growth Chamber Studies ◽

Stimulation Of

The effects of ethylene upon germination of common cocklebur (Xanthium pensylvanicumWallr.) and redroot pigweed (Amaranthus retroflexusL.) seeds were studied. In laboratory tests with seeds in sealed flasks in the dark, 10 μl/L ethylene increased germination of redroot pigweed seeds from 7% to 52% at 30 C, and increased germination of large and small common cocklebur seeds from 30% and 0% to 100% and 90% respectively, at 25 C. At least 12 h of exposure to ethylene was necessary for appreciable stimulation of germination. In growth chamber studies with known numbers of seeds in pots of soil, ethylene at 11 kg/ha was injected into the soil, and the pots were enclosed in plastic bags for 24 h. One such injection at 2 weeks after planting, and successive injections at 2, 3, and 4 weeks, significantly increased redroot pigweed seedling emergence, and significantly decreased the numbers of dormant, viable seeds remaining in the soil. When pots were not enclosed, injections did not significantly effect redroot pigweed seeds, but significantly increased common cocklebur seedling emergence and decreased the number of viable common cocklebur seeds remaining in the soil.

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Germination of Solanum nigrum L. (Black Nightshade) in Response to Different Abiotic Factors

Planta Daninha ◽

10.1590/s0100-83582020380100049 ◽

2020 ◽

Vol 38 ◽

Author(s):

H. DONG ◽

Y. MA ◽

H. WU ◽

W. JIANG ◽

X. MA

Keyword(s):

Seed Germination ◽

Abiotic Factors ◽

Seedling Emergence ◽

Farming Systems ◽

Solanum Nigrum ◽

Central China ◽

Burial Depth ◽

Perennial Weed ◽

Black Nightshade ◽

Solanum Nigrum L

ABSTRACT: Solanum nigrum L. (black nightshade), an annual to short-lived perennial weed, has become a problem weed in farming systems in central China. Laboratory and greenhouse experiments were conducted to examine the influence of various abiotic factors on seed germination of black nightshade to develop effective weed control programs. Seeds germinated at a range of constant temperatures from 15 to 30 oC, but no germination occurred at temperatures below 10 oC or above 35 oC. Seeds also germinated at alternating temperature regimes from 15/5 to 40/30 oC, with maximum germination (> 93.5%) at the alternating temperatures of 25/15 and 30/20 oC. Germination decreased as osmotic potential became more negative, and no germination was observed at ≤ -0.8 MPa. Moreover, germination was reduced by saline and alkaline stresses and no germination occurred at ≥ 200 mM NaCl or ≥ 150 mM NaHCO3 concentrations. Seed germination was not significantly affected by pH values from 5 to 10. Seedling emergence was significantly affected by burial depth with maximum emergence (93.1%) at 1 cm depth.

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Persistence of bellyache bush (Jatropha gossypifolia L.) soil seed banks

The Rangeland Journal ◽

10.1071/rj12051 ◽

2012 ◽

Vol 34 (4) ◽

pp. 429 ◽

Cited By ~ 7

Author(s):

Faiz F. Bebawi ◽

Shane D. Campbell ◽

Robert J. Mayer

Keyword(s):

Abiotic Factors ◽

Seedling Emergence ◽

Seed Banks ◽

Burial Depth ◽

Seed Type ◽

Natural Rate ◽

Soil Seed Banks ◽

Natural Rainfall ◽

Jatropha Gossypifolia ◽

Heavy Clay

Bellyache bush (Jatropha gossypifolia L.) is an invasive shrub that adversely impacts agricultural and natural systems of northern Australia. While several techniques are available to control bellyache bush, depletion of soil seed banks is central to its management. A 10-year study determined the persistence of intact and ant-discarded bellyache bush seeds buried in shade cloth packets at six depths (ranging from 0 to 40 cm) under both natural rainfall and rainfall-excluded conditions. A second study monitored changes in seedling emergence over time, to provide an indication of the natural rate of seed bank depletion at two sites (rocky and heavy clay) following the physical removal of all bellyache bush plants. Persistence of seed in the burial trial varied depending on seed type, rainfall conditions and burial depth. No viable seeds of bellyache bush remained after 72 months irrespective of seed type under natural rainfall conditions. When rainfall was excluded seeds persisted for much longer, with a small portion (0.4%) of ant-discarded seeds still viable after 120 months. Seed persistence was prolonged (>96 months to decline to <1% viability) at all burial depths under rainfall-excluded conditions. In contrast, under natural rainfall, surface located seeds took twice as long (70 months) to decline to 1% viability compared with buried seeds (35 months). No seedling emergence was observed after 58 months and 36 months at the rocky and heavy clay soil sites, respectively. These results suggest that the required duration of control programs on bellyache bush may vary due to the effect of biotic and abiotic factors on persistence of soil seed banks.

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Effects of placement of urea with a urease inhibitor on seedling emergence, N uptake and dry matter yield of wheat

Canadian Journal of Plant Science ◽

10.4141/cjps95-075 ◽

1995 ◽

Vol 75 (2) ◽

pp. 449-452 ◽

Cited By ~ 9

Author(s):

Wang Xiaobin ◽

Xin Jingfeng ◽

C. A. Grant ◽

L. D. Bailey

Keyword(s):

N Uptake ◽

Seedling Emergence ◽

Wheat Seedling ◽

Nitrogen Accumulation ◽

N Availability ◽

Urease Inhibitor ◽

Hard Red Spring Wheat ◽

Urea Fertilizer ◽

Chamber Studies ◽

Growth Chamber Studies

Growth chamber studies were conducted to determine the effect of seed-placed and surface dribble-banded urea fertilizer, with and without the addition of two levels of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on seedling emergence, vegetative yield and nitrogen accumulation of hard red spring wheat. Seedling emergence was reduced with increasing applications of seed-placed urea, but nBTPT reduced the damage from seed-placed urea. The 0.15% inhibitor level was as effective as the 0.25% level in reducing seedling damage. Vegetative yield increased with application of urea fertilizer but no difference in vegetative yield resulted from varying fertilizer placement or additions of nBTPT. Nitrogen accumulation increased with increasing N application and with the use of the urease inhibitor, indicating an increase in N availability due to slowing of urea hydrolysis. Use of the urease inhibitor nBTPT shows promise in reducing seedling damage from seed-placed urea fertilizer and increasing the utilization of seed-placed and surface-applied urea fertilizer on a black Chernozemic soil. Further studies are in progress to assess the performance of nBTPT under field conditions. Key words: N-(n-butyl) thiophosphoric triamide

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Seed Germination and Seedling Emergence of Scotch Broom (Cytisus scoparius)

Weed Science ◽

10.1614/ws-09-078.1 ◽

2009 ◽

Vol 57 (6) ◽

pp. 620-626 ◽

Cited By ~ 7

Author(s):

Timothy B. Harrington

Keyword(s):

Seed Germination ◽

Temperature Regime ◽

Root Biomass ◽

Seedling Emergence ◽

Soil Drought ◽

Dark Light ◽

Scotch Broom ◽

Effects Of Temperature ◽

Chamber Studies ◽

Growth Chamber Studies

Scotch broom is a large, leguminous shrub that has invaded 27 U.S. states. The species produces seeds with a hard coat that remain viable in the soil for years. Growth-chamber studies were conducted to determine effects of temperature regime and cold-stratification period on seed germination. Seedling emergence, mortality, and biomass also were studied in response to sulfometuron and metsulfuron herbicides and variation in soil texture and watering regime. Germination was greatest for a dark/light temperature regime of 15/20 C. Initial rates of germination increased as stratification period was varied from 0 to 60 d, but final germination after 90 d did not differ significantly among periods. Applied alone or in combination, sulfometuron and metsulfuron decreased biomass and increased mortality of seedlings. Mortality from simulated soil drought was greater in the presence versus absence of sulfometuron (20 and 6% mortality, respectively) probably because the herbicide reduced root biomass by 58 to 95%. Invasiveness of Scotch broom is facilitated by a prolonged period of germination across a broad temperature range. Increased control of Scotch broom seedlings with sulfometuron is likely if application is timed to expose recently emerged seedlings to developing conditions of soil drought.

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Theory and Applications of the Unit Gamma/Gompertz Distribution

Mathematics ◽

10.3390/math9161850 ◽

2021 ◽

Vol 9 (16) ◽

pp. 1850

Author(s):

Rashad A. R. Bantan ◽

Farrukh Jamal ◽

Christophe Chesneau ◽

Mohammed Elgarhy

Keyword(s):

Stochastic Ordering ◽

Real Data ◽

Rate Function ◽

The Other ◽

Likelihood Method ◽

Model Parameters ◽

Data Sets ◽

Gompertz Distribution ◽

Probability And Statistics ◽

Analytical Behavior

Unit distributions are commonly used in probability and statistics to describe useful quantities with values between 0 and 1, such as proportions, probabilities, and percentages. Some unit distributions are defined in a natural analytical manner, and the others are derived through the transformation of an existing distribution defined in a greater domain. In this article, we introduce the unit gamma/Gompertz distribution, founded on the inverse-exponential scheme and the gamma/Gompertz distribution. The gamma/Gompertz distribution is known to be a very flexible three-parameter lifetime distribution, and we aim to transpose this flexibility to the unit interval. First, we check this aspect with the analytical behavior of the primary functions. It is shown that the probability density function can be increasing, decreasing, “increasing-decreasing” and “decreasing-increasing”, with pliant asymmetric properties. On the other hand, the hazard rate function has monotonically increasing, decreasing, or constant shapes. We complete the theoretical part with some propositions on stochastic ordering, moments, quantiles, and the reliability coefficient. Practically, to estimate the model parameters from unit data, the maximum likelihood method is used. We present some simulation results to evaluate this method. Two applications using real data sets, one on trade shares and the other on flood levels, demonstrate the importance of the new model when compared to other unit models.

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Bayesian Inference of Species Trees using Diffusion Models

Systematic Biology ◽

10.1093/sysbio/syaa051 ◽

2020 ◽

Vol 70 (1) ◽

pp. 145-161 ◽

Cited By ~ 1

Author(s):

Marnus Stoltz ◽

Boris Baeumer ◽

Remco Bouckaert ◽

Colin Fox ◽

Gordon Hiscott ◽

...

Keyword(s):

Bayesian Inference ◽

Numerical Algorithms ◽

Diffusion Models ◽

Model Parameters ◽

Data Sets ◽

Species Trees ◽

Computationally Efficient ◽

Data Set ◽

Snp Data ◽

Binary Markers

Abstract We describe a new and computationally efficient Bayesian methodology for inferring species trees and demographics from unlinked binary markers. Likelihood calculations are carried out using diffusion models of allele frequency dynamics combined with novel numerical algorithms. The diffusion approach allows for analysis of data sets containing hundreds or thousands of individuals. The method, which we call Snapper, has been implemented as part of the BEAST2 package. We conducted simulation experiments to assess numerical error, computational requirements, and accuracy recovering known model parameters. A reanalysis of soybean SNP data demonstrates that the models implemented in Snapp and Snapper can be difficult to distinguish in practice, a characteristic which we tested with further simulations. We demonstrate the scale of analysis possible using a SNP data set sampled from 399 fresh water turtles in 41 populations. [Bayesian inference; diffusion models; multi-species coalescent; SNP data; species trees; spectral methods.]

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Seasonal cycles in germination and seedling emergence of summer and winter populations of catchweed bedstraw (Galium aparine) and wild mustard (Brassica kaber)

Weed Science ◽

10.1614/ws-05-107r1.1 ◽

2006 ◽

Vol 54 (1) ◽

pp. 114-120 ◽

Cited By ~ 50

Author(s):

Husrev Mennan ◽

Mathieu Ngouajio

Keyword(s):

Soil Depth ◽

Cropping Systems ◽

Seedling Emergence ◽

Seed Mass ◽

Soil Surface ◽

Burial Depth ◽

Galium Aparine ◽

Wild Mustard ◽

Seed Population ◽

Brassica Kaber

Catchweed bedstraw and wild mustard each produce two populations per year: a winter population (WP) in June, and a summer population (SP) in September. Experiments were conducted to determine whether the WP and SP differ in seed mass and seasonal germination. Seeds of both weeds were buried at 0, 5, 10, and 20 cm in cultivated fields, and retrieved at monthly intervals for 24 mo for germination tests in the laboratory. Additionally, seedling emergence from seeds buried at 0, 5, and 10 cm in the field was evaluated for 1 yr. Seeds from the WP were heavier than those from the SP for both species. Germination of exhumed seeds was affected by burial depth and by seed population. It was highest for seeds that remained on the soil surface and declined with increasing depth of burial. The WP of catchweed bedstraw produced two germination peaks per year, whereas the SP and all populations of wild mustard had only one peak. The WP of both weeds germinated earlier than the SP. Seedling emergence for both species in the field was greater for the WP than for the SP. Increasing soil depth reduced seedling emergence of both the WP and SP of wild mustard and affected only the WP of catchweed bedstraw. We conclude that the WP and SP of catchweed bedstraw and wild mustard seeds used in this study differed in seed mass, seasonal germination, and seedling emergence. The ability of a WP to produce large seeds that germinate early and have two germination peaks per year could make these populations a serious problem in cropping systems.

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