scholarly journals Short communication: A predictive model for the time course of seedling emergence of Phalaris brachystachys (short-spiked canary grass) in wheat fields

2021 ◽  
Vol 19 (3) ◽  
pp. e10SC02-e10SC02
Author(s):  
Fernando Bastida ◽  
Keyword(s):  
Predictive Model ◽  
Time Course ◽  
Seedling Emergence ◽  
Control Measures ◽  
Cereal Crops ◽  
Hydrothermal Time ◽  
Northern Spain ◽  
Winter Cereal ◽  
Emergence Pattern ◽  
Canary Grass

Aim of study: A predictive model of the seedling emergence pattern of Phalaris brachystachys Link (short-spiked canary grass) was developed, aimed to contribute to support a more efficient management of this troublesome, competitive weed in winter cereal crops around its native Mediterranean range and in different areas of the world where it is introduced. Area of study: Southern (Andalusia) and northern Spain (Navarra). Material and methods: A model describing the emergence pattern of P. brachystachys in cereal fields based on accumulation of hydrothermal time in soil was developed and validated. For model development, cumulative emergence data were obtained in an experimental field, while an independent validation of the model was conducted with data collected in two commercial wheat fields from climatically contrasting regions of Spain. Main results: The relationship between cumulative emergence and cumulative hydrothermal time (CHT) was well described by a Logistic model. According to model predictions, 50% and 95% seedling emergence takes place at 108 and 160 CHT above base water potential for seed germination, respectively. The model accurately predicted the seedling emergence time course of P. brachystachys in the two commercial wheat fields (R2 ≥ 0.92). Research highlights: This model is a new tool that may be useful to improve the timing of control measures to maximize efficiency in reducing P. brachystachys infestations in cereal crops.

A Hydrothermal Seedling Emergence Model for Giant Ragweed (Ambrosia trifida)

Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 555-560 ◽  
Author(s):  
Brian J. Schutte ◽  
Emilie E. Regnier ◽  
S. Kent Harrison ◽  
Jerron T. Schmoll ◽  
Kurt Spokas ◽  
...  
Keyword(s):  
Seedling Emergence ◽  
Geographic Location ◽  
Control Measures ◽  
Weather Data ◽  
No Tillage ◽  
Hydrothermal Time ◽  
Crop Fields ◽  
Giant Ragweed ◽  
Weibull Models ◽  
Soil Temperatures

Late-season giant ragweed emergence in Ohio crop fields complicates decisions concerning the optimum time to implement control measures. Our objectives were to develop a hydrothermal time emergence model for a late-emerging biotype and validate the model in a variety of locations and burial environments. To develop the model, giant ragweed seedlings were counted and removed weekly each growing season from 2000 to 2003 in a fallow field located in west central Ohio. Weather data, soil characteristics and geographic location were used to predict soil thermal and moisture conditions with the Soil Temperature and Moisture Model (STM2). Hydrothermal time (θHT) initiated March 1 and base values were extrapolated from the literature (Tb= 2 C, ψb= −10 MPa). Cumulative percent emergence initially increased rapidly and reached 60% of maximum by late April (approximately 400 θHT), leveled off for a period in May, and increased again at a lower rate before concluding in late July (approximately 2,300 θHT). The period in May when few seedlings emerged was not subject to soil temperatures or water potentials less than the θHTbase values. The biphasic pattern of emergence was modeled with two successive Weibull models that were validated in 2005 in a tilled and a no-tillage environment and in 2006 at a separate location in a no-tillage environment. Root-mean-square values for comparing actual and model predicted cumulative emergence values ranged from 8.0 to 9.5%, indicating a high degree of accuracy. This experiment demonstrated an approach to emergence modeling that can be used to forecast emergence on a local basis according to weed biotype and easily obtainable soil and weather data.

Emergence Pattern of Five Weeds in the Central Great Plains

1996 ◽  
Vol 10 (4) ◽  
pp. 744-749 ◽  
Author(s):  
R. L. Anderson ◽  
D. C. Nielsen
Keyword(s):  
Great Plains ◽  
Seedling Emergence ◽  
Growing Season ◽  
Crop Canopy ◽  
Emergence Pattern ◽  
Proso Millet ◽  
Annual Crops ◽  
No Till ◽  
Green Foxtail ◽  
Wheat Stubble

Seedling emergence was characterized for five weeds that infest summer annual crops in the central Great Plains as affected by crop canopy or tillage. The study was established in winter wheat stubble between 1987 and 1990, with seedling emergence recorded weekly between April 1 and November 1. Kochia emerged primarily from early April to late June, whereas green foxtail, wild-proso millet, and redroot pigweed began emerging in late May and continued until August. Volunteer wheat emerged throughout the growing season. Tillage did not affect the emergence pattern of any species, but the numbers of kochia, volunteer wheat, and green foxtail seedlings were increased in no-till. Conversely, wild-proso millet emergence was greater with tillage. Only volunteer wheat's emergence was affected by crop canopy, as fall emergence of volunteer wheat was more than three times greater in corn than in proso millet.

ASSESSMENT OF THE INFLUENCE OF THE MAIN CLIMATIC FACTORS ON THE YIELD OF WINTER CEREAL CROPS ON THE TERRITORY OF BELARUS FOR FORECASTING PURPOSES

2021 ◽  
pp. 41-48
Author(s):  
Halina A. Kamyshenka
Keyword(s):  
Computational Models ◽  
Climatic Factors ◽  
Climatic Conditions ◽  
Yield Variability ◽  
Cereal Crops ◽  
Winter Rye ◽  
Statistical Assessment ◽  
Winter Cereal ◽  
Temperature And Precipitation

The results of a statistical assessment of the influence of changing weather and climatic conditions of the territory of Belarus on the productivity of the main winter cereal crops are presented in order to build computational models of productivity. The calculations were made with respect to the climatic component as a predictor, taking into account the deviations of air temperature and precipitation from the long-term climatic norm of months that have the most significant effect on the yield of the studied crops. For winter rye and wheat, adequate models of yield variability have been built. The research results are relevant for solving forecasting problems.

Survey of Barley yellow dwarf virus incidence in winter cereal crops, and assessment of wheat and barley resistance to the virus

2016 ◽  
Vol 67 (10) ◽  
pp. 1054 ◽  
Author(s):  
Eva Beoni ◽  
Jana Chrpová ◽  
Jana Jarošová ◽  
Jiban Kumar Kundu
Keyword(s):  
Barley Yellow Dwarf Virus ◽  
Rhopalosiphum Padi ◽  
Wheat Breeding ◽  
Yellow Dwarf ◽  
Dwarf Virus ◽  
Cereal Crops ◽  
Winter Cereal ◽  
Barley Yellow Dwarf ◽  
Significant Difference ◽  
Yellow Dwarf Virus

A survey of Barley yellow dwarf virus (BYDV) incidence in cereal crops in the Czech Republic over 4 years showed, on average, 13.3% BYDV-positive, randomly tested wheat and barley samples. The cultivated wheat and barley cultivars had different levels of susceptibility to BYDV infection. Field trials were performed with different barley and wheat breeding lines and cultivars, and resistance traits were evaluated after artificial inculcation by the viruliferous aphid vector Rhopalosiphum padi L. with BYDV-PAV. Our results showed high variability of visual symptom score (VSS) and reduction in grain weight per spike (GWS-R) in trials within the tested lines and cultivars. The barley line (WBON 96-123) and cultivars (Wysor, Travira) that contained RYd2 differed significantly from other cultivars in VSS. Line WBON 96-123 and cvv. Wysor and Yatzi showed the lowest GWS-R. Wheat line PSR 3628 and cvv. Altigo, Elan, Sparta, Aladin and Hewit showed significant difference from other cultivars in VSS. PSR 3628, Sparta, and Elan showed the lowest GWS-R. Similar results were obtained from BYDV titre analysis by RT-qPCR corresponding to the VSS and GWS-R traits. A low virus titre corresponded to low VSS and GWS-R. Hence, our results suggest that laborious and time-consuming GWS-R analysis could be replaced in some cases by qPCR-based BYDV titre analysis and, together with VSS evaluation, could enhance the efficiency of resistance assessment.

Modeling germination and seedling elongation of common lambsquarters (Chenopodium album)

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Erivelton S. Roman ◽  
A. Gordon Thomas ◽  
Stephen D. Murphy ◽  
Clarence J. Swanton
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Mechanistic Model ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Probit Analysis ◽  
Hydrothermal Time ◽  
Time Model ◽  
Common Lambsquarters ◽  
Radicle Elongation

The ability to predict time of weed seedling emergence relative to the crop is an important component of a mechanistic model describing weed and crop competition. In this paper, we hypothesized that the process of germination could be described by the interaction of temperature and water potential and that the rate of seedling shoot and radicle elongation vary as a function of temperature. To test these hypotheses, incubator studies were conducted using seeds and seedlings of common lambsquarters. Probit analysis was used to account for variation in cardinal temperatures and base water potentials and to develop parameters for a new mathematical model that describes seed germination and shoot and radicle elongation in terms of hydrothermal time and temperature, respectively. This hydrothermal time model describes the phenology of seed germination using a single curve, generated from the relationship of temperature and water potential.

Seed-bed cultivations and sugar-beet seedling emergence

1989 ◽  
Vol 112 (2) ◽  
pp. 159-169 ◽  
Author(s):  
R. J. Gummerson
Keyword(s):  
Sugar Beet ◽  
Time Course ◽  
Seedling Emergence ◽  
Physical Characteristics ◽  
Thermal Time ◽  
Fine Aggregates ◽  
Soil Physical Characteristics

SummaryExperiments are described in which a range of seed beds was created in each of 5 years. The weather in these years produced wet, dry and capping seed-bed conditions. The time course of sugar-beet seedling emergence on each seed bed was recorded each year and the differences were considered in terms of soil physical characteristics: much of the year-to-year variation was accounted for by considering thermal time above 3 °C. The differences in emergence between seed beds were large only when conditions were dry, but in all years it was advantageous to level the seed bed in autumn or winter. Seed beds with a dense soil below the seed and fine aggregates above gave the most suitable conditions for rapid and successful emergence.

Measurement of gaseous emissions from denitrification of applied N-15 .3. Field-measurements

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 101 ◽  
Author(s):  
UK Avalakki ◽  
WM Strong ◽  
PG Saffigna
Keyword(s):  
Mass Balance ◽  
Field Experiments ◽  
Field Measurements ◽  
Cereal Crops ◽  
Gaseous Emissions ◽  
Gas Emission ◽  
Winter Cereal ◽  
Autumn And Winter ◽  
Balance Loss ◽  
Peak Emission

Field experiments were conducted during autumn and winter (April-July) at four locations on Vertisol or Alfisol soils on the Darling Downs of Queensland in 1988 and 1989 to determine 15N losses when soil was saturated after applications of 15N labelled nitrate-N prior to sowing winter cereal crops. Losses of applied 15N were quantified by either gas emission or mass balance measurements on microplots (0.043 m2) confined laterally to a depth of 110 or 260 mm. At each field location, two experiments were established, one on a soil containing little visible crop residue where winter cereal had been harvested the previous November and another site containing residues of a recently harvested sorghum crop. Because shallow (110 mm) confinement was found to be unsatisfactory for both gas emission and mass balance measurement of 15N losses, comparison of the two methods was not applicable at one of the four field locations. Loss estimates for the six field sites by accumulating daily gas emissions averaged 80.7 � 33.4% (range 43-132%) of that estimated by mass balance. Loss estimates from peak emission measurements were generally closer to that estimated by mass balance 100.8� 39.9% (range 56-169%). Loss of applied 15N (40 kg N ha-1) when soils were saturated in April was several-fold more (19-29 kg N ha-1)) than that lost when soils were saturated in July (3.9-6.4 kg N ha-1)). Loss of 15N following saturation during July 1988 was similar in magnitude to the quantity of 15N apparently immobilized into soil organic forms (5.8-6.0 kg N ha-1)). Sorghum residues returned in March, or wheat straw added in December prior to a long period of dry weather, promoted loss of 15N applied prior to soil saturation in April or July. Alternatively, where residues of a previous winter cereal had decomposed considerably, loss of applied 15N was much lower than where sorghum residues had been added prior to saturations in April (15.3 cf. 28.6 kg N ha-1)) or July (3.9 cf. 6.4 kg N ha-1)).

scholarly journals Pink snow mold in winter cereal crops in Belarus and in the South of Russia

2020 ◽  
Vol 21 ◽  
pp. 00006
Author(s):  
Alexander Zhukovskiy ◽  
Natalia Krupenko ◽  
Yana Yakhnik ◽  
Olga Tarancheva ◽  
Galina Volkova
Keyword(s):  
Weather Conditions ◽  
Cereal Crops ◽  
Disease Development ◽  
The South ◽  
Snow Mold ◽  
Winter Cereal ◽  
Krasnodar Krai ◽  
Spring Period ◽  
Southern Russia ◽  
The Republic

The article presents an analysis of the distribution and development of pink snow mold (pathogen Microdochium nivale (Fr.) Samuels & I.C. Hallett) on winter cereal crops in the Republic of Belarus and in the South of Russia. Pink snow mold is currently one of the most harmful diseases of winter cereal crops, as it can cause damage not only to various parts of the plants, but also lead to their complete death. The intensity of the disease development mainly depends on weather conditions in the autumn-spring period, namely, on the duration of snow cover, its height and the rate of melting in spring. We determined the dependence of the disease development progress on agroclimatic conditions. There is a description of weather conditions in combination with a gradation of the disease development level in the Republic of Belarus and in Krasnodar Krai (southern Russia) during the epiphytotic and depressive years of the pink snow mold development. The article provides a retrospective analysis of the crops infected with pink snow mold and the treated cereal crops in southern Russia in 2011 -2019.

Comparison of three different statistical approaches (non-linear least-squares regression, survival analysis and Bayesian inference) in their usefulness for estimating hydrothermal time models of seed germination

2020 ◽  
Vol 30 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Elena Moltchanova ◽  
Shirin Sharifiamina ◽  
Derrick J. Moot ◽  
Ali Shayanfar ◽  
Mark Bloomberg
Keyword(s):  
Seed Germination ◽  
Linear Regression ◽  
Least Squares ◽  
Time Course ◽  
Efficient Estimation ◽  
Model Parameters ◽  
Least Squares Regression ◽  
Hydrothermal Time ◽  
Linear Least Squares ◽  
Non Linear

AbstractHydrothermal time (HTT) models describe the time course of seed germination for a population of seeds under specific temperature and water potential conditions. The parameters of the HTT model are usually estimated using either a linear regression, non-linear least squares estimation or a generalized linear regression model. There are problems with these approaches, including loss of information, and censoring and lack of independence in the germination data. Model estimation may require optimization, and this can have a heavy computational burden. Here, we compare non-linear regression with survival and Bayesian methods, to estimate HTT models for germination of two clover species. All three methods estimated similar HTT model parameters with similar root mean squared errors. However, the Bayesian approach allowed (1) efficient estimation of model parameters without the need for computation-intensive methods and (2) easy comparison of HTT parameters for the two clover species. HTT models that accounted for a species effect were superior to those that did not. Inspection of credibility intervals and estimated posterior distributions for the Bayesian HTT model shows that it is credible that most HTT model parameters were different for the two clover species, and these differences were consistent with known biological differences between species in their germination behaviour.

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