scholarly journals Predicting Seedling Emergence of Three Canarygrass (Phalaris) Species under Semi-Arid Conditions Using Parametric and Non-Parametric Models

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 893
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
José María Urbano
Keyword(s):  
Field Experiments ◽  
Seedling Emergence ◽  
Parametric Models ◽  
Base Temperature ◽  
Weed Species ◽  
Emergence Period ◽  
Growing Seasons ◽  
Ceiling Temperature ◽  
Base Water Potential ◽  
Non Parametric

The Phalaris genus includes annual weed species such as short-spiked canarygrass (Phalaris brachystachys Link.), little-seed canarygrass (Phalaris minor Retz.) and hood canarygrass (Phalaris paradoxa L.), which are especially problematic in Spain; as such, there is a need to develop models to predict the timing of their emergence. Field experiments were conducted at two different locations during two (2006/07 and 2007/08) and three (from 2005/06 to 2007/08) growing seasons. In both locations, 500 seeds of each Phalaris species were sown each growing season, simulating rain-fed cereal field conditions. In addition, the models were validated with three, four and eight independent experiments for P. brachystachys, P. minor and P. paradoxa, respectively. The emergence period of the three Phalaris species lasted between 31 and 48 days after sowing (DAS), showing two main flushes. The three cardinal points for parametric and non-parametric models were established to be between −1 °C and 1 °C for base temperature, between 9.8 °C and 11.8 °C for optimal temperature and between 21.2 °C and 23.4 °C for ceiling temperature; base water potential was estimated to be between −1 and −1.1 MPa. Both parametric and non-parametric models obtained similar results and were successfully validated in 12 out of 15 independent experiments.

scholarly journals Biological Parameters for Germination of Selected Summer Weed Species: First Step to Transfer the Hydrothermal Model Alertinf to Croatia

2021 ◽  
Author(s):  
Valentina Šoštarčić ◽  
Roberta Masin ◽  
Donato Loddo ◽  
Ema Brijačak ◽  
Maja Šćepanović
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Base Temperature ◽  
Weed Species ◽  
Time Model ◽  
Emergence Patterns ◽  
Base Water Potential

The efficacy of weed management depends on the correct control timing according to the seedling emergence dynamics. Since soil temperature and soil moisture are two main factors that determine weed germination, the hydrothermal time model can be used to predict their emergence. The aim of this study was to estimate the base temperature (Tb) and base water potential (Ψb) for germination of Chenopodium album, Amaranthus retroflexus, Setaria pumila and Panicum capillare collected from fields in continental Croatia and then to compare these values with those of Italian populations embedded in the AlertInf model. Germination tests were performed at seven constant temperatures (ranging from 4 to 27°C) and eight water potentials (0.00 to - 1.00 MPa). Estimated Tb and Ψb were 3.4°C, -1.38 MPa for C. album, 13.9°C, -0.36 MPa for A. retroflexus, 6.6°C, -0.71 MPa for S. pumila and 11.0°C, -0.87 MPa for P. capillare, respectively. According to the criterion of overlap of the 95% confidence intervals, only Tb of C. album, and Ψb of A. retroflexus were similar between Croatian and Italian populations. Further field experiments should be conducted in the Croatian field to monitor weed emergence patterns of C. album and to calibrate the AlerInf equation parameters.

Predicting Emergence of 23 Summer Annual Weed Species

Weed Science ◽  
2014 ◽  
Vol 62 (2) ◽  
pp. 267-279 ◽  
Author(s):  
Rodrigo Werle ◽  
Lowell D. Sandell ◽  
Douglas D. Buhler ◽  
Robert G. Hartzler ◽  
John L. Lindquist
Keyword(s):  
Soil Temperature ◽  
Field Experiments ◽  
Seedling Emergence ◽  
Information Criterion ◽  
Weibull Function ◽  
Base Temperature ◽  
Weed Species ◽  
Penalty Cost ◽  
Second Year ◽  
Best Fit

First- and second-year seedbank emergence of 23 summer annual weed species common to U.S. corn production systems was studied. Field experiments were conducted between 1996 and 1999 at the Iowa State University Johnson Farm in Story County, Iowa. In the fall of 1996 and again in 1997, 1,000 seeds for most species were planted in plastic crates. Seedling emergence was counted weekly for a 2-yr period following seed burial (starting in early spring). Soil temperature at 2 cm depth was estimated using soil temperature and moisture model software (STM2). The Weibull function was fit to cumulative emergence (%) on cumulative thermal time (TT), hydrothermal time (HTT), and day of year (DOY). To identify optimum base temperature (Tbase) and base matric potential (ψbase) for calculating TT or HTT, Tbaseand ψbasevalues ranging from 2 to 17 C and −33 to −1,500 kPa, respectively, were evaluated for each species. The search for the optimal model for each species was based on the Akaike's Information Criterion (AIC), whereas an extra penalty cost was added to HTT models. In general, fewer seedlings emerged during the first year of the first experimental run (approximately 18% across all species) than during the second experimental run (approximately 30%). However, second-year seedbank emergence was similar for both experimental runs (approximately 6%). Environmental effects may be the cause of differences in total seedling emergence among years. Based on the AIC criterion, for 17 species, the best fit of the model occurred using Tbaseranging from 2 to 15 C with four species also responding to ψbase= −750 kPa. For six species, a simple model using DOY resulted in the best fit. Adding penalty costs to AIC calculation allowed us to compare TT and HTT when both models behaved similarly. Using a constant Tbase, species were plotted and classified as early-, middle-, and late-emerging species, resulting in a practical tool for forecasting time of emergence. The results of this research provide robust information on the prediction of the time of summer annual weed emergence, which can be used to schedule weed and crop management.

scholarly journals Germination Parameters of Selected Summer Weeds: Transferring of the AlertInf Model to Other Geographical Regions

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 292
Author(s):  
Valentina Šoštarčić ◽  
Roberta Masin ◽  
Donato Loddo ◽  
Ema Brijačak ◽  
Maja Šćepanović
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Base Temperature ◽  
Time Model ◽  
Emergence Patterns ◽  
Geographical Regions ◽  
Base Water Potential

Effective weed management depends on correct control timing, which depends on seedling emergence dynamics. Since soil temperature and soil moisture are the two main factors that determine weed germination, the hydrothermal time model can be used to predict their emergence. The aim of this study was to estimate the base temperature (Tb) and base water potential (Ψb) for the germination of Chenopodium album, Amaranthus retroflexus, Setaria pumila, and Panicum capillare collected from fields in continental Croatia and then to compare these values with those of Italian populations embedded in the AlertInf model. Germination tests were performed at seven constant temperatures (ranging from 4 to 27 °C) and eight water potentials (0.00–1.00 MPa). The estimated Tb and Ψb were 3.4 °C and −1.38 MPa for C. album, 13.9 °C and −0.36 MPa for A. retroflexus, 6.6 °C and −0.71 MPa for S. pumila, and 11.0 °C and −0.87 MPa for P. capillare, respectively. According to the criterion of overlap of the 95% confidence intervals, only the Tb of C. album and the Ψb of A. retroflexus of the Croatian and Italian populations were similar. Further field experiments should be conducted to monitor the weed emergence patterns of C. album and calibrate the AlerInf equation parameters.

scholarly journals Modeling emergence of sterile oat (Avena sterilis ssp. ludoviciana) under semiarid conditions

Weed Science ◽  
2021 ◽  
Vol 69 (3) ◽  
pp. 341-352
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
Iñigo Loureiro ◽  
Ana I. Marí ◽  
Juan A. Lezáun ◽  
...  
Keyword(s):  
Weed Species ◽  
Avena Sterilis ◽  
Prediction Ability ◽  
Average Percentage ◽  
Growing Seasons ◽  
Ceiling Temperature ◽  
Special Concern ◽  
Cardinal Temperatures ◽  
Base Water Potential ◽  
Semiarid Conditions

AbstractWinter wild oat [Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne; referred to as A. sterilis here] is one of the major weed species of the Avena genus, given its high competitive ability to infest cereal crops worldwide, with special concern in Spain. A nine-location field experiment was established across Spain where a total of 400 A. sterilis seeds per location were sowed in four replicates in autumn 2016 to monitor the emergence during two growing seasons in dryland conditions. The data were used to test the prediction ability of previously published thermal (TT) and hydrothermal time (HTT) models and to develop new models, if required. Overall, the average percentage of emergence was 30% during the first season and 21% during the second season. In both seasons, the main emergence flush occurred between November and February. According to the phenological stage, A. sterilis achieved the tillering earlier in southern sites, between November 25 and the end of December, compared with northern sites, where this stage was reached at the end of January. The newly developed model described the emergence with precision, using three cardinal temperatures to estimate the TT. The three cardinal points were established at −1.0, 5.8, and 18.0 C for base (Tb), optimum (To), and ceiling temperature (Tc), while the base water potential (Ψb) was established at −0.2 MPa for the HTT estimation. This study contributes to improving prediction of the emergence of A. sterilis and provides knowledge for decision support systems (DSS) for the control of this weed.

Interference between pigweed (Amaranthusspp.), barnyardgrass(Echinochloa crus-galli), and soybean (Glycine max)

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 533-539 ◽  
Author(s):  
Paul Cowan ◽  
Susan E. Weaver ◽  
Clarence J. Swanton
Keyword(s):  
Competitive Ability ◽  
Field Experiments ◽  
Yield Loss ◽  
Seedling Emergence ◽  
Growth Time ◽  
Weed Species ◽  
Soybean Yield ◽  
Competitive Index ◽  
Loss Maximum ◽  
Weed Emergence

Field experiments were conducted to determine the influence of time of emergence and density of single and multispecies populations of pigweed and barnyardgrass on soybean yield and competitive abilities of pigweed and barnyardgrass. Pigweed and barnyardgrass were established at selected densities within 12.5 cm on either side of the soybean row. Pigweed and barnyardgrass seeds were sown concurrently with soybean and at the cotyledon stage of soybean growth. Time and density of pigweed and barnyardgrass seedling emergence relative to soybean influenced the magnitude of soybean yield loss. Maximum soybean yield loss ranged from 32 to 99%, depending upon time of emergence relative to soybean. Pigweed was more competitive than barnyardgrass across all locations, years, and time of weed emergence. When pigweed was assigned a competitive index of 1 on a scale from 0 to 1, the competitive ability of barnyardgrass ranged from 0.075 to 0.40 of pigweed, depending upon location and time of emergence. This is the first multiple weed species study to include time of weed emergence relative to the crop. Competitive index values for multiple weed species must be calculated from field experiments in which weeds are grown with the crop under differing environmental conditions.

Functional and quantitative analysis of seed thermal responses in prostrate knotweed (Polygonum aviculare) and common purslane (Portulaca oleracea)

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 83-90 ◽  
Author(s):  
B. C. Kruk ◽  
R. L. Benech-Arnold
Keyword(s):  
Quantitative Analysis ◽  
Seedling Emergence ◽  
Screening Method ◽  
Thermal Conditions ◽  
Thermal Time ◽  
Base Temperature ◽  
Emergence Period ◽  
Thermal Range ◽  
Polygonum Aviculare ◽  
Common Purslane

A screening method was used to characterize seed thermal responses of prostrate knotweed and common purslane, two important weeds invading wheat in the humid Pampa. Through this method, it was possible to detect thermal conditions that induce or break dormancy in both species. In addition, we were able to quantify changes in dormancy level in seed populations as a function of time of burial after dispersal, through changes in width of the thermal range within which germination can occur. Plotting the overlap of this thermal range and observed soil temperature throughout the year allowed the prediction of the seedling emergence period. This prediction was in agreement with observed seedling emergence in the field for both species, during 2 consecutive yr. From the analysis carried out under laboratory conditions, it was also possible to estimate required thermal time for germination of the nondormant fraction of the population and the base temperature above which thermal time is accumulated. The results obtained from this study are the basis for the formulation of seed germination models that predict not only the occurrence of seedling emergence in the field, but also the dynamics of germination within those periods.

Calibration and validation of a common lambsquarters (Chenopodium album) seedling emergence model

Weed Science ◽  
2004 ◽  
Vol 52 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Maryse L. Leblanc ◽  
Daniel C. Cloutier ◽  
Katrine A. Stewart ◽  
Chantal Hamel
Keyword(s):  
Soil Texture ◽  
Chenopodium Album ◽  
Seedling Emergence ◽  
Base Temperature ◽  
Weed Species ◽  
Spring Temperature ◽  
Common Lambsquarters ◽  
Predicted Values ◽  
Using Data ◽  
Seedbed Preparation

Studies were conducted to calibrate and validate a mathematical model previously developed to predict common lambsquarters seedling emergence at different corn seedbed preparation times. The model was calibrated for different types of soil by adjusting the base temperature of common lambsquarters seedling emergence to the soil texture. A relationship was established with the sand mineral fraction of the soil and was integrated into the model. The calibrated model provided a good fit of the field data and was accurate in predicting cumulative weed emergence in different soil types. The validation was done using data collected independently at a site located 80 km from the original experimental area. There were no differences between observed and predicted values. The accuracy of the model is very satisfactory because the emergence of common lambsquarters populations was accurately predicted at the 95% probability level. This model is one of the first to take into consideration seedbed preparation time and soil texture. This common lambsquarters emergence model could be adapted to model other weed species whose emergence is limited by low spring temperature.

Growth, Development, and Seed Biology of Feather Fingergrass (Chloris virgata) in Southern Australia

Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 413-425 ◽  
Author(s):  
The D. Ngo ◽  
Peter Boutsalis ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Summer Rainfall ◽  
Management Program ◽  
Field Conditions ◽  
Shoot Biomass ◽  
Base Temperature ◽  
Weed Species ◽  
Seed Biology ◽  
Growth Development

Feather fingergrass is a major weed in agricultural systems in northern Australia and has now spread to southern Australia. To better understand the biology of this emerging weed species, its growth, development, and seed biology were examined. Under field conditions in South Australia, seedlings that emerged after summer rainfall events required 1,200 growing degree days from emergence to mature seed production and produced 700 g m−2shoot biomass. Plants produced up to 1,000 seeds panicle−1and more than 40,000 seeds plant−1, with seed weight ranging from 0.36 to 0.46 mg. Harvested seeds were dormant for a period of about 2 mo and required 5 mo of after-ripening to reach 50% germination. Freshly harvested seed could be released from dormancy by pretreatment with 564 mM sodium hypochlorite for 30 min. Light significantly increased germination. Seed could germinate over a wide temperature range (10 to 40 C), with maximum germination at 15 to 25 C. At 20 to 25 C, 50% germination was reached within 2.7 to 3.3 d, and the predicted base temperature to germinate was 2.1 to 3.0 C. The osmotic potential and NaCl concentration required to inhibit germination by 50% were −0.16 to −0.20 MPa and 90 to 124 mM, respectively. Seedling emergence was highest (76%) for seeds present on soil surface and was significantly reduced by burial at 1 (57%), 2 (49%), and 5 cm (9%). Under field conditions, seeds buried in the soil persisted longer than those left on the soil surface, and low spring–summer rainfall increased seed persistence. This study provides important information on growth, development, and seed biology of feather fingergrass that will contribute to the development of a more effective management program for this weed species in Australia.

Seed Germination and Seedling Recruitment Behavior of Winged Sea Lavender (Limonium lobatum) in Southern Australia

Weed Science ◽  
2018 ◽  
Vol 66 (4) ◽  
pp. 485-493 ◽  
Author(s):  
Samuel G. L. Kleemann ◽  
Gurjeet Gill
Keyword(s):  
Seed Germination ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Base Temperature ◽  
Weed Species ◽  
Factors Affecting ◽  
Weed Seeds ◽  
Sea Lavender ◽  
C 50

AbstractWinged sea lavender [Limonium lobatum(L.f. Chaz)] is emerging as a significant weed of field crops in southern Australia. Several environmental factors affecting germination and seedling recruitment were examined to provide a better understanding of the behavior of its seedbank. At maturity, weed seeds were dormant for a period of around 2 mo, but dormancy was easily broken with scarification or by pretreatment with 564 mM NaOCL for 30 min, which confirms the role of the seed coat in regulating seed germination. Exposure to light significantly increased germination. Seeds were able to germinate over a broad range of temperatures (5 to 30 C), with maximum germination (~92%) at temperatures between 10 and 30 C. At 20 to 25 C, 50% germination was reached within 1.3 to 2 d, and the predicted base temperature for germination of the two populations ranged from 1.4 to 3.9 C. The NaCl concentration required to inhibit germination by 50% was 230 mM, with some seeds capable of germination at salinity levels as high as 480 mM. These results indicated greater tolerance to salinity inL. lobatumthan many other Australian agricultural weed species previously investigated. Seedling emergence was the highest (51% to 57%) for seeds present on the soil surface and was significantly reduced by burial at 1 cm (≤11%) and 2 cm (≤2%), with no emergence at 5 cm. Under field conditions, seedling recruitment varied considerably among the three experimental sites. The level of seedling recruitment was negatively associated with rainfall received at the site, organic carbon (OC) level, and microbial biomass of the soil. Rapid decay of weed seeds in high-OC soils appears to be an important determinant of seedling recruitment in this species and could explain greater occurrence ofL. lobatumon soils with low OC and low microbial activity in low-rainfall areas of southern Australia. Furthermore, many such soils in southern Australia are affected by salinity, which would enableL. lobatumto be more competitive with crops and other weeds present at a site.

Phyllochron and tillering of wheat in response to soil aluminum toxicity and phosphorus deficiency

2010 ◽  
Vol 61 (11) ◽  
pp. 863 ◽  
Author(s):  
Susana R. Valle ◽  
Daniel F. Calderini
Keyword(s):  
Field Experiments ◽  
Aluminum Toxicity ◽  
Phosphorus Deficiency ◽  
Seedling Emergence ◽  
Al Toxicity ◽  
Degree Days ◽  
Area Index ◽  
Growing Seasons ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

Soil constraints affect potential grain yield of wheat. Among these constraints acidic soils are especially important due to their combined effect on aluminum (Al) toxicity and phosphorus (P) fixation. The objective of the present study was to evaluate the response of final leaf number (FLN), phyllochron and tillering dynamic of wheat in response to different Al and P concentrations in the soil under field conditions. Two field experiments were conducted in an Andisol in Valdivia (39°47′S, 73°14′W), Chile, during the 2006–07 (Expt 1) and 2007–08 (Expt 2) growing seasons. Treatments in Expt 1 consisted of a factorial arrangement of: (i) two spring wheat cultivars with different sensitivities to Al toxicity (the sensitive cultivar: Domo.INIA and the tolerant cultivar: Dalcahue.INIA) and (ii) five exchangeable soil Al levels (from 0 to 2.7 cmolc kg–1). In Expt 2 treatments consisted of a control, two levels of Al toxicity and two P treatments with three replicates in both experiments. Leaf appearance was measured from seedling emergence to anthesis; their dynamics were recorded according to the scale developed by Haun. FLN and tiller appearance were recorded in the same plants at the same time. Exchangeable Al affected FLN in Expt 1 showing a linear association in both cultivars (r = 0.99). In Expt 2 FLN was unaffected by both Al and P levels because there was a lower soil Al concentration in this experiment. Leaf appearance rate (LAR) was adjusted to bilinear equations, differentiating among early and later leaves. In Expt 1 soil Al concentration affected phyllochron of early leaves, increasing this trait by 14 and 33 degree-days in the Al-sensitive and Al-tolerant cultivars, respectively. Similarly, phyllocron of later leaves was also increased but at a higher extent in the same cultivars (62 and 38 degree-days). Both Al toxicity and P shortage decreased the maximum (MNT) and final number of tillers (FNT). Leaf area index at anthesis was positively associated with FLN (r = 0.77) and MNT (r = 0.95 and 0.99 in the Al-sensitive and Al-tolerant cultivars, respectively), with no regard to Al or P constraints.

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