Urochloa platyphylla (broadleaf signalgrass).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Environmental Conditions ◽  
Crop Residue ◽  
Soil Surface ◽  
Grass Species ◽  
Crop Fields ◽  
Wide Range ◽  
Germinating Seeds

Abstract U. platyphylla is a weedy grass species commonly found in disturbed, open and sandy sites such as crop fields, ditches and roadsides. It is considered a troublesome weed because of its tolerance to some herbicides principally in maize plantations (Chamblee et al., 1982; Gallaher et al.,1999). U. platyphylla is highly adaptable and it is able to germinate and grow throughout a wide range of soil and environmental conditions (Burke et al., 2003). Additionally, its seeds may remain on the crop residue until pre-emergence herbicides are no longer effective in controlling the germinating seeds, at which time the seeds fall to the soil surface and germinate (Alford et al., 2005).

Germination ecology of Sonchus oleraceus L. in the northern region of Australia

2018 ◽  
Vol 69 (9) ◽  
pp. 926 ◽  
Author(s):  
Sudheesh Manalil ◽  
Hafiz Haider Ali ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Environmental Conditions ◽  
Osmotic Potential ◽  
Crop Residue ◽  
Soil Surface ◽  
Northern Region ◽  
Agricultural Systems ◽  
Widespread Occurrence ◽  
Sonchus Oleraceus

In Australia, Sonchus oleraceus has been emerging as a major weed in conservation agricultural systems. The effect of environmental factors on germination and emergence of S. oleraceus was assessed on populations collected from Gatton (SOG) and St. George (SOS) regions of Australia, which are high and low rainfall regions respectively. Germination of both populations responded similarly to various environmental factors studied. Although S. oleraceus seeds germinated under a broad range of temperatures (15/5, 20/10, 25/15 and 30/20°C day/night), germination was lower at 15/5°C. There was only 47–53% germination under dark conditions compared with 62–87% under alternating light–dark. Germination was only 2 and 3% at –0.8 MPa osmotic potential for SOG and SOS populations respectively, and no germination occurred at –1 MPa. Germination was 6 and 8% at 200 mM NaCl for SOG and SOS populations respectively. Although S. oleraceus seed germination exceeded 80% for pH 6–7, germination was reduced at pH outside this range. Germination was 83 and 87% for SOG and SOS populations respectively at the soil surface; and emergence decreased with increasing depth, with none from seeds buried at 6 cm depth. Wheat residue amount within the range of 0–2000 kg ha–1 did not alter germination; however, germination was significantly reduced when the crop residue amount increased to 4000 kg ha–1 and the lowest germination was at 6000 kg ha–1. The potential to germinate under diverse environmental conditions correlates with the widespread occurrence of this weed in the northern region of Australia. High residue amounts and occasional tillage leading to deep burial of seeds may reduce its emergence and incidence.

scholarly journals One Way to Achieve Germination: Common Molecular Mechanism Induced by Ethylene and After-Ripening in Sunflower Seeds

2018 ◽  
Vol 19 (8) ◽  
pp. 2464 ◽  
Author(s):  
Qiong Xia ◽  
Marine Saux ◽  
Maharajah Ponnaiah ◽  
Françoise Gilard ◽  
François Perreau ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Conditions ◽  
Storage Period ◽  
Sugar Metabolism ◽  
Transcriptional Level ◽  
Sunflower Seeds ◽  
Wide Range ◽  
Number Of Genes ◽  
Favorable Conditions ◽  
Germinating Seeds

Dormancy is an adaptive trait that blocks seed germination until the environmental conditions become favorable for subsequent vegetative plant growth. Seed dormancy is defined as the inability to germinate in favorable conditions. Dormancy is alleviated during after-ripening, a dry storage period, during which dormant (D) seeds unable to germinate become non-dormant (ND), able to germinate in a wide range of environmental conditions. The treatment of dormant seeds with ethylene (D/ET) promotes seed germination, and abscisic acid (ABA) treatment reduces non-dormant (ND/ABA) seed germination in sunflowers (Helianthus annuus). Metabolomic and transcriptomic studies have been performed during imbibition to compare germinating seeds (ND and D/ET) and low-germinating seeds (D and ND/ABA). A PCA analysis of the metabolites content showed that imbibition did not trigger a significant change during the first hours (3 and 15 h). The metabolic changes associated with germination capacity occurred at 24 h and were related to hexoses, as their content was higher in ND and D/ET and was reduced by ABA treatment. At the transcriptional level, a large number of genes were altered oppositely in germinating, compared to the low-germinating seeds. The metabolomic and transcriptomic results were integrated in the interpretation of the processes involved in germination. Our results show that ethylene treatment triggers molecular changes comparable to that of after-ripening treatment, concerning sugar metabolism and ABA signaling inhibition.

Effects of Environmental Factors on Seed Germination and Emergence of Smutgrass (Sporobolus indicus) Varieties

Weed Science ◽  
2012 ◽  
Vol 60 (4) ◽  
pp. 558-563 ◽  
Author(s):  
Neha Rana ◽  
Barton J. Wilder ◽  
Brent A. Sellers ◽  
Jason A. Ferrell ◽  
Gregory E. MacDonald
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Environmental Conditions ◽  
Germination Rate ◽  
Warm Season ◽  
Soil Surface ◽  
Moisture Stress ◽  
Tropical Asia ◽  
Wide Range ◽  
Germination Experiments

Smutgrass is an invasive warm-season perennial bunch-type grass native to tropical Asia. The two varieties of smutgrass prevalent in Florida are small smutgrass and giant smutgrass. Laboratory seed germination experiments were conducted on both smutgrass varieties to determine the effect of various environmental factors on germination and emergence. The average germination rate for both varieties was 88% at 30/20 C day/night temperatures. Seed germination for both varieties was greater under simulated temperature flux than at constant temperatures. Seed of both varieties germinated at four simulated Florida temperature fluxes (22/11, 27/15, 33/24, and 29/19 C day/night), although the germination of small smutgrass and giant smutgrass was reduced at 33/24 and 22/11 C, respectively. Germination of small and giant smutgrass under dark conditions was 27 and 53%, respectively. Both smutgrass varieties germinated over a wide range of pH values. Small and giant smutgrass germination was inhibited at water potentials below −0.2 MPa and when small smutgrass seed was placed below the soil surface. Emergence of giant smutgrass seed did not occur below 3 cm. Both smutgrass varieties germinated over a broad range of environmental conditions, indicating their capability of year-round germination; however, germination is only likely to occur under field conditions during the summer growing season when rainfall is prevalent. These results indicate that both species have the ability to germinate over a wide range of environmental conditions but that germination is inhibited by moisture stress and depth of burial. Considering that giant smutgrass prefers higher temperatures than small smutgrass, the advent of rainfall from June through September is conducive for germination. Practices that focus on the germination pattern of smutgrass could lead to better long-term management of smutgrass in Florida.

First Detection of Tobacco Mosaic Virus in Tobacco Fields in Northern Lebanon

2020 ◽  
Vol 20 ◽  
Author(s):  
Rami Obeid ◽  
Elias Wehbe ◽  
Mohamad Rima ◽  
Mohammad Kabara ◽  
Romeo Al Bersaoui ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Viral Genome ◽  
Virus Genome ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Family ◽  
Crop Fields ◽  
Wide Range ◽  
Almost All ◽  
Das Elisa

Background: Tobacco mosaic virus (TMV) is the most known virus in the plant mosaic virus family and is able to infect a wide range of crops, in particularly tobacco, causing a production loss. Objectives: Herein, and for the first time in Lebanon, we investigated the presence of TMV infection in crops by analyzing 88 samples of tobacco, tomato, cucumber and pepper collected from different regions in North Lebanon. Methods: Double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), revealed a potential TMV infection of four tobacco samples out of 88 crops samples collected. However, no tomato, cucumber and pepper samples were infected. The TMV+ tobacco samples were then extensively analyzed by RT-PCR to detect viral RNA using different primers covering all the viral genome. Results and Discussion: PCR results confirmed those of DAS-ELISA showing TMV infection of four tobacco samples collected from three crop fields of North Lebanon. In only one of four TMV+ samples, we were able to amplify almost all the regions of viral genome, suggesting possible mutations in the virus genome or an infection with a new, not yet identified, TMV strain. Conclusion: Our study is the first in Lebanon revealing TMV infection in crop fields, and highlighting the danger that may affect the future of agriculture.

Use of tall fescue EST-SSR markers in phylogenetic analysis of cool-season forage grasses

Genome ◽  
2005 ◽  
Vol 48 (4) ◽  
pp. 637-647 ◽  
Author(s):  
M A. Rouf Mian ◽  
Malay C Saha ◽  
Andrew A Hopkins ◽  
Zeng-Yu Wang
Keyword(s):  
Phylogenetic Analysis ◽  
Ssr Markers ◽  
Tall Fescue ◽  
Related Species ◽  
Grass Species ◽  
Forage Grass ◽  
Forage Grasses ◽  
Cool Season ◽  
Phylogenetic Relations ◽  
Wide Range

Microsatellites or simple sequence repeats (SSRs) are highly useful molecular markers for plant improvement. Expressed sequence tag (EST)-SSR markers have a higher rate of transferability across species than genomic SSR markers and are thus well suited for application in cross-species phylogenetic studies. Our objectives were to examine the amplification of tall fescue EST-SSR markers in 12 grass species representing 8 genera of 4 tribes from 2 subfamilies of Poaceae and the applicability of these markers for phylogenetic analysis of grass species. About 43% of the 145 EST-SSR primer pairs produced PCR bands in all 12 grass species and had high levels of polymorphism in all forage grasses studied. Thus, these markers will be useful in a variety of forage grass species, including the ones tested in this study. SSR marker data were useful in grouping genotypes within each species. Lolium temulentum, a potential model species for cool-season forage grasses, showed a close relation with the major Festuca–Lolium species in the study. Tall wheatgrass was found to be closely related to hexaploid wheat, thereby confirming the known taxonomic relations between these species. While clustering of closely related species was found, the effectiveness of such data in evaluating distantly related species needs further investigations. The phylogenetic trees based on DNA sequences of selected SSR bands were in agreement with the phylogenetic relations based on length polymorphism of SSRs markers. Tall fescue EST-SSR markers depicted phylogenetic relations among a wide range of cool-season forage grass species and thus are an important resource for researchers working with such grass species.Key words: phylogeny, EST-SSR, forage grasses, tall fescue.

Analysis of high yielding maize production - a study based on a commercial crop

2008 ◽  
Vol 48 (3) ◽  
pp. 296 ◽  
Author(s):  
C. J. Birch ◽  
G. McLean ◽  
A. Sawers
Keyword(s):  
Retrospective Analysis ◽  
Environmental Conditions ◽  
Sowing Date ◽  
Plant Population ◽  
Higher Plant ◽  
Maize Crop ◽  
Wide Range ◽  
Commercial Crop ◽  
Reduced Temperature

This paper reports on the use of APSIM – Maize for retrospective analysis of performance of a high input, high yielding maize crop and analysis of predicted performance of maize grown with high inputs over the long-term (>100 years) for specified scenarios of environmental conditions (temperature and radiation) and agronomic inputs (sowing date, plant population, nitrogen fertiliser and irrigation) at Boort, Victoria, Australia. It uses a high yielding (17 400 kg/ha dry grain, 20 500 kg/ha at 15% water) commercial crop grown in 2004–05 as the basis of the study. Yield for the agronomic and environmental conditions of 2004–05 was predicted accurately, giving confidence that the model could be used for the detailed analyses undertaken. The analysis showed that the yield achieved was close to that possible with the conditions and agronomic inputs of 2004–05. Sowing dates during 21 September to 26 October had little effect on predicted yield, except when combined with reduced temperature. Single year and long-term analyses concluded that a higher plant population (11 plants/m2) is needed to optimise yield, but that slightly lower N and irrigation inputs are appropriate for the plant population used commercially (8.4 plants/m2). Also, compared with changes in agronomic inputs increases in temperature and/or radiation had relatively minor effects, except that reduced temperature reduces predicted yield substantially. This study provides an approach for the use of models for both retrospective analysis of crop performance and assessment of long-term variability of crop yield under a wide range of agronomic and environmental conditions.

ASSESSING ENVIRONMENTAL IMPACTS DURING NATURAL DISASTER: THE DEVELOPMENT OF A RAPID ENVIRONMENTAL ASSESSMENT METHODOLOGY

2002 ◽  
Vol 04 (04) ◽  
pp. 475-492 ◽  
Author(s):  
CHARLES KELLY
Keyword(s):  
Environmental Impact ◽  
Impact Assessment ◽  
Environmental Impact Assessment ◽  
Environmental Conditions ◽  
Environmental Damage ◽  
Assessment Procedure ◽  
Disaster Victims ◽  
Wide Range ◽  
Negative Impacts ◽  
The Impact

The linkages between disaster and environmental damage are recognized as important to predicting, preventing and mitigating the impact of disasters. Environmental Impact Assessment (EIA) procedures are well developed for non-ndisaster situations. However, they are conceptually and operationally inappropriate for use in disaster conditions, particularly in the first 120 days after the disaster has begun. The paper provides a conceptual overview of the requirements for an environmental impact assessment procedure appropriate for disaster conditions. These requirements are captured in guidelines for a Rapid Environmental Impact Assessment (REA) for use in disasters. The REA guides the collection and assessment of a wide range of factors which can indicate: (1) the negative impacts of a disaster on the environment, (2) the impacts of environmental conditions on the magnitude of a disaster and, (3) the positive or negative impacts of relief efforts on environmental conditions. The REA also provides a foundation for recovery program EIAs, thus improving the overall post disaster recovery process. The REA is designed primarily for relief cadres, but is also expected to be usable as an assessment tool with disaster victims. The paper discusses the field testing of the REA under actual disaster conditions.

scholarly journals Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

2016 ◽  
Vol 43 (4) ◽  
pp. 324 ◽  
Author(s):  
Supriya Tiwari ◽  
Rüdiger Grote ◽  
Galina Churkina ◽  
Tim Butler
Keyword(s):  
Stomatal Conductance ◽  
Environmental Conditions ◽  
Economic Losses ◽  
Plant Responses ◽  
Damage Scenarios ◽  
Biochemical Processes ◽  
Wide Range ◽  
Defence Responses ◽  
High Concentrations ◽  
The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

Distribution, feeding behaviour, and condition of Cape horse mackerel early life stages, Trachurus capensis, under different environmental conditions in the northern Benguela upwelling ecosystem

2014 ◽  
Vol 72 (2) ◽  
pp. 543-557 ◽  
Author(s):  
S. J. Geist ◽  
A. Kunzmann ◽  
H. M. Verheye ◽  
A. Eggert ◽  
A. Schukat ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Feeding Ecology ◽  
Environmental Conditions ◽  
Early Life ◽  
Early Life History ◽  
Horse Mackerel ◽  
Larval Phase ◽  
Recruitment Success ◽  
Wide Range ◽  
Variable Recruitment

Abstract Early life history (ELH) traits are key to understand variable recruitment success and hence the stock size of marine fish. One of the currently most puzzling ecosystems in this regard is the northern part of the Benguela Current upwelling system off Namibia. Here, populations of the formerly dominant pelagic species, sardine and anchovy, failed to recover during the last three decades after a dramatic decline. In contrast, Cape horse mackerel, Trachurus capensis, maintained a constant population size. Warming of the system and shoaling of hypoxic zones together with feedback loops within an altered foodweb are discussed to be responsible for this regime shift. In this study, we address the role of larval traits for the successful performance of the T. capensis population under the present environmental conditions with the focus on feeding ecology. We investigated seasonal variations of the geographical distribution, growth rate, feeding ecology, and nutritional condition of their ELH stages and examined relationships with water temperature, dissolved oxygen concentration, and micro-zooplankton composition. T. capensis' ELH stages showed a wide spatial and seasonal distribution, a preference for higher water temperatures (18–21°C) and presence over a wide range of dissolved oxygen concentrations (0.13–6.35 ml O2 l−1). Feeding success was high and mainly different groups of Copepoda were targeted, which were strongly size selected. The high dietary importance of micro-copepods during large parts of the larval phase indicates successful exploitation of this food source, which has increased in abundance during the last decade. It also explains observed best nutritional conditions at temperatures between 18 and 21°C, since these small copepods are commonly associated with warmer temperatures. Altogether, these traits enhance the species' probability to encounter suitable environments for the survival of their ELH stages, which is likely to lead to their high recruitment success in the northern Benguela ecosystem.

scholarly journals Separating damage from environmental effects affecting civil structures for near real-time damage detection

2017 ◽  
Vol 17 (4) ◽  
pp. 850-868 ◽  
Author(s):  
William Soo Lon Wah ◽  
Yung-Tsang Chen ◽  
Gethin Wyn Roberts ◽  
Ahmed Elamin
Keyword(s):  
Damage Detection ◽  
Real Time ◽  
Environmental Effects ◽  
Environmental Conditions ◽  
Principal Component ◽  
Detection Methods ◽  
Real Time Monitoring ◽  
Civil Structures ◽  
Data Set ◽  
Wide Range

Analyzing changes in vibration properties (e.g. natural frequencies) of structures as a result of damage has been heavily used by researchers for damage detection of civil structures. These changes, however, are not only caused by damage of the structural components, but they are also affected by the varying environmental conditions the structures are faced with, such as the temperature change, which limits the use of most damage detection methods presented in the literature that did not account for these effects. In this article, a damage detection method capable of distinguishing between the effects of damage and of the changing environmental conditions affecting damage sensitivity features is proposed. This method eliminates the need to form the baseline of the undamaged structure using damage sensitivity features obtained from a wide range of environmental conditions, as conventionally has been done, and utilizes features from two extreme and opposite environmental conditions as baselines. To allow near real-time monitoring, subsequent measurements are added one at a time to the baseline to create new data sets. Principal component analysis is then introduced for processing each data set so that patterns can be extracted and damage can be distinguished from environmental effects. The proposed method is tested using a two-dimensional truss structure and validated using measurements from the Z24 Bridge which was monitored for nearly a year, with damage scenarios applied to it near the end of the monitoring period. The results demonstrate the robustness of the proposed method for damage detection under changing environmental conditions. The method also works despite the nonlinear effects produced by environmental conditions on damage sensitivity features. Moreover, since each measurement is allowed to be analyzed one at a time, near real-time monitoring is possible. Damage progression can also be given from the method which makes it advantageous for damage evolution monitoring.

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