scholarly journals The Impact of Polyploidization on the Evolution of Weed Species: Historical Understanding and Current Limitations

2021 ◽  
Vol 3 ◽  
Author(s):  
Claudia Ann Rutland ◽  
Nathan D. Hall ◽  
Joseph Scott McElroy
Keyword(s):  
Environmental Change ◽  
Weed Management ◽  
Weed Species ◽  
Adaptive Genetic Variation ◽  
Ploidy Levels ◽  
Resistance Evolution ◽  
Resistance To Stress ◽  
Weed Evolution ◽  
The Impact ◽  
Rapid Environmental Change

Whole genome duplication via polyploidization is a major driver of diversification within angiosperms and it appears to confer the most benefit during times of rapid environmental change. Polyploidization offers expanded access to novel phenotypes that facilitate invasion of new environments and increased resistance to stress. These new phenotypes can arise almost immediately through the novel interactions among or between transcription factors of the duplicated genomes leading to transgressive traits, and general heterosis, or they can occur more slowly through processes like neofunctionalization, and subfunctionalization. These processes are characterized by the changes within homologs of the duplicated genomes, homoeologs. It has been proposed that redundant homoeologs are released from selective constraints and serve as an additional source of adaptive genetic variation, particularly in neo and meso-polyploids. Current practices in weed management create rapid environmental change through the use of chemicals, practices that are meant to cause the extirpation of the designated weed, and represent a strong recurrent selective event—a scenario that should favor polyploidy species. Here we ask the question, “Do polyploids make better weeds?” It is our conclusion that such a question is impossible to answer at this time due to the lack of resources and understanding in weed genomics. The growing contingent of research in weed genomics, however, driven by herbicide resistance evolution is rapidly improving our understanding of weed molecular biology and will aid in improving understanding of the impacts of ploidy levels on weed evolution and adaptation in the future.

Effects of Water on Recovery of Weed Seedlings Following Burial

Weed Science ◽  
2016 ◽  
Vol 64 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Charles L. Mohler ◽  
Javaid Iqbal ◽  
Jianying Shen ◽  
Antonio DiTommaso
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Burial Depth ◽  
Management Problem ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Giant Foxtail ◽  
Organic Weed Management ◽  
The Impact ◽  
Better Than

Recovery of common agricultural weeds after burial by soil was studied in four greenhouse and three field experiments. Species studied included velvetleaf, Powell amaranth, common lambsquarters, barnyardgrass, and giant foxtail. Seedlings were bent over before burial to simulate the effect of the impact of soil thrown by a cultivator. Altogether, more than 35,000 seedlings were marked and observed for recovery. No seedlings recovered from 4 cm of burial. Recovery from complete burial under 2 cm of soil ranged from 0 to 24% depending on the experiment, species, and watering treatment, but recovery greater than 5% was rare. Large-seeded species tended to recover from complete burial under 2 cm of soil better than small-seeded species. The study did not reveal a difference in recovery of grasses relative to broadleaf weeds. Overall, seedlings tended to recover best when water was applied daily after burial, worst when water was applied once on the day of burial, and to an intermediate extent when no water was applied. However, difference in recovery between the no-water and watering-once treatments were usually small. Also, many experiment by species combinations showed no significant differences among watering treatments. When even a small portion of the seedling was left exposed, recovery generally exceeded 50%. Organic weed management systems commonly use burial of weed seedlings with tine weeders and soil thrown by sweeps and hilling disks to control weeds in crop rows. Recovery from burial could pose a substantial weed management problem in some circumstances, particularly for large-seeded weed species. Maximizing burial depth is important for limiting recovery. Recovery from burial can be minimized by withholding irrigation for several days after hilling-up operations.

scholarly journals Seed contamination in sheep: new investigations into an old problem

2018 ◽  
Vol 58 (8) ◽  
pp. 1538 ◽  
Author(s):  
J. E. Kelly ◽  
J. C. Quinn ◽  
P. Loukopoulos ◽  
J. C. Broster ◽  
K. Behrendt ◽  
...  
Keyword(s):  
Weed Management ◽  
Management Strategies ◽  
Production Capacity ◽  
Current Status ◽  
Future Research ◽  
Financial Loss ◽  
Weed Species ◽  
Sheep Production ◽  
The Impact ◽  
Grass Weed

Seed contamination significantly affects production capacity and animal welfare in Australian sheep flocks and causes considerable financial loss to producers and processors across sheepmeat value chains. Seven grass-weed species contribute to seed contamination in Australia, with barley grass (Hordeum spp.) identified as a key perpetrator. Herbicide resistance and variable dormancy emerging in southern Australian barley grass populations are thought to enhance its capacity for successful pasture invasion, further exacerbating the potential for seed contamination in sheep. The present article reviews the current literature regarding the impact and incidence of seed contamination on sheepmeat production, with particular reference to key grass-weed species prevalence across Australia. Data are presented on a recent incidence of carcass contamination across years, where incidence varied between 11% and 80% from 2009 to 2013, contracting to between 2% and 60% during 2014 and 2015. Key areas requiring future research are defined. Understanding the biology of key grass weeds, historical influences and economic consequences associated with seed contamination in sheep may assist in defining future risks to sheep production and improve weed management. Furthermore, examining more recent data describing the current status of seed contamination across Australia and the associations with causal weed species may aid the development of critical weed-management strategies in highly infested regions, subsequently limiting the extent of future seed contamination.

Economic Importance of Managing Spatially Heterogeneous Weed Populations

1998 ◽  
Vol 12 (1) ◽  
pp. 7-13 ◽  
Author(s):  
John L. Lindquist ◽  
J. Anita Dieleman ◽  
David A. Mortensen ◽  
Gregg A. Johnson ◽  
Dawn Y. Wyse-Pester
Keyword(s):  
Crop Yield ◽  
Weed Management ◽  
Negative Binomial ◽  
Spatial Location ◽  
Economic Importance ◽  
Expected Returns ◽  
Weed Species ◽  
Grid Sampling ◽  
Weed Interference ◽  
The Impact

Three methods of predicting the impact of weed interference on crop yield and expected economic return were compared to evaluate the economic importance of weed spatial heterogeneity. Density of three weed species was obtained using a grid sampling scheme in 11 corn and 11 soybean fields. Crop yield loss was predicted assuming densities were homogeneous, aggregated following a negative binomial with known population mean and k, or aggregated with weed densities spatially mapped. Predicted crop loss was lowest and expected returns highest when spatial location of weed density was utilized to decide whether control was justified. Location-specific weed management resulted in economic gain as well as a reduction in the quantity of herbicide applied.

Weed Control in Corn (Zea mays) as Affected by Till-Plant Systems and Herbicides

1989 ◽  
Vol 3 (1) ◽  
pp. 162-165 ◽  
Author(s):  
Edward E. Schweizer ◽  
Robert L. Zimdahl ◽  
Rome H. Mickelson
Keyword(s):  
Weed Management ◽  
Management Systems ◽  
Weed Seed ◽  
Weed Species ◽  
Corn Production ◽  
Common Lambsquarters ◽  
Seed Reserves ◽  
Total Seed ◽  
Annual Weeds ◽  
The Impact

The impact of three till-plant and two weed management systems on weed seed reserves of soil, yearly weed problems, and corn production was assessed under center-pivot irrigation for 3 consecutive years. Annual weeds were controlled in disced, bedded, and strip rotary till-plant systems with a moderate or intensive level of herbicides. Weed seed of seven annual weed species were identified, with common lambsquarters and stinkgrass, comprising 45 and 41%, respectively, of the initial 305 million seed/ha in the upper 25 cm of the soil profile. After the third cropping year, overall decline in total seed number in soil was 45% when averaged over till-plant and weed management systems. Grain yields did not differ between weed management systems, but the disced till-plant system produced 16% less grain than the bedded and strip rotary till-plant systems over 2 yr.

scholarly journals Weeds and Their Responses to Management Efforts in A Changing Climate

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1921
Author(s):  
Md. Parvez Anwar ◽  
A. K. M. Mominul Islam ◽  
Sabina Yeasmin ◽  
Md. Harun Rashid ◽  
Abdul Shukor Juraimi ◽  
...  
Keyword(s):  
Climate Change ◽  
Elevated Co2 ◽  
Global Climate Change ◽  
Weed Management ◽  
Global Climate ◽  
C4 Plants ◽  
C3 Plants ◽  
Weed Species ◽  
Co2 Levels ◽  
The Impact

Crop production is a constant battle with weeds, in which weeds, generally, are victorious. Therefore, rather than channeling our efforts into the development of a “silver bullet” to control weeds, the focus should be on sustainable weed management in both natural- and agro-ecosystems. However, sustainable weed management can be a challenge in the context of global climate change. Over the past few decades, global climate change, mostly indicated by phenomena such as increased atmospheric temperature and elevated CO2 levels, is evident due to human activities and natural events. These phenomena also affect regional/local climate, resulting in significant influences on the agricultural systems of a particular region. Rising CO2 levels may give comparative advantages to C3 plants through increased photosynthesis, biomass production and yield, compared to C4 plants. Plants with C4 photosynthetic pathways, on the other hand, are likely to benefit more from rising global temperatures than C3 plants. Thus, the differential responses of C3 and C4 plants to climate change may alter crop–weed interactions and competition outcomes, most likely at the expense of the crop. Climate change will likely cause shifts in weed community compositions, their population dynamics, life cycle, phenology, and infestation pressure. Some weed species may go extinct, while some others may become more aggressive invaders. Weeds are, generally, colonizers and have some unique biological traits and ecological amplitudes that enable them to successfully dominate crops in a habitat with changed environmental conditions. Moreover, climate shifts, especially erratic rainfall and drought, may affect herbicide selectivity and efficacy or the success of bio-control agents resulting in an establishment of a mixed and complex population of C3 and C4 weed species adding to the complexity of weed management. Although elevated CO2 levels will stimulate the productivity of major C3 crops, most troublesome agricultural weeds will likely be more responsive to a rise in CO2 than crops, and thus may dominate the agro-ecosystem. It is predicted that, as temperature rises, the majority of the C4 weeds will flourish and will pose serious crop yield losses. Understanding and assessment of the impact of simultaneous changes in multiple climate factors and their complex interactions on crops and weeds are therefore necessary to formulate an adaptive weed management approach and build resilience. Moreover, strategic policies and strong actions need to be taken to reduce the root causes of CO2 and other greenhouse gas emissions to minimize the impact of climate change on weed biology and management.

scholarly journals Mulch-Based No-Tillage Effects on Weed Community and Management in an Organic Vegetable System

Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 594 ◽  
Author(s):  
Elena Testani ◽  
Corrado Ciaccia ◽  
Gabriele Campanelli ◽  
Fabrizio Leteo ◽  
Luca Salvati ◽  
...  
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
N Availability ◽  
No Tillage ◽  
Soil N ◽  
Weed Species ◽  
Hordeum Vulgare L ◽  
Polygonum Aviculare ◽  
Shannon Diversity ◽  
The Impact

Weeds can cooperate with the agroecosystem’s functioning by providing ecosystem services. Effective weed management should mitigate negative weed–crop interference, while maintaining a functional and balanced weed community. In a two-year trial, the in-line/roller crimper (RC) was used to terminate an agroecological service crop (ASC; here barley, Hordeum vulgare L.) before organic zucchini (Cucurbita pepo, L.) and compared with green manure (GM) ASC and tilled no-ASC with Mater-Bi mulch on the rows (No_ASC). Zucchini yield, soil N availability, weed density/cover, biomass, and community composition were assessed. Analysis of variance, exploratory statistical analysis, and non-parametric inferential approaches were run, respectively, on agronomic data, species-specific weed frequencies, and Shannon diversity. Zucchini yield was the highest in No_ASC, due to soil N immobilization under high C:N barley residues in GM and RC. Multivariate analysis discriminated RC from tilled systems, outlining a specific ensemble of weed species correlated to Shannon diversity. From zucchini fruit set, RC selectively favored Polygonum aviculare L. and Helminthotheca echioides (L.), reasonably because of their oligotrophy and creeping habit. Their dominance finally caused low RC weed control. Results highlight strong weed selective pressure by the mulch-based no-tillage. Understanding the mechanisms underpinning the impact of soil management practices on weed community can drive towards a tailor-made and more effective weed management.

scholarly journals Glyphosate as a Tool for the Incorporation of New Herbicide Options in Integrated Weed Management in Maize: A Weed Dynamics Evaluation

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 876
Author(s):  
Iñigo Loureiro ◽  
Inés Santin-Montanyá ◽  
María-Concepción Escorial ◽  
Esteban García-Ruiz ◽  
Guillermo Cobos ◽  
...  
Keyword(s):  
Species Diversity ◽  
Weed Management ◽  
Management Program ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Additional Tool ◽  
Cropping Season ◽  
Farm Scale ◽  
Weed Dynamics ◽  
The Impact

A farm-scale investigation was conducted to evaluate the potential impact of integrating glyphosate into different weed management programs when cultivating herbicide-tolerant maize in central Spain from 2012 to 2014. The weed management programs were (1) a conventional weed management with pre- and post-emergent herbicide applications, (2) a weed management program in which the number and total amount of conventional herbicides applied were reduced, and (3) three weed management programs that comprised either two post-emergent applications of the herbicide glyphosate, or only one glyphosate application combined with pre- and/or post-emergent herbicides. Weed density throughout each cropping season was greater in those weed management programs that did not include a pre-emergence application of herbicides than those that did. Moreover, none of the weed management programs affected the richness and species diversity of the weeds or reduced yields. Although the impact of the different programs was similar in terms of weed species diversity, the composition of the weed community differed and this effect must be considered when providing agroecosystem services. Our results indicate that glyphosate-tolerant maize provides an additional tool that allows integrated weed control of the weed populations without reducing yields.

scholarly journals The impact of aqueous and N-hexane extracts of three Fabaceae species on seed germination and seedling growth of some broadleaved weed species

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0258920
Author(s):  
Muhammad Ehsan Safdar ◽  
Xiukang Wang ◽  
Mudasar Abbas ◽  
Cumali Ozaslan ◽  
Muhammad Asif ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seedling Growth ◽  
Plant Extracts ◽  
Weed Management ◽  
Foliar Spray ◽  
Aqueous Extracts ◽  
Weed Species ◽  
Persistent Problem ◽  
Dry Biomass ◽  
The Impact

Weed infestation is a persistent problem for centuries and continues to be major yield reducing issue in modern agriculture. Chemical weed control through herbicides results in numerous ecological, environmental, and health-related issues. Moreover, numerous herbicides have evolved resistance against available herbicides. Plant extracts are regarded as an alternative to herbicides and a good weed management option. The use of plant extracts is environmentally safe and could solve the problem of herbicide resistance. Therefore, laboratory and wire house experiments were conducted to evaluate the phytotoxic potential of three Fabaceae species, i.e., Cassia occidentalis L. (Coffee senna), Sesbania sesban (L.) Merr. (Common sesban) and Melilotus alba Medik. (White sweetclover) against seed germination and seedling growth of some broadleaved weed species. Firstly, N-hexane and aqueous extracts of these species were assessed for their phytotoxic effect against lettuce (Lactuca sativa L.). The extracts found more potent were further tested against germination and seedling growth of four broadleaved weed species, i.e., Parthenium hysterophorus L. (Santa-Maria), Trianthema portulacastrum L. (Pigweed), Melilotus indica L (Indian sweetclover). and Rumex dentatus L. (Toothed dock) in Petri dish and pot experiments. Aqueous extracts of all species were more toxic than their N-hexane forms for seed germination and seedling growth of lettuce; therefore, aqueous extracts were assessed for their phytotoxic potential against four broadleaved weed species. Aqueous extracts of all species proved phytotoxic against T. portulacastrum, P. hysterophorus, M. indica and R. dentatus and retarder their germination by 57, 90, 100 and 58%, respectively. Nevertheless, foliar spray of C. occidentalis extract was the most effective against T. portulacastrum as it reduced its dry biomass by 72%, while M. alba was effective against P. hysterophorus, R. dentatus and M. indica and reduced their dry biomass by 55, 68 and 81%, respectively. It is concluded that aqueous extracts of M. alba, S. sesban and C. occidentalis could be used to retard seed germination of T. portulacastrum, P. hysterophorus, M. indica and R. dentatus. Similarly, aqueous extracts of C. occidentalis can be used to suppress dry biomass of T. portulacastrum, and those of M. alba against P. hysterophorus, R. dentatus. However, use of these extracts needs their thorough testing under field conditions.

scholarly journals Genetically Engineered Herbicide-Resistant Crops and Herbicide-Resistant Weed Evolution in the United States

Weed Science ◽  
2017 ◽  
Vol 66 (2) ◽  
pp. 260-273 ◽  
Author(s):  
Andrew R. Kniss
Keyword(s):  
United States ◽  
The United States ◽  
Genetically Engineered ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Resistant Varieties ◽  
Weed Evolution ◽  
Sites Of Action ◽  
Herbicide Use ◽  
The Impact

Genetically engineered (GE) herbicide-resistant crops have been widely adopted by farmers in the United States and other countries around the world, and these crops have caused significant changes in herbicide use patterns. GE crops have been blamed for increased problems with herbicide-resistant weeds (colloquially called by the misnomer “superweeds”); however, there has been no rigorous analysis of herbicide use or herbicide-resistant weed evolution to quantify the impact of GE crops on herbicide resistance. Here, I analyze data from the International Survey of Herbicide Resistant Weeds and the USDA and demonstrate that adoption of GE corn varieties did not reduce herbicide diversity, and therefore likely did not increase selection pressure for herbicide-resistant weeds in that crop. Adoption of GE herbicide-resistant varieties substantially reduced herbicide diversity in cotton and soybean. Increased glyphosate use in cotton and soybean largely displaced herbicides that are more likely to select for herbicide-resistant weeds, which at least partially mitigated the impact of reduced herbicide diversity. The overall rate of newly confirmed herbicide-resistant weed species to all herbicide sites of action (SOAs) has slowed in the United States since 2005. Although the number of glyphosate-resistant weeds has increased since 1998, the evolution of new glyphosate-resistant weed species as a function of area sprayed has remained relatively low compared with several other commonly used herbicide SOAs.

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