Environmental Implications of Herbicide Resistance: Soil Biology and Ecology

Weed Science ◽  
2014 ◽  
Vol 62 (2) ◽  
pp. 415-426 ◽  
Author(s):  
Robert J. Kremer
Keyword(s):  
Herbicide Resistance ◽  
Soil Microorganisms ◽  
Soil Biology ◽  
Plant Metabolites ◽  
Environmental Implications ◽  
Soil Microbial Community Structure ◽  
Herbicide Resistant ◽  
Soil Microbial ◽  
Microbial Groups ◽  
Acquisition Processes

Soil microbial community structure and activity are linked to plant communities. Weeds may alter their soil environment, selecting for specific rhizosphere microbial communities. Rhizosphere modification occurs for many crop and horticultural plants. However, impacts of weeds in agroecosystems on soil biology and ecology have received less attention because effective weed management practices were developed to minimize their impacts on crop production. The recent development of herbicide resistance (HR) in several economically important weeds leading to widespread infestations in crop fields treated with a single herbicide has prompted a re-evaluation of the effects of weed growth on soil biology and ecology. The objective of this article is to review the potential impacts of herbicide-resistant weeds on soil biological and ecological properties based on reports for crops, weeds, and invasive plants. Persistent weed infestations likely establish extensive root systems and release various plant metabolites through root exudation. Many exudates are selective for specific soil microbial groups mediating biochemical and nutrient acquisition processes. Exudates may stimulate development of microbial groups beneficial to weed but detrimental to crop growth or beneficial to both. Changes in symbiotic and associative microbial interactions occur, especially for arbuscular mycorrhizal fungi (AMF) that are important in plant uptake of nutrients and water, and protecting from phytopathogens. Mechanisms used by weeds to disrupt symbioses in crops are not clearly described. Many herbicide-resistant weeds includingAmaranthusandChenopodiumdo not support AMF symbioses, potentially reducing AMF propagule density and establishment with crop plants. Herbicides applied to control HR weeds may compound effects of weeds on soil microorganisms. Systemic herbicides released through weed roots may select microbial groups that mediate detrimental processes such as nutrient immobilization or serve as opportunistic pathogens. Understanding complex interactions of weeds with soil microorganisms under extensive infestations is important in developing effective management of herbicide-resistant weeds.

scholarly journals Soil Microbial Community Structure and Target Organisms under Different Fumigation Treatments

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Sadikshya R. Dangi ◽  
James S. Gerik ◽  
Rebecca Tirado-Corbalá ◽  
Husein Ajwa
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Methyl Bromide ◽  
Soil Microorganisms ◽  
Phospholipid Fatty Acid ◽  
Natural Soil ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Field Samples

Producers of several high-value crops in California rely heavily on soil fumigants to control key diseases, nematodes, and weeds. Fumigants with broad biocidal activity can affect both target and nontarget soil microorganisms. The ability of nontarget soil microorganisms to recover after fumigation treatment is critical because they play an important role in sustaining the health of agricultural and natural soil systems. Fumigation trial was conducted in Parlier, CA, and the study focuses on the effects of different rates of Telone C35 and also methyl bromide fumigation with polyethylene (PE) and totally impermeable film (TIF) tarps on target and nontarget soil microorganisms using field samples. Results indicated that the populations of target organisms, such asFusarium oxysporumandPythiumspp., were reduced at all rates of fumigants. Phospholipid fatty acid (PLFA) analysis indicated that all major nontarget soil microbial groups such as Gram positive bacteria, Gram negative bacteria, fungi, and arbuscular mycorrhizal fungi (AMF) were affected by methyl bromide (MeBr) fumigation treatment. In general, the effects of Telone C35 (299 L/ha) under PE tarp had the least impact on microbial community structure and better effect on controlling target microorganisms and, therefore, indicated the better option among fumigation treatments.

scholarly journals Effects of microplastic and microglass particles on soil microbial community structure in an arable soil (Chernozem)

2019 ◽  
Author(s):  
Katja Wiedner ◽  
Steven Polifka
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Soil Microbial Community ◽  
Soil Microorganisms ◽  
Soil Microbiology ◽  
Soil Microbial Community Structure ◽  
Treated Soil ◽  
Soil Microbial ◽  
Terrestrial Environments

Abstract. Since decades, microplastics and microglass enter aquatic and terrestrial environments. The complexity of the environmental impact is difficult to capture and consequences on ecosystem components e.g. such as soil microorganisms are virtually unknown. Addressing this issue, we performed an incubation experiment by adding 1 % of five different types of impurities (≤ 100 µm) to an agricultural used soil (Chernozem). Four microplastic types (polypropylene (PP), low density polyethylene (LD-PE), polystyrene (PS) and polyamide12 (PA12)) and microglass were used as treatment variants. After 80 days of incubation at 20 °C, we examined soil microbial community structure by using phospholipid fatty acids (PLFA) as markers for bacteria, fungi and protozoa. The results showed that soil microorganisms were not significantly affected by the presence of microplastic and microglass. However, PLFAs tend to increase in LD-PE (27 %), PP (18 %) and microglass (11 %) treated soil in comparison with untreated soil, whereas PLFAs in PA12 (32 %) and PS (11 %) treated soil decreased. Interestingly, the comparison of PLFA contents between microplastic types revealed significant differences of PA12 (−87 %) and PS (−42 %) compared to LD-PE. Furthermore, bacterial PLFAs showed a much higher variability after microplastic incubation whereby fungi seem to be more unaffected after 80 days of incubation. Same for protozoa, which were more or less unaffected by microplastic treatment showing only minor reduction of the PLFA contents compared to control. In contrast, microglass has obviously an inhibiting effect on protozoa because PLFAs were under the limit of determination. Our study provides hints, that microplastics have, depending on type, contrary effects on soil microbiology and microglass seems to be highly toxic for protozoa.

scholarly journals Soil microorganisms and their role in the interactions between weeds and crops

2014 ◽  
Vol 32 (4) ◽  
pp. 873-884 ◽  
Author(s):  
A.M. Massenssini ◽  
V.H.A. Bonduki ◽  
C.A.D. Melo ◽  
M.R. Tótola ◽  
F.A. Ferreira ◽  
...  
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
Competitive Ability ◽  
Soil Microorganisms ◽  
Root Colonization ◽  
Arbuscular Mycorrhizal ◽  
Future Research ◽  
Positive Interactions ◽  
Soil Microbial ◽  
Microbial Groups

The competition between weeds and crops is a topic of great interest, since this interaction can cause heavy losses in agriculture. Despite the existence of some studies on this subject, little is known about the importance of soil microorganisms in the modulation of weed-crop interactions. Plants compete for water and nutrients in the soil and the ability of a given species to use the available resources may be directly affected by the presence of some microbial groups commonly found in the soil. Arbuscular mycorrhizal fungi (AMF) are able to associate with plant roots and affect the ability of different species to absorb water and nutrients from the soil, promoting changes in plant growth. Other groups may promote positive or negative changes in plant growth, depending on the identity of the microbial and plant partners involved in the different interactions, changing the competitive ability of a given species. Recent studies have shown that weeds are able to associate with mycorrhizal fungi in agricultural environments, and root colonization by these fungi is affected by the presence of other weeds or crops species. In addition, weeds tend to have positive interactions with soil microorganisms while cultures may have neutral or negative interactions. Competition between weeds and crops promotes changes in the soil microbial community, which becomes different from that observed in monocultures, thus affecting the competitive ability of plants. When grown in competition, weeds and crops have different behaviors related to soil microorganisms, and the weeds seem to show greater dependence on associations with members of the soil microbiota to increase growth. These data demonstrate the importance of soil microorganisms in the modulation of the interactions between weeds and crops in agricultural environments. New perspectives and hypotheses are presented to guide future research in this area.

scholarly journals Effects of microplastic and microglass particles on soil microbial community structure in an arable soil (Chernozem)

SOIL ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 315-324
Author(s):  
Katja Wiedner ◽  
Steven Polifka
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Soil Microbial Community ◽  
Soil Microorganisms ◽  
Soil Microbiology ◽  
Worst Case ◽  
Soil Microbial Community Structure ◽  
Treated Soil ◽  
Soil Microbial

Abstract. Microplastic and microglass particles from different sources enter aquatic and terrestrial environments. The complexity of their environmental impact is difficult to capture, and the consequences for ecosystem components, for example, the soil microorganisms, are virtually unknown. To address this issue, we performed an incubation experiment by adding 1 % of five different types of impurities (≤100 µm) to an agriculturally used soil (Chernozem) and simulating a worst-case scenario of contamination. The impurities were made of polypropylene (PP), low-density polyethylene (LDPE), polystyrene (PS), polyamide 12 (PA12) and microglass. After 80 d of incubation at 20 ∘C, we examined the soil microbial community structure by using phospholipid fatty acids (PLFAs) as markers for bacteria, fungi and protozoa. The results showed that soil microorganisms were not significantly affected by the presence of microplastic and microglass. However, PLFAs tend to increase with LDPE (28 %), PP (19 %) and microglass (11 %) in treated soil in comparison with untreated soil, whereas PLFAs in PA12 (32 %) and PS (11 %) in treated soil decreased. Interestingly, PLFAs revealed significant differences in PA12 (−89 %) and PS (−43 %) in comparison with LDPE. Furthermore, variability of bacterial PLFAs was much higher after microplastic incubation, while fungi seemed to be unaffected from different impurities after 80 d of incubation. Similar results were shown for protozoa, which were also more or less unaffected by microplastic treatment as indicated by the minor reduction in PLFA contents compared to the control group. In contrast, microglass seems to have an inhibiting effect on protozoa because PLFAs were under the limit of determination. Our study indicated that high amounts of different microplastics may have contrary effects on soil microbiology. Microglass might have a toxic effect for protozoa.

Real time interactions between soil microorganisms and microplastics at microscale

2021 ◽  
Author(s):  
P. Micaela Mafla-Endara ◽  
Pelle Ohlsson ◽  
Edith Hammer
Keyword(s):  
Microbial Community ◽  
Soil Microorganisms ◽  
Pore Space ◽  
Microbial Community Composition ◽  
Terrestrial Ecosystems ◽  
Microbial Colonization ◽  
Soil Mesofauna ◽  
Soil Macrofauna ◽  
Soil Microbial ◽  
Microbial Groups

<p>Terrestrial ecosystems are under threat due to the continuous accumulation of plastics in soils. Particularly, microplastics have been proven to negatively affect the performance of soil macrofauna such as earthworms, as well as soil mesofauna including springtails and nematodes. Unfortunately, two big groups remain largely unexplored: the soil microfauna and microflora.</p><p>Recent studies have shown that soil microbial community composition can significantly vary depending on the concentration and type of plastic, favouring some groups and disfavouring others. To have a better understanding of these relationships, it is necessary to study them at relevant scale: the microscale.</p><p>Considering that in situ observations are hard to achieve due to the opacity of soil and ever-changing soil architecture, we used transparent micro-engineered chips to study interactions between microplastics and soil microorganisms live. We hypothesized that different concentrations of microplastics interfere with a natural microbial community in terms of 1. Soil microbial colonization/succession of the chips and 2. Soil microbial growth inside the chips’ pore space.</p><p>We fabricated chips containing different microstructures that simulate soil pore spaces. The chips were bonded to a glass slide and one side was opened to allow microbial colonization. Each chip was filled with a mix of liquid nutrient medium and 1.0 µm polystyrene microbeads at microplastic concentrations of 0.0, 0.006, 0.001 and 0.0005 mg/ml. The chip´s opening was inoculated with 5 g of soil and incubated in the laboratory at room temperature for one month. We documented the presence/absence and abundance of different soil microbial groups changing over time by using an inverted microscope.</p><p>Our preliminary study reveals that larger microorganisms are sensitive to the presence of microbeads 1.0 µm size. We found that all major soil microbial groups (fungi, bacteria, and protists) and nematodes colonized the chips. However, their abundance was affected by the presence of microplastics, irrespective of the concentration. Particularly protists and nematodes were lower in number during the first days of the exposure. The beads were clearly visibly taken up into the cells of the protists or the digestive tract of the nematodes.</p><p>We are now investigating what consequences the lower abundance of certain soil microbial groups have for the soil food web. As seen here, micro-engineered chips are useful tools to provide visual access at the scale where most cell-to-cell interactions occur.</p>

scholarly journals Changes in Bacterial and Fungal Soil Communities in Long-Term Organic Cropping Systems

Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 445
Author(s):  
Jessica Cuartero ◽  
Onurcan Özbolat ◽  
Virginia Sánchez-Navarro ◽  
Marcos Egea-Cortines ◽  
Raúl Zornoza ◽  
...  
Keyword(s):  
Microbial Community ◽  
Crop Yield ◽  
Soil Microbial Community ◽  
Cropping Systems ◽  
Sequencing Analysis ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Network Analyses ◽  
Organic Cultivation

Long-term organic farming aims to reduce synthetic fertilizer and pesticide use in order to sustainably produce and improve soil quality. To do this, there is a need for more information about the soil microbial community, which plays a key role in a sustainable agriculture. In this paper, we assessed the long-term effects of two organic and one conventional cropping systems on the soil microbial community structure using high-throughput sequencing analysis, as well as the link between these communities and the changes in the soil properties and crop yield. The results showed that the crop yield was similar among the three cropping systems. The microbial community changed according to cropping system. Organic cultivation with manure compost and compost tea (Org_C) showed a change in the bacterial community associated with an improved soil carbon and nutrient content. A linear discriminant analysis effect size showed different bacteria and fungi as key microorganisms for each of the three different cropping systems, for conventional systems (Conv), different microorganisms such as Nesterenkonia, Galbibacter, Gramella, Limnobacter, Pseudoalteromonas, Pantoe, and Sporobolomyces were associated with pesticides, while for Org_C and organic cultivation with manure (Org_M), other types of microorganisms were associated with organic amendments with different functions, which, in some cases, reduce soil borne pathogens. However, further investigations such as functional approaches or network analyses are need to better understand the mechanisms behind this behavior.

Investigating the resistance levels and mechanisms to penoxsulam and cyhalofop-butyl in barnyardgrass (Echinochloa crus-galli) from Ningxia province, China

Weed Science ◽  
2021 ◽  
pp. 1-25
Author(s):  
Qian Yang ◽  
Xia Yang ◽  
Zichang Zhang ◽  
Jieping Wang ◽  
Weiguo Fu ◽  
...  
Keyword(s):  
Herbicide Resistance ◽  
Molecular Mechanisms ◽  
Acetolactate Synthase ◽  
Rice Fields ◽  
Target Site ◽  
Herbicide Resistant ◽  
Susceptible Populations ◽  
High Level ◽  
Als Inhibitor ◽  
Encoding Genes

Abstract Barnyardgrass (Echinochloa crus-galli) is a noxious grass weed which infests rice fields and causes huge crop yield losses. In this study, we collected twelve E. crus-galli populations from rice fields of Ningxia province in China and investigated the resistance levels to acetolactate synthase (ALS) inhibitor penoxsulam and acetyl-CoA carboxylase (ACCase) inhibitor cyhalofop-butyl. The results showed that eight populations exhibited resistance to penoxsulam and four populations evolved resistance to cyhalofop-butyl. Moreover, all of the four cyhalofop-butyl-resistant populations (NX3, NX4, NX6 and NX7) displayed multiple-herbicide-resistance (MHR) to both penoxsulam and cyhalofop-butyl. The alternative herbicides bispyribac-sodium, metamifop and fenoxaprop-P-ethyl cannot effectively control the MHR plants. To characterize the molecular mechanisms of resistance, we amplified and sequenced the target-site encoding genes in resistant and susceptible populations. Partial sequences of three ALS genes and six ACCase genes were examined. A Trp-574-Leu mutation was detected in EcALS1 and EcALS3 in two high-level (65.84- and 59.30-fold) penoxsulam-resistant populations NX2 and NX10, respectively. In addition, one copy (EcACC4) of ACCase genes encodes a truncated aberrant protein due to a frameshift mutation in E. crus-galli populations. None of amino acid substitutions that are known to confer herbicide resistance were detected in ALS and ACCase genes of MHR populations. Our study reveals the widespread of multiple-herbicide resistant E. crus-galli populations at Ningxia province of China that exhibit resistance to several ALS and ACCase inhibitors. Non-target-site based mechanisms are likely to be involved in E. crus-galli resistance to the herbicides, at least in four MHR populations.

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