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Recently, due to the widespread use of the acetolactate synthase (ALS)-inhibiting herbicide penoxsulam in paddy fields in China, Echinochloa crus-galli (L.) P. Beauv. has become a problematic grass weed that is frequently not controlled, posing a threat to weed management and rice yield. There are many reports on target-site mutations of ALS inhibiting herbicides; however, the detailed penoxsulam resistance mechanism in E. crus-galli remains to be determined. Greenhouse and laboratory studies were conducted to characterize target-site resistance mechanisms in JL-R, AH-R, and HLJ-R suspected resistant populations of E. crus-galli survived the field-recommended dose of penoxsulam. The whole-plant dose–response testing of E. crus-galli to penoxsulam confirmed the evolution of moderate-level resistance in two populations, JL-R (9.88-fold) and HLJ-R (8.66-fold), and a high-level resistance in AH-R (59.71-fold) population. ALS gene sequencing identified specific mutations in resistant populations, including Pro-197-His in ALS1 for JL-R, Trp-574-Leu in ALS1 for AH-R, and Pro-197-Leu in ALS2 for HLJ-R. In vitro ALS activity assays demonstrated a significantly higher activity in AH-R compared to the susceptible population (YN-S). Molecular docking studies revealed that Trp-574-Leu mutation primarily reduced the enzyme's ability to bind to the triazole-pyrimidine ring of penoxsulam due to decreased π–π stacking interactions, while Pro-197-His/Leu mutations impaired binding to the benzene ring by altering hydrogen bonds and hydrophobic interactions. Additionally, the Pro-197-His/Leu amino acid residue changes resulted in alterations in the shape of the active channel, impeding the efficient entry of penoxsulam into the binding site in the ALS protein. The three mutant ALS proteins expressed via the Bac-to-Bac baculovirus system exhibited notably lower activity inhibition rates than the non-mutant ALS proteins to penoxsulam, indicating all three ALS mutations reduce sensitivity to penoxsulam. This study elucidated the distinct impacts of the Pro-197-His/Leu and Trp-574-Leu mutations in E. crus-galli to penoxsulam resistance. Notably, the Trp-574-Leu mutation conferred stronger resistance to penoxsulam compared to the Pro-197-His/Leu mutations in E. crus-galli. The Pro-197-His/Leu mutations were first detected in E. crus-galli conferring penoxsulam resistance. These findings provide deeper insights into the molecular mechanisms underlying target-site resistance to penoxsulam in E. crus-galli. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Pesticide Science / Nongyaoxue Xuebao is the property of Chinese Journal of Pesticide Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Echinochloa crus‐galli is the most troublesome and widespread weed of most rice‐growing regions of the world. Cyhalofop‐butyl, a herbicide within the acetyl‐CoA carboxylase (ACCase) chemical group, has been extensively used to control barnyardgrass in rice. The repeated exposure to cyhalofop‐butyl has led to resistance evolution in E. crus‐galli populations. RESULTS: In this study, we identified a population of E. crus‐galli (R‐HN) in a rice field in Hunan, China, that developed resistance to cyhalofop‐butyl at 4.49‐fold the recommended field dose. No known target mutation was detected in the ACCase gene of the R‐HN population by ACCase sequencing compared to sensitive populations. Both cytochrome P450 (CYP450) and glutathione S‐transferase (GST) inhibitors could not significantly reverse the resistance to cyhalofop‐butyl. The nontarget‐site resistance (NTSR) mechanism was investigated by transcriptome sequencing. Validation of the screened candidate genes by quantitative real‐time (qRT)‐PCR revealed that six glycosyltransferases (GTs) and four ATP‐binding cassette (ABC) transporter genes were consistently upregulated in the R‐HN population. Five GTs and one ABC transporter genes were constitutively upregulated after cyhalofop‐butyl treatment in the R‐HN population. Molecular docking results showed that the significant binding energy of GT79, GT75L6 and GT74E among all candidate genes. CONCLUSION: Thus, the GT genes appear to be directly implicated in NTSR to cyhalofop‐butyl in the R‐HN populations through metabolic enhancement, but their functional characterization needs to be studied. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Knowledge of herbicidal targets is critical for weed management and food safety. The phytotoxin isovaleric acid (ISA) is effective against weeds with a broad spectrum, carries low environmental risks, and is thus an excellent herbicide lead. However, the biochemical and molecular mechanisms underlying the action of ISA remain unclear. RESULTS: Multi‐omics data showed that acetyl coenzyme A (acetyl‐CoA) was the key affected metabolite, and that citrate synthase (CS) 4 was substantially down‐regulated under ISA treatment in Echinochloa crus‐galli leaves. In particular, the transcript level of EcCS4 was the most significantly regulated among the six genes involved in the top 10 different pathways. The EcCS4 encodes a protein of 472 amino acids and is localized to the cell membrane and mitochondria, similar to the CS4s of other plants. The protein content of EcCS4 was down‐regulated after ISA treatment at 0.5 h. ISA markedly inhibited the CS4 activity in vitro in a concentration‐dependent manner (IC50 = 41.35 μM). In addition, the transgenic rice plants overexpressing EcCS4 (IC50 = 111.8 mM for OECS4‐8 line) were more sensitive, whereas loss‐of‐function rice mutant lines (IC50 = 746.5 mM for oscs4‐19) were more resistant to ISA, compared to wild type (WT) plants (IC50 = 355.6 mM). CONCLUSION: CS4 was first reported as a negative regulator of plant responses to ISA. These results highlight that CS4 is a candidate target gene for the development of novel herbicides and for breeding herbicide‐resistant crops. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The present research is an attempt to manage Barnyard grass (Echinochloa crus-galli), a common rice weed, sustainably by vermicomposting technology. Echinochloa crus-galli (EC) biomass blended with cow dung in combination: 20:80, 40:60, 50:50, 60:40, and 80:20 with two controls 100% CD and 100% EC were vermicomposted for 63 days. Earthworms could not grow well in feedstocks having higher percentage of EC. Total Kjeldahl nitrogen, total available phosphorus and total potassium in final vermicomposts were in the range of 13.6–21.5 g kg−1, 11.8–15.9 g kg−1, and 20.1–27.6 g kg−1, respectively. Respiration rate (42–98 mgCO2 kg−1 VC 48 h−1) confirms vermicompost maturity and falls within the recommended limits (< 120 mgCO2 kg−1 VC 48 h−1). Vermicomposting process reduced the weed mass by 2.20–3.03 folds depicting its effective decomposition. It was inferred from the results that this weed can be converted into nutrient-rich manure employing vermicomposting and this process facilitating the management of E. crus-galli in a cost-effective and environmentally sustainable manner. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciências Agrárias is the property of Sociedade de Ciencias Agrarias de Portugal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many plant species in nature exert significant allelopathic potential as part of the defense mechanism system, many among their secondary metabolites (allelochemicals), including mineral constituents, which are responsible for the suppression of weeds and enhancing crop yield when directly incorporated into paddy fields. Cissus sicyoides is considered a high-potential allelopathic plant because of its invasion in nature and detected allelochemicals from the plant parts in some studies. The objective of this research was to exploit the allelopathic properties of C.sicyoides against paddy weeds and some indicator plants under laboratory bioassays and greenhouse conditions. The results demonstrated that C. sicyoides had significant inhibition on E. crusgalli, tested plants, and other paddy weeds. In the laboratory conditions, the extracts from C.sicyoides leaves inhibited the growth of Echinochloa crus-galli by 54.3%. The powders from C.sicyoides leaves inhibited the emergence of paddy weeds by approximately 100.0%. In the greenhouse conditions, the powders from C.sicyoides leaves by adding after 3 and 13 days inhibited the growth of E. crus-galli and the emergence of paddy weeds by 64.4%. Remarkably, negligible harmful effects on rice growth were observed. The findings of the study may provide useful information for the exploitation of this plant species to effectively control weeds in the rice fields for sustainable agriculture production. [ABSTRACT FROM AUTHOR]

Penoxsulam is an acetolactate synthase (ALS)-inhibiting herbicide usually applied by post-emergence foliar spraying (PFS) for the control of Echinochloa crus-galli and numerous annual weeds in paddy fields. Herbicides applied by foliar spraying can have negative impacts on the environment, ecosystems, and human health. In this study, the response of E. crus-galli and rice to the PFS and post-emergence water-dispersal (PWD) applications of penoxsulam, and the differences in the detoxification displayed by them between the two treatment methods were compared. The results showed that the PWD application of penoxsulam provides a similar control efficacy against E. crus-galli as PFS at the 1-, 3-, and 5-leaf stages. Meanwhile, the PWD application had a higher safety for the rice. After being treated with 30 g a.i. ha−1 penoxsulam, residues were not detected in the rice treated by the PWD application method, whereas, with the PFS treatment, there was 59.0 µg/kg penoxsulam remaining. With the PFS application, there were many more residues of penoxsulam in the E. crus-galli than with the PWD method; the amount of residues was 32-fold higher 12 h after treatment. The in vitro enzyme activity assays revealed that the activities of ALS, glutathione-S-transferase (GST), and cytochrome P450 monooxygenases (P450) were increased in the PWD treatments, and were 1.5-, 1.3-, and 2.3-fold higher than with PFS 72 h after treatment. The real-time quantitative PCR (qRT-PCR) revealed that the GST1 and P450 genes, CYP81A14, CYP81A12, CYP81A18, and CYP81A21 were upregulated with the PWD application versus PFS in the E. crus-galli. In summary, these results demonstrate that the herbicidal activity was not affected by the upregulation of target and metabolic enzyme activities with the PWD application of penoxsulam. This research could contribute to application strategies reducing the risk of rice injury and environmental impacts by using water-dispersal formulations of penoxsulam. [ABSTRACT FROM AUTHOR]

Copyright of Anadolu Tarım Bilimleri Dergisi is the property of Ondokuz Mayis Universitesi, Ziraat Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Allelopathy is a phenomenon by which plants positively or negatively affect neighboring plants by releasing allelopathic compounds. These allelochemicals are secondary metabolites found in different concentrations in shoots, roots, leaves, flowers, and even pollen grains. Allelochemicals have potential as natural bioherbicides for controlling weeds when applied in the form of extracts or through intercropping, cover cropping, and mulching. The present study was conducted to investigate the allelopathic potential of Ficus nitida leaves against Echinochloa crus-galli L. and Corchorus olitorius L weeds associated with sunflower plant via two application methods (mixing of F. nitida leaf powder with soil and foliar spray of F. nitida leaf powder alcoholic extract). Two pot experiments were carried out for the two summer seasons of 2020 and 2021 in the greenhouse of the National Research Centre (NRC), Dokki, Giza, Egypt. Nine treatments were applied in a completely randomized block design. Three treatments were applied before sowing, namely F. nitida leaf powder was mixed with the soil at rates of 15, 30, and 45 g/pot. The other three treatments of alcoholic leaf powder extract of F. nitida were sprayed twice on both plants and weeds at 10, 20, and 30% (w/v) concentrations. Additionally, three check treatments—healthy (sunflower only), unweeded, and both weeds only—were applied for comparison. The recorded results showed that F. nitida had an allelopathic bioherbicidal effect on both weeds. By increasing the concentration of F. nitida extract, the bioherbicidal potential increased. Moreover, the recorded results showed that foliar spray of alcoholic extract at 30% concentration was the superior application method for controlling weeds. Mixing of F. nitida leaf powder at 45 g/pot ranked second after this superior treatment. A noticeable result is that these two superior treatments improved sunflower growth parameters and yield traits. Quantitative estimation of phenolic compounds and flavonoids demonstrated that the concentration of these allelochemicals is higher in alcoholic extract than in water extract. Moreover, phenolic acid concentrations as detected by high-performance liquid chromatography fractionation are higher in alcoholic extract than in water extract. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Pesticide Science / Nongyaoxue Xuebao is the property of Chinese Journal of Pesticide Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Pesticide Science / Nongyaoxue Xuebao is the property of Chinese Journal of Pesticide Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Labdane-related diterpenoids, momilactones A and B were isolated and identified in rice husks in 1973 and later found in rice leaves, straws, roots, root exudate, other several Poaceae species and the moss species Calohypnum plumiforme. The functions of momilactones in rice are well documented. Momilactones in rice plants suppressed the growth of fungal pathogens, indicating the defense function against pathogen attacks. Rice plants also inhibited the growth of adjacent competitive plants through the root secretion of momilactones into their rhizosphere due to the potent growth-inhibitory activity of momilactones, indicating a function in allelopathy. Momilactone-deficient mutants of rice lost their tolerance to pathogens and allelopathic activity, which verifies the involvement of momilactones in both functions. Momilactones also showed pharmacological functions such as anti-leukemia and anti-diabetic activities. Momilactones are synthesized from geranylgeranyl diphosphate through cyclization steps, and the biosynthetic gene cluster is located on chromosome 4 of the rice genome. Pathogen attacks, biotic elicitors such as chitosan and cantharidin, and abiotic elicitors such as UV irradiation and CuCl2 elevated momilactone production through jasmonic acid-dependent and independent signaling pathways. Rice allelopathy was also elevated by jasmonic acid, UV irradiation and nutrient deficiency due to nutrient competition with neighboring plants with the increased production and secretion of momilactones. Rice allelopathic activity and the secretion of momilactones into the rice rhizosphere were also induced by either nearby Echinochloa crus-galli plants or their root exudates. Certain compounds from Echinochloa crus-galli may stimulate the production and secretion of momilactones. This article focuses on the functions, biosynthesis and induction of momilactones and their occurrence in plant species. [ABSTRACT FROM AUTHOR]

Barnyardgrass (Echinochloa crus‐galli (L.) Beauv.), an annual species of the family Poaceae, is a major weed problem in rice‐producing countries throughout the globe. Synthetic herbicides can effectively control this grass in rice paddies, but the development of resistant biotypes after the continuous use of the same active ingredients has led to low herbicide efficacy and yield losses. In this review, a summary of resistant‐barnyardgrass cases in global rice production is reported based on data from the International Herbicide‐Resistant Weed Database. The first case of resistant barnyardgrass in rice paddies was to the photosystem‐II inhibitor propanil in the late 1980s. Eighty‐five (85) out of 116 cases in the period from 1986 to 2022 refer to resistant barnyardgrass (E. crus‐galli var. crus‐galli, E. crus‐galli var. formosensis and E. crus‐galli var. zelayensis) in 16 countries. Barnyardgrass has been found resistant to acetolactate synthase (ALS) inhibitors (34 cases), acetyl‐CoA carboxylase (ACCase) inhibitors (23 cases), photosystem‐II inhibitors (11 cases), auxin mimics/cellulose biosynthesis inhibitors (9 cases), very long chain fatty acid inhibitors (6 cases), and microtubule assembly inhibitors (1 case). The majority of all resistance cases reported to the active ingredients penoxsulam, bispyribac‐sodium, and imazamox (ALS inhibitors), cyhalofop‐butyl and fenoxaprop‐ethyl (ACCase inhibitors), propanil (photosystem‐II inhibitors), and quinclorac (auxin mimics/cellulose biosynthesis inhibitors). Although target‐site resistance with specific mutations has been identified, non‐target site resistance mainly through herbicide detoxification is also of great concern increasing the chance of multiple herbicide resistance evolution. Rotation of herbicides should be adopted concerning the modes of action used as well as the application methods to mitigate resistance evolution of this weed in rice paddies. [ABSTRACT FROM AUTHOR]

Implementation of water‐saving irrigation practices in lowland rice results in increased availability of nitrate (NO3−) in the soil and favours germination of upland weeds. Since plant species show a specific preference for either ammonium (NH4+) or NO3− as nitrogen (N) source, changes in both soil NO3− concentration and weed flora may affect the competition between rice and weeds. Further, the transpirational demand of the atmosphere might affect growth and competitiveness of lowland (wetland) and upland (dryland) weeds differently due to their adaptation to different ecological environments. Therefore, the study aimed to evaluate the effects of N source on growth, N uptake and competition between rice and common upland and lowland weeds under high and low vapour pressure deficit (VPD). Two rice (Oryza sativa) varieties (NU838 and KD18) differing in growth characteristics and two weed species (Echinochloa crus‐galli and Solanum nigrum) differing in their natural habitat were selected and grown hydroponically as monoculture or mixed culture at low or high VPD. N was supplied as 75%/25% or 25%/75% NH4+/NO3−. N uptake rates were measured in the first week, whereas dry matter (DM), N concentration in the plant, total N uptake and the activities of nitrate reductase and glutamine synthetase in the fresh leaves were determined two weeks after the onset of treatments. Independent of N source, both rice varieties and E. crus‐galli took up a larger share of NH4+, whereas S. nigrum took up a larger share of NO3−. N uptake of rice and E. crus‐galli was hardly affected by N source, whereas high NO3− led to significantly higher N uptake rates and total N uptake of S. nigrum. NU838 showed a higher competitiveness against weeds than KD18. In competition, high NO3− decreased the competitiveness of E. crus‐galli against NU838 but increased the competitiveness of S. nigrum against NU838. High VPD did not affect DM but increased N uptake of S. nigrum, leading to increased competitiveness of the weed at high transpirational demand. Competitiveness for N uptake appears to be an important trait as the relative N concentration in mixed plant communities was correlated with the activity of N‐assimilating enzymes and leaf growth, with a stronger response in rice than in weeds. Our results support the hypothesis that increased availability of NO3− in aerobic rice soils may be advantageous for the competitiveness of upland weeds, especially at high VPD, whereas it may be disadvantageous for common lowland weeds. [ABSTRACT FROM AUTHOR]

Fungi colonizing the surface and endosphere of two widespread Poaceae weed species, Avena fatua and Echinochloa crus-galli, were isolated to compare the taxonomic composition between the plant species, location, and year of the seed collection. The seed-degrading potential of Fusarium isolated from the seeds was tested by inoculating seeds of E. crus-galli with spore suspension. Molecular identification of epiphytic and endophytic fungal genera was performed by sequencing the ITS region of rDNA. Endophytes comprised of significantly lower fungal richness compared to epiphytes. A significant taxonomic overlap was observed between the endosphere and seed surface. The most abundant genera were Alternaria, Fusarium, Cladosporium, and Sarocladium. Analysis of similarities and hierarchical clustering showed that microbial communities were more dissimilar between the two plant species than between the years. Fusarium isolates with a high potential to infect and degrade E. crus-galli seeds in laboratory conditions belong to F. sporotrichioides and F. culmorum. [ABSTRACT FROM AUTHOR]

Berberine (Ber) is easy to synthesize and has a variety of biological and pharmacological activities. At present, the existing studies on berberine have focused predominantly on its antibacterial activity; its herbicidal activity is rarely reported. In addition, there are a number of preparations of berberine, which are not enough to solve its shortcomings of low solubility and biological activity and the difficult storage of berberine. Here, berberine was combined with carbon dots to obtain carbon dots-berberine (CDs-Ber) nano formulation. The fluorescence quenching results showed that the CDs-Ber nano drug delivery system was successfully constructed, and the fluorescence quenching mechanism of the two was static quenching. The bioassay results showed that CDs had no adverse effects on the growth of barnyard grass (Echinochloa crus-galli) and redroot pigweed (Amaranthus retroflexus), and had high biocompatibility. Berberine and CDs-Ber predominantly affected the root growth of barnyard grass and redroot pigweed and could enhance the growth inhibition effect on weeds, to some extent. The results of the protective enzyme system showed that both berberine and CDs-Ber could increase the activities of Superoxide dismutase (SOD), Peroxidase (POD), and Catalase (CAT) in barnyard grass, and CDs-Ber had a stronger stress effect on barnyard grass than berberine. The determination of the number of bacterial communities in the soil after the berberine and CDs-Ber treatments showed that there was no significant difference in the effects of the two, indicating that CDs-Ber would not have more negative impacts on the environment. The CDs-Ber nano formulation improved the biological activity of berberine, enhanced the herbicidal effect, and was relatively safe for soil colonies. [ABSTRACT FROM AUTHOR]

The resistance of weeds to herbicides poses a major threat to agricultural production, and non-target-site resistance (NTSR) is often a serious problem as its mechanisms can in some cases confer resistance to herbicides with different modes of action. In this study, we hypothesized that bZIP transcription factors (TFs), which regulate abiotic stress responses in many plants, play a regulatory role in NTSR. Whole-plant assays indicated that the wild grasses Echinochloa crus-galli and E. glabrescens are resistant to the herbicides penoxsulam, cyhalofop-butyl, and quintrione. Transcriptome sequencing then identified 101 and 49 bZIP TFs with differential expression following penoxsulam treatment in E. crus-galli and E. glabrescens , respectively. Twelve of these genes had >60% homology with rice genes. The expression of bZIP88 was considerably up-regulated 6 h after treatment with the three different herbicides, and it was similar between resistant and susceptible populations; however, the relative expression levels before herbicide treatment and 24 h after were the same. We used rice (Oryza sativa ssp. japonica cv Nipponbare) as a model system for functional validation and found that CRISPR-Cas9-knockout of the rice bZIP88 ortholog increased the sensitivity to herbicide, whereas overexpression reduced it. The OsbZIP88 protein was localized to the nucleus. Using ChIP coupled with high-throughput sequencing, OsbZIP88 was found to form a network regulatory center with other TFs such as bZIP20/52/59 to regulate OsKS1 , OsCOE1 , and OsIM1 , which are related to auxin, abscisic acid, brassinosteroids, and gibberellic acid. Based on these results, we have established a database of bZIP TFs corresponding to herbicide stress, and resolved the mechanisms of the positive regulation of herbicide resistance by bZIP88, thereby providing new insights for NTSR. [ABSTRACT FROM AUTHOR]

BACKGROUND: Barnyardgrass (Echinochloa crus‐galli (L.) P. Beauv) has evolved resistance to the acetolactate synthase (ALS) inhibitor penoxsulam which is used to control weeds in rice fields in China. The present study is conducted to identify the target‐site resistance (TSR) mechanisms conferring resistance in a penoxsulam‐resistant population. RESULTS: The ALS sensitivity in vitro of the resistant population was sixfold lower to penoxsulam than that of the sensitive population. ALS sequencing revealed that no known mutation conferring ALS herbicide resistance was detected. However, a novel mutation Phe‐206‐Leu was identified in the ALS gene. Additionally, ALS gene expression level of the resistant population was lower than that of the sensitive population. Therefore, the penoxsulam resistance was not due to the overexpression of ALS gene. Molecular docking revealed that this mutation may change the interaction of the penoxsulam‐ALS binding and weaken its mutual affinity by approximately 10%. Arabidopsis thaliana transformed with mutant ALS had fourfold greater resistance to penoxsulam and varied cross‐resistance to other ALS herbicides than those transformed with sensitive ALS. Mutant and sensitive ALS proteins expressed by the baculovirus system exhibited different in vitro penoxsulam sensitivity levels. Mutant ALS had eightfold lower sensitivity to penoxsulam than sensitive ALS. CONCLUSION: This report provides clear evidence that the ALS mutation at position 206 (Phe‐206‐Leu) confers penoxsulam resistance in barnyardgrass. Phe‐206 was confirmed to be the ninth amino acid residue related to ALS herbicide resistance in weeds. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Rice, one of the most consumed cereal crops worldwide, is commonly grown under flooded conditions, which directly influences the nematode community. Meloidogyne graminicola is the predominant species in rice fields, causing significant damage and requiring integrated management practices. This study aimed to investigate the response of different Poaceae crops, soybean, and common weeds of rice to three biotypes of M. graminicola (G1, G2 and G3) recently detected in Brazil. The highest reproduction factor (RF) for the three nematode populations was detected in the weeds Echinochloa colonum and E. crus-galli , followed by rice and Italian ryegrass. Wheat 'TBio Sonic' and millet 'ADR 500' served as poor hosts to the nematodes, whereas black oat, white oat, signalgrass, millet 'ADR 905', maize, wheat 'TBio Toruk', and soybean acted as non-hosts (RF < 1) in both experiments. Of the three M. graminicola biotypes, G1 was the most aggressive, followed by G3 and G2 (lowest RF values). The findings of the current study can support the selection of crop rotation or succession approaches for the management of different biotypes of M. graminicola in irrigated rice fields. [ABSTRACT FROM AUTHOR]

Copyright of Agricultural Research in the Tropics / Pesquisa Agropecuária Tropical is the property of Pesquisa Agropecuaria Tropical and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant parasitic nematodes and weeds are among the many biotic stresses that crops production suffers from during their growing season. Their management relies mainly on chemical pesticides. To decrease the extent of environment degradation and hazards to human health and livestock due to the prolonged use of these chemicals, biological control using soil microorganisms is considered as a new ecofriendly and efficient control method. The main objective of this work was to improve the inhibition of two local bacterial strains, Pseudomonas aeruginosa and Bacillus cereus, against root knot nematode and weed seeds germination. To achieve this goal, protoplast fusion experiments were performed to gather all their properties in bacterial fusants and increase production of such toxic compounds. The results showed that P. aeruginosa was Rifampicin (Rif) resistance, but B. cereus was sensitive. In contrast to this B. cereus was Neomycin (Nm) resistance but P. aeruginosa was sensitive. A total of 40 fusants derived from the protoplast fusion experiments were selected by antibiotic resistance markers. SDS-PAGE analysis of the proteins confirmed that six recombinants acquired and expressed many specific protein bands from their parental strains. Three fusants, No. F7, F20 and F35, were selected and evaluated for their nematicidal potential in comparison with their parent against root knot nematode Meloidogyne incognita J2 and Echinochloa crus-galli and Portulaca oleracea seeds germination during in vitro experiments. Data showed that the fusants exhibited more antagonistic effects than their parents. After 72hrs of exposure, the three fusants caused 80.6, 96.5 and 97.7% mortality as compared to control, while the % mortality after the same duration by P. aeruginosa, B. cereus singly and combined resulted in 52.2, 65.9 and 48.8%, respectively as compared to control. Furthermore, the three fusants completely inhibited the germination of P. oleracea seeds and resulted in small radicals in E. crus-galli seeds as compared to control. These fusants show great potential to be selected as possible potential biopesticide. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tomato is one of the widely cultivated crops worldwide that is affected by several pests, such as fungi (Fusarium oxysoporum, Alternaria solani), bacteria (Pectobacterium carotovorum) and weeds (Cyperus iria L., Amaranthus spinosus). A growing interest has emerged for developing plant‐derived pesticidal compounds to counteract these pests. One attractive alternative is to use barnyard grass (Echinochloa crus‐galli), known to be widely resistant to synthetic herbicides, as a potential biopesticide compound source. RESULTS: Phytochemical screening of the crude extract showed that phenolic compounds were the most abundant component present in barnyard grass. The crude extract was evaluated for antifungal, antibacterial and herbicidal activities. Bioassays showed inhibition against F. oxysporum (10.73 ± 1.30%) and A. solani (20.47 ± 3.51%), the causative agent of Fusarium rot and early blight disease in tomato, respectively. Antibacterial activity against P. carotovorum gave a mean zone of inhibition (paper disc diffusion assay) of 17.00 ± 1.00 mm and an IC50 (dose–response assay) of 2.26 mg mL−1 was observed. Dose–responsive herbicidal activity on the lettuce seed germination bioassay produced an IC50 of 459.30 ppm. Selectivity studies showed inhibition towards C. iria and A. spinosus with no effect on tomato. Lastly, bioassay‐guided fractionation coupled with untargeted metabolomics studies using ultra‐performance liquid chromatography with diode array detection–tandem mass spectrometry mass analyses revealed loliolide and tricin as the putative metabolites present in barnyard grass. CONCLUSION: To date, this is the first reported study on using barnyard grass as a potential alternative biopesticide against tomato pests such as fungi, bacteria and weeds. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A novel protease was purified from Echinochloa crus-galli utilizing precipitation by ammonium sulfate, DEAESephadex ion exchange and Sephacryl S-200 gel filtration. The purified enzyme at final steps of purification has 340 U/ mg of the specific activity acts on casein as substrate and 6.76 purification fold. Studied protease classified as alkaline, active at high temperature, serine protease when subjected to different values of pH, temperatures and inhibitors respectively. Ability of alkaline protease to reduces of silver nitrate to form nanoparticles was observed through color changing, absorbance, scanning electron microscope and energy dispersive-x-ray spectroscopy. Our research is the first work characterizing the synthesis of silver nanoparticles by alkaline protease purified from Echinochloa crus-galli. [ABSTRACT FROM AUTHOR]

In the struggle to secure nutrient access and to outperform competitors, some plant species have evolved a biochemical arsenal with which they inhibit the growth or development of neighbouring plants. This process, known as allelopathy, exists in many of today's major crops, including rice. Rice synthesizes momilactones, diterpenoids that are released into the rhizosphere and inhibit the growth of numerous plant species. While the allelopathic potential of rice was recognized decades ago, many questions remain unresolved regarding the biosynthesis, exudation, and biological activity of momilactones. Here, we review current knowledge on momilactones, their role in allelopathy, and their potential to serve as a basis for sustainable weed management. We emphasize the gaps in our current understanding of when and how momilactones are produced and of how they act in plant cells, and outline what we consider the next steps in momilactone and rice allelopathy research. [ABSTRACT FROM AUTHOR]

BACKGROUND: Clausena lansium (Lour.) Skeels, belonging to the genus Clausena of the family Rutaceae, has a wide range of medical and agricultural activities. Previous studies on agricultural activities have shown that C. lansium extracts and some components have obvious herbicidal activities. In order to study systematically herbicidal activity of this plant, we studied the herbicidal effect of ethyl acetate (EtOAc) extract from the stems and leaves of this plant and further isolated the active compounds. RESULTS: The EtOAc extract inhibited the growth of roots and shoots of Echinochloa crus‐galli (L.) Beauv., and the inhibitory effect of the EtOAc extract on roots were stronger than those on shoots with half maximal inhibitory concentration (IC50) values of 420.45 and 585.05 mg L−1, respectively. Fifteen compounds were subsequently isolated and identified from the stems and leaves of C. lansium, including nine O‐monoterpenoid furanocoumarins and six cinnamamides. Our results showed that most compounds exhibited varying degrees of herbicidal activities to E. crus‐galli. Among them, compounds 3, 8, and 13–15 showed the best inhibitory activities on the growth of E. crus‐galli roots, with inhibition rate values ranging from 70% to 83% at a concentration of 300 mg L−1. Compounds 1 and 2 are two new compounds, and their structures were established as 5‐O‐monoterpenoid furanocoumarin and 8‐O‐monoterpenoid furanocoumarin, and named as claulansicoumarin‐A and ‐B, respectively. CONCLUSION: The EtOAc extract and pure compounds showed noticeable herbicidal activities against E. crus‐galli and indicated a great potential for these natural compounds to be developed as a herbicide. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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Echinochloa crus- galli (Barnyard grass) is a world’s most harmful weed species. Echinochloa crus-galli weed species compete with many economically important crops and causes serious problem in rice production. The virulent strain LD2 (leaf disease) of Curvularia lunata was screened out from 25 fungus strains isolated from the diseased leaves of barnyard grass (Echinochloa crus-galli). Greenhouse pot studies were conducted to the feasibility of the strain being as a mycoherbicide for barnyard grass control. The results of pathogenicity experiments showed that this strain was highly pathogenic to barnyard grass at the 2 to 3 leaf stages. Strain LD2 provided excellent barnyard grass control when it was applied at the concentration of 1×104, 1×106 conidia ml1. This strain was very safe to rice and the most plant species except wheat, barley and corn. Findings of this study indicated that this strain could be a potential mycoherbicide for barnyard grass control in paddy fields in the future. [ABSTRACT FROM AUTHOR]

Echinochloa crus- galli (Barnyard grass) is a world’s most harmful weed species. Echinochloa crus-galli weed species compete with many economically important crops and causes serious problem in rice production. The virulent strain LD2 (leaf disease) of Curvularia lunata was screened out from 25 fungus strains isolated from the diseased leaves of barnyard grass (Echinochloa crus-galli). Greenhouse pot studies were conducted to the feasibility of the strain being as a mycoherbicide for barnyard grass control. The results of pathogenicity experiments showed that this strain was highly pathogenic to barnyard grass at the 2 to 3 leaf stages. Strain LD2 provided excellent barnyard grass control when it was applied at the concentration of 1×104, 1×106 conidia ml1. This strain was very safe to rice and the most plant species except wheat, barley and corn. Findings of this study indicated that this strain could be a potential mycoherbicide for barnyard grass control in paddy fields in the future. [ABSTRACT FROM AUTHOR]

The phytotoxic effects of two allelochemicals (trans-cinnamic acid and syringaldehyde) at different concentrations (1000, 100, 10, and 1 µM) on seed germination, seedling growth, and physiological and biochemical changes of Echinochloa crus-galli L. were tested by comparison to a commercial herbicide 'Nominee' (that is, 100 g/L bispyribac-sodium). trans-Cinnamic acid and the herbicide inhibited seed germination completely at 100 µM, whereas for syringaldehyde, complete inhibition required 1000 µM. However, with 100 µM syringaldehyde, the seed germination of the test species was 53% of the control. Allelochemicals and the herbicide delayed seed germination and significantly affected the speed of germination index (S), speed of cumulative germination index (AS), and coefficient of germination rate (CRG). The roots were more affected when nutrients were not added to the growth bioassay. In general, with the increasing concentration of allelochemicals from 100 to 1000 µM, the inhibitory effects increased. Via microscopy analysis, we found leaf blade wilting and necrosis at concentrations above 100 µM in allelochemical-treated plants. Roots of E. crus-galli treated with 1000 µM allelochemicals had black points on root nodes but had no root hairs. The anatomy of roots treated with allelochemicals (1000 µM) showed contraction or reduction of root pith cells as well as fewer and larger vacuoles compared to the control. The allelochemicals also showed remarkable effects on seedling growth, SPAD index, chlorophyll content, and free proline content in a pot culture bioassay, indicating that trans-cinnamic acid and syringaldehyde are potent inhibitors of E. crus-galli growth and can be developed as herbicides for future weed management strategies. [ABSTRACT FROM AUTHOR]

Poor crop establishment, high weed infestation, and consequent yield loss are major concerns for dry-seeded rice (DSR). Flooding after seeding helps in managing weeds but reduces seed germination and crop stand. Anaerobic germination (AG)-tolerant rice genotypes could overcome these problems in DSR. Screenhouse experiments were established to evaluate the effect of seed sowing depth (SD) (0.5 cm, 1 cm, and 2 cm) and flooding depth (FD) (saturated, 2 cm, and 5 cm) on crop establishment, early growth, and weed competitiveness in DSR using AG-tolerant genotypes (Khao Hlan On, Ma-Zhan Red, IR64+AG1, and IR64). Echinochloa crus-galli , Ludwigia hyssopifolia , and Cyperus difformis were used in the weedy treatment. Rice plants reached maximum emergence 9–13 days later under flooding compared with saturated conditions. Crop emergence decreased by 12–22% at 0.5 and 1 cm SD and by 48–60% at 2 cm SD, when combined with 2 or 5 cm FD compared with saturated conditions. The 2 cm SD reduced seedling emergence by 23–42% in Khao Hlan On and Ma-Zhan Red, by 62–70% in IR64+AG1, and by 90–92% in IR64 under flooding. Initial growth in rice plant height was slow under flooding but increased progressively after the seedlings emerged from water and the final height was not affected by FD. Leaf area, total shoot biomass, tiller density, and leaf number per pot of rice were higher at 1 cm SD (P < 0.05), but decreased drastically at 2 cm SD under flooding. The emergence of E. crus-galli and L. hyssopifolia decreased by 53–65% and 89–95%, respectively, but increased by 49–68% in C. difformis under 2 and 5 cm FD, respectively, compared with saturated conditions. The shoot biomass of the weeds followed the same trend. Khao Hlan On showed the highest weed-competitive ability under all FD while the biomass of IR64+AG1 and IR64 decreased by 10–14% due to weed competition under 2 cm FD. The 1 cm SD showed better growth for all genotypes under different FD. The 2 cm FD is sufficient to have a significant control of problematic weed species. The tolerance of AG of rice genotypes should be further enhanced to increase their weed-competitive ability. [ABSTRACT FROM AUTHOR]

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Abstract: Questions: Does the mere introduction of maize into the crop sequence change the weed species community? Does a growing share of maize cropping lead to a more problematic weed species community? Do we generally have to expect problematic weed species communities when maize is continuously cultivated? Location: Northern Germany. Methods: Weeds in 224 maize fields were surveyed in 3 years and management data of these fields collected for the previous ten cropping years. We arranged seven parameters describing maize cropping patterns and used them as constraining variables in redundancy analysis. Results: The weed species community was immediately altered by the introduction of maize into the crop sequence. Of those weed species known to be adapted to maize, in our study Echinochloa crus‐galli and to a lesser extent Setaria spp. were strongly related to dense maize cropping patterns, other summer annuals were much less affected. Conclusions: The spatial growth of areas dedicated to maize cropping will change the weed species communities and, in turn, the arable landscape. E. crus‐galli deserves particular attention due to its tendency to develop herbicide resistance and its positive reaction to dense maize cropping patterns. [ABSTRACT FROM AUTHOR]

The differentiation of roots of agricultural species is desired for a deeper understanding of the belowground root interaction which helps to understand the complex interaction in intercropping and crop-weed systems. The roots can be reliably differentiated via Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). In two replicated greenhouse experiments, six pea cultivars, five oat cultivars as well as seven maize cultivars and five barnyard grass proveniences (n = 10 plants/cultivar or provenience) were grown under controlled conditions. One root of each plant was harvested and five different root segments of each root were separated, dried and measured with FTIR-ATR spectroscopy. The results showed that, firstly, the root spectra of single pea and single oat cultivars as well as single maize and single barnyard grass cultivars/proveniences separated species-specific in cluster analyses. In the majority of cases the species separation was correct, but in a few cases, the spectra of the root tips had to be omitted to ensure the precise separation between the species. Therefore, species differentiation is possible regardless of the cultivar or provenience. Consequently, all tested cultivars of pea and oat spectra were analyzed together and separated within a cluster analysis according to their affiliated species. The same result was found in a cluster analysis with maize and barnyard grass spectra. Secondly, a cluster analysis with all species (pea, oat, maize and barnyard grass) was performed. The species split up species-specific and formed a dicotyledonous pea cluster and a monocotyledonous cluster subdivided in oat, maize and barnyard grass subclusters. Thirdly, cultivar or provenience differentiations within one species were possible in one of the two replicated experiments. But these separations were less resilient. [ABSTRACT FROM AUTHOR]

Barnyardgrass (Echinochloa crus-galli) is one of most important weeds in rice field in Vietnam. Seventy-eight barnyardgrass seed samples were collected from rice fields in seven provinces in Mekong Delta of Vietnam. The seedlings grown from collected seed samples were evaluated to determine the level of resistance to bispyribac, penoxsulam and quinclorac. Farmers who managed the fields from which samples collected were interviewed about weed management practices and the cost of weed control per season. The average cost for weed management was 1,980,000 VND per hectare, the total cost included 650,000 VND for herbicide and 1,330,000 VND for hand-weeding. Echinochloa crus-galli biotypes resistant to bispyribac, penoxsulam and quinclorac were found and biotypes with resistance to multiple herbicides were detected. The average resistancescore of three tested herbicides was 3.4 in the 78 samples collected. There was a correlation between field size, hand-weeding practice, and the herbicide-resistance level, herbicideresistant weeds were less common in smaller fields where hand-weeding was commonly used. The high cost and limited labour pool for hand-weeding in this region of Vietnam limits the long-term viability of this approach. [ABSTRACT FROM AUTHOR]

The genus Echinochloa (Poaceae) includes numerous problematic weeds over a wide range of ecoregions in the world. To date, molecular markers for species identification and assessing phylogenetic relationship are still limited in the genus Echinochloa. In this study, we developed seven chloroplast molecular markers based on divergent chloroplast regions of E. crus-galli and E. oryzicola. Furthermore, Marker #1 ( psbA) was examined in more than 200 Echinochloa accessions and a phylogenetic tree grouped these Echinochloa accessions into four clades. Additionally, two different E. crus-galli varieties ( E. crus-galli var. crus-galli, E. crus-galli var. praticola) and E. colona were successfully distinguished by this marker. The developed molecular markers contribute to better identification of Echinochloa taxa. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two major weeds in rice in the Philippines, Sphenochlea zeylanica Gaertn. and Echinochloa crus-galli (L.) Beauv., are controlled with chemical and cultural methods. In the 1980s, after >10 years of continuous use of 2,4-D, S. zeylanica evolved resistance to the chemical in those rice fields that had been treated with 2,4-D once or twice every cropping season. In the 1990s, E. crus-galli evolved resistance to butachlor and propanil in rice monocrop areas where both herbicides were used continuously for 7-9 years. Rice farmers continue to use 2,4-D, butachlor and propanil extensively and are often unaware of herbicide resistance or the potential for cross-resistance, its causes or its implications. In order to control herbicide-resistant E. crus-galli, farmers are shifting to locally available herbicides with different modes of action, such as bispyribac, an acetolactate synthase inhibitor, and cyhalofop, an acetyl coenzyme A carboxylase inhibitor. Follow-up manual weeding or rotary weeding after herbicide spraying, a common farmers' practice, removes the susceptible and resistant biotypes and could help to delay or prevent the evolution of resistance. Although the resistance mechanisms of both weeds are not determined yet, they could be related to enhanced degradation that is similar to the mechanisms that are shown by the resistant biotypes in other countries. [ABSTRACT FROM AUTHOR]

Echinochloa crus-galli is a serious weed worldwide. Microsatellite markers (simple sequence repeats, SSRs) are important molecular markers that are used widely for studying genetic diversity in plants. However, a limited number of SSRs is available for E. crus-galli. The restriction site-associated DNA ( RAD) sequencing approach was combined with Illumina DNA sequencing for the rapid and mass detection of SSRs in E. crus-galli. The RAD tags were generated from the genomic DNA of E. crus-galli and were sequenced in order to produce 6921.6 Mb of high-quality sequences with 45.1% guanine-cytosine content. In total, 3081 putative SSRs were detected, of which 82.2% were dinucleotide motif-repeats. AT was the most frequent motif, accounting for 35.0% of the SSRs. In order to test the validity of the SSRs that were developed here, eight SSRs that were selected from putative SSRs were used to study the genetic diversity and structures of 20 E. crus-galli populations that had been collected from rice fields in eastern China. Ninety-seven alleles were amplified from the eight microsatellite loci among the 20 E. crus-galli populations. These populations showed low genetic diversity and were classified on the basis of their genetic structures into three distinct groups that corresponded to the three regions of population sampling. The SSRs that were identified in this study represent a valuable resource for studying the genetic diversity, population biology and evolution of E. crus-galli. [ABSTRACT FROM AUTHOR]

A series of experiments was conducted in the laboratory and greenhouse of the Subtropical Field Science Center, University of the Ryukyus, Japan, from April to October 2015 to assess the allelopathic potential of 50 indigenous Bangladeshi rice varieties by using the donor-receiver bioassay, equal compartment agar method ( ECAM), plant residue extract method and pot culture method. Lettuce ( Lactuca sativa L.), cress ( Lepidium sativum L.), radish ( Raphanus sativus L.), barnyard grass ( Echinochloa crus-galli L. Beauv.) and jungle rice ( Echinochloa colona L.) were used as the test plants. The highest inhibition effect was given by Boterswar, while the stimulating effect was given by Kartikbalam and Panbira in the donor-receiver bioassay and ECAM tests. Boterswar, Goria, Biron and Kartiksail were selected as the highest allelopathic-potential varieties by the donor-receiver bioassay and ECAM. In the methanol extract test, Boterswar gave the strongest inhibitory effect on both barnyard grass and jungle rice, while Kartiksail gave the highest inhibitory effect on the jungle rice shoot. The growth parameters and total dry matter of barnyard grass in the greenhouse pot experiment were significantly reduced as a result of the application of aqueous extracts of the selected rice varieties, which was similar to the results of the laboratory experiments. The varieties of Boterswar, Goria, Biron and Kartiksail were selected as the most allelopathic among the 50 indigenous Bangladeshi rice varieties. These rice varieties could be used for the isolation and identification of allelochemicals and to further develop new varieties that are tolerant to weeds. [ABSTRACT FROM AUTHOR]

Invasive weeds pose serious threat to aquatic ecosystems such as wet land paddy rice. An investigation was made to compare the allelopathic effects of aqueous extracts and residues of two invasive weeds viz., Alternanthera philoxeroides and A. sessilis with those of three native weeds viz., Conyza stricta, Polygonum barbatum and Echinochloa crus-galli of rice (Oryza sativa L.) in Pakistan. All weeds under study showed phytotoxic effects on germination and seedling growth of rice through their aqueous extracts as well as residues to variable degree compared with control treatment. However, significantly lower germination percentages (10 and 35%), germination/emergence index (0.5 and 0.4), shoot lengths (2 and 7 cm), root lengths (1.5 and 1.9 cm), seedling biomass (5 and 6 mg), seedling vigor indices (25 and 100) and higher mean germination/emergence times (6.8 and 8 days) were observed in case of 5% aqueous extract of A. sessilis and 4% residue of A. philoxeroides, respectively. Overall, phyto-inhibitory effects of water extracts were more severe than residues. The highest suppressive action of A. philoxeroides and A. sessilis seem not only due to their higher total phenolic contents (116 and 106 mg L-1) but complex interaction of potent phenolic compounds namely 4-hydroxy-3-methoxybenzoic acid, chlorogenic acid, ferulic acid, gallic acid, mcoumaric acid, p-coumaric acid and vanillic acid as shown by their HPLC analysis. It can be concluded that these two invasive weed species are bigger threat to local wet land rice ecosystems and may result in greater yield losses of rice crop in the country. [ABSTRACT FROM AUTHOR]

Echinochloa crus-galli and Echinochloa muricata are common weeds in Belgian maize fields. Both species are morphologically difficult to distinguish and exhibit high morphological variability. Their response to herbicides varies from field to field. This study investigated whether the considerable morphological polymorphism found among Belgian Echinochloa accessions has a genetic background and whether it is consistently associated with differences in sensitivity to maize herbicides. For this purpose, accessions of E. crus-galli and E. muricata were compared for morphological and genetic resemblance and tested for herbicide sensitivity. All accessions were planted in the field to examine the morphological traits. A cluster analysis was conducted to assess them for morphological diversity. DNA of leaf material was used for amplified fragment length polymorphism analysis to cluster the accessions genetically. Dose-response pot experiments were conducted in the glasshouse to assess the effectiveness of an acetolactate synthase (nicosulfuron), acetyl-CoA carboxylase (cycloxydim) and 4-hydroxyphenyl phosphate dioxygenase (topramezone) inhibiting herbicide. The genetic and morphological clusters were compared with the effective doses obtained from the dose-response bioassays. Morphological variation significantly correlated with genetic variation, but the relation with herbicide sensitivity was weak. Spikelet size and biomass characteristics are reliable discriminating characteristics for (sub)species classification. Intraspecies identification does not seem essential for optimisation of chemical control of E. crus-galli and E. muricata in the field. [ABSTRACT FROM AUTHOR]

Barnyardgrass ( Echinochloa crus-galli) proliferation seriously threatens rice production worldwide. Whole-plant bioassays were conducted in order to test the sensitivity to penoxsulam of 52 barnyardgrass populations and the resistance of six penoxsulam-resistant populations to 12 other herbicides that are commonly used in rice fields. Among the 48 populations that had escaped penoxsulam control in the rice fields, 8.3% showed a very high level of resistance, 58.3% showed a high level of resistance and 10.4% showed a moderate level of resistance. Multiple resistance was confirmed in all six penoxsulam-resistant populations that were tested further. They exhibited at least a moderate level of resistance; that is, to 6-10 of the total of 13 herbicides that was tested. Most of the six penoxsulam-resistant populations showed at least a moderate level of resistance to bispyribac-sodium, quinclorac, metamifop, cyhalofop-butyl and oxadiazon, three populations held at least a moderate level of resistance to oxyfluorfen and pretilachlor, two populations also held at least a moderate level of resistance to pyrazosulfuron-ethyl, pyribenzoxim and fenoxaprop-P-ethyl, but the resistance indices of the six populations to pendimethalin were all low. This study has confirmed resistance to pretilachlor and oxadiazon in weeds for the first time. [ABSTRACT FROM AUTHOR]

Copyright of Julius-Kühn-Archiv is the property of Julius Kuehn Institut and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genus Echinochloa (Poaceae) includes orphan crops and important agricultural weeds. Here, we assembled the complete chloroplast genome of a diploid Echinochloa species (E. haploclada). The chloroplast genome is 139,844 bp in length, which includes a large single copy region (81,893 bp), a small single copy region (12,533 bp) and two separated inverted repeat regions (45,418 bp). A total of 119 unique genes were annotated, consisting of 83 protein-coding genes, 32 tRNA genes and 4 rRNA genes. Hexaploid E. crus-galli, one of the most serious weeds worldwide, was derived from a hybrid between tetraploid E. oryzicola and an unknown diploid species. Based on chloroplast genomes of eight Echinochloa species (varieties), the phylogenetic analysis showed that E. crus-galli clustered firstly with diploid E. haploclada rather than tetraploid E. oryzicola, supporting previous assumption that E. oryzicola is the paternal donor of E. crus-galli. [ABSTRACT FROM AUTHOR]

Deficiencies of metal micronutrients are common in some calcareous soils. Samples of aerial parts of maize and five common weeds and also soil beneath these plants were collected and analyzed to investigate the status and relationships of metal micronutrients in soil, crop, and common weeds of maize field trials at two sites. Results showed that Fe concentration in five studied weeds was higher than that of maize; the highest Fe concentration was found inConvolvolus arvensisandEchinochloa crus-galli(first site) and inConvolvolus arvensistissues (second site). At both sites, the highest Mn concentration was observed in aboveground parts ofEchinochloa crus-galli. The concentration of Mn (both sites) and Fe and Cu (second site) were remarkably higher inEchinochloa crus-gallitissues in comparison with maize. Also the concentrations of Fe (both sites) and Cu (second site) were considerably higher inConvolvolus arvensistissues in comparison with maize. Available Fe was the highest in the soil beneathConvolvolus arvensisandPortulaca oleracea(first site) and beneathConvolvolus arvensisandCenopodium album(second site). The high value of available Fe in the soil beneathConvolvolus arvensismay explain why Fe concentration was the highest in aerial parts of this weed species. [ABSTRACT FROM AUTHOR]

Coumarin is a natural compound well known for its phytotoxic potential. In the search for new herbicidal compounds to manage weeds, three synthetic derivatives bearing the coumarin scaffold (1-3), synthesized by a carbonylative organometallic approach, were in vitro assayed on germination and root growth of two noxious weeds, Amaranthus retroflexus and Echinochloa crus-galli. Moreover, the synthetic coumarins 1-3 were also in vitro assayed on seedlings growth of the model species Arabidopsis thaliana to identify the possible physiological targets. All molecules strongly affected seed germination and root growth of both weeds. Interestingly, the effects of synthetic coumarins on weed germination were higher than template natural coumarin, pointing out ED50 values ranging from 50-115 μM. Moreover, all synthetic coumarins showed a strong phytotoxic potential on both Arabidopsis shoot and root growth, causing a strong reduction in shoot fresh weight (ED50 values ≤ 60 μM), accompanied by leaf development and a decrease in pigment content. Furthermore, they caused a strong alteration in root growth (ED50 values ≤ 170 μM) and morphology with evident alterations in root tip anatomy. Taken together, our results highlight the promising potential herbicidal activity of these compounds. [ABSTRACT FROM AUTHOR]

Screening crop accessions for allelopathic activity is of paramount importance for crop allelopathy research. Previous bioassays often did not use a mixed culture of donor and target plants, did not use soil and were not conducted under natural conditions. In this study, we designed an inhibitory-circle method in which a rice accession (donor plant) and Echinochloa crus-galli (target plant) were cultured together in paddy soil under natural conditions. First, we determined that the highest allelopathic activity of allelopathic rice accession PI312777 was at the 5-leaf stage, and the suitable distance of rice seedlings and E. crus-galli was 12 cm apart. This method was then validated by a field test. A further 40 rice accessions were evaluated for allelopathic activity to E. crus-galli using this method. Two rice accessions, PI312777 and Taichung Native 1, had highly allelopathic activity to E. crus-galli (inhibitory rate > 50%), while another accession, Lemont, had non-allelopathic activity. These experimental results were in accordance with previous studies using direct field experiments. The inhibitory-circle method integrated three necessary conditions, that is donor and target plants grown together, with soil as the medium and under natural conditions for reliable results. The 'inhibitory-circle method', which combined donor and target plants, soil medium and field conditions, can give reliable results in one step, compared with laboratory screening methods. Also, the 'inhibitory-circle method' gave results in 30-35 days, thereby substantially reducing the requirements for time, labour and cost. [ABSTRACT FROM AUTHOR]