Echinochloa Crus-galli Research Articles

Crop Safety and Weed Control of Foliar Application of Penoxsulam in Foxtail Millet.

Grass damage has become an important factor restricting foxtail millet production; chemical weeding can help resolve this issue. However, special herbicides in foxtail millet fields are lacking. Penoxsulam has a broad weed control spectrum and a good control effect. In this project, Jingu 21 was used as the test material, and five different concentrations of penoxsulam were used for spraying test in the three-five leaf stage. In this experiment, the effects on the growth of foxtail millet were discussed by measuring the agronomic characters and antioxidant capacity of foxtail millet after spraying penoxsulam. The results showed that: (1) penoxsulam is particularly effective in controlling Amaranthus retroflexus L. (A. retroflexus) and Echinochloa crus-galli (L.) Beauv. (E. crus-galli), but is ineffective in controlling Chenopodium album L. (C. album) and Digitaria sanguinalis (L.) Scop. (D. sanguinalis); (2) the stem diameter, fresh weight, and dry weight of the above-ground parts decreased with the increase in spraying amount; (3) as the spraying dosage increased, the superoxide (SOD), peroxidase (POD), and catalase (CAT) activities in the foxtail millet initially increased and subsequently decreased; the malonaldehyde (MDA) content increased. Our experiment found that 1/2X and 1X spraying dosages had certain application value in controlling gramineous weeds in foxtail millet field. Other spraying dosages are not recommended as they may harm the crops. Our findings provide reference for identifying new herbicides in the foxtail millet field.

The Allelopathy of the Invasive Plant Species Ludwigia decurrens against Rice and Paddy Weeds

Ludwigia decurrens Walter, belonging to the Onagraceae family, is native to southeastern and southcentral USA and has spread quickly, colonizing wetlands in South and Central America, East and South Asia and Africa. Ludwigia decurrens also infests rice paddy fields and causes serious damage to rice production. The phenomenon of allelopathy is often observed in invasive plant species and contributes to their invasive characteristics. However, no information has been made available on the allelopathy of L. decurrens against wetland species, including Oryza sativa (rice), or on its allelochemicals. Aqueous methanol extracts of whole L. decurrens plants showed allelopathic activity against O. sativa and paddy weeds, Echinochloa crus-galli and Monochoria vaginalis in an extract-concentration-dependent manner. Two allelochemicals, loliolide and dehydrololiolide, were isolated from the L. decurrens extracts through a bioassay-guided separation process using O. sativa as the test plant species. Loliolide and dehydrololiolide also suppressed the growth of O. sativa and E. crus-galli in a concentration-dependent manner. Thus, loliolide and dehydrololiolide may be involved in the allelopathy of L. decurrens and may provide a competitive advantage for L. decurrens due to their growth inhibitory activity. However, the inhibitory activity of loliolide was about 3-fold greater than that of dehydrololiolide. These investigations suggest the allelopathy of L. decurrens may play an important role in the invasion of the species into rice paddy fields and other wetlands. This is the first report on the allelopathy of L. decurrens against wetland species and the isolation and identification of the allelochemicals in L. decurrens.

Volatolomics to Decrypt the Monophagous Nature of a Rice Pest, Scirpophaga Incertulas (Walker).

Scirpophaga incertulas Walker (Lepidoptera: Crambidae, yellow stem borer, YSB) is a monophagous insect pest that causes significant yield loss in rice (Oryza staiva L.). Semiochemical based pest management is being sought as an alternate to chemical pesticides to reduce pesticide footprints. We hypothesized differential release of volatiles from host rice and two companion non-host weeds, Echinochloa colona and Echinochloa crus-galli could be responsible for oviposition and biology of YSB and these chemicals could be used for YSB management. Number of eggs laid, and number of larvae hatched were significantly higher in rice plant as compared to weeds. YSB could only form dead hearts in rice plants. YSB significantly preferred host-plant volatiles compared to the non-host plants both in choice and no-choice tests in an Y-tube olfactometer. 2-Hexenal, hexanal, 2,4-hexadienal, benzaldehyde, nonanal, methyl salicylate and decanal were found in the leaf volatolomes of both the host and non-host plants in HS-SPME-GC-MS (Headspace-Solid phase micro extraction-Gas chromatography-Mass spectrometer). Pentene-3-one, 2-pentyl furan, 2,4-heptadienal, 2-octenal, 2-octenol and menthol were present only in the non-host plants. Fourteen rice unique compounds were also detected. The built-in PCA (Principal Component Analysis) and PLS-DA (Partial least squares-discriminant analysis) analysis in the MS-DIAL tool showed that the volatiles emitted from TN1 formed a cluster distinct from Echinochloa spp. and 2-octenal was identified as a unique compound. Olfactometer bioassays using synthetic compounds showed that rice unique compounds, like xylene, hexanal served as attractants whereas non-host unique compounds, like 2-pentylfuran, 2-octenal acted as repellent. The results indicate that the rice unique compounds xylene, hexanal along with other volatile compounds could be responsible for higher preference of YSB towards rice plants. Similarly, the non-host unique compounds 2-pentylfuran, 2-octenal could possibly be responsible for lower preference and defence against YSB. These compounds could be utilised for devising traps for YSB monitoring and management.

Molecular structure regulation and herbicidal activity of dibutyltin aryloxyacetate complexes

Six dibutyltin aryloxyacetate complexes [(X-C6H4OCH2COO)(SnBu2)2(μ3O)(OMe)]2 (A1, B1), [(X-C6H4OCH2COO)2(SnBu2)2(μ3O)]2 (A2, B2), and [(X-C6H4OCH2COO)2SnBu2] (A3, B3) were synthesized and characterized by IR, NMR, HRMS, and TGA techniques. The molecular structure of complexes A1, A3 and B1-B3 was confirmed by single-crystal X-ray crystallography. Complexes A1, B1, A2, and B2 are dimeric carboxylate tetraorganodistannoxanes, displaying a "ladder-like" molecular arrangement. The aryloxyacetate ligands in A1 and B1 adopt a monodentate mode, while they function as bridging coordination ligands in A2 and B2. Complexes A3 and B3 represent dibutyltin carboxylates with crystallographically imposed two-fold symmetry, with the aryloxyacetate ligands adopting a bidentate mode. Aryloxyacetic acids demonstrate a propensity for assuming various coordination modes, leading to the formation of diverse molecular architectures in organotin carboxylates. In addition, complex B1 exhibits polymorphism. Echinochloa crus-galli and Portulaca oleracea L. were used as target organisms for herbicidal activity testing using a petri dish method. It was found that they have a significant inhibitory effect on weed roots and stems at 200 μmol/L, and the structure-activity relationship analysis revealed the important influence of substituent types and complex structures on their activity.

Design, Synthesis, and Herbicidal Activity of Natural Naphthoquinone Derivatives Containing Diaryl Ether Structures.

Photosynthesis system II (PS II) is an important target for the development of bioherbicides. In this study, a series of natural naphthoquinone derivatives containing diaryl ether were designed and synthesized based on the binding model of lawsone and PS II D1. Bioassays exhibited that most compounds had more than 80% inhibition of Portulaca oleracea and Echinochloa crusgalli roots at a dose of 100 μg/mL and compounds B4, B5, and C3 exhibited superior herbicidal activities against dicotyledonous and monocotyledon weeds to commercial atrazine. In particular, compound B5 exhibited excellent herbicidal activity at a dosage of 150 g a.i./ha. In addition, compared with atrazine, compound B5 causes less damage to crops. Molecular docking studies revealed that compound B5 effectively interacted with Pisum sativum PS II D1 via diverse interaction models, such as π-π stacking and hydrogen bonds. Molecular dynamics simulation studies and chlorophyll fluorescence measurements revealed that compound B5 acted on PS II. This is the first report of natural naphthoquinone derivatives targeting PS II and compound B5 may be a candidate molecule for the development of new herbicides targeting PS II.

Allelopathic Effects of Sugarcane Leaves: Optimal Extraction Solvent, Partial Separation of Allelopathic Active Fractions, and Herbicidal Activities.

The inhibitory potential of allelopathic plants is the subject of increasing research attention for their application in weed management. The sugarcane leaf is an agricultural waste product that has been reported to have allelopathic potential. Therefore, the present study determined the optimal organic solvent system and fractionation procedure to enhance the quantity of this extract and its allelopathic efficiency. Sugarcane leaves were extracted using five ethanol/water solvent ratios (v/v): 00:100, 25:75, 50:50, 75:25, and 100:00. Their allelopathic effects on seed germination and seedling growth were assayed in two major weeds, Echinochloa crus-galli (L.) Beauv. and Amaranthus viridis L. The results showed that the extract concentration, solvent ratio, and their interaction significantly inhibited the growth parameters in A. viridis. Consequently, a crude ethanol/water ratio of 00:100 was used to separate the active fraction via acid-base solvent partitioning. The acidic fraction (AE) exerted the greatest inhibitory effect and completely (100%) inhibited A. viridis at all concentrations, followed by the original crude fraction, neutral fraction, and aqueous fraction. Moreover, all of the fractions had selective effects, inhibiting A. viridis much more than E. crus-galli in the laboratory tests. The chemical analysis using gas chromatography/mass spectrometry indicated that the AE fraction contained 20 different compounds. The five major compounds included alkaloids, organic acids, and phenols. Therefore, the AE fraction was selected for formulation in a concentrated suspension and tested for its herbicidal characteristics. The formulation exhibited early post-emergence activities and had a stronger effect on A. viridis compared to E. crus-galli. The physiological mechanism of the formulation was tested against A. viridis. The thiobarbituric acid reactive substances and H2O2 occurred in the A. viridis leaf, which suggests lipid peroxidation and cell disruption.

Allelopathy and Allelochemicals in Chamaecyparis obtusa Leaves for the Development of Sustainable Agriculture

Chamaecyparis obtusa (Siebold et Zucc.) Endl. is cultivated in the temperate region of East Asia for its high-quality and profitable timber. The timber-processing industry produces a large amount of waste, such as tree bark, branches, and leaves, and finding ways to minimize such waste is economically and environmentally efficient. In the present study, the allelopathic activity and allelochemicals of the C. obtusa leaves were investigated to develop potential application methods. C. obtusa leaves were phytotoxic and associated leaf extracts significantly suppressed the growth of the weeds; Echinochloa crus-galli, Phleum pratense and Lolium multiflorum under laboratory conditions. The leaf powder applied onto the soil surface also suppressed the germination of E. crus-galli and P. pratense under greenhouse conditions. Hinokiic acid and (+)-dihydrosesamin were isolated from the leaves and structurally identified. Both compounds suppressed the growth of cress and P. pratense in a concentration dependent manner. When the leaves of C. obtua were applied as a soil additive, hinokiic acid and (+)-dihydrosesamin in the leaves potentially cause the growth inhibitory activity by leaching into the soil. These experiments showed that the leaves and the leaf extracts of C. obtusa are phytotoxic. These experiments also demonstrated that the leaves and the leaf extracts of C. obtusa have growth inhibitory potential against several plant species, and the leaves produce allelochemicals. Therefore, the leaves and leaf extracts of C. obtusa may be useful for weed suppression purposes. The leaf biomass of C. obtusa is frequently large and the timber processing industry produces significant leaf waste. The development of weed control products using waste leaves may be a solution to minimize the timber processing waste to reduce environmental impact and provide economic value. However, leaf material should be evaluated for weed suppression and herbicidal activity as a soil additive and also possible as a foliar spray under field conditions.

UAV imaging hyperspectral for barnyard identification and spatial distribution in paddy fields

Barnyard grass (Echinochloa crus-galli), a noxious weed prevalent in rice fields, poses a significant threat to rice growth and development, ultimately leading to substantial yield reductions. Its morphological resemblance to rice plants complicates its identification and management. Consequently, accurately identifying and mapping barnyard grass in intricate rice field environments holds substantial research value and significance. Furthermore, most existing weed detection studies rely on single-day data, limiting the models’ generalizability. Therefore, incorporating multi-temporal data into modeling is highly desirable. This study utilized an unmanned aerial vehicle (UAV) to capture multi-temporal, low-altitude hyperspectral imagery of paddy fields, which were subsequently stitched, calibrated, and filtered using the SG convolution filter. The continuous projection algorithm (SPA) was employed to extract sensitive bands for discriminating between rice and barnyard grass. Initially, single-time data was utilized for barnyard grass identification, with models such as support vector machine (SVM), random forest (RF), 1D convolutional neural network (1DCNN), and 3D convolutional neural network (3DCNN) constructed using both full-spectrum and feature bands. The results indicated that the SPA-3DCNN model exhibited the highest performance in identifying rice (F1-score: 0.942) and barnyard grass (F1-score: 0.8936). Seven selected feature bands (482.5234, 546.5415, 675.0806, 709.1382, 762.0431, 922.0157, and 944.6371 nm) were found to be highly discriminative for distinguishing barnyard grass from rice. Subsequently, multi-temporal data modeling was employed to enhance the models’ generalization ability, resulting in improved overall accuracy (OA) and Kappa coefficients for each model, along with reduced misclassification rates. The spatial distribution maps also exhibited better performance with increased temporal data. The infestation trend of barnyard grass was visualized using multi-temporal difference maps, and a density map of barnyard grass was generated through image binarization. This study successfully demonstrated the feasibility of utilizing UAV-borne hyperspectral imagery for identifying barnyard grass in complex paddy field environments. By improving the model’s generalization ability through multi-temporal modeling, the study provided robust data support for managing and preventing barnyard grass infestations, including the creation of spatial distribution and density maps for barnyard grass.

Physiological Basis for the Mechanism of Selectivity of Tripyrasulfone between Rice (Oryza sativa) and Barnyard Grass (Echinochloa crus-galli).

Tripyrasulfone is currently the only HPPD-inhibiting herbicide that possesses outstanding selectivity even for direct-seeded rice (Oryza sativa) when applied POST to control grass weeds; however, the underlying mechanisms remain unclear. In this study, the inhibitory effects of the real active HDT of tripyrasulfone on recombinant 4-hydroxyphenylpyruvate dioxygenase (HPPDs) from rice and barnyard grass (Echinochloa crus-galli) were similar, with consistent structural interactions and similar binding energies predicted by molecular docking. However, the HPPD expression level in rice was significantly greater than that in barnyard grass after tripyrasulfone treatment. Tripyrasulfone was rapidly taken up and hydrolyzed into HDT, which was similarly distributed within the whole plants of rice and barnyard grass at 24 h after treatment. Compared with barnyard grass, rice has more uniform epicuticular wax in the cuticle of its leaves, absorbing less tripyrasulfone and metabolizing much more tripyrasulfone. Overall, to a greater extent, the different sensitivities to tripyrasulfone between barnyard grass and rice resulted from metabolic variations.

How the Management and Environmental Conditions Affect the Weed Vegetation in Canary Grass (Phalaris canariensis L.) Fields

Canary grass (Phalaris canariensis L.) is a versatile crop with global significance; it is primarily cultivated for its small elliptical seeds, which are used as bird feed and for human consumption. This crop is adapted to various climates and soils, so it can be grown successfully in Hungary. However, challenges such as weed control, climate change impacts, and soil factors require strategic management for sustained success in canary grass cultivation. Our study investigated the impact of management and environmental (as seasonal and soil) factors on pre-harvest weed vegetation in canary grass fields in Southeast Hungary between 2017 and 2020. In addition to showing the weed vegetation of the canary grass, the aim of our work was to promote more effective weed management of canary grass by revealing correlations between soil, seasonality, and management variables, influencing weed diversity and coverage. Using the analysis of covariance (ANCOVA) and correlation tests, we tested significant variables, providing insights into the complex interactions affecting weed composition. A redundancy analysis (RDA) further unveiled the relationships between explanatory variables and weed species’ composition. The findings offer valuable information for effective weed management strategies in canary grass cultivation. Our comprehensive study on canary grass fields in Southeast Hungary sheds light on significant factors influencing weed composition and abundance. The average weed coverage was 10.8%, with summer annuals and creeping perennials being the most prevalent life forms. Echinochloa crus-galli, Cirsium arvense, Xanthium italicum, and Setaria viridis were among the dominant species. ANCOVAs revealed the impact of soil, management, and seasonal factors on weed cover, species richness, diversity, and yield levels. Soil properties like texture, pH, and nitrogen content showed varying effects on weed parameters. The vintage effect, tillage systems, and farming practices also played crucial roles. The redundancy analysis highlighted the influence of the year, soil sulfur content, and winter preceding crops on weed composition. In conclusion, the herbaceous vegetation in the studied area is dominated by summer germinating and creeping perennial species. Despite slight differences in average coverage and occurrence, a well-defined set of significant species is evident. Multicollinearity among variables suggests limitations to further increase the number of variables that can be included in the analysis. The ANCOVAs showed that the soil, seasonal, and farming variables significantly influence overall weed vegetation and crop yield, with a lesser impact on species richness and diversity. The reduced RDA model highlights the strong influence of the year on species’ composition, emphasizing the inherent factors during canary grass cultivation that are challenging to modify through farming practices.

Discovery of Novel N-Phenyltriazinone Derivatives Containing Oxime Ether or Oxime Ester Moieties as Promising Protoporphyrinogen IX Oxidase Inhibitors.

Protoporphyrinogen IX oxidase (PPO, EC 1.3.3.4) is one of the most important targets for the discovery of green herbicides. In order to find novel PPO inhibitors with a higher herbicidal activity, a series of novel N-phenyltriazinone derivatives containing oxime ether and oxime ester groups were designed and synthesized based on the strategy of pharmacophore and scaffold hopping. Bioassay results revealed that some compounds showed herbicidal activities; especially, compound B16 exhibited broad-spectrum and excellent 100% herbicidal effects to Echinochloa crusgalli, Digitaria sanguinalis, Setaria faberii, Abutilon juncea, Amaranthus retroflexus, and Portulaca oleracea at a concentration of 37.5 g a.i./ha, which were comparable to trifludimoxazin. Nicotiana tabacum PPO (NtPPO) enzyme inhibitory assay indicated that B16 showed an excellent enzyme inhibitory activity with a value of 32.14 nM, which was similar to that of trifludimoxazin (31.33 nM). Meanwhile, compound B16 revealed more safety for crops (rice, maize, wheat, peanut, soybean, and cotton) than trifludimoxazin at a dose of 150 g a.i./ha. Moreover, molecular docking and molecular dynamics simulation further showed that B16 has a very strong and stable binding to NtPPO. It indicated that B16 can be used as a potential PPO inhibitor and herbicide candidate for application in the field.

Effects of bed width and crop row spacing on barnyardgrass (Echinochloa crus-galli) emergence and seed production in furrow-irrigated rice

Abstract Furrow-irrigated rice (Oryza sativa L.) has become a popular option for rice production in Arkansas. Highly troublesome weeds like barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] are a major problem for producers in all rice production systems. Cultural tactics should become a priority to enhance crop growth and competitiveness. This research aimed to determine the effects of bed width (irrigation furrow spacing) and crop row spacing manipulation on E. crus-galli emergence and seed production in a furrow-irrigated rice system. Three bed widths (76, 97, and 152 cm) (whole-plot factor) were used, and plots were drill seeded in four crop row spacings (13, 19, 25, and 38 cm) (subplot factor). The widest width of 152 cm had a slight increase in E. crus-galli density in the early rice life cycle but, by the end of the season, did not differ from the narrower bed widths. Conversely, a decrease in E. crus-galli seed production was observed as the bed width increased. Similar rice canopy coverage and yields occurred among all three bed widths. As for crop row spacing, as the width increased, E. crus-galli density also increased. The 13-cm crop row spacing had the lowest preflood E. crus-galli density, preharvest panicle count, and seed production. No effect of crop row spacing was observed on rice canopy coverage; however, the 13-cm crop row spacing produced the greatest rice yield. The 13-cm crop row spacing paired with the 152-cm bed width may be the optimum combination of ecological strategies in furrow-irrigated rice to reduce E. crus-galli seed production while maintaining rice growth and yield.

Эффективность пироксасульфона на посевах сои

The purpose of research is to study the effect of the herbicide Karitori, WSG (850 g/kg), based on the new active ingredient pyroxasulfone, on the weed component in soybean crops in the conditions of the Russian Federation. Objectives: to evaluate the biological effectiveness of the herbicide Karitori, WSG, against a complex of weeds; to assess the safety of using the drug for soybean plants; to carry out crop harvest accounting. The experiments were carried out during two growing seasons, 2018 and 2019. In the Altai Region, experiments were carried out on soybean crops of the Altom variety, in the Astrakhan Region – on soybean crops of the Vilana variety, in the Krasnodar Region - on soybean crops of the Bara variety (in 2018) and Arleta variety (in 2019). Spraying the soil with herbicide was carried out before crop germination. The assessment of weediness was carried out using the quantitative-weight method in accordance with the “Guidelines for registration testing of herbicides in agriculture”. The greatest reduction in the overall infestation of soybean crops was noted in the Altai Region under conditions of severe infestation by common barnyard grass. Application 0.1; 0.2 and 0.3 kg/ha of the drug in this region provided an efficiency of 76.3; 88.7 and 92.3 % respectively. The reduction in overall weed infestation in other regions was smaller – the use of 0.3 kg/ha of the drug provided an efficiency of 66.4–67.4 %. In all regions, the effectiveness of the minimum application rate of the herbicide Karitori, WSG (0.1 kg/ha), exceeded the efficiency of 0.1 kg/ha of the standard Pledge, WP. The noted trend was supported by data on the mass of cereal weeds. The treatments had a positive effect on the amount of soybean yield obtained in the experiments. In all experiments conducted (except for the 2018 experiment in the Astrakhan region), the increase in crop yield due to reduced competition from weeds after the application of herbicides was significant. The most significant increases (from 8.2 to 10.1 c/ha) were obtained in 2019 in an experiment on soybean crops of the Arleta variety in the conditions of the KrasnodarRegion.

Засоренность посевов яровой пшеницы при применении ресурсосберегающих технологий обработки почвы

The purpose of research is to study the influence of primary tillage systems on the weed infestation of spring wheat crops placed on green manure fallow in a five-field grain-fallow crop rotation. Objectives: to study the weed infestation of spring wheat crops; to establish the effectiveness of herbicide use; to determine the grain yield of spring wheat. The study was carried out in 2017–2022 in the conditions of the Krasnoyarsk forest-steppe on leached chernozem, which is characterized by an increased humus content (6.1–8.0 %) and a neutral reaction of the soil solution (pH – 6.1–7.0). The object of the study is spring wheat of the Novosibirskaya 15 variety. The research results showed that the bulk of weeds in the studied variants are represented by a group of young plants. Different tillage systems influenced the quantitative and species composition of weeds. When soil tillage is minimized, the number of weeds increases and their species composition changes. In spring wheat crops under the studied tillage options, the most numerous group of weeds were young ones. The most common species found in spring wheat crops were bedstraw (Galium aparine L.) and millet (Echinochloa crusgalli (L.). Their share in the total number of weeds in the variant with plowing was 71.4 %, without tillage – 81.4 %. There was a significant change in the share of biological groups of young and perennial weeds in the option without tillage during the study period. The share of young weeds in 2022 decreased compared to 2017 from 93.1 to 58.8 %, while the number of perennial weeds increased from 6.9 to 41.2 %.Over the years of the study (2017–2022), a change in the species composition of weeds was established. In the option without tillage, such species as yellow sow thistle, medicinal dandelion, hemlock, and small petal, which were absent in 2017, appear in spring wheat crops.

Allelopathic Effects of Corn Straw and Its Water Extracts on Four Weed Species and Foxtail Millet.

Straw covering is a protective tillage measure in agricultural production, but there is relatively little research on the allelopathic effects of corn straw on weeds and foxtail millet. This experiment studied the allelopathic effects of corn straw on four weeds (Chenopodium album, Setaria viridis, Echinochloa crus-galli and Amaranthus retroflexus) in foxtail millet fields, and also measured the growth indicators of foxtail millet. The study consisted of Petri dish and field experiments. Five treatments were used in the Petri dish experiment: clear water as control (0 g/L, TCK) and four types of corn straw water extracts. They were, respectively, the stock solution (100 g/L, T1), 10 X dilution (10 g/L, T2), 50 X dilution (2 g/L, T3), and 100 X dilution (1 g/L, T4) of corn straw water extracts. Additionally, seven treatments were set up in the field experiment, consisting of three corn straw covering treatments, with covering amounts of 3000 (Z1), 6000 (Z2) and 12,000 kg/ha (Z3), and four control treatments-one treatment with no corn straw cover (CK) and three treatments involving the use of a black film to create the same shading area as the corn straw covered area, with black film coverage areas of 50% (PZ1), 70% (PZ2), and 100% (PZ3), respectively. The results showed that the corn straw water extract reduced the germination rate of the seeds of the four weeds. The T1 treatment resulted in the allelopathic promotion of C. album growth but the inhibition of S. viridis, E. crus-galli, and A. retroflexus growth. Treatments T2, T3, and T4 all induced the allelopathic promotion of the growth of the four weeds. The order of the effects of the corn straw water extracts on the comprehensive allelopathy index of the four weed seeds was as follows: C. album > S. viridis > A. retroflexus > E. crus-galli. With an increase in the corn straw mulching amount, the density and total coverage of the four weeds showed a gradual downward trend, whereas the plant control effect and fresh weight control effect showed a gradual upward trend. All indices showed the best results under 12,000 kg/ha of mulching and returning to the field. Overall, corn straw coverage significantly impacted the net photosynthetic rate and transpiration rate of foxtail millet and increased the yield of foxtail millet. Under coverages of 6000 and 12,000 kg/ha, the growth of foxtail millet is better. Based on our findings, we recommend a corn straw coverage of 12,000 kg/ha for the allelopathic control of weeds in foxtail millet fields.

Enhanced Herbicide Metabolism and Target Site Mutation Enabled the Multiple Resistance to Cyhalofop-butyl, Florpyrauxifen-benzyl, and Penoxsulam in Echinochloa crus-galli.

This study investigated the multiple herbicide resistance (MHR) mechanism of one Echinochloa crus-galli population that was resistant to florpyrauxifen-benzyl (FPB), cyhalofop-butyl (CHB), and penoxsulam (PEX). This population carried an Ala-122-Asn mutation in the acetolactate synthase (ALS) gene but no mutation in acetyl-CoA carboxylase (ACCase) and transport inhibitor response1 (TIR1) genes. The metabolism rate of PEX was 2-fold higher, and the production of florpyrauxifen-acid and cyhalofop-acid was lower in the resistant population. Malathion and 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) could reverse the resistance, suggesting that cytochrome P450 (CYP450) and glutathione S-transferase (GST) contribute to the enhanced metabolism. According to RNA-seq and qRT-PCR validation, two CYP450 genes (CYP71C42 and CYP71D55), one GST gene (GSTT2), two glycosyltransferase genes (rhamnosyltransferase 1 and IAAGLU), and two ABC transporter genes (ABCG1 and ABCG25) were induced by CHB, FPB, and PEX in the resistant population. This study revealed that the target mutant and enhanced metabolism were involved in the MHR mechanism in E. crus-galli.

Novel Uracilphenyl sulfonamide-based inhibitors of protoporphyrinogen oxidase: Design, synthesis, and herbicidal activity

Herein, we aimed to develop effective herbicidal compounds by synthesizing 26 novel uracil derivatives containing sulfonamide groups based on the active group splicing principle, with saflufenacil as the reference compound. The structures of the final products were confirmed through 1H NMR, 13C NMR, and HRMS analyses. According to the results, 21 and 19 compounds exhibited outstanding (80 %-100 %) and 60–100 % control efficacies against broadleaf weeds (Zinnia elegans and Abutilon theophrasti) at concentrations of 150 g/hm2 and 37.5 g/hm2, respectively. Notably, compound 2a demonstrated 100 % control efficacy against Zinnia elegans even at the lowest tested concentration of 9.375 g/hm2. On the other hand, the examined compounds exhibited minimal efficacy against other grass weeds, such as Setaria glauca and Echinochloa crusgalli. Furthermore, molecular docking analysis revealed that compound 2a formed hydrogen bonds with Protoporphyrinogen Oxidase (PPO).Studies of the electrostatic potential analysis of the molecular surface showed that the highly active compounds 2a and saflufenacil have similar charge distributions, which may play an important role in the docking of the compounds with their target receptors.These findings offer valuable insights and guidance for developing more effective herbicides, paving the way for future advances in weed control tactics.

Design, Synthesis, and Herbicidal Evaluation of Pyrrolidinone-Containing 2-Phenylpyridine Derivatives as Novel Protoporphyrinogen Oxidase Inhibitors.

In this work, a series of pyrrolidinone-containing 2-phenylpyridine derivatives were synthesized and evaluated as novel protoporphyrinogen IX oxidase (PPO, EC 1.3.3.4) inhibitors for herbicide development. At 150 g ai/ha, compounds 4d, 4f, and 4l can inhibit the grassy weeds of Echinochloa crus-galli (EC), Digitaria sanguinalis (DS), and Lolium perenne (LP) with a range of 60 to 90%. Remarkably, at 9.375 g ai/ha, these compounds showed 100% inhibition effects against broadleaf weeds of Amaranthus retroflexus (AR) and Abutilon theophrasti (AT), which were comparable to the performance of the commercial herbicides flumioxazin (FLU) and saflufenacil (SAF) and better than that of acifluorfen (ACI). Molecular docking analyses revealed significant hydrogen bonding and π-π stacking interactions between compounds 4d and 4l with Arg98, Asn67, and Phe392, respectively. Additionally, representative compounds were chosen for in vivo assessment of PPO inhibitory activity, with compounds 4d, 4f, and 4l demonstrating excellent inhibitory effects. Notably, compounds 4d and 4l induced the accumulation of reactive oxygen species (ROS) and a reduction in the chlorophyll (Chl) content. Consequently, compounds 4d, 4f, and 4l are promising lead candidates for the development of novel PPO herbicides.

Menthalactone from Mentha piperita L., a Monocot-Selective Bioherbicide

The challenge of managing invasive weed species continues to affect the agricultural industry, presenting ecological, economic, and agronomic hurdles that lead to over 100 billion USD in annual crop losses globally. One such concern is the management of Agrostis stolonifera L., commonly known as creeping bentgrass, particularly due to its ability to form hybrids. This scenario underscores the urgent need for innovative, effective, and environmentally sustainable herbicides, steering the focus toward natural substances as potential candidates. We report here a promising natural lactone, commonly known as menthalactone, which is derived from Mentha piperita L. Its phytotoxic activity was assessed against the monocot, bentgrass, and a dicot, lettuce (Lactuca sativa L.). Menthalactone displayed outstanding activity against bentgrass and was further evaluated for phytotoxic characteristics. The germination of A. stolonifera seeds was significantly inhibited with an IC50 value of 4.9 ± 1.2 µM. In contrast to bentgrass seeds, Lemna pausicostata L. plants were less responsive to menthalactone treatment, shown by an IC50 of 293.4 ± 70.6 µM. Both species are monocots, and the results suggest that menthalactone might have effects on seed germination but not on the metabolism of green tissues. The susceptibility of three common, obnoxious weed species, i.e., ryegrass (Lilium perenne), barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), and crabgrass (Digitaria sanguinalis (L.) Scop.), to menthalactone was assessed. Menthalactone at 1000 µM completely inhibited the germination of all three species of grasses, while 330 µM inhibited germination by less than 50%. The post-emergence application of menthalactone at 1% did not produce a significant inhibitory effect against ryegrass, barnyard grass, or crabgrass.

Comparison of Straw Mulching and Herbicide Levels for Control of Various Weed Species in Maize (Zea mays L.)

Weed management in maize is one of biggest concerns for growers. To reduce dependence on chemicals and chances of herbicide resistant weeds, and to improve soil status, thus straw mulching was added as cultural component with chemicals for improving weed management in maize. Field experiments were conducted at two locations (Punjab Agricultural University, Ludhiana, and Regional Research Station, Gurdaspur) during kharif season to find out the influence of different paddy straw mulch and herbicides for control of various weeds species in maize. The results showed that application of paddy straw mulch 6.25 t/ha effectively controlled Eleusine indica, Cynodon dactylon, Commelina benghalensis, Eragrostis tenella, Digitaria sanguinalis, Echinochloa colona, Trianthema portulacastrum, Portulaca oleracea, Phyllanthus niruri, Euphorbia hirta, Conyza stricta and Cyperus compressus over no mulching. In addition to above weed species, paddy straw mulch 9.0 t/ha also effectively reduced density of Dactyloctenium aegyptium, Acrachne racemosa, Digera arvensis, Mollugo nudicaulis, Alternanthera philoxeroides, Amaranthus viridis and Veronica agrestis and Cyperus rotundus as compared to 6.25 t/ha and no mulch treatment. Atrazine pre emergence at 1.0 kg/ha controlled Eleusine indica, Echinochloa crusgalli, Eragrostis tenella, Digitaria sanguinalis, Echinochloa colona, Trianthema portulacastrum, Mollugo nudicaulis, Alternanthera philoxeroides, Digera arvensis, Amaranthus viridis and Cyperus compressus compared to its lower dose (0.8 kg/ha) and control at all stages. Post emergence application of tembotrione reduced the density of all weed species compared to atrazine and unweeded control.