Dicotyledonous Weeds Research Articles

Efficacy mixture of fomesafen and clomazone for weed control in potato

In 2022–2023 in Leningrad region at potato Liga variety trials were conducted to evaluate mixture of herbicides Nexus (240 g/l of fomesafen) and Traser (480 g/l of clomazone) in the following schedules: 1.0 l/ha + 0.25 l/ha; 1.0 l/ha + 0.5 l/ha; 1.25 l/ha + 0.25 l/ha and 1.25 l/ha + 0.5 l/ha. The use of herbicides in their pure form acted as standard. The experiments were carried out in accordance with the methods of herbicide registration trials (2013; 2020). The use of tank-mix of herbicides Nexus + Traser made it possible to most fully control of mixed type of weediness, typical for the North-Western region. When applying a tank-mix herbicides in the regulations of 1.0…1.25 l/ha + 0.5 l/ha, the decrease in the weight of annual dicotyledonous weeds was at a level exceeding 75.0 %; the decrease in the weight of annual cereal weeds reached 88.3 %. The use of the herbicide Nexus in its pure form was most noticeably inferior to the application of tank-mix of herbicides Nexus + Traser (1.0…1.25 l/ha + 0.5 l/ha) in terms of effect on plants of barnyard grass (Echinochloa crusgalli (L.) Beauv.)) and baconweed (Chenopodium album L.). The main advantage of a tank-mix of herbicides over the herbicide Traser in its pure form was realized in relation to the effect on pale persicaria (Polygonum lapathifolium L.). Reduced competition from weeds contributed to the preservation of potato yields of Liga variety cultivated in the North-Western region. Under normal moisture conditions, the potato yield after using a tank-mix of herbicides Nexus and Traser (31.0…35.8 t/ha) significantly exceeded the crop yield after using these herbicides in their pure form (17.5…23.3 t/ha).

Ginger Phytotoxicity: Potential Efficacy of Extracts, Metabolites and Derivatives for Weed Control

The negative implications for weeds encourage the finding of novel sources of phytotoxic agents for sustainable management. While traditional herbicides are effective, especially at large scales, the environmental impact and proliferation of resistant biotypes present major challenges that natural sources could mitigate. In this study, the potential of ginger metabolites as phytotoxic agents has been investigated for the first time. Root extracts, prepared via various extraction techniques, showed phytotoxicity in wheat (Triticum aestivum L. cv. Burgos) coleoptile bioassays at 800–100 ppm, and the most active extract (prepared by sonication with ethyl acetate) was purified by chromatographic methods, yielding seven compounds: five phenolic metabolites with gingerol and shogaol structures, β-sitosterol, and linoleic acid. Some of the major phenolic metabolites, especially [6]-shogaol and [6]-gingerol, exerted phytotoxicity on wheat coleoptiles, Plantago lanceolata and Portulaca oleracea (broadleaf dicotyledon weeds). This promoted the study of a collection of derivatives, revealing that the 5-methoxy, oxime, and acetylated derivatives of [6]-shogaol and [6]-gingerol had interesting phytotoxicities, providing clues for improving the stability of the isolated structures. Ginger roots have been demonstrated to be a promising source of bioactive metabolites for weed control, offering novel materials with potential for the development of agrochemicals based on natural products.

Chemical Management of Helianthus annuus L. as a Broadleaf Weed in Interaction with the Zea mays L. Crop

Objective: To evaluate the biological effectiveness of progressive doses of the herbicide Condraz® (tritosulfuron + dicamba) in post-emergence in dicotyledonous plants grown in consortium with corn in a greenhouse. Design/methodology/approach: The research was performed out in a greenhouse within the facilities of the Colegio Superior Agropecuario del Estado de Guerrero. Dekalb 357® corn was established, planted in a consortium with sunflower, to measure the response to different dosages of the herbicide Condraz® (tritosulfuron + dicamba). We worked with a completely randomized block experimental design (DBCA). Results: The treatments were 100% effective, because they eliminated the sunflower plants used as a representative of dicotyledonous weeds; while, in treatment T1 (water) the number of these was not affected, which was 10 sunflower plants per pot in the two experiments. Limitations on study/implications: Our results are specific for the management of dicotyledonous weeds in corn. Findings/conclusions: Condraz® herbicide is effective in eliminating dicotyledonous weeds when applied in doses ranging from 100 to 190 g per ha.

A205V, D376E, W574L, S653T, and S653N Substitutions in Acetohydroxy Acid Synthase from Amaranthus retroflexus L. Show Different Functional Impacts on Herbicide Resistance

Amaranthus retroflexus L. is a troublesome dicot weed in crop fields and has developed high resistance to nicosulfuron in China. The objective of this study was to determine the effects of specific resistance mutations (A205V, D376E, W574L, S653T, and S653N) of the acetohydroxy acid synthase enzyme (AHAS) on the resistance of A. retroflexus to nicosulfuron. The resistance mutations in A. retroflexus not only conferred 17.17- to 31.70-fold resistance to nicosulfuron but also greatly decreased AHAS sensitivity and increased AHAS binding affinity to substrate pyruvate, which mechanisms were primarily responsible for the observed A. retroflexus resistance. Molecular docking results indicated that these resistance mutations altered AHAS binding free energy with nicosulfuron. All the resistance mutations showed less sensitivity to feedback inhibition by branched-chain amino acids, but the mutations did not necessarily affect biosynthesis in A. retroflexus. This report to compares the various mutations of ArAHAS in vitro and contributes to understanding herbicide resistance in this field weed.

Algorithm for Locating Apical Meristematic Tissue of Weeds Based on YOLO Instance Segmentation

Laser technology can be used to control weeds by irradiating the apical meristematic tissue (AMT) of weeds when they are still seedlings. Two factors are necessary for the successful large-scale implementation of this technique: the ability to accurately identify the apical meristematic tissue and the effectiveness of the localization algorithm used in the process. Based on this, this study proposes a lightweight weed AMT localization algorithm based on YOLO (look only once) instance segmentation. The YOLOv8n-seg network undergoes a lightweight design enhancement by integrating the FasterNet lightweight network as its backbone, resulting in the F-YOLOv8n-seg model. This modification effectively reduces the number of parameters and computational demands during the convolution process, thereby achieving a more efficient model. Subsequently, F-YOLOv8n-seg is combined with the connected domain analysis algorithm (CDA), yielding the F-YOLOv8n-seg-CDA model. This integration enables the precise localization of the AMT of weeds by calculating the center-of-mass coordinates of the connected domains. The experimental results indicate that the optimized model significantly outperforms the original model; the optimized model reduces floating-point computations by 26.7% and the model size by 38.2%. In particular, the floating-point calculation is decreased to 8.9 GFLOPs, and the model size is lowered to 4.2 MB. Comparing this improved model against YOLOv5s-seg and YOLOv10n-seg, it is lighter. Furthermore, it exhibits exceptional segmentation accuracy, with a 97.2% accuracy rate. Experimental tests conducted on five different weed species demonstrated that F-YOLOv8n-seg-CDA exhibits strong generalization capabilities. The combined accuracy of the algorithm for detecting these weeds was 81%. Notably, dicotyledonous weeds were detected with up to 94%. Additionally, the algorithm achieved an average inference speed of 82.9 frames per second. These results indicate that the algorithm is suitable for the real-time detection of apical meristematic tissues across multiple weed species. Furthermore, the experimental results demonstrated the impact of distinctive variations in weed morphology on identifying the location of the AMT of weeds. It was discovered that dicotyledonous and monocotyledonous weeds differed significantly in terms of the detection effect, with dicotyledonous weeds having significantly higher detection accuracy than monocotyledonous weeds. This discovery can offer novel insights and avenues for future investigation into the identification and location of the AMT of weeds.

THE PRE-em USE OF SOME HERBICIDES IN THE CONTROL OF WEEDS IN POTATOES AND THEIR INFLUENCE ON THE YIELD

In order to mitigate the problem with weeds in the potato crop in the 2017 growing season in the towns Bogovinje-Tetovo (Polog region), a field experiment was established according to the randomized block system with three replications with experimental plot sizes of 21 m2. In the experiment, we investigated the structure of weeds, the degree of appearance, the efficacy of herbicides and the eventual phytotoxicity of the herbicides used. The potato planted was the cultivar "Silvana" and the following treatment variants were included: pendimetalin 5 l/ha, linuron 2.5 l/ha, metobromuron 3 l/ha, metobromuron 4 l/ha, metribuzin 0.75 kg/ha PRE-em, metribuzin 1 kg/h PRE-em, mechanical controls and absolute controls. From the obtained results, it was found that the structure of weeds consists of 9 types of weeds, of which 3 species from the group of monocotyledonous weeds and 6 species from the group of dicotyledonous weeds. The number of weeds was 126 plants/m2. The dominant weeds were Echinochloa crus-galli with 93.7 plants/m2, Polygonum lapathifolium with 10.0 plants/m2, and Polygonum aviculare with 9.3 plants/m2. The efficiency of herbicides in the fight against dicotyledonous weeds has been from 97.7-100%, monocotyledonous weeds from 95.8-98.2%, while the overall efficiency without geophytes has been from 96.8-98.4%. Regarding phytotoxicity in the potato culture, no signs of phytotoxicity were observed in any variant of the treatment.

Discovering Novel Bioherbicides: The Impact of Hemp-derived Phytocannabinoid Applications on Zea mays L. and Relevant Weeds

In addition to competition, phytotoxic plant metabolites contribute to the weed-suppressing properties of cover crops, which could be the basis for the development of novel bioherbicides. We investigated the impact of five Cannabis sativa L. -derived neutral phytocannabinoids and an aqueous C. sativa tissue extract (HE) at six concentrations on the germination rate (GR) and seedling root length (RL) of Zea mays L., two monocotyledonous and two dicotyledonous weed species in laboratory Petri dish bioassays. Additionally, the effect of pre-emergence applications of HE, cannabidiol (CBD), and cannabidivarin (CBDV) formulations on GR and shoot dry matter (SDM) were examined in greenhouse pot studies. The effects of phytocannabinoids and HE were analyzed in dose-response curves. For the highest rates, the effects on GR, RL and SDM were calculated by ANOVA and HSD test (p < 0.05). HE exhibited the greatest suppression on GR and RL for all plant species in the Petri dish bioassay, with RGR, RL exceeding −90%. Phytocannabinoids reduced mainly RL of all plants and decreased the GR of most weed species. Effects varied among plants and phytocannabinoids, with CBDV and CBD showing similar high inhibitory effects on RL as HE in the Petri dish bioassay. All pre-emergence applications resulted in a positive RGR across all studied plants and in a positive RSDM in Z. mays and Echinochloa crus-galli (L.) P. Beauv, whereas in the other weed species the RSDM was negative. In conclusion, phytocannabinoids play a major role in weed suppression of HEs. CBDV and CBD are the most promising candidates for bioherbicide development especially against annual dicotyledonous weed species.

Reappraisal of Didymella macrostoma causing white tip disease of Canada thistle as a new species, Didymella baileyae, sp. nov., and bioactivity of its major metabolites

ABSTRACT Bioherbicides are expected to be a supplement to integrated pest management, assisting in the control of problematic weed species. For instance, bioherbicides (Phoma and BioPhoma) were recently registered in Canada and the USA for the control of some perennial dicotyledonous weeds in lawns. These products are based on strains of the fungus Didymella macrostoma (syn. Phoma macrostoma) that causes white tip disease (WTD) in Canada thistle (Cirsium arvense). In this study, WTD was reported for the first time in the Russian Federation. Analysis of the internal transcribed spacer (ITS) region of nuc rDNA and secondary metabolite profiling confirmed the identity of Russian WTD isolates to Canadian biocontrol strains identified as D. macrostoma. Multilocus phylogenetic analysis based on sequencing of the ITS region, partial large subunit nuc rDNA region (28S), RNA polymerase II second largest subunit gene (rpb2), and partial β-tubulin gene (tub2) has differentiated the WTD isolates from C. arvense and D. macrostoma isolates from other plant hosts. Based on phylogenetic, morphological, and chemotaxonomic features, these WTD isolates were described as a new species named Didymella baileyae, sp. nov. This study also demonstrated the low pathogenicity of the ex-type D. baileyae isolate VIZR 1.53 to C. arvense seedlings and its asymptomatic development in the leaves of aboveground shoots. The organic extracts from mycelium and culture filtrate of D. baileyae, as well as macrocidin A and macrocidin Z, displayed phytotoxicity both to C. arvense leaves and seedlings. Macrocidin A was only detected in the naturally infected leaf tissues of C. arvense showing WTD symptoms. Macrocidins A and Z demonstrated low antimicrobial and cytotoxic activities, exhibiting no entomotoxic properties. The data obtained within this study on the pathogenicity and metabolites of D. baileyae may be important for the rational evaluation of its prospects as a biocontrol agent.

Significance of Insuring Herbicides for Stabilization of Weed Control Effectiveness and Quality when Using Betanals-Generics for Sugar Beet

In the field in 2014–2020, three-component herbicides of betanal generics were tested against juvenile dicotyledonous weeds in sugar beet crops to compare with the effectiveness of the use of the original herbicide Betanal Expert of (BEOF) at application rate of 1.0 l/ha. It is shown that the stability of dilute emulsions of generic betanals depended on the characteristics of the structure and dispersion of working solutions, the ability to crystallize active substances, and reactions to various environmental conditions. The BEOF herbicide in the application rate of 1.0 l/ha differed from generic betanals in the same application rate by a higher effect on weeds. The weeds that formed 2 real leaves showed phase resistance to generic betanals more noticeably. The effectiveness of BEOF on weeds in the cotyledon phase was 6–8% higher than that of generics, and 18% higher when treating weeds in the phase of 2 real leaves. It was found that in the temperature range of 19–22°C, the efficiency of generic betanals was closest to the efficiency of the original BEOF. To stabilize the generic betanals efficacy on weeds with the original BEOF 1.0 l/ha, their application rate was increased by 15–20%. A mixture of generic betanals with the insurance herbicides Mitron and Caribou, applied 3 times in the recommended application rates in accordance with the phase of development of sugar beet, provided high purity of sowing and crop yield at the level of the control group with manual weeding. Herbicides, in addition to broad-leaved dicotyledonous weeds, effectively suppressed young plants of aspens and field bindweed. The insurance herbicides Mitron and Caribou offset the disadvantages of generic betanals when used together in the fight against weeds in sugar beet crops.

Chiral Herbicide Fluorochloridone: Absolute Configuration, Stereoselective Bioactivity, Toxicity, and Degradation in the Potatoes.

Fluorochloridone (FLC) is a chiral herbicide that has four stereoisomers. This study systematically assessed the stereoselectivity of FLC to reveal the selective environmental behavior of its four isomers. Absolute configuration confirmation, evaluation of stereoselective bioactivity toward monocotyledonous and dicotyledonous weeds, toxicity to Danio rerio, and the stereoselective degradation in the potato system under field conditions of FLC were conducted. The four FLC stereoisomers were effectively separated on a superchiral S-AD column. The absolute configurations of the four stereoisomers of FLC were confirmed as (-)-(3S, 4S), (+)-(3S, 4R), (-)-(3R, 4S), and (+)-(3R, 4R)-FLC using single-crystal X-ray diffraction. The activities of the four stereoisomers were in the order of (-)-(3S, 4S)-FLC > (+)-(3R, 4R)-FLC > (+)-(3S, 4R)-FLC > (-)-(3R, 4S)-FLC, and the rate of selective degradation were in the order of (-)-(3R, 4S)-FLC > (+)-(3R, 4R)-FLC > (-)-(3S, 4R)-FLC > (+)-(3S, 4S)-FLC. The toxicity of the isomers were in the order of (-)-(3R, 4S)-FLC > (+)-(3R, 4R)-FLC > (-)-(3S, 4S)-FLC > (+)-(3S, 4R). Based on the results of bioactivity, toxicity, and degradation behavior assessments, the stereoisomer mixture containing (3R,4R)-FLC and (3S,4S)-FLC was concluded to be a better option than racemic FLC for increasing bioactivity and reducing usage.

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.

Eryngial: An α,β-Unsaturated Fatty Aldehyde as the Major Phytotoxin in Spiny Coriander (Eryngium foetidum L.) Essential Oil.

Weed species many times possess allelochemicals as a part of their survival strategy. These metabolites can be potential targets in search of natural phytotoxins. This study aims to evaluate the phytotoxic ability of fatty aldehyde-rich essential oil from spiny coriander (Eryngium foetidum) leaves, also known as fitweed or spiritweed and to further identify the active phytotoxins. This oil dose-dependently inhibited the wheatgrass coleoptile and radicle growth in multiple bioassays with half maximal inhibitory concentration (IC50) 30.6-56.7 μg/mL, while exhibiting a less pronounced effect on the germination (IC50 181.8 μg/mL). The phytotoxicity assessment of two oil constituents identified eryngial (trans-2-dodecenal), exclusively major fatty aldehydic constituent as the potent growth inhibitor with IC50 in the range 20.8-36.2 μg/mL during an early phase of wheatgrass emergence. Eryngial-inspired screening of eleven saturated fatty aldehydes and alcohols did not find a significantly higher phytotoxic potency. In an open vessel, eryngial as the supplementation in agar medium, dose-dependently inhibited the growth of pre-germinated seeds of one monocot (bermudagrass) and one dicot (green amaranth) weed species with IC50 in the range 23.8-65.4 μg/mL. The current study identified eryngial, an α,β-unsaturated fatty aldehyde of coriander origin to be a promising phytotoxic candidate for weed control.

A Phytotoxin with Selective Herbicidal Activity and Related Metabolites from the Phytopathogenic Fungus Bipolaris cookei SYBL03.

Weeds are a serious threat to crop production, and the utilization of secondary metabolites of phytopathogenic fungi is considered to be an effective method of weed control. In this study, eight compounds were isolated and purified from the mycelium and fermentation broth extracts of Bipolaris cookei SYBL03. The compounds (1-8), except 2 and 6, are reported for the first time from this genus. The herbicidal activities of compounds 1-8 were studied by evaluating their effects on the seed germination and seedling growth of monocotyledonous and dicotyledonous weeds. The results indicated that compound 7 (Cyclo-N-methylphenylalanyltryptophenyl, cNMPT) exhibited a concentration-dependent dual effect on the growth of weed seedlings and selective herbicidal activity against dicotyledonous weeds. We further investigated the morphological and physiological responses of roots of Amaranthus retroflexus, a dicotyledonous weed, to compound 7. Some changes were found in seedlings grown in 400 μg/mL compound 7 solution for 96 h, such as shortening and swelling of elongation zone cells, reduced number and length of root hairs, damage and wrinkling of the root surface, occurrence of electrolyte leakage, and an increase in ethylene content. These results suggest that compound 7 may exert herbicidal activity by causing stress to weed seedlings. Increased ethylene production could be involved in the response of plants to compound 7.

Spring sown camelina (Camelina sativa) contributes to the management of three summer weeds

Camelina (Camelina sativa (L.) Crantz) is an attractive drought-tolerant crop for Mediterranean regions due to its rapid growth and ability to out-compete many dicotyledonous winter annual weeds. In this experiment the weed suppression capacity of spring sown camelina against Chenopodium album L. (common lambsquarters), Polygonum aviculare L. (prostrate knotweed), and Xanthium spinosum L. (spiny cocklebur) was studied. The trial was conducted in Lleida (Spain) between 2019 and 2021. Camelina was sown in March each year. Experimental plots contained quadrats with each weed species as well as weed-free and crop-free quadrats. Height and aboveground biomass of weeds in competition with camelina decreased by over 50 % compared to the controls. However, crop and weed growth had seasonal differences depending on the weather conditions: (1) a moderately dry spring promoted crop production (1573 kg ha−1); (2) a rainy spring benefited weed development, negatively affecting crop growth and yield (739 kg ha−1); and (3) a severe dry spring affected growth of both crop and weeds, reducing crop production by up to 80 % (298 kg ha−1). The summer weed suppression capacity of camelina is enhanced by drought conditions, which makes camelina useful for managing these weeds.

Features of the protection of phaseolus vulgaris crops from weeds

Goal. To determine the effect of herbicides on the weediness of crops and the yield of Phaseolus vulgaris seeds in the conditions of the Right Bank Forest Steppe of Ukraine. Methods. Informational and analytical (collection of materials and analysis of literary sources), field research (setting up experiments, observing the development of plants, determining biometric indicators, accounting for the number of weeds, collecting and determining the structure of the harvest), mathematical and statistical (processing of research results). The field experiment design included weeded and weed-protected plots to compare the development of common bean plants under different growing conditions. The results. It was established that the dominant weeds among cereals were chicken millet and gray mouse millet, and among dicotyledonous weeds - ragweed, white quinoa, common sedge, black solanum, field mustard, etc. The use of herbicide protection significantly improves the yield of Phaseolus vulgaris. The obtained yield increased on average by 1.93 - 2.01 t/ha compared to the weeded control. Conclusions. Weeding can significantly reduce the yield of common bean crops by competing for resources such as light, water and nutrients. Weed control helps conserve these resources for the Phaseolus vulgaris and increase its yield. The use of herbicides is an effective method of weed control, which promotes optimal growth of Phaseolus vulgaris. The increase in yield due to the application of herbicide protection can offset the costs of purchasing and applying the herbicide. It is important to consider the effectiveness of specific herbicides when choosing crop protection methods. Different herbicides can have different spectrums of action, that is, be effective against different types of weeds. The right choice will help optimize results and save costs. Therefore, weed control in common Phaseolus vulgaris crops through the application of herbicide protection is an important and effective strategy that can increase the yield and economic efficiency of common bean cultivation technology.

Effect of sowing management and herbicides application on weeds and yield of berseem (Trifolium alexandrinum)

A field experiment was conducted during winter (rabi) seasons of 2020–2021 and 2021–2022 at research farm of College of Agriculture, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh to study the impact of planting time and herbicides application on weeds and berseem (Trifolium alexandrinum L.) yield. Experiment was conducted in a split plot design with 20 treatments comprising of 4 dates of sowing, viz. October 15th, October 30th, November 15th and November 30th in main plots and these were superimposed with 5 weed control treatments i.e. Pyroxasulfone 125 g/ha as pre emergence; Pyroxasulfone 125 g/ha at 14 DAS; Oxyfluorfen 100 g/ ha + Imazethapyr 15 g/ha after first cutting; Oxyfluorfen 100 g/ha + Imazethapyr 15 g/ha after first and second cutting, replicated thrice. Berseem variety JB 05-9 was sown in the experimental field with recommended package of practices. There was predominance of dicot weeds as compared to monocot in berseem at Jabalpur, Madhya Pradesh. Among the dicot weeds, Medicago truncatula Gaertn. (37.48%) and Cichorium intybus (L.) (27.74%) were predominant. However, other weeds like Cyperus rotundus (L.) (13.79%), Anagallis arvensis (L.) (11.21%) and Chenopodium album (L.) (9.78%) were also present in good numbers. Sowing of berseem in the thermal regimes of 15th October and application of Oxyfluorfen 100 g/ha + Imazethapyr 15 g/ha after first and second cutting was most effective treatment for curbing the growth of weeds as it attained the minimum density and dry weight of weeds during both the years. However, sowing of 15th October with application of Oxyfluorfen 100 g/ha + Imazethapyr 15 g/ha after first cutting recorded the superior values of growth parameters, yield attributing traits, green fodder yield, dry matter yield and seed yield and found more remunerative as it fetched the higher NMR and B:C ratio as compared to other combinations.

Design, synthesis and herbicidal activity of novel cyclohexanedione derivations containing pyrazole and pyridine groups as potential HPPD inhibitors.

4-Hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27; HPPD) is one of the important target enzymes in the development of herbicides. To discover novel HPPD inhibitors with unique molecular, 39 cyclohexanedione derivations containing pyrazole and pyridine groups were designed and synthesized. The preliminary herbicidal activity test results showed that some compounds had obvious inhibitory effects on monocotyledon and dicotyledonous weeds. The herbicidal spectrums of the highly active compounds were further determined, and the compound G31 exhibited the best inhibitory rate over 90% against Plantago depressa Willd and Capsella bursa-pastoris at the dosages of 75.0 and 37.5g ai/ha, which is comparable to the control herbicide mesotrione. Moreover, compound G31 showed excellent crop safety, with less than or equal to 10% injury rates to corn, sorghum, soybean and cotton at a dosage of 225g ai/ha. Molecular docking and molecular dynamics simulation analysis revealed that the compound G31 could stably bind to Arabidopsis thaliana HPPD (AtHPPD). This study indicated that the compound G31 could be used as a lead molecular structure for the development of novel HPPD inhibitors, which provided an idea for the design of new herbicides with unique molecular scaffold.

Weed management in isabgul (Plantago ovata Forsk)

A field experiment was conducted during 2013-14 to 2015-16 at SeedSpice Research Station, S.D. Agricultural University, Jagudan on“Integrated weed management in isabgol ( Plantago ovata Forsk )”. Thesoil was loamy sand in texture, neutral in soil reaction, with low in organiccarbon, medium in available phosphorus and potash. There were tentreatments consisting physical and chemical weed control as well as theirintegration. Weed control treatments affected considerably on growth andyield attributes of isabgol. Whereas, there was no positive impact on testweight. The maximum and minimum values of all the growth and yieldattributes were achieved under treatment when crop was facilitate with twointer-culturing fb hand weeding at 25 and 40 DAS and unweeded controltreatments, respectively. Similarly, Physical method of weed control i.e.Two inter-culturing fb hand weeding at 25 and 40 DAS recordedsignificantly higher seed yield over rest of the treatments. The weeds werecontrolled efficiently resulted in higher seed yield under physical method.Effective removal of weeds throughout the crop growth period better spaceand resources utilization i.e., moisture, nutrients, solar radiation etc. Theadoption of a purely physical method of weed control i.e. treatment T : two9inter-culturing fb hand weeding at 25 and 40 DAS recorded significantlylower sedges, monocot, dicot and total weed count and dry weight ofweeds during investigation. Thus, performing two inter-culturing followedby hand weedings at 20 and 40 DAS produced sustainable and qualityseed yield and maintained the soil health.

Design, Synthesis, and Biological Activity of Novel Phenyltriazolinone PPO Inhibitors Containing Five-Membered Heterocycles.

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX, which is a key step in the synthesis of porphyrins in vivo. PPO inhibitors use protoporphyrinogen oxidase as the target and block the biosynthesis process of porphyrin by inhibiting the activity of the enzyme, eventually leading to plant death. In this paper, phenyl triazolinone was used as the parent structure, and the five-membered heterocycle with good herbicidal activity was introduced by using the principle of substructure splicing. According to the principle of bioisosterism, the sulfur atoms on the thiophene ring were replaced with oxygen atoms. Finally, 33 phenyl triazolinones and their derivatives were designed and synthesized, and their characterizations and biological activities were investigated. The in vitro PPO inhibitory activity and greenhouse herbicidal activity of 33 target compounds were determined, and compound D4 with better activity was screened out. The crop safety determination, field weeding effect determination, weeding spectrum determination, and crop metabolism study were carried out. The results showed that compound D4 showed good safety to corn, soybean, wheat, and peanut but poor selectivity to cotton. The field weeding effect of this compound is comparable to that of the commercial herbicide sulfentrazone. The herbicidal spectrum experiment showed that compound D4 had a wide herbicidal spectrum and a good growth inhibition effect on dicotyledonous weeds. Molecular docking results showed that compound D4 forms a hydrogen bond with amino acid residue Arg-98 in the tobacco mitochondria (mtPPO)-active pocket and forms two π-π stacking interactions with Phe-392. This indicates that compound D4 has stronger PPO inhibitory activity. This indicates that compound D4 has wide prospects for development.

Efficacy of pyroxasulfone and its combinations against weeds in wheat (Triticum aestivum)

A field experiment was conducted during the winter (rabi) season of 2021–22 at the research farm of Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh to study the efficacy of pre-emergence herbicides against weeds in wheat (Triticum aestivum L.). The experiment was laid out in a randomized block design with 3 replications and 8 weed control treatments. Major weed flora in the experimental site, viz. Medicago polymorpha (L.) (28.97%) and Cichorium intybus (L.) (26.19%) were predominant in dicot weeds and in monocot weeds, Phalaris minor (17.82%) was dominant. The weedy check plot had the higher density and dry weight of weeds. Hand weeding (once) was done at 25 DAS (day after sowing) in wheat, reducing weeds density and dry weight to the maximum extent at 40 DAS with a weed control efficiency (WCE) of 92.8%, proving superiority over other treatments. Among the herbicidal applications, pyroxasulfone + metribuzin at 127.5 + 280 g a.i./ha significantly reduced the monocot and dicot weeds density and dry weight, followed by pendimethalin + pyroxasulfone at 1250 + 127.5 g a.i./ha. Pyroxasulfone + metribuzin at 127.5 + 280 g a.i./ha resulted in maximum values of growth parameters, viz. plant height (66.38 cm), number of tillers/m2 (403.14) and yield attributing characters, viz. grains per earhead (51.00) and grain yield (5.65 t/ha) as compared to other herbicidal treatments.