Maize Herbicides Research Articles

Foliar application of phosphoric acid mitigates oxidative stress induced by herbicides in soybean, maize, and cotton crops

Foliar fertilization presents a potential solution in alleviating oxidative stress triggered by herbicide exposure. Enhancing our comprehension of the interplay between foliar fertilization, oxidative stress, and herbicide application is pivotal for enhancing crop yield. Carfentrazone, a herbicide, prompts the buildup of reactive oxygen species, leading to detrimental effects on cell membranes and the manifestation of chlorotic spots on leaves. This research administered carfentrazone-ethyl to soybean, maize, and cotton to induce stress. The herbicide application was followed by foliar application of phosphorus (H3PO4) to evaluate its effect on phytotoxicity recovery. The evaluations included leaf nutritional analyses, gas exchange measurements (photosynthesis, stomatal conductance, substomatal CO2 concentration, and Leaf transpiration), photosynthetic pigments (chlorophylls and carotenoids), oxidative stress indicators (MDA, H2O2, SOD, CAT and APX), and productivity parameters (height, number of branches, pods, grains, 100-grain weight, and yield), in addition to the activity of the enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), which is crucial for carbon fixation and the photosynthetic efficiency of plants. Phosphorus (P) improved chlorophyll levels by up to 28.8% and Rubisco activity by up to 24.8%, leading to increases in the net photosynthetic rate by up to 40.2%, stomatal conductance, water use efficiency, and carboxylation. In addition, foliar P fertilization enhanced antioxidant metabolism, with reductions in markers of oxidative stress (H2O2 and MDA) by up to 39.1%. Collectively, these effects of foliar P fertilization increased the productivity of the three crops by up to 55.9%, indicating that foliar supplementation with P is an effective strategy to mitigate phytotoxicity symptoms.. In soybeans at the V4 and V6 stages, it has been shown to improve net photosynthesis, enhance Rubisco activity, and reduce oxidative stress. In maize, the V4 stage proved to be more effective, increasing Rubisco activity and improving productivity. For cotton, the B1 stage was more beneficial, resulting in increased boll weight and fiber yield. This study introduces an innovative approach of foliar P-supplementation to mitigate herbicide-induced oxidative stress in crops. This management strategy enhances crop resilience, improves yield stability, and provides a sustainable solution to a critical challenge in modern agriculture.

Comparison of soxhlet and microwave‐assisted extractions efficiency for the determination of herbicides in soil and maize crop: Cumulative and health risks assessment

AbstractThe effectiveness of microwave‐assisted extraction (MAE) and Soxhlet extraction (SE) was compared for the determination of herbicides (atrazine, 2.4 dichlorophenoxyacetic acid, mesotrione, and glyphosate) in soil and maize crop followed by gas chromatography with flame ionization detector. The recoveries of herbicides in maize and soil were 62%–80% and 70%–81%, respectively, for SE, whereas they were 80%–98% and 85%–101%, respectively, for MAE. The analysis repeatability, represented as relative standard deviations were <20% for all herbicides in both methods. All the herbicides calibration curves showed a good correlation coefficient (R2) ≥ 0.996, indicating good linearity. The SE limits of detection and quantification ranged between 0.22 and 0.32 µg L−1, and between 2.2 and 3.2 µg L−1, respectively, whereas they were between 0.1 and 0.29 µg L−1, and between 1.0 and 2.9 µg L−1, respectively for MAE. These findings showed that MAE method is more accurate and sensitive than SE, thus can be accurately applied for the determination of the assessed herbicides in soil and maize cop. Herbicides concentrations obtained ranged from 2.7 to 20.4 µg L−1 in maize and from 1.2 to 30.5 µg L−1 in soil samples. The concentrations obtained in maize were higher than the maximum residue limits suggesting that health effect may occur upon continuous consumption. The herbicides toxicity index further confirmed the possible high toxicity effect of the studied maize crop as it exceeded the threshold value of 1. However, the health risk index was lower than 100% limit and did not exceed the acceptable daily intake of the maize crop in both adult and children indicating no health effect.

Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH4, 0.01m sodium citrate and 4g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Regulating pathway for bacterial diversities toward improved ecological benefits of thiencarbazone-methyl·isoxaflutole application: A field experiment

Herbicide abuse has a significantly negative impact on soil microflora and further influences the ecological benefit. The regulating measures and corresponding mechanisms mitigating the decreased bacterial diversity due to herbicide use have rarely been studied. A field experiment containing the application gradient of an efficient maize herbicide thiencarbazone-methyl·isoxaflutole was performed. The relationship between soil bacterial community and thiencarbazone-methyl·isoxaflutole use was revealed. Modified attapulgite was added to explore its impacts on soil microflora under the thiencarbazone-methyl·isoxaflutole application. Based on the analytic network process–entropy weighting method–TOPSIS method model, the ecological benefit focusing on microbial responses was quantitatively estimated along with technical effectiveness and economic benefit. The results showed that the diversity indices of soil microflora, especially the Inv_Simpson index, were reduced at the recommended, 5 and 10 times the recommended dosages of thiencarbazone-methyl·isoxaflutole use. The Flavisolibacter bacteria was negatively correlated with the residues in soils based on the random forest model and correlation analysis, indicating a potential degrader of thiencarbazone-methyl·isoxaflutole residues. The structural equation model further confirmed that the high soil water content and soil pH promoted the function of Flavisolibacter bacteria, facilitated the dissipation of thiencarbazone-methyl·isoxaflutole residues and further improved the diversity of soil microflora. In addition, the presence of modified attapulgite was found to increase the soil pH, which may improve bacterial diversity through the regulating pathway. This explained the high ecological benefits of the treatment where the thiencarbazone-methyl·isoxaflutole was applied at the recommended dosage rates in conjunction with modified attapulgite addition. Therefore, the comprehensive benefits of thiencarbazone-methyl·isoxaflutole application with a focus on ecological benefits can be improved by regulating the soil pH with modified attapulgite.

Fate of herbicides in cropped lysimeters: 2. Leaching of four maize herbicides considering different processes

AbstractThis study investigates the contamination potential of herbicides to groundwater with the help of numerical modeling (HYDRUS‐1D) and stable carbon isotopes for characterizing biodegradation. Four herbicides, metolachlor, terbuthylazine, prosulfuron, and nicosulfuron, were applied over a period of 4.5 years on two lysimeters located in Wielenbach, Germany, and monitored by lysimeter drainage. These lysimeters contained soil cores dominated by sandy gravel (Ly1) and clayey sandy silt (Ly2) and were both cropped with maize (Zea mays). In the preceding study, we characterized flow within the lysimeters by using stable water isotopes and unsaturated flow models. Building up on these findings, models were extended for describing reactive transport of the herbicides and investigating process contributions. At the end of the experiment, 0.9%–15.9% of the applied herbicides (up to 20.9% if including metabolites) were recovered by lysimeter drainage. Metabolite formation and accumulation was observed, and biodegradation was also indicated by small changes in carbon isotope signals (δ13C) between applied and leached herbicides. Model setups could describe the dynamics of herbicide concentrations in lysimeter drainage well. Concentration peaks in drainage were partly also linked with strong precipitation events, indicating preferential flow influence. The soil core with the coarser texture (Ly1) showed less herbicide leaching than the finer texture (Ly2), which can be explained by a larger mobile phase in Ly1. Overall, our approaches and findings contribute to the understanding of multi‐process herbicide transport in the vadose zone and leaching potentials to groundwater, where δ13C can provide valuable hints for microbial degradation.

Weed Dynamics of Fodder Maize as Influenced by Different Herbicides

The advancements in fodder maize cultivation practices over the past few years, has paved a change in the makeup of weed associations. This made it necessary to incorporate new, effective herbicides in the struggle against maize's primary weeds. Therefore, a field experiment was conducted at Research Farm, AICRP on Forage Crops, Department of Agronomy, JNKVV, Jabalpur (Madhya Pradesh) during Kharif season 2019 to devise an appropriate combination of herbicides required for the control of the complex weed diversity in fodder maize. The field experiment was laid out in randomized block design (RBD) with ten treatments (eight herbicidal combinations along with hand weeding twice at 20 and 40 DAS and a weedy check) and replicated thrice. Observations were recorded on the weed parameters and fodder yield of maize. Among monocots, the experimental field was infested with Echinochloa colona, Commelina communis and Digitaria sanguinalis. Phyllanthus niruri and Eclipta alba were dominated among dicots. Among all herbicidal treatment, topramezone 35 g/ha plus atrazine 250 g/ha was found to be significantly superior in reducing total weed density (9.49/m2, 11.50/m2) and total weed dry weight (6.43 g/m2, 7.91 g/m2) at 30 and 45 DAS, respectively and recorded the lowest weed index (1.82%). Also, the maximum green fodder yield (472.68 q/ha) was recorded in topramazone 35 g/ha + atrazine 250 g/ha compared to other treatments. Overall, this study indicated that the combination of topramazone 35 g/ha + atrazine 250 g/ha could be an alternative approach to hand weeding and alone herbicides in fodder maize.

Growth analysis and yield evaluation under tillage and weed management practices in maize-wheat cropping system

Integrated weed management strategies combine tillage systems and weed control strategies. Conservation agriculture (CA) and sustainable intensification cropping systems are potential sources of improved growth and overall productivity. This study evaluated tillage and weed management strategies effects on crop growth parameters and biological yields in maize-wheat cropping system in North Western Himalayan region. Different tillage (five) and weed management practices (three) were evaluated from 2018 to 2020 on growth indices and yield with fifteen treatments. Conservation agriculture (CA) based production system (ZT, zero tillage; crop rotation and intensification; residue management i.e. ZTR-ZTR) had higher crop dry matter accumulation (DMA), relative growth rate (RGR), crop growth rate (RGR) and biological yield of maize (28698 kg/ha) and wheat crops (18750 kg/ha). The zero tillage in maize and wheat (ZT-ZT) resulted in lowest maize (24677 kg/ha) and wheat biological yield (14009 kg/ha. Among weed management treatments, application of recommended herbicides in maize and wheat crop (H-H) resulted in higher crop DMA and biological yield of maize (27652 kg/ha) and wheat crop (19540 kg/ha). Therefore, for North Western Himalayan conditions, ZTR+H-ZTR+H (Conservation tillage combined with herbicide application in maize and wheat) is superior to other combinations for growth and yield.

Management of Weeds in Maize by Sequential or Individual Applications of Pre- and Post-Emergence Herbicides

Weeds impose serious problems in maize (corn) production, resulting in reduced crop yields and lower profits for farmers. The adverse effects of weeds have been attributed to the competition with maize plants for light, water, and nutrients, which can result in reduced growth and yield of the crop. In this context, effective weed management is important to minimize the negative impact of weeds on maize production. This can be achieved through a combination of cultural, mechanical, and chemical control methods. The use of pre-emergence and post-emergence herbicides as sequential or individual applications of these herbicides can be an effective way to manage weeds in maize. Two consecutive field experiments were conducted in 2019 and 2020 in order to determine the efficacy of sequential and individual applications of Dimethenamid-P + Terbuthylazine and Isoxaflutole + Thiencarbazone methyl + Cyprosulfamide as pre- emergence. On the other hand, Mesotrione + Nicosulfuron and Dicamba + Nicosulfuron were used as post-emergence herbicides. The effects of the herbicides were also assayed on corn yield and related parameters. In this regard, we designed the experiment in a randomized complete block design with four replications. Accordingly, the effect of the herbicides varied according to the active ingredients of the herbicide and the weed species. In addition, the effectiveness of herbicides varied according to the assessment times. The lowest effect was found on E. crus-galli, which was obtained from Mesotrione + Nicosulfuron (MN) (35%) plots. Other herbicides showed high efficacy (95–100%). Concerning values of both years, the highest cob length, cob diameter, 1000-grain weight, and plant height were obtained in weed-free control plots and the highest grain yield was obtained in the control plots with weed-free checks as 12.88 tons/ha and 12.37 tons/ha, respectively. The lowest corn grain yield was obtained in weedy control plots in both years. Our findings demonstrate that the combination of pre- and post- emergence herbicides in maize can be an effective way chemical weed control option.

New Perspective on Comparative Chemometric and Molecular Modeling of Antifungal Activity and Herbicidal Potential of Alkyl and Cycloalkyl s-Triazine Derivatives

The contamination of the environment by pesticides is becoming a burning issue in many countries in the World. Development, design, and synthesis of new eco-friendly pesticides and modification of existing ones in order to improve their efficacy with the lowest impact on the environment are two main future possibilities in crop protection and the provision of sufficient food for the growing world population. The present study is focused on the comparative analysis of a series of eight symmetrical triazine derivatives, as potential herbicide candidates with acyclic (alkyl) and cyclic (cycloalkyl) substituents, in terms of their antifungal activity towards Aspergillus flavus as an opportunistic fungal pathogenic microorganism responsible for frequent contaminations of crops with aflatoxin, and in terms of their potential application as herbicides in maize, common wheat, barley, and rice crops. The applied methods include the chemometric pattern recognition method (hierarchical cluster analysis), experimental microbiological analysis of antifungal activity (agar well-diffusion method), and molecular docking of the triazines in the corresponding enzymes. The main findings of the conducted study indicate the significant antifungal activity of the studied triazine derivatives towards A. flavus, particularly the compounds with acyclic substituents; five out of eight studied triazines could be applied as systematic herbicides, while the other three triazines could be used as contact herbicides; the compounds with acyclic substituents could be more suitable for application for various crops protection than triazines with cyclic substituents.

Efficiency of post-emergence herbicides for enhancing growth and yield of hybrid maize (Zea mays) in Kandahar, Afghanistan

A field experiment was conducted at research farm of the Afghanistan National Agricultural Science and Technology University (ANASTU), Kandahar, Afghanistan, in randomized complete- block (RCBD) design during summer 2017, to evaluate the effect of post-emergence (PoE) herbicides in maize (Zea mays L.). Results revealed that sequential application of atrazine @ 1,500 g/ha as pre-emergence followed by (fb) tembotrione @ 120 g/ha as post emergence (PoE) 25 days after sowing (DAS) recorded significantly higher plant height and leaf-area index at 60 and 90 days after sowing (DAS), while dry-matter accumulation and the yield attributes as grains/row, grain/cob and grain weight/cob at harvesting stages. Weed infestation in hybrid maize caused 35.8% yield loss compared to weed-free control. Application of the weed-management treatments increased the maize yield by 35.2% (11.6 – 51.2) over unweeded check. Significantly higher grain yield (6.50 t/ha) was recorded with sequential application of atrazine (1,500 g/ha) as pre-emergence followed by tembotrione (120 g/ha) at 25 DAS, which was at par with pendimethalin (1,000 ml/ha) as pre-emergence followed by atrazine (750 g/ha) + 2,4-D amine (400 g/ha) at 25 DAS as PoE (6.21.3 t/ha) and atrazine (1,500 g/ha) as pre-emergence fb 2,4-D amine (400 g/ha) at 25 DAS (6.12 t/ha). Therefore, the sequential application of pre-and post-emergence herbicides could be opted for enhancing growth and yield and weed control of hybrid maize in Afghanistan and similar ecologies.

Weed management with pre- and post-emergence herbicides in Kharif maize in sub-mountainous area of Punjab, India

Weed management with pre- and post-emergence herbicides in Kharif maize in sub-mountainous area of Punjab, India

Phytotoxicity and allelopathic potential of Juglans regia L. leaf extract.

Implementation of plant extracts that are rich in phytochemicals and have the allelopathic potential for weed management could help reduce the use of chemical herbicides. The present study investigated the herbicidal potential of walnut (Juglans regia L.) leaf extract (WLE) against two weeds, Amaranthus retroflexus L. and Chenopodium album L., by testing in vitro their seed germination and seedling growth, and then evaluated in vivo the oxidative stress of potted plants. The effects of the walnut leaf extract were also tested on maize (Zea mays L.) to eliminate possible negative impacts on a cultivated plant. Total phenolic acids and total flavonoid content in the extract were determined in prior bioassays, followed by separation and analysis of flavonoids and phenolic acids by high-performance liquid chromatography (HPLC). Phytochemical analysis revealed that the obtained extract was notably rich in phenolic compounds, while HPLC analysis confirmed the presence of (+)-catechin, luteolin, myricetin, rutin, (–)-epicatechin, genistin, protocatechuic acid, and caffeic acid as major extract components. The results obtained in bioassays revealed a significant negative impact of the walnut leaf extract on germination and seedling growth of the tested weeds, as well as significant oxidative stress in weeds grown in pots. Although it affected the maize seedling growth in vitro similar to the tested weeds, maize germination was less sensitive to treatment, and the extract did not have a significant negative impact in terms of oxidative stress in maize plants grown in pots. The findings show that walnut leaf extract may have a promising role in replacing chemical herbicides in maize.

Genetic Analysis and Fine Mapping of ZmGHT1 Conferring Glufosinate Herbicide Tolerance in Maize (Zea mays L.).

Weed interference in the crop field is one of the major biotic stresses causing dramatic crop yield losses, and the development of herbicide-resistant crops is critical for weed control in the application of herbicide technologies. To identify herbicide-resistant germplasms, we screened 854 maize inbreed lines and 25,620 seedlings by spraying them with 1 g/L glufosinate. One plant (L336R), possibly derived from a natural variation of line L336, was identified to have the potential for glufosinate tolerance. Genetic analysis validated that the glufosinate tolerance of L336R is conferred by a single locus, which was tentatively designated as ZmGHT1. By constructing a bi-parental population derived from L336R, and a glufosinate sensitive line L312, ZmGHT1 was mapped between molecular markers M9 and M10. Interestingly, genomic comparation between the two sequenced reference genomes showed that large scale structural variations (SVs) occurred within the mapped region, resulting in 2.16 Mb in the inbreed line B73, and 11.5 kb in CML277, respectively. During the fine mapping process, we did not detect any additional recombinant, even by using more than 9500 F2 and F3 plants, suspecting that SVs should also have occurred between L336R and L312 in this region, which inhibited recombination. By evaluating the expression of the genes within the mapped interval and using functional annotation, we predict that the gene Zm00001eb361930, encoding an aminotransferase, is the most likely causative gene. After glufosinate treatment, lower levels of ammonia content and a higher activity of glutamine synthetase (GS) in L336R were detected compared with those of L336 and L312, suggesting that the target gene may participate in ammonia elimination involving GS activity. Collectively, our study can provide a material resource for maize herbicide resistant breeding, with the potential to reveal a new mechanism for herbicide resistance.

Integration of Metabolomics and Transcriptomics for Investigating the Tolerance of Foxtail Millet (Setaria italica) to Atrazine Stress

Foxtail millet (Setaria italica) is a monotypic species widely planted in China. However, residual atrazine, a commonly used maize herbicide, in soil, is a major abiotic stress to millet. Here, we investigated atrazine tolerance in millet based on the field experiments, then obtained an atrazine-resistant variety (Gongai2, GA2) and an atrazine-sensitive variety (Longgu31, LG31). To examine the effects of atrazine on genes and metabolites in millet plants, we compared the transcriptomic and metabolomic profiles between GA2 and LG31 seedling leaves. The results showed that 2,208 differentially expressed genes (DEGs; 501 upregulated, 1,707 downregulated) and 192 differentially expressed metabolites (DEMs; 82 upregulated, 110 downregulate) were identified in atrazine-treated GA2, while in atrazine-treated LG31, 1,773 DEGs (761 upregulated, 1,012 downregulated) and 215 DEMs (95 upregulated, 120 downregulated) were identified. The bioinformatics analysis of DEGs and DEMs showed that many biosynthetic metabolism pathways were significantly enriched in GA2 and LG31, such as glutathione metabolism (oxiglutatione, γ-glutamylcysteine; GSTU6, GSTU1, GSTF1), amino acid biosynthesis (L-cysteine, N-acetyl-L-glutamic acid; ArgB, GS, hisC, POX1), and phenylpropanoid biosynthesis [trans-5-o-(4-coumaroyl)shikimate; HST, C3′H]. Meanwhile, the co-expression analysis indicated that GA2 plants had enhanced atrazine tolerance owing to improved glutathione metabolism and proline biosynthesis, and the enrichment of scopoletin may help LG31 plants resist atrazine stress. Herein, we screened an atrazine-resistant millet variety and generated valuable information that may deepen our understanding of the complex molecular mechanism underlying the response to atrazine stress in millet.

Residues of Reduced Herbicides Terbuthylazine, Ametryn, and Atrazine and Toxicology to Maize and the Environment through Salicylic Acid.

Terbuthylazine (TBA), ametryn (AME), and atrazine (ATZ) are triazine family herbicides. They are dominantly used in the field of cereal crops like wheat and maize for prevention of upland from annual gramineous and broad-leaved weeds, with attributes of weed efficiency broad spectrum and good market performance. Salicylic acid (SA) is a kind of natural plant growth regulator existing widely in the plant kingdom and participating in many physiological and defense processes. In this study, the effects of SA on the detoxification and degradation of herbicides TBA, AME, and ATZ in maize were investigated. When maize plants were exposed to 6 mg kg–1 of the triazine herbicides, the growth and chlorophyll concentration were reduced, while the membrane permeability increased. After maize was sprayed with 5 mg kg–1 SA, the herbicide-induced phytotoxicity was significantly assuaged, with the increased content of chlorophyll and decreased cellular damage in plants. Activities of several biomarker enzymes such as SOD, POD, and GST were repressed in the presence of SA. The concentration of the triazine herbicides in maize and the soil determined by high-performance liquid chromatography was drastically reduced by spraying SA. Using LC/Q-TOF-MS/MS, six metabolites and nine conjugates of AME in maize and soil were characterized. The relative contents of AME metabolites and conjugates in maize with SA were higher than those without SA. These results suggest that SA is able to promote the detoxification and decay of these triazine herbicides in maize and soil.

​​Preceding Maize Crop Herbicide Residual Effect on Germination, Growth and Vigour of Succeeding Blackgram

Background: Weeds are the most critical pest, which cause the highest yield reduction in food grain crops. Weeds interfere with maize growth by competing one or more growth limiting factors, controlling of weeds in maize during the critical period assumes great importance for realizing higher yield. Unavailability of relatively cheap labour in time necessitated the use of herbicides in maize. Residual impact of herbicides caused significant influence on germination and growth of succeeding crop. Methods: The field experiment was carried out during kharif 2019 at Agricultural College and Research Institute, Madurai to evaluate the residual effect of herbicides used in preceding maize on succeeding blackgram. Treatments were application of pre emergence herbicide atrazine at 0.25 kg ha-1 or pendimethalin 1 kg ha-1 applied singly on 3 days after sowing and in combination with post emergence herbicide tembotrione 120 g ha-1 or halosulfuron methyl 90 g ha-1 on 25 DAS, weed free check, unweeded check in maize crop. Result: Among the weed control treatments, pre emergence herbicides atrazine 0.25 kg ha-1 or pendimethalin 1 kg ha-1 singly and in combination with post emergence herbicides tembotrione 120 g ha-1 or halosulfuron methyl 90 g ha-1 applied in maize crop did not caused any phyotoxicity and residual impact on succeeding blackgram. However, the highest plant height (29.5 cm), dry matter production (1.17 g plant-1) and seedling vigour index (1473) of succeeding blackgram was recorded in atrazine at 0.25 kg ha-1 as pre emergence at 3 DAS followed by tembotrione at 120 g ha-1 as post emergence at 25 DAS.

Efficiency of post-emergence herbicide for enhancing yield attributes, yield, and economics of hybrid maize (Zea mays L.)

An experiment was conducted at the research farm of National Agricultural Science and Technology University (ANASTU), Kandahar, Afghanistan in a randomized complete block (RCBD) during the summer season of 2017 to evaluate the effect of post-emergence herbicides in maize. The experiment consisted of ten treatments and was replicated thrice. Among the weed control treatments, sequential application of atrazine @ 1.5 kg/ha pre-emergence followed by tembotrione 120 g/ha as PoE at 25 DAS recorded significantly higher grain row-1 (36.18), the number of grain cob-1 (502.48), and Grain weight cob-1 (137.63 g). Significantly higher grain and stover yield (6.7 and 11.6 t ha-1) were recorded in weed-free check plot which is on par with (T10) atrazine @ 1.5 kg/ha pre-emergence fb tembotrione 120 g /ha PoE at 25 DAS (6.5 and 11.4 t ha-1) and (T9) pendimethalin (1000 ml/ha) pre-emergence fb atrazine (750 g/ha) + 2,4-D Amine 0.4 kg /ha at 25 DAS as PoE (6.2 and 11.0 t ha-1). The benefit-cost ratio was higher (1.57) in the sequential application of Atrazine 1.5 kg/ha fb 2,4-D Amine 0.4 kg/ha at 25 DAS as PoE, which was on par with Pendimethalin (1000 ml/ha) pre-emergence fb Atrazine (750 g/ha) + 2,4-D Amine 0.4 kg/ha at 25 DAS as PoE and (T7) Atrazine @ 1.5 kg/ha pre-emergence fb Halosulfuron67 g/ha 25 DAS.

Effectiveness of systems of herbicides in maize cultivated at conditions of tipical Chernozem

In 2017 and 2018 is displayed on at temp by block method with 9 herbicides in the experimental field of the Institute of maize in Knezha. The study is performed with a maize hybrid Knezha 613 – group 500-600 by FAO, cultivated without irrigation. Five systems of herbicides were studied, which includes five soil preparations: Adengo 465SC (isoxaflutole + tiencarbazon-metil) at a dose 35 ml/da; Merlin Flex 480SC (isoxaflutole) at a dose 42 ml/da; Spectrum (dimetenamid-P) at a dose 140 ml/da; Gardoprim plus gold (S-metolachlor + terbutilazin) at a dose 450 ml/da and Dual gold 960EK (S-metolaclor) at a dose 150 ml/da. The study includes also 4 foliar preparations, applied in a phase fourth-fifths leaf of the crop, after the soil products: Elumis (nicosulfuron + mezotrion) at a dose 200 ml/da; Aminopielic 600SL (2,4-D) at a dose 120 ml/da; Lumax (S-metolachlor + terbutilazin + mezotrion) at a dose 300 ml/da; Maton 600EK (2,4-D-ester) at a dose 110 ml/da. Of the tested systems of herbicides with highest efficacy is the system of Dual gold 960EK + Elumis, which reduced the sensitive weeds with 96,6%.

Comparative effect of weed control methods on Mexican sunflower (Tithonia diversifolia) in maize

Mexican sunflower management in arable crops is becoming increasingly important due to its prevalent growth habit. The field experiments were conducted to compare weed suppressive abilities of two cover crops and two maize herbicides on Mexican sunflower. The treatments consist of the pre-emergence application of Primextra Gold (atrazine + metolachlor) at 4 l/ha, a post-emergence application of Aminoforce (2, 4-D) at 1.6 l/ha, two cover crops, Centrosema pubescens (Centro) at 2.5 kg/ha and Pueraria phaseoloides (Puero) at 2.0 kg/ha, hand weeding at 2 and 5 weeks after sowing (WAS) and no weeding. The experimental design was a randomized complete block design with four replications. Pre-emergence herbicide produced taller plants at 8 and 12 WAS and higher number of leaves at 12 WAS. Despite two hand weedings (at 2 and 5 WAS), the weed biomass of hand weeding treatment was not different from no weeding. Higher weed densities produced by hand weeding and no weeding at 12 WAS indicated that the two herbicides and the two cover crop treatments gave better weed control than both weed checks. Weed control was 4, 7 and 8 times better in pre-emergence, post-emergence and Centro; respectively, than no weeding at 8 WAS. Although Centro provided long term weed control, the herbicides were able to provide early protection for the maize plants. The highest maize yield of 2.21 t/ha obtained from Primextra Gold (atrazine + metolachlor) at 4l/ha was significantly higher than yields from the other treatments. Yield reduction of 24.5, 27.7, 34.4, 40.8 and 94.2% was obtained in 1.6 l/ha Aminoforce, Centro, hand weeding, Puero and no weeding, respectively, when compared to maize yield from Primextra Gold. Key words: Mexican sunflower, cover crops, herbicides, hand weeding, weed control.

Selective and Sensitive Quantification of Acetochlor and S-Metolachlor in Maize and Soybean Plant Samples by Gas Chromatography-Tandem Mass Spectrometry

Herbicide residue analysis has gained importance worldwide, mainly for food quality control to minimize potentially adverse impacts on human health. A Gas chromatography-tandem mass spectrometry (GC-MS) method for quantitative analysis of acetochlor and s-metolachlor in maize and soybean straw has been developed, validated and applied to analyze the residues of anilide herbicides. Straw material was dried, homogenized and extracted with a mixture of n-hexane and acetone by an accelerated solvent extraction method. Chromatographic separation of the target analytes was performed on an Agilent 7832 GC equipped with a mass spectrometer detector, a split-splitless injector and an HP-5 MS (5% phenylmethyl siloxane) capillary column (30 m × 0.25 mm × 0.25 µm). Under these parameters, the limit of detection (LOD) values were 0.2 ng g−1 for acetochlor and 0.07 ng g−1 for s-metolachlor, with average recoveries between 86% and 119.7%. The method was validated for acetochlor and s-metolachlor in maize and soybean straw at 0.5 and 0.01 mg kg −1. Furthermore, the final residues of the two herbicides in maize and soybean straw were below the maximum residue limit (MRL) at harvest time. The proposed method is suitable for routine analysis.