Phytotoxicity Of Herbicides Research Articles

Multiomics Analysis of the Mechanism by Which Gibberellin Alleviates S-Metolachlor Toxicity in Rice Seedlings.

S-metolachlor is a selective pre-emergence herbicide used in dryland. However, it is challenging to employ in paddy fields due to its phytotoxic effects on rice. As a common phytohormone, Gibberellin-3 (GA3) is inferred to have the ability to alleviate herbicide phytotoxicity. This study first quantitatively verified the phytotoxicity of s-metolachlor to rice and then demonstrated the mitigative effect of GA3 on these adverse reactions. Furthermore, a transcriptome of rice seedlings subjected to different treatments was constructed to assemble the reference genes, followed by comparative metabolomics and proteomics analyses. Metabolomics revealed an enrichment of flavonoid metabolites in the group of adding GA3, and these flavonoids can eliminate ROS in plants. Proteomics analysis indicated that differential proteins were enriched in the phenylpropanoid biosynthesis pathway responsible for the synthesis of flavonoids and that the functions of most differential proteins are associated with peroxidase. The proteome, combined with the transcriptome, revealed that the expressions of proteins and genes was related to the POD activity in the group of adding GA3. It was speculated that the elimination of ROS is key to alleviating the stress of s-metolachlor on rice growth. It was inferred that the mechanism of GA3 in alleviating the phytotoxicity of the substance s-metolachlor is by increasing the activity of the POD and influencing the growth of rice seedlings through the restoration of flavonoid synthesis. In this study, we screened GA3 as a safener to alleviate the phytotoxicity of s-metolachlor on rice. On this basis, the mechanism of alleviating phytotoxicity was studied. The application range of s-metolachlor might be expanded, providing a new supplementary method for weed control and herbicide resistance management.

Bio-Efficacy of Pre-and Post-Emergence Herbicides on Growth, Productivity, Nodulation of Black Gram (Vigna mungo L.) under Coastal Plain of Odisha

Background: Weeds compete with plants for resources during cultivation and the control of weeds during the critical period of crop-weed competition is crucial to avoid yield loss ranging from 50%-90% in black gram. The first 4-5 weeks are critical for black gram crop-weed competition. The composition of weed flora, the duration of crop-weed competition and its intensity significantly impact yield losses in black gram cultivation. Therefore, the current study aims to evaluate weed management practices in rabi black gram, with a focus on identifying herbicides that enhance weed control, increase productivity and profitability. Methods: A field experiment was conducted during the rabi season of 2021-2022 and 2022-2023 consecutively at Odisha University of Agriculture and Technology, Bhubaneswar. The field experiment comprised of eight treatments on different herbicide applications as T1- Fenoxaprop-p-ethyl @ 65 g a.i. ha-1, T2- Quizalofop-p-ethyl @ 50 g a.i. ha-1, T3-Cyhalofop-butyl @ 75 g a.i. ha-1, T4-Pendimethalin @ 750 g a.i. ha-1, T5- Oxyflourfen @ 50 g a.i. ha-1, T6- Tembotrione @ 120 g a.i. ha-1, T7- Weed check (control) and T8- Weed free, which was laid under randomised block design. Collected samples were analyzed in the field and laboratory for crop-weed competition, herbicide phytotoxicity and yield attributes. Result: The results revealed that weed-free treatment recorded the lowest weed population (5.27-5.45), weed dry weight (1.35g-2.20 g) and lowest weed index (0.00%) at all growth stages followed by pendimethalin (PE) application. Among yield attributes, weed-free treatment recorded the highest plant height (cm) which was at par with pendimethalin (PE) followed by cyhalofop-butyl (PoE) application. The magnitude of seed yield was increased under weed-free (1035.46 kg ha-1) and pendimethalin (PE) and cyhalofop-butyl (PoE) applications by 53.62% and 48.40%, respectively over the weedy check. Application of tembotrione recorded the highest herbicide phytotoxicity (5.3-7.6) over the rest of the treatments. It can be concluded that the application of pendimethalin 30 EC 750 g ha-1 as PE at 2 DAS followed by cyhalofop-butyl 10 EC 75 g ha-1 can be advisable for better weed control, lower herbicide phytotoxicity and higher yield.

Effect of Different Herbicides on Development and Productivity of Sweet White Lupine (Lupinus albus L.)

White lupine (Lupinus albus L.) is a well-known green manure crop in Hungary, but the production of seeds can be badly impacted by weeds. The sweet white lupine ‘Nelly’ was grown on acidic sandy soil, and experimental plots were treated with different herbicides. Flumioxazin (0.06 kg ha−1), pendimethalin (5 L ha−1), dimethenamid-P (1.4 L ha−1), pethoxamid (2 L ha−1), clomazone (0.2 L ha−1), metobromuron (3 L ha−1), and metribuzin (0.55 L ha−1) were applied pre-emergence (1–2 days after sowing). Imazamox was also tested and applied post-emergence (1 L ha−1) when some basal leaves were clearly distinct (BBCH 2.3). In this paper, the weed control efficiency and the phytotoxicity of herbicides applied to lupine are examined. Vegetation index datasets were collected 12 times using a manual device and 2 times using an unmanned aerial vehicle (UAV). The phytotoxicity caused by herbicides was visually assessed on several occasions throughout the breeding season. The frequency of weed occurrence per treatment was assessed. The harvested seed yields, in kg ha−1, were analyzed after the seeds were cleaned. The herbicides metribuzin and imazamox caused extensive damage to white lupine. While pendimethalin, dimethenamid-P, pethoxamid, and clomazone were outstanding in several measured indicators, the final ranking which summarizes all the variables showed that only the pethoxamid and clomazone treatments performed better than the control. Metribuzin and imazamox were highly phytotoxic to white lupine. In the future, it would be appropriate to integrate more post-emergence active substances into trials, and the pre-emergence herbicides involved in this study should be further tested.

Herbicide Safeners: From Molecular Structure Design to Safener Activity.

Herbicide safeners, highly effective antidotes, find widespread application in fields for alleviating the phytotoxicity of herbicides to crops. Designing new herbicide safeners remains a notable issue in pesticide research. This review focuses on discussing and summarizing the structure-activity relationships, molecular structures, physicochemical properties, and molecular docking of herbicide safeners in order to explore how different structures affect the safener activities of target compounds. It also provides insights into the application prospects of computer-aided drug design for designing and synthesizing new safeners in the future.

Effect of Plant Growth-Promoting Bacteria on Antioxidant Status, Acetolactate Synthase Activity, and Growth of Common Wheat and Canola Exposed to Metsulfuron-Methyl.

Metsulfuron-methyl, a widely used herbicide, could cause damage to the sensitive plants in crop-rotation systems at extremely low levels in the soil. The potential of plant growth-promoting bacteria (PGPB) for enhancing the resistance of plants against herbicide stress has been discovered recently. Therefore, it is poorly understood how physiological processes occur in plants, while PGPB reduce the phytotoxicity of herbicides for agricultural crops. In greenhouse studies, the effect of strains Pseudomonas protegens DA1.2 and Pseudomonas chlororaphis 4CH on oxidative damage, acetolactate synthase (ALS), enzymatic and non-enzymatic antioxidants in canola (Brassica napus L.), and wheat (Triticum aestivum L.) were investigated under two levels (0.05 and 0.25 mg∙kg-1) of metsulfuron-methyl using spectrophotometric assays. The inoculation of herbicide-exposed wheat with bacteria significantly increased the shoots fresh weight (24-28%), amount of glutathione GSH (60-73%), and flavonoids (5-14%), as well as activity of ascorbate peroxidase (129-140%), superoxide dismutase SOD (35-49%), and ALS (50-57%). Bacterial treatment stimulated the activity of SOD (37-94%), ALS (65-73%), glutathione reductase (19-20%), and the accumulation of GSH (61-261%), flavonoids (17-22%), and shoots weight (27-33%) in herbicide-exposed canola. Simultaneous inoculation prevented lipid peroxidation induced by metsulfuron-methyl in sensitive plants. Based on the findings, it is possible that the protective role of bacterial strains against metsulfuron-metil is linked to antioxidant system activation.

Rationalizing Herbicide Use in Maize within the Framework of Climatic Change and Extreme Hydrometeorological Phenomena

The aim of this study was to investigate specific management methods for controlling weeds under different climate conditions by reducing the risk of herbicide resistance in maize. Herbicide trials were placed at two locations during 2017 and 2018 and organized in a randomized block design with four replicates of all herbicide combinations (terbuthylazine—pre-emergence and mesotrione post-emergence treatment, terbuthylazine + mesotrione in post-emergence treatment, and terbuthylazine—pre-emergence and dicamba in post-emergence treatment). In the trials, 13 specific weeds were observed. High effectiveness was achieved when using commercial preparations with two active ingredients (terbuthylazine and mesotrione) in both years of research. As the year 2018 featured a higher amount of precipitation, uneven weed sprouting occurred, which resulted in a large number of Setaria glauca (18.50 No m−2), Solanum nigrum (16.50 No m−2), Datura stramonium (13.75 No m−2), and Chenopodium hybridum (10.50 No m−2) plants. Herbicide phytotoxicity was not expressed in maize. Ambrosia artemisiifolia, Solanum nigrum, and Datura stramonium had the highest competitive index (CI 10). The highest maize yield was observed under the application of terbuthylazine + mesotrione in post-emergence (14.223 t/ha). This combination led to the highest weed control costs (35.60 EUR/ha) in 2018, while in 2017, the yield was 12.829 t/ha, with a control cost of 33.99 EUR/ha.

Review on the Discovery of Novel Natural Herbicide Safeners.

The phytotoxicity of herbicides on crops is a major dilemma in agricultural production. Fortunately, the emergence of herbicide safeners is an excellent solution to this challenge, selectively enhancing the performance of herbicides in controlling weeds while reducing the phytotoxicity to crops. But owing to their potential toxicity, only a tiny proportion of safeners are commercially available. Natural products as safeners have been extensively explored, which are generally safe to mammals and cause little pollution to the environment. They are typically endogenous signal molecules or phytohormones, which are generally difficult to extract and synthesize, and exhibit relatively lower activity than commercial products. Therefore, it is necessary to adopt rational design approaches to modify the structure of natural safeners. This paper reviews the application, safener effects, structural characteristics, and modifications of natural safeners and provides insights on the discovery of natural products as potential safeners in the future.

Response of soybean cultivars with different maturation times to pre-emergence herbicides

Herbicide selectivity is the basis for chemical control of weeds; however, it depends on the interactions between herbicide, crop, and edaphoclimatic conditions. The objective of this work was to evaluate the selectivity of herbicides applied at the pre-emergence stage of soybean cultivars with different maturation times grown in different locations. The experiment was conducted under field conditions, in two crop seasons (2019/2020 and 2020/2021), in Lages and Curitibanos, state of Santa Catarina, Brazil. A randomized block experimental design was used, with treatments organized in 4×3 (2019/2020) and 4×4 (2020/2021) factorial arrangements, with four replications. The treatments consisted of interactions between four soybean cultivars: BMX Raio IPRO® (Raio), BMX Zeus IPRO® (Zeus), MONSOY 5947 IPRO® (Monsoy), and BMX Fibra IPRO® (Fibra) and three or four herbicide treatments: control with no herbicides, sulfentrazone + diuron, and diclosulam in 2019/2020; and control with no herbicide, sulfentrazone + diuron, diclosulam, and pyroxasulfone + flumioxazin in 2020/2021. The plots were evaluated for phytotoxicity of herbicides, canopy closure, plant height, stand of plants, number of pods per plant, one-thousand grain weight, and grain yield. The phytotoxicity of herbicides on the soybean plants was mild, under 11%, regardless of the cultivar and growth location. The soybean plants fully recovered from the injuries at 14 days after herbicide application. In Curitibanos, the cultivar Zeus presented higher grain yield in both crop seasons. The herbicide factor showed that sulfentrazone + diuron and diclosulam decreased the grain yield of the cultivars Raio and Zeus in 2019/2020. In the following crop season, only the cultivar Raio presented decreases in grain yield due to the application of diclosulam and pyroxasulfone + flumioxazin. In Lages, the soybean cultivar factor affected the grain yield; the cultivars Monsoy and Fibra were the most productive.

The phytotoxicity of soil-applied herbicides is enhanced in the first-year post strategic deep tillage

The sandplain soils of WA are inherently fragile with surface layers that are very low in organic matter and clay content. The advent of minimum- and no-till farming has seen the increase in frequency and intensity of cropping on these soils. However, a combination of soil physio-chemical constraints and agronomic issues remain a challenge to the sustainability of cropping systems on them. These constraints include sub-soil compaction, soil water repellence, sub soil acidity and herbicide resistant weeds. Strategic deep tillage such, as soil inversion and deep soil mixing, have been shown to ameliorate these multiple constraints and dramatically increase crop production. For WA soils, an increase in herbicide usage is correlated with a decrease in regular tillage, and how the two interact is imperfectly understood. As a result, current herbicide strategies and rates are designed to perform optimally in a minimum tillage environment. Two field experiments were established to compare crop damage from a range of commonly used pre-emergent herbicides when grown in soil that remained under minimum tillage, was deep mixed or inverted. These trials demonstrated that both strategic tillage methods significantly changed the soil surface composition that would be expected to directly affect the bioavailability of some herbicides. Two commonly used herbicides, Metribuzin and Diuron, detrimentally impacted crop performance following tillage in both trials. These same treatments reduced yield by a greater extent on both the soil inversion and deep mixing treatments (p < 0.001). No other herbicides, when applied at either label or triple label rates, significantly impacted yield on any of the soil treatments. There was a substantial crop production benefit from strategic deep tillage at Esperance but not at Geraldton. These results reflect that the influence of deep tillage on the toxicity of herbicides is highly dependent upon soil properties and rainfall.

Eucalyptus and Ipomoea nil phytotoxicity after herbicide application

The presence of weeds in forest estates is considered one of the biggest problems in the implantation, maintenance, and renovation of eucalyptus plantations. This research aims to evaluate the phytotoxicity of herbicides on eucalyptus and I. nil. The experiment was installed inside a greenhouse in a completely randomized design with five replications. The treatments consisted of the application of 0.2% (v/v) adjuvant with the herbicides: atrazine (2250 g i.a. ha-1), clomazone (720 g i.a. ha-1), sulfentrazone (600 g i.a. ha-1), glyphosate (1440 g i.a. ha-1), and control. The following variables were analyzed: electron transport rate (ETR), water consumption, and plant phytotoxicity. For I. nil plants treated with atrazine, it was possible to detect phytotoxicity previous to the appearance of symptoms in the visual analysis, due to the inhibition of ETR at 24 hours after application (HAA). The highest levels of phytotoxicity for eucalyptus and I. nil were obtained by glyphosate and sulfentrazone, respectively.

Фотосинтетична активност и продуктивност на царевица (Zea mays L.), изложена на симулиран дрифт oт хербицида имазамокс и лечебно приложение на протеинови хидролизати

The use of herbicides is а traditional method for weed control in crop-producing systems. Along with the high effective weed control, herbicides might cause phytotoxicity for crop plants, due to insufficient herbicide selectivity, combining herbicide treatment with unsuitable meteorological conditions, long-term persistence of herbicide in the soil or off-target transfer of the herbicide – drift. Imazamox is a selective herbicide of imidazolinone group, used to control annual and perennial weeds in imidazolinone-resistant (IMI-R) crops. Protein hydrolysates (PHs) are a group of plant biostimulants containing small peptides and free amino acids, reported to ameliorate plant abiotic stress tolerance, including herbicide phytotoxicity. This report evaluates the damaging effect of simulated imazamox drift on growth, photosynthetic performance and productivity of maize plants as well as the efficiency of foliar application by protein hydrolysates as therapy means. The received results demonstrated that the simulated imazamox herbicide drift has a strong inhibiting effect on maize plants. This is well illustrated by the retarded growth of maize plants, their disrupted photosynthetic activity and productivity losses. The foliar supply of PHs to imazamox damaged maize plants ameliorates their photosynthetic performance, growth and crop productivity.

Борьба с засорителем посевов масличного льна – имидазолиноноустойчивым подсолнечником

The research was conducted in 2020-2022 to find effective ways of controlling the volunteer plants of imidazolinone-resistant sunflower in oil flax sowings, providing high biological and economic efficiency, crop yield, and seed quality on leached chernozem in natural and climatic conditions of the Western Ciscaucasia. We studied methods of chemical protection of oil flax with tank mixtures of herbicide combinations: anticotyledonous contact herbicide Basagran, WS and systemic herbicide Cleo, WDG, Sekator Turbo, OD, and graminicide Zellek-super, EC. We used established methods for field agronomic experiments with oil crops. Seeds of imidazolinone-resistant sunflower hybrid were evenly sown on the experimental plot to simulate the volunteer plants. The phytotoxicity of herbicides on sunflower plants was evaluated using a 9-point EWRC scale. The tank mixtures Basagran,WS (4 l/ha) + Zellek-super, EC (1.0 l/ha) and Basagran, WS (4 l/ha) + Sekator Turbo, OD (0.1 l/ha) + Zellek-super, EC (1.0 l/ha) do not provide ef-fective control of the volunteer plants and are not recommended for use. The composition Basagran, WS (4 l/ha) + Cleo, WDG (0.12 kg/ha) + Zellek-super, EC (1.0 l/ha) provides destruction of the volunteer plants, contributing to higher yield and oil content of seeds, but it is very expensive and decreases the laboratory germinating ability of flax seeds, so it cannot be used in industrial seed production. A tank mixture of Cleo, WDG (0.12 kg/ha) + Sekator Turbo, OD (0.1 l/ha) + Zellek-super, EC (1.0 l/ha) has lower cost, provides high herbicidal effectiveness against the volunteer plants of imidazolinone-resistant sunflower, contributes to obtaining a high yield, oil content and laboratory germination of oil flax seeds and is recommended for use both in industrial seed production and in the production of commercial seeds.

Current Advances in the Action Mechanisms of Safeners

Herbicide safeners are a series of agrochemicals that can selectively protect crop plants from herbicide injury without affecting herbicidal efficacy. Understanding mechanisms by which safeners act is significant for discovery of novel types. Safeners primarily alleviate herbicide phytotoxicity to crop plants via several actions: (i) enhancing metabolism of herbicides in crops; (ii) affecting absorption and transportation of herbicides in crops; (iii) competitively binding to herbicide target sites; and (iv) affecting activity of target enzymes. This review describes recent advances in the action mechanisms of safeners, analyzes existing problems, anticipates the future direction of studies of modes of action of safeners, and prospects potential strategies to design safeners related to their reported mechanisms. The aim of this paper is to provide insight into mechanisms of safeners and give tips for development of new safeners.

Environmental-friendly hydrochar-montmorillonite composite for efficient catalytic degradation of dicamba and alleviating its damage to crops

In recent years, carbon-based materials catalyzing peroxymonosulfate (PMS) for green degradation of persistent organic pollutants have attracted increasing attention. However, PMS activation by hydrochar composite (e.g. hydrochar-montomorillonite) has rarely been investigated. Herein, a simple preparation, low-cost and eco-friendly catalyst of hydrochar-montmorillonite composite (HC-Mt) was prepared to firstly catalyze PMS for the degradation of dicamba (DIC). The as-prepared HC-Mt showed a remarkably better catalyzing performance for PMS than pure hydrochar (HC) due to its good physicochemical characteristics and abundant oxygen-containing groups. Furthermore, the electron spin resonance (ESR) and quenching tests revealed that active species such as SO4–, OH and O2– all participated in the degradation process. DIC sites on C6, Cl 10, and O15 exhibited higher reactivity according to the density functional theory (DFT) calculation, which were easily attacked by active species. The DIC degradation mainly occurred via hydroxyl substitution, decarboxylation, oxidation and ring-cleavage and finally most of the intermediates were mineralized into CO2 and H2O. Finally, the phytotoxicity assessment was measured by the germination growth situation of tobacco and mung beans in the presence of DIC (with or without treatment by HC-Mt/PMS). The result showed that HC-Mt/PMS could significantly reduce the phytotoxicity of DIC to crops, suggesting that catalyzing PMS using HC-Mt was environmentally friendly. Therefore, this work did not only provide a novel catalyzing PMS strategy using hydrochar composite for wastewater treatment, but also give a new idea for herbicide phytotoxicity management.

Triangular Greenness Index to Evaluate the Effects of Dicamba in Soybean

Significant losses in agricultural production are due to abiotic stresses, such as herbicide phytotoxicity. Dicamba (diglycolamine salt) is a herbicide used for post-emergent control of broadleaf weeds. It has a possibility to vapor-spread into neighboring fields causing damage to other crops. However, not every stress can be easily identified. Therefore, remote sensing has the potential as a new tool in early injury detection. This study evaluated the effects of simulated dicamba drift on the occurrence of phytotoxicity in soybeans (Glycine max). Soybean was assessed in seven dicamba doses (0, 0.056, 0.56, 5.6, 11.2, 28, 112 g ha−1) for changes in plant injury (scale of notes), spectral aspects (triangular greenness index (TGI), and shoot dry mass. The plants were photographed using a digital camera positioned at 1.2 m above the planting media level. The results indicate a positive effect of low dicamba doses (0.56 and 0.056 g a.e. ha−1) on TGI canopy distinction and shoot dry mass. Soybean TGI canopy distinction and the injury scale estimated at 45 days after sowing, and the soybean shoot dry mass observed at 99 days after sowing, presented significant and moderate Pearson’s r coefficient of correlations (r = −0.609 and 0.625), indicating TGI as a valid and practical spectral index for plant dicamba-injured evaluations.

Effects of Different Environment-Friendly Gibberellic Acid Microcapsules on Herbicide Injury of Wheat.

Environmentally friendly microcapsules are becoming more and more widely used due to the increasing demand for environmental safety in pesticides. To compare the impact of differences in wheat herbicide phytotoxicity of different gibberellic acid microcapsule suspensions, two microcapsule suspensions were separately formulated using the phase transfer method and the in situ polymerization method, and the key performance indicators are the size of microcapsules and the degree of encapsulation. Meanwhile, through field trials, the pharmacological and detoxification effects of different types of microcapsule suspensions on the herbicide methyldisulfuron in wheat fields were compared. The microcapsule suspension was prepared by the phase transfer method and the particle sizes D10, D50, and D90 are 0.990, 2.136, and 5.201 μm, respectively; the microcapsule suspension was prepared by the in situ polymerization, the particle sizes D10, D50, and D90 are 4.365, 8.547, and 16.782 μm, respectively. The encapsulation rate of the microcapsules prepared by the phase transfer method and the in situ polymerization method was 86.9% and 91.2%, being higher than 80%, the national standard for capsules. Meanwhile, the release rate conforms to first-order release kinetics in 0–4 days and zero-order release kinetics in 5–28 days. The plot trials' result showed that the detoxification effect of the microcapsules prepared by the in situ polymerization method was significantly better than the detoxification effect of the microcapsules prepared by the phase transfer method and the control agent. The growth index of wheat was higher than that of the untreated check after using the agent.

Enantioselective Response of Wheat Seedlings to Imazethapyr: From the Perspective of Fe and the Secondary Metabolite DIMBOA.

The responses of trace elements and secondary metabolites to stress can reflect plant adaptation to the environment. If and how the imperative trace element Fe and the defensive secondary metabolite 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazine-3(4H)-one (DIMBOA) mediate the toxicity of chiral herbicides to nontarget plants remains inconclusive. We found that the herbicidal-active imazethapyr enantiomer [(R)-IM] stimulated heme oxygenase-1 activity, triggered the release of the catalytic product Fe2+, increased reactive oxygen species production, decreased the DIMBOA content, and increased the DIMBOA-Fe content. XAFS analyses and in vitro Fenton assays demonstrated that DIMBOA could relieve phytotoxicity by chelating excessive Fe3+ to restore Fe homeostasis. The free radical scavenging ability of the chelate of DIMBOA and Fe was also involved. This work refines the dual role of DIMBOA and Fe in mediating the enantioselective phytotoxicity of chiral herbicides, which provides a new direction for improving the herbicide resistance of crops.

Vegetation analysis and the effectiveness of methyl metsulfuron herbicide to control weeds in immature oil palm plantation

One of the obstacles faced in oil palm cultivation, especially in the immature plant phase, is weeds, weeds can inhibit oil palm growth. So that weeds require special attention during cultivation, the presence of these weeds will become competitors for oil palm plants in fulfilling nutrients, light and water. This study aims to determine the composition of the types and vegetation structure of weeds in immature oil palm plants in large plantations so that the dose of herbicide with active ingredient Methyl Metsulfuron 20% is effective in controlling weeds in immature oil palm plantations in large plantations and studying the phytotoxicity of herbicides made from 20% active Methyl Metsulfuron in immature oil palm trees in large plantations. This study used a randomized block design (RBD), which consisted of 7 levels of treatment, 5 of which used the herbicide methyl metsulfuron 20% at a dose of 87.50 g / ha, 75.00 g / ha, 62.50 g / ha, 50.00 g / ha, 37.50 g / ha. ha and 2 including mechanical and control weeding which is repeated 4 times. Data analysis was performed with the F test, followed by the DMRT test at 5% level. The results showed that there were two species of weeds that dominated the research area, namely B. mutica and A. gangetica weeds with SDR values of 33.13% and 24.73%. The application of herbicides made from 20% methyl metsulfuron as active ingredients in controlling weeds in immature oil palm plantations is able to control 2 types of weeds, namely weeds including Melastoma malabathricum, Clidemia hirta with the best dose of 50.00 g / ha and 37.50 g / ha from the first 4 weeks up to 12 Weeks After Application (MSA).

Does the application of herbicides with distinct mechanisms of action change enzymatic activity and grain yield of Clearfield® canola?

Herbicides have a high potential for phytotoxicity and generate oxidative stress, even on tolerant crops. The canola hybrid Hyola 571 CL obtained through Clearfield® technology shows tolerance to imidazolinones. Given the importance of this hybrid, this work assessed the effect of using herbicides with different mechanisms of action on the activity of antioxidant enzymes, ALA-D, gas exchange, and grain yield of canola hybrid tolerant to imidazolinones. Treatments applied to Hyola 571 CL canola hybrid were: control without herbicides, diclosulam, imazaquim, sulfentrazone, sulfentrazone + diuron pendimenthalin, flumioxazin, imazethapyr + imazapic, imazapic + imazapyr, imazethapyr, imazamox, nicosulfuron, chlorimuron, netsulfuron-methyl, iodosulfuron, and pyroxsulam. Seven, 14, 21, and 28 days after application we assessed herbicide phytotoxicity to canola. Antioxidant enzyme systems, variables related to plant physiology, and grain yield of Hyola 571 CL were also determined. It was observed that the hybrid, even tolerant, showed sensitivity to herbicides. Pendimethalin, flumioxazin, chlorimuron-ethyl, metsulfuron-methyl, and iodosulfuron were the most harmful to Hyola 571 CL. Commercial mixtures by [imazethapyr + imazapic] and [imazapic + imazapyr], as well as imazamox, were the most selective ones. Catalase was inhibited by most treatments. Sulfentrazone promoted the greatest negative interference along with its mixture with diuron and nicosulfuron, chlorimuron, and metsulfuron-methyl. The hybrid showed sensitivity to herbicides and the differences in gas exchange rates and other analyzes for the types of treatment do not result in productivity.

ОЦЕНКА ЭФФЕКТИВНОСТИ И ФИТОТОКСИЧНОСТИ ГЕРБИЦИДОВ НА КУКУРУЗЕ

The aim of our research was to study the effect of modern highly effective herbicides on weeds and corn plants. One of the criteria for assessing the effectiveness of herbicides is the manifestation phytotoxicity signs of on corn. Phytotoxicity reduces corn grain yield, and plant death may occur if significant damage occurs. The resistance of corn plants to herbicides is determined by the genetic characteristics of hybrids and self-pollinated lines, and depends on external factors, in particular, on air temperature during the chemical treatment of crops. Studies on phytotoxicity of herbicides were conducted for several years in the experimental field of the All-Russian Research Institute of Corn, which is located in the zone of sufficient moisture in Stavropol Territory, at an altitude of 541 m above sea level, 44°N, 43°E. Phyt otoxicity of herbicide Cordus Plus, VDG, was studied in 2017–2018, a tank mixture of herbicides Dublon Super, VDG + Aegis, SC in 2017–2019, herbicide Kreutzer, VDG – in 2018–2021. To study phytotoxicity of herbicides, the same set of hybrids and self-pollinated corn lines of different ripeness groups was sown in each year of research. In the prevailing favorable weather conditions in 2017–2018, the herbicide Cordus Plus destroyed most of the wees phytocenosis and did not cause phytotoxicity in the studied corn samples, except for the sensitive single cross hybrid Alpha M. Application of the tank mixture Dublon Super + Egida in 2017–2018 had no phytotoxic effect on hybrids and parental forms of corn plants. In 2019, under severe drought conditions, phytotoxicity of these herbicides was observed in most of the studied samples. The response of hybrids and self-pollinated lines to the application of Kreutzer herbicide over the years of research was different over the years of research. Even in the absence of drought, the herbicide effected harshly on some corn hybrids and lines and caused significant damage to the plants.