Iodosulfuron-methyl Sodium Research Articles

Effect of weed management options and nitrogen scheduling on weed dynamics and yield of wheat (Triticum aestivum) under Central Plain Zone of Uttar Pradesh

A field experiment was conducted during the winter (rabi) seasons of 2014–2015 and 2015–16 at Kanpur, Uttar Pradesh, to study the effect of weed-management options and nitrogen scheduling on weed dynamics and yield of wheat (Triticum aestivum L.). Common infesting weeds which appeared in wheat field were Phalaris minor Retz. and Cynodon dactylon (L.) Pers. among grasses, and Chenopodium album L., Anagallis arvensis L., Melilotus alba Medik. and Convolvulus arvensis L. as broad-leaf weeds. Moreover, among sedges, only 1 species, Cyperus rotundus L. was observed. Among the weed-management options, mesosulfuron-methyl + Iodosulfuron-methyl sodium (400 g/ha) with higher dose of nitrogen (150 kg N/ha) applied in 3 spilt applications [50% as basal + 25% at crown-root initation (CRI) + 25% at flowering] proved significantly superior in minimizing the density (33%) and biomass of weeds (34%) at 60 days after sowing (DAS). The former treatment increased the leaf-area index (LAI) and SPAD values that elevated the production of wheat grain yield. Among time of nitrogen application, 3 splits (50% as basal + 25% at CRI + 25% at flowering) enhanced the nutrient-uptake efficiency (27.4%) and total nutri ent uptake (40.2%) by crop than 3 equal splits at sowing (basal), CRI and flowering. Higher dose of nitrogen (150 kg N/ha) resulted in higher yield (15.7%) and nutrient uptake (13.4%) than its lower dose. Thus, application of ready-mixed post-emergence herbicides, i.e. mesosulfuron + iodosulfuron (400 g/ha) with higher dose of nitrogen (150 kg N/ha) applied 50% as basal and 25% top-dressed at CRI and 25% at flowering was most effective with re spect to weed-suppression, yield and economics of wheat.

Current Status of Herbicide Resistance of Wild Oats (Avena spp) in Wheat Fields in Mardin and Şanlıufa Provinces of Türkiye

Wheat is a strategic crop with its role in human nutrition. In Türkiye, it has importance in agriculture and economy as well as being a staple crop. Mardin and Şanlıurfa provinces of Türkiye approximately produces 1.6 million tons of wheat on 600 thousand ha fields. One of the important factors limiting wheat production is weeds. Weeds compete with the wheat plant and cause significant yield and quality loss. Wild oat (Avena spp.) species are an important problem in wheat fields in both provinces. Herbicide applications are widely used to control wild oats due to their ease of use, short duration of action and low cost. Wheat fields were surveyed to supply data for strategies to be followed via determining the current situation of herbicide resistance in these provinces where herbicide resistant wild oats had been reported. Out of 95 fields visited, 65 fields had significant wild oat populations of which 61 A. sterilis and four A. fatua. Then these populations were tested to find out herbicide resistance levels against clodinafop-propargyl (ACCase inhibitor) and formulated mix of mesosulfuron-methyl and iodosulfuron-methyl sodium (ALS inhibitors). Only two populations, one low level and the other medium level were found to be resistant to the formulated mix of mesosulfuron and iodosulfuron while 11 populations were resistant to clodinafop, one high level, three medium level and the remaining low level. It was assumed that longer use history and wider use of clodinafop as well as herbicides used in winter rotational crops might cause more clodinafop resistant populations. It was concluded that a strategy to prevent or delay herbicide resistance in these provinces should be prepared because herbicide resistance has continued evolving.

Synthetic approach to iodosulfuron-methyl and metsulfuron-methyl metabolites and their application for water analysis.

A synthetic approach to ten metabolites of iodosulfuron-methyl sodium and metsulfuron-methyl was performed and reported in this study. The compounds of interest were prepared by controlled hydrolytic degradation of active substances or by de novo synthesis from commercially available triazine precursor 10. Obtained compounds were characterized by IR, NMR, and elemental analysis techniques. Metabolites and active substances were utilized during the development of a separation and quantification method using reversed-phase high-performance liquid chromatography coupled with tandem mass spectrometry. The validated method was applied for the analysis of all studied compounds in the extracts from water samples collected from the Vistula river (Toruń, Poland).

Determination of the efficiency and intensity of the phytotoxic effect of herbicides in winter cereal crops

Research on the study of the effective use of herbicides, and subsequently their effect directly on the plants of agricultural crops, is an urgent task in both agroecology and agronomy. Ago, the study was conducted to determine the effectiveness and intensity of the phytotoxic effect of one- and twocomponent systemic herbicides in winter wheat crops in the field conditions, on the Skvyra Experimental Station of Organic Production (SESOP) in the city of Skvyra, during October — December 2022, in the phase of VVSN 13–20 (before the tillering phase). The effectiveness of herbicides was determined on the 23rd day after spraying of the crops. Therefore, the preparation with the active ingredient 2,4-d, 2-ethyl hexyl ester 300 g/l + iodosulfuron methyl sodium 15 g/kg, in the consumption rate of 0.7 l/ha for 21 days after spraying wheat had an efficiency of 65.8 — 83,0 which was the highest among the studied variants. After spraying the crops and studying the effectiveness of of herbicides, the intensity of phytotoxic effects of the preparations on winter wheat was determined. The herbicide variant with the highest phytotoxicity on plants was tribenuron-methyl, 102.5 g/kg + dicamba, 659 g/kg at a consumption rate of 20.0 g/ha. It was showed that on the 7th day after application, the intensity of phytotoxicity was 12.02%, and on 21st day after application — 7.14%. The phytotoxic effect of the herbicide with the active substance aclonifen 520 g/kg at a consumption rate of 2.0 l/ha, on wheat plants, which was 9.16% on 7th day after application and 4.80% — on the 21st day after application. In the variants where the abovementioned preparations were applied, yellowing of the leaves, curling of the leaf edges (single), and minor necrosis on the tops of the leaves were observed. It has been proved that on the scale of phytotoxicity, all the studied herbicides had a barely noticeable degree of phytotoxicity — 10%, which corresponded to 1 point.

Oxygen-defective graphdiyne for ultra-efficient removal of sulfonylurea herbicides from aqueous solution

The irrational use of sulfonylurea herbicides (SUHs) has brought many environmental problems due to their long-term residue and toxicity on non-target organisms. In this study, oxygen-defective graphdiyne (GDY) was applied as an adsorption material to remove pesticides from water for the first time under various conditions and exhibited remarkable adsorption properties for seven SUHs. The maximum adsorption capacity of GDY reached up to 795.51 mg/g for iodosulfuron-methyl sodium, which was over 130 times higher than that of modified graphene oxide (6 mg/g) and modified biochar (1.5 mg/g) reported by others. Additionally, the pseudo-second-order kinetic model and Langmuir isotherm model were well fitted for the experimental data. The thermodynamic results revealed that the adsorption process was physical, spontaneous and endothermic in nature. Further studies verified that π-π interaction, hydrophobic interaction and hydrogen bonding played an important role in SUHs adsorption on GDY. This work clarifies that oxygen-defective GDY is an ultra-efficient, sustainable and anti-interference adsorbent for the removal of SUHs from aqueous solution.

Resistance of blackgrass (Alopecurus myosuroides Huds.) to ALS inhibitors in region of south-western Poland

The aim of the research was to identify resistant and sensitive biotypes of Alopecurus myosuroides to various substances from the ALS inhibitors group and to determine the degree of resistance to these compounds in south-western Poland. The experiments were performer by the method of biological tests. Three substances from the group of ALS inhibitors were tested. On the basis of the reduction in fresh weight of the plants, the ED50 index and the resistance index (RI) was determined. The conducted research confirmed the presence of A. myosuroides biotypes resistant to ALS inhibitors in the fields of Lower Silesia and Opole Silesia. Cross-resistance of blackbrass to sulfonylurea herbicides (i.e. sulfosulfuron, iodosulfuron-methylsodium + mesosulfuron-methyl) and to sulfonylaminocarbonyltriazolinones (sodium propoxycarbazone) was identified. Among all resistant samples, as much as 76% of A. myosuroides biotypes showed cross resistance. The highest index of resistance to propoxycarbazone and the mixture of iodosulfuron-methyl sodium with mesosulfuron-methyl was over 100 and for sulfosulfuron over 200.

Weed control in maize crops with various schemes of herbicide application

Goal. Carry out a comparative evaluation of the effectiveness of different schemes of application of modern herbicides in maize crops.
 Methods. Field, phenological, statistical. Conducted spraying of corn crops to seedlings (ВВСН 00) with herbicides Adengo 465 SC, hp (thiencarbazone-methyl, 90 g/l + isoxaflutol, 225 g/l + cyprosulfamide, 150 g/l), 0.5 l/ha, Primextra TZ Gold 500 SC, (S-metachlor. 312.5 g/l + terbuthylazine, 187.5 g/l), 4.5 l/ ha, Merlin Flex Duo 475 SC, (isoxaflutop, 50 g/l + cyprosulfamide, 50 g/l + terbuthylazine, 375 g/l, 2.0 l/ha. After germination in the phase of 4—5 leaves (ВВСН 14—15) applied insurance herbicides Milagro 040 SC, (nicosulfuron, 40 g/l), Basis 75 v.g. rimsulfuron, 500 g/kg + thifensulfuron-methyl, 250 g/l), MаisTer Power OD (foramsulfuron, 31.5 g/l + iodosulfuron-methyl sodium, 1.0 g/l + thiencarbazone-methyl, 10 g/l + cyprosulfamide, 15 g/l), Laudis 30 WG, VG (tembotrione, 200 g/kg + isoxadifen-ethyl, 100 g/kg) and Stellar, RK (topramezone, 50 g/l + dicamba, 160 g/k) in the recommended consumption rates. The experimental plots were 1000 m2 in the first experiment, the recurrence of 3-fold and 25 m2 in the second experiment, the recurrence of 4-fold. Observations were made for meteorological indicators. Statistical processing of the results was performed according to computer «Statgraphic plus» programs. 
 Results. Mixed type of segetal vegetation prevailed in the experimental plots. Among the perennial weeds dominated by Sonchus arvensis L., Cirsium vulgare Savi Ten., Convolvulus arvensis L., among annuals — Setaria glauca L., Setaria viridis L., Echinochloa crus-galli L., Polygonum convolvulus L., Calinsoga parviflora L., Stellaria media (L.) Vill.), Chenopodium album L., Raphanus raphanistrum L., Thlaspi arvense L., Amaranthus retroflexus L. The application of pre-emergence herbicides effectively inhibited the growth and development of weeds. 60 days after application, the effectiveness of herbicides was 87—97% against cereals and 89—98% against dicotyledonous weeds, which did not require the application of insurance herbicides. During the critical periods of maize development, a sufficient level of soil moisture was recorded during the research years. After 60 days, the effectiveness of herbicides applied after crop germination was 65—95% against dicotyledonous and 65—92% against cereal weeds. The highest effect in killing weeds was provided by MaysTer Power, 1.5 l/ha, Laudis 30 WG, VG, 0.5 kg/ha + surfactant Mero, 2.0 l/ha and Stellar, RK, 1.25 l/ha + surfactant Metholate, 1.25 l/ha. The application of herbicides has significantly reduced the aboveground mass of weeds and increased crop yields. Maize grain yield from weed-protected areas was at the level of 8.0—9.7 t/ha against 4.1—4.9 t/ha in the control.
 Conclusions. Both herbicide application schemes under favorable weather conditions provide effective weed control of maize crops The efficiency of pre-emergence herbicides was at the level of 87—98%, post-emergence — 65—95%. At the same time, the reduction of aboveground mass of weeds was 75—95%, and crop yields increased by 1.6—2.2 times depending on the drug.

Effect of different levels of urea and herbicide application on the yield of wheat (Triticum aestivum) in competition with Sinapis arvensis and Avena ludoviciana Durieu

Understanding the interaction between crop-weed competition and herbicide doses may, in many cases, result in a recommendation to reduce the consumption of the herbicide, which is both environmentally and economically important. Nitrogen fertilizer also influences the competitive balance through changes in weed density and biomass, and also contributes to environmental pollution. Hence, the evaluation of the interaction of herbicide doses and nitrogen fertilizer application is necessary for proper management of weeds and achieving acceptable economic yield along with minimizing environmental negative impacts.Therefore, in order to Quantify wheat-weed competition to levels of urea and reduced dose of herbicide (mesosulfuron methyl + iodosulfuron methyl sodium + diflufenican + mefenpyr-diethyl) brand (othello OD) this experiment was conducted during 2019–20 at Khuzestan University of Agricultural Sciences and Natural Resources, Iran. The experiment was laid out in split plots under randomized complete block design wherein urea fertilizer included five levels of 0, 45, 90, 180 and 330 kg/ha as the main plot and the herbicide dose of “othello OD” in six levels of 0, 0.32, 0.64, 0.96, 1.28 and 1.6 L/ha (1.6 L/ha the recommended dose) was considered as the sub plot. The results showed that wheat grain yield and weed biomass response to herbicide doses of sigmoid response and response dosage models, and developed in response to an increase in urea fertilizer consumption. Based on the prediction of the combined model, The achieving a yield of about 500 g/m2 with the application of 140 kg of urea fertilizer per hectare with 1.04 L/ha of Othello OD herbicide or the application of 265 kg of urea fertilizer per hectare and 0.64 L/ha. Hectare of herbicide or application of 330 kg urea fertilizer per hectare with 0.72 L/ha of herbicide was possible.

Comparison of extraction procedures for the determination of mesosulfuron methyl and iodosulfuron methyl sodium from soil and wheat using response surface modelling

Screening of herbicides is important due to their widespread use, phytotoxicity to succeeding crop and residues in soil and crop produce. For this development of simple, sensitive and cost effective analytical method for tracer level quantification of herbicides in different matrices is a challenging task. In present study, different extraction techniques viz. ultrasonic assisted extraction (UAE), matrix solid phase dispersion (MSPD), microwave assisted extraction (MAE) and liquid solid extraction (LSE) were compared for recovery and quantification of mesosulfuron methyl and iodosulfuron methyl sodium from soil and wheat samples by high performance liquid chromatography. Different factors affecting the extraction efficiency of the herbicides using these extraction methods were optimised. Response surface methodology (RSM) based on three factor and three level box behnken designs (BBD) were also employed to obtain a mathematical model representing the relationship between the response (percent recovery) and variables. The mean percent recoveries of herbicides varied from 89.80 to 101.20%, 89.20 to 99.75%, 81.10 to 90.75% and 83.40 to 94.75% using UAE, MSPD, MAE and LSE, respectively with RSD% <14% for all the four methods. The developed methods are reliable and can be useful for routine monitoring in soil and crop produce. The experimental results were extended to the analysis of real sample and residues in these were below the maximum residue limits (<0.01 mg kg−1) imposed by the principal regulatory agencies.

Iodosulfuron-Methyl-Based Herbicidal Ionic Liquids Comprising Alkyl Betainate Cation as Novel Active Ingredients with Reduced Environmental Impact and Excellent Efficacy.

A new family of bio-based herbicidal ionic liquids (HILs) has been synthesized starting from the renewable resource glycine betaine (a derivative of natural amino acids). After esterification, the obtained alkyl betainate bromides containing straight alkyl chains varying from ethyl to octadecyl were combined with a herbicidal anion from the sulfonylurea group (iodosulfuron-methyl). The melting points of the iodosulfuron-methyl-based salts were in a range from 51 to 99 °C, which allows their classification as ionic liquids (ILs). In addition, the new HILs exhibited good affinity for polar and semipolar organic solvents, such as DMSO, methanol, acetonitrile, acetone, and chloroform, while the presence of bulky organic cations reduced their solubility in water. The synthesized products turned out to be stable during storage at 25 °C for over 6 months; however, at 75 °C they underwent fast, progressive degradation and released volatile byproducts. The values of the logarithm of the octanol–water partition coefficient of ILs with alkyls longer than hexyl occurred in the “safe zone” (between 0 and 3); hence, the risk of their migration into groundwater after application or the possibility of their bioaccumulation in the environment is lower in comparison with the currently available commercial form (iodosulfuron-methyl sodium salt). Greenhouse studies confirmed a very high herbicidal efficacy for the obtained salts toward tested plants of oilseed rape, indicating that they may become an attractive replacement for the currently available sulfonylurea-based formulations.

Accumulation of Target Gene Mutations Confers Multiple Resistance to ALS, ACCase, and EPSPS Inhibitors in Lolium Species in Chile.

Different Lolium species, common weeds in cereal fields and fruit orchards in Chile, were reported showing isolated resistance to the acetyl CoA carboxylase (ACCase), acetolactate synthase (ALS) and 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibiting herbicides in the late 1990s. The first case of multiple resistance to these herbicides was Lolium multiflorum found in spring barley in 2007. We hypothesized that other Lolium species may have evolved multiple resistance. In this study, we characterized the multiple resistance to glyphosate, diclofop-methyl and iodosulfuron-methyl-sodium in Lolium rigidum, Lolium perenne and Lolium multiflorum resistant (R) populations from Chile collected in cereal fields. Lolium spp. populations were confirmed by AFLP analysis to be L. rigidum, L. perenne and L. multiflorum. Dose-response assays confirmed multiple resistance to glyphosate, diclofop-methyl and iodosulfuron methyl-sodium in the three species. Enzyme activity assays (ACCase, ALS and EPSPS) suggested that the multiple resistance of the three Lolium spp. was caused by target site mechanisms, except the resistance to iodosulfuron in the R L. perenne population. The target site genes sequencing revealed that the R L. multiflorum population presented the Pro-106-Ser/Ala (EPSPS), Ile-2041-Asn++Asp-2078-Gly (ACCase), and Trp-574-Leu (ALS) mutations; and the R L. rigidum population had the Pro-106-Ser (EPSPS), Ile-1781-Leu+Asp-2078-Gly (ACCase) and Pro-197-Ser/Gln+Trp-574-Leu (ALS) mutations. Alternatively, the R L. perenne population showed only the Asp-2078-Gly (ACCase) mutation, while glyphosate resistance could be due to EPSPS gene amplification (no mutations but high basal enzyme activity), whereas iodosulfuron resistance presumably could involve non-target site resistance (NTSR) mechanisms. These results support that the accumulation of target site mutations confers multiple resistance to the ACCase, ALS and EPSPS inhibitors in L. multiflorum and L. rigidum from Chile, while in L. perenne, both target and NTSR could be present. Multiple resistance to three herbicide groups in three different species of the genus Lolium in South America represents a significant management challenge.

Study on the effect of application of urea fertilizer and reduced herbicide doses on wheat (Triticum aestivum) - weed competition

The amount of weed control not only depends solely on the use of herbicides, but also on interactions with other inputs, including the interaction of herbicides and levels of urea fertilizers. In order to study wheat -Sinapis arvensis and Avenaludo viciana competition in response to urea fertilizer and herbicide, a field experiment was laid out in split plots in randomized complete block design with four replications at Agricultural Sciences and Natural Resources University of Khuzestan, Iran. Main plot comprised of urea fertilizer with 5 levels of 0, 45, 90, 180 and 330 kg/ha of urea and herbicide dose of “mesosulfuron methyl + iodosulfuron methyl sodium + diflufenican + mefenpyr-diethyl” Branded (Othello OD) in 6 doses of 0, 0.32, 0.64, 0.96, 1.28 and 1.6 L/ha (recommended dose 1.6 L/ha) as sub plot. The results showed that the response of weed and wheat biomass to herbicide doses was described, respectively, with dose-response and sigmoid models, and developed in response to an increase in urea fertilizer consumption. Based on the prediction of the combined model, the dosage required for reducing the weed biomass to less than 150 g/m2 with consuming of 0, 45, 90, 180, 250 and 330 kg/ha of urea fertilizer was predicted to be 0.64, 1.04, 1.12, 0.96, 0.88, and 0.80L/ha of herbicide, respectively. From the results it could be observed that 1172 g/m2 of wheat biomass can be achieved using 225 kg/ha of urea fertilizer plus 0.96 L/ha.

Effects of herbicide mixtures on freshwater microalgae with the potential effect of a safener

Freshwater microalgae are primary producers and cosmopolitan species subjected to the effects of herbicides. In this work, thein vitroalgal growth inhibitory effects of 11 agrochemicals (9 herbicides, 1 metabolite, and 1 safener) were quantified. Chemical compounds were applied singly and in specific mixtures. Three species were used in axenic condition: the green algaDesmodesmus subspicatus(Chodat), the diatomsNitzschia palea(Kützing) W. Smith andNavicula pelliculosa(Kützing) Hilse. When exposed to single compounds,N. paleaandN. pelliculosawere only sensitive to atrazine/desethylatrazine and the safener benoxacor (BE), respectively.D. subspicatuswas equally sensitive to four herbicides including atrazine and its metabolite and significantly more sensitive to iodosulfuron-methyl-sodium (IODO). The mixture of these five compounds induced a significantly higher growth inhibition of about 1.5-fold than IODO alone, which could be attributed to the four other herbicides. The mixture of all compounds was twofold less toxic than IODO onD. subspicatus. A halogen atom is present in IODO as in the herbicides to which the safener BE − known to induce glutathione-S-transferases − is associated in agrochemical preparations. We then showed that IODO was less toxic when combined with non-toxic concentrations of BE. These results indicated that the toxicity of the most active herbicide studied was decreased by a non-herbicide compound present in agrochemical formulations of other herbicides. These results suggest the importance to take into account the chemistry and the mechanisms of action for each compound in a risk assessment approach of a complex mixture.

Alkyl Ether Sulfate Improves Efficacy of Herbicides Against Common Goosefoot and Field Bindweed in Wheat

ABSTRACT: Tank mixed application of herbicides with adjuvant is required for effective weed management and to reduce herbicide load on agricultural crops. Field studies were conducted to investigate the effect of herbicides at reduced rates with adjuvant on common goosefoot (Chenopodium album) and field bindweed (Convolvulus arvensis) and grain yield of wheat for two consecutive winter seasons. Treatments included post-emergence foliar application of four herbicides viz., fluroxypyr + tribenuron-methyl + clopyralid, mesosulfuron-methyl + iodosulfuron-methyl sodium, bromoxynil + MCPA, iodosulfuron-methyl sodium (pre mixed formulations) at their recommended rates 244.5, 14.2, 444.6, 10 g a.i. ha-1, respectively and 25% reduced rates with alkyl ether sulfate Na salt at 400 mL ha-1 as adjuvant. A weedy check was kept as control. All the herbicide treatments caused a significant reduction in densities (up to 85% and 89.2%) of C. arvensis and C. album, respectively and total dry weight (12.4-56%), N (3.7-50%), P (25-63.6%) and K (1.4-56.6%) uptakes from weedy check. Better weed control was achieved with 25% lower dose of all herbicides along with adjuvant in comparison with that recorded with their full doses without adjuvant. All herbicide treatments increased the grain yield of wheat ranging from 10.4 6-56.1% over control during both years. Herbicides with adjuvant produced significantly the higher grain yield of wheat than those observed with herbicides alone. Among all herbicide treatments, 75% doses of bromoxynil + MCPA and iodosulfuron-methyl sodium along with alkyl ether sulfate adjuvant were proved to be the best as they gave significantly the higher (4902.3 and 5159.0 kg ha-1 and 4566.5 and 4891.0 kgha-1) grain yields of wheat during years 2013-14 and 2014-15, respectively.

Use of Adjuvants to Optimize the Activity of Two Broad-Spectrum Herbicides for Weed Control in Wheat

ABSTRACT: Herbicide resistance development among weeds, environmental contamination and health concerns due to the overuse of herbicides have led researchers to focus on ways to reduce herbicides to be sprayed for weed management. Adjuvants are best suited for that purpose, as they accomplish a crucial role in achieving satisfactory control of weeds by maximizing herbicidal activity. A two-year field investigation was carried out at the Agronomic Research Area, in the University of Agriculture, in Faisalabad, Pakistan during the winter of 2014 and 2015, with the objective to optimize the activity of two broad-spectrum herbicides at reduced dose (75% of the label mentioned rate) for weed control in wheat. Minimum weed density, weed dry weight and NPK uptake were recorded with reduced dosed mesosulfuron methyl + iodosulfuron methyl sodium at 10.60 g a.i. ha-1 combined with fatty alcohol ethoxylate at 200 mL ha-1. This was followed by reduced dosed sulfosulfuron at 18.75 g a.i. ha-1 combined with the same adjuvant. Among various herbicidal treatments, application of reduced dosed mesosulfuron methyl + iodosulfuron methyl sodium at 10.60 g a.i. ha-1 combined with fatty alcohol ethoxylate at 200 mL ha-1 was proved to be most cost effective and resulted in maximum wheat yield during both years of study.

Efeito da redução de luz na seletividade a herbicidas e rendimento de grãos do trigo

A redução da radiação solar incidente na superfície terrestre pode alterar o comportamento vegetal e a seletividade de herbicidas. O objetivo deste trabalho foi avaliar a seletividade dos herbicidas bentazona, iodosulfuron-methyl-sodium e o rendimento de grãos do trigo, em condições de redução de luminosidade em diferentes estádios fenológicos da cultura. Foram conduzidos dois experimentos, o primeiro (I) em condições controladas e o segundo (II) a campo. Nos dois experimentos foram avaliadas variáveis no trigo em função da aplicação de herbicidas (bentazona, 900 g ha-1 i.a.; iodosulfuron-methyl-sodium, 5 g ha-1 i.a.; e testemunha, sem aplicação de herbicida) e da variação da taxa luminosa (testemunha; redução de luz durante todo o ciclo; redução no estádio inicial, da emergência até três folhas; redução no estádio vegetativo, entre três folhas até a emergência completa da inflorescência; e redução na fase reprodutiva, da inflorescência até a colheita). Os resultados demonstram que a redução de luz altera características morfofisiológicas do trigo, aumenta a estatura de plantas, reduz a taxa de transpiração e condutância estomática, mas não interfere na fotossíntese do cereal. No entanto, o rendimento de grãos é afetado negativamente pela redução de luz durante o estádio vegetativo, período ontogenético que coincide com a formação dos principais componentes de rendimento da cultura. Os herbicidas avaliados são seletivos ao trigo, com ou sem redução de luminosidade.

Assessment of pre-mix broad spectrum herbicides for weed management in wheat

A field experiment was carried out during the Rabi season of 2014 and 2015 on sandy loam soil to test the bio-efficacy of pre-mix broad spectrum herbicides for weed management in wheat. Major dominant weed flora in the experimental plot were Chenopodium murale (54.1%), Chenopodium album (11.9%), Phalaris minor (10.4%) and Melilotus alba (9.6%). Application of pre-mix sulfosulfuron (75%) + metsulfuron-methyl (5%) 32 g/ha as post-emergence, clodinafop (15%) + metsulfuron-methyl (1.0%) 64 g/ha as post-emergenc (PoE), mesosulfuron (3%) + iodosulfuron-methyl sodium (0.6%) 14.4 g/ha as PoE and hand weeding at 20 and 40 DAS remained at par with each other and significantly reduced the density and biomass of both monocot as well as dicot weeds and resulted in significantly more number of effective tillers and yield of grain and straw. However, mesosulfuron (3%) + iodosulfuron-methyl sodium (0.6%) 14.4 g/ha PoE showed phytotoxic effect on plant.

Effects of Soil Residues of Sulfosulfuron and Mesosulfuron Methyl + Iodosulfuron Methyl Sodium on Sunflower Varieties

Using field assays, we studied how the residues of sulfosulfuron and mesosulfuron methyl + iodosulfuron methyl sodium (ME+IMS) applied at two spraying times and three application rates affected two sunflower varieties seeded 12 months after treatment (MAT) in Central Anatolian Region, Turkey. Specifically, we studied their effects on the shoot length, seed yield, and yield components, including plant length, head diameter (HD), and 1000-seed weight. Sunflower yield was found to be the most sensitive biological parameter to the herbicidal residue in the soil, while the 1000-seed weight was the least sensitive. Sulfosulfuron previously applied to winter wheat at two sites greatly reduced subsequent sunflower yield depending on application time, rate, and sunflower variety. At site 1, all sunflower seedlings planted in several plots that were treated with doubled rates of sulfosulfuron died. Similar to the effects of sulfosulfuron residue, ME+IMS previously applied to winter wheat also greatly reduced sunflower yield. Generally, the sunflower yields decreased as the dose of the chosen herbicide increased at both sites. More herbicide molecules were leached or degraded by a variety of pathways when sulfosulfuron and ME+IMS were applied early. The responses of sunflower cultivars to residues of sulfosulfuron and ME+IMS were very similar. Sulfosulfuron residue was more phytotoxic to the sunflower varieties than was ME+IMS at the both sites.

Safety of herbicide Sigma Broad on Radix Isatidis (Isatis indigotica Fort.) seedlings and their photosynthetic physiological responses

The study was performed to explore the safety of sulfonylurea herbicide Sigma Broad (mesosulfuron-methyl and iodosulfuron-methyl sodium) on Radix Isatidis (Isatis Indigotica Fort.) seedlings and the photosynthetic physiological response of the crop to the herbicide. Through pot experiment, biological mass, leaf area, photosynthetic pigment content, photosynthetic rate, chlorophyll fluorescence characteristics, and P700 parameters of Radix Isatidis seedlings were analyzed 10days after Sigma Broad treatment at 5th leaf stage. The results showed that biological mass, leaf area, total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids content, Pn, transpiration rate, stomatal conductance, PSII maximum quantum yield, PSII effective quantum yield, PSII electron transport rate, photochemical quenching, quantum yield of regulated energy dissipation in PS II, maximal P700 change, photochemical quantum yield of PS I, PS I electron transport rate, and quantum yield of non-photochemical energy dissipation due to donor side limitation in PS I decreased with increasing herbicide dosages, whereas chlorophyll a/b, stomatal limitation value, initial fluorescence, quantum yield of non-regulated energy dissipation in PS II and quantum yield of non-photochemical energy dissipation due to accepter side limitation in PS I increased. In conclusion, treatment with Sigma Broad higher than 13.48gai/ha was extremely unsafe to Radix Isatidis seedlings, which might be associated with damage of chloroplast, PS II and PS I structure, electron transport and its distribution between PS II and PS I, and decreased photosynthesis caused by the herbicide.

Wplyw wybranych parametr�w opryskiwania na skutecznosc dw�ch form uSytkowych herbicyd�w sulfonylomocznikowych

The objective of this study was the evaluation of spray volume and nozzle type effect on different formulation (water dispersible granules - WG and oil dispersion - OD) of two sulfonylurea herbicides: the mixture iodosulfuron methyl sodium + amidosulfuron and iodosulfuron methyl sodium + mesosulfuron methyl efficacy. There were investigated three levels of spray volume (125 l*ha-1, 250 l*ha-1 and 350 l*ha-1) and two types of nozzle (extended range flat nozzle TeeJet XR 11003-VS and drift guard flat nozzle TeeJet DG 11003-VS). Each herbicide was used at recommended dose and reduced by half. Spray volume and nozzle type did not affect activity of the mixture iodosulfuron methyl sodium + amidosulfuron, but differentiated the efficacy of OD formulation of iodosulfuron methyl sodium + mesosulfuron methyl, when it was applied at lowered dose. As spray volume rose, herbicide efficacy decreased. Nozzle type influenced OD formulation of the mixture iodosulfuron methyl sodium + mesosulfuron methyl, independently on dose. Significantly weaker efficacy was obtained when drift guard nozzle was used.