Soybean Weed Research Articles

Influence of Broadcast Spray Nozzle on the Deposition, Absorption, and Efficacy of Dicamba plus Glyphosate on Four Glyphosate-Resistant Dicot Weed Species

AbstractDicamba-resistant soybean technology provides an additional site of action for POST control of herbicide-resistant broadleaf weeds in soybean but also raises concern of off-site movement and damage to sensitive crops in adjacent fields. Dicamba formulations approved for use on dicamba-resistant soybean require applicators to use nozzles producing large droplets to reduce the risk of spray-particle drift. The use of nozzles with relatively larger droplet spectra can reduce herbicide deposition on target weeds, especially if a filtering effect from the crop canopy occurs. Experiments were conducted to evaluate the influence of broadcast nozzle design on the deposition and efficacy of 280 g ha−1glyphosate plus 140 g ha−1dicamba applied POST to four herbicide-resistant weed species. The TTI11004 nozzle, the original nozzle labeled for dicamba applications on dicamba-resistant soybean, reduced deposition coverage and density on spray cards compared with the TT11004 and XR11004 nozzle. The AIXR11004 nozzle produces a very coarse droplet spectrum and did not reduce coverage on spray cards, though it did reduce deposition density. Herbicide solution deposition onto Palmer amaranth, tall waterhemp, giant ragweed, and horseweed ranged from 0.41 to 0.52, 0.55 to 0.87, 0.49 to 0.58, and 0.38 to 0.41 µl cm−2, respectively. Nozzle design and droplet spectrum did not influence the deposition of herbicide solution onto the target weed, as all nozzles were equivalent for all species and site-years. Herbicide efficacy was not influenced by nozzle design, as weed control and plant height reduction were similar for all species. The results of this experiment show that the use of the TTI11004 nozzle for dicamba applications to dicamba-resistant soybean will provide acceptable herbicide deposition and efficacy when applied under the label requirements of weed height and carrier volume.

PP 1/305 (1) Weeds in soybean

Specific scopeThis Standard describes the conduct of trials for the evaluation of herbicides in soybean.Specific approval and amendmentFirst approved in 2017‐09.

Efficacy of the Integrated Harrington Seed Destructor on Weeds of Soybean and Rice Production Systems in the Southern United States

Herbicide‐resistant weeds affect every major cropping system today. Worldwide, there are 47 and 51 confirmed cases of herbicide‐resistant weed populations in soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) production systems, respectively. Alternatives to herbicides are necessary to help combat herbicide‐resistant weeds. The integrated Harrington Seed Destructor (iHSD) has been developed to destroy weed seeds during crop harvest but has yet to be tested on weeds in soybean or rice. Thus, the objective of this research was to determine the effectiveness of the iHSD in soybean and rice and to evaluate any limitations. Three experiments were conducted using a stationary iHSD mill. First, the efficacy of the iHSD was evaluated on weed seeds incorporated into soybean residue or rice chaff. Second, varying soybean chaff feeding rates were tested to determine the amount that could be processed without interfering with weed seed destruction. Third, varying soybean chaff moisture levels were tested to determine any limitations that high moisture content may have on the iHSD. The iHSD demonstrated high weed seed destruction efficacy (<1% survival) for 11 of the 12 weed species of soybean. Common cocklebur (Xanthium strumarium L.) seed had 3% survival. In rice, <1% survival was observed in all weed species. The soybean feeding rate and moisture experiments yielded <1% survival across all treatments. These results show that the use of the iHSD can be highly effective in soybean and rice production for reducing inputs to the soil seedbank. These studies highlight the promising seed destruction potential of the iHSD but also demonstrate opportunities for further research evaluating the iHSD as a combine‐fitted system operating under commercial scale production fields.

RELATIVE COMPETITIVENESS OF GOOSEGRASS BIOTYPES AND SOYBEAN CROPS

ABSTRACT The goosegrass (Eleusine indica (L.) Gaertn) is an annual plant that has a low-level resistance to glyphosate (LLRG), resulting in control failure in genetically modified soybean crops for resistance to this herbicide. Alleles related to resistance may cause changes in the plant biotype, such as inferior competitive ability. Thus, the objective of this work was to evaluated the competitive ability of soybean crops and susceptible and resistant (LLRG) goosegrass biotypes. Replacement series experiments were conducted with soybean crops and goosegrass biotypes. The ratios of soybean to susceptible or resistant (LLRG) goosegrass plants were 100:0, 75:25, 50:50, 25:75 and 0:100, with a total population of 481 plants m-2. The leaf area, plant height and shoot dry weight were evaluated at 40 days after emergence of the soybean crops and weeds. The soybean crop had superior competitive ability to the susceptible and resistant (LLRG) goosegrass biotypes. The soybean crop showed similar competitive ability in both competitions, either with the susceptible or resistant (LLRG) goosegrass biotypes. The intraspecific competition was more harmful to the soybean crop, while the interspecific competition caused greater damage to the goosegrass biotypes competing with the soybean crop.

High-Residue Cultivation Timing Impact on Organic No-Till Soybean Weed Management

A cereal rye cover crop mulch can suppress summer annual weeds early in the soybean growing season. However, a multi-tactic weed management approach is required when annual weed seedbanks are large or perennial weeds are present. In such situations, the weed suppression from a cereal rye mulch can be supplemented with the use of high-residue cultivators which can prolong the weed-free period during soybean growth. Research trials were conducted to determine the optimum timing of high-residue cultivation for weed control in rolled-crimped cereal rye mulches. Treatments included three cultivation timings with a high-residue cultivator: early (3-4 wk after soybean planting (WAP)), intermediate (5-6 WAP), and late (7-8 WAP), a weed-free and no-cultivation control. Crop and weed measurement included cereal rye biomass, weed biomass, soybean population and biomass, and yield. Cereal rye biomass was 50% lower and weed biomass was three times greater in 2011 than in 2010 and 2012 due to 2011 being a dry year. There was no significant effect of cultivation timing on soybean population when compared to no-cultivation or hand-weeded treatments. While cultivation reduced weed biomass by 67% compared to no-cultivation, soybean yield was only improved by 12% in early and late cultivation treatments and 22% in intermediate cultivation treatment when compared to no-cultivation. Effective strategies for improving weed management by integrating the use of a high-residue cultivator in no-till organic systems could help existing organic field crop producers to reduce tillage while also encourage adoption of organic crop production by conventional growers who prefer reduced-tillage systems. Unlike traditional organic cultivation equipment, therefore, optimal timing of cultivation should be delayed several weeks in organic cover crop-based no-till planted soybean production as compared to the typical tillage-based approach to ensure both weed control and optimal yield.

Artropoda yang berasosiasi pada ekosistem tanaman lada

Association of Arthropod on Pepper Plant Ecosystem. Ecosystem management of pepper between cover crops, Arachis pintoii, cropping system with corn, soybean and limited weeding. The objectives of this research was to find out biodiversity of arthropod on the paper ecosystem. This experiment was conducted in Lampung since May to September 2002. They are divided 5 treatments they are paper with A. pintoii, pepper with corn, pepper with soybean, pepper with limited weeding and control. The randomize blok design was used 44 kind of arthropods. The status of arthropod are: fitofag (47.73%), omnivorus (6.82%), natural enemies (34.09%) and pollination (11.36%). Distribution of each species was various at each treatment, between 26-34 species. The lowest population was found on pepper with corn, while on the highest population were occurred on the pepper with A. pintoii and control. The insect population of Acrididae, Tetrigidae, Grylidae (Orthroptera), Blattidae, Drosophillidae and Farmicidae always higher than an other insect. In this research were found 10 ordo of arthropod. Hymenoptera (Formicidae) and Araneida are dominant of arthropod and distributed at all treatment. Arthropod at pepper plant was the most abundant at pepper plan with A. pintoii. In the pepper standing plant it were only found three other, they are Hymenoptera, Araneida and Hemiptera. Beside at pepper plant and pepper standing plant, some of arthropod was found associated with A. pintoii, corn, soybean weed. Other of Orthoptera mainly grasshopper was dominating at all of plant.

Evaluation of 2,4-D-Choline Based Herbicide Systems in 2,4-D Tolerant Soybean (<i>Glycine max</i> L.)

Weeds are the most limiting factor in soybean production in South Carolina. With early emergence and rapid growth, weeds effectlively compete for water, nutrients, and light resources. The recent evolution of herbicide resistant weeds has made it increasingly difficult for growers to effectively control weeds in soybean. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina, especially in areas where resistance management is lacking. Soybean varieties have been recently developed with tolerance to 2,4-D. Field experiments were conducted at the Clemson University Edisto Research and Education Center located near Blackville, SC in 2012 and 2013 to evaluate selected 2,4-D choline based herbicide programs for weed management in 2,4-D tolerant soybean. Overall, all herbicide treatments were effective in controlling weeds at the POST2 timing. Palmer amaranth control was excellent; however, pitted morningglory was the most difficult. The 2,4-D plus glyphosate pre-mixture provided excellent control for all three weed species with >95% control at POST2 timing. In these treatments, the rate of 2,4-D choline plus glyphosate (1.09 kg ae ha-1 or 1.64 kg ae ha-1) did not have a significant effect on weed control (P = 0.3772). There was a decrease in pitted morningglory control 3 WAP in 2012 vs 2013 in plots treated with S-metolachlor + fomesafen because of a lack of activating soil moisture in 2012. Results from this study showed that all treatments evaluated provided good to excellent control of all 3 weed species. Based on the herbicide programs evaluated in the study, herbicide resistant weeds, such as Palmer amaranth, can be effectively controlled when treated at the correct growth stage.

Sulfentrazone plus a Low Rate of Halosulfuron for Weed Control in White Bean (<i>Phaseolus vulgaris</i> L.)

Halosulfuron was recently registered as the second soil-applied herbicide for broadleaf weed control in Ontario dry beans, but does not provide an alternative mode of action. Sulfentrazone is used to control broadleaf weeds in soybean and other pulse crops, and its registration for Ontario dry beans would provide a different mode of action for broadleaf weed control. Five field studies were conducted over two years (2014, 2015) to determine if the spectrum of broadleaf weed control is improved by adding a half-rate of halosulfuron to sulfentrazone PRE, and to determine the tolerance of white bean to sulfentrazone (140 or 210 g ai ha-1), s-metolachlor (1050 g ai ha-1), and halosulfuron (17.5 g ai ha-1) applied alone and in combination. Crop injury was assessed at 2 and 4 weeks after crop emergence. Weed control was assessed at 4 and 8 weeks after herbicide application (WAA), and weed density and biomass were determined at 8 WAA. Seed moisture and yield were determined at harvest. Halosulfuron added to sulfentrazone improved the control of Ambrosia artemisiifolia and Sinapis arvensis. Sulfentrazone + s-metolachlor + halosulfuron caused up to 23% crop injury. Therefore, this study concludes that sulfentrazone + s-metolachlor + halosulfuron provides broad spectrum weed control, but is too injurious to white bean for registration in Ontario.

Comparison of Herbicide Programs for Season-Long Control of Glyphosate-Resistant Common Waterhemp (Amaranthus rudis) in Soybean

The evolution of glyphosate and acetolactate synthase (ALS) inhibitor-resistant common waterhemp in the Midwestern United States has reduced the number of effective POST herbicide options for management of this problem weed in glyphosate-resistant soybean. Moreover, common waterhemp emerges throughout the crop growing season, justifying the need to evaluate herbicide programs that provide season-long control. The objectives of this study were to compare POST-only and PRE followed by (fb) POST herbicide programs for control of glyphosate-resistant common waterhemp in glyphosate-resistant soybean. Field experiments were conducted in 2013 and 2014 in Dodge County, NE, in a field infested with glyphosate-resistant common waterhemp. Programs containing PRE herbicides resulted in ≥83% control of common waterhemp and densities of ≤35 plantsm–2at 21 d after PRE (DAPRE). Post-only herbicide programs resulted in <70% control and densities of 107 to 215 plants m–2at 14 d after early-POST (DAEPOST) treatment. PRE fb POST herbicide programs, including saflufenacil plus imazethapyr plus dimethenamid-P, sulfentrazone plus cloransulam, orS-metolachlor plus metribuzin, fb fomesafen plus glyphosate;S-metolachlor plus fomesafen fb acifluorfen plus glyphosate resulted in >90% control of glyphosate-resistant common waterhemp throughout the growing season, reduced density to ≤7plantsm–2, ≥92% biomass reduction, and soybean yield >2,200kg ha–1. Averaged across herbicide programs, common waterhemp control was 84%, and density was 15 plants m–2with PRE fb POST herbicide programs compared with 42% control, and density of 101 plants m–2with POST-only herbicide programs at harvest. Results of this study indicated that PRE fb POST herbicide programs with effective modes of action exist for season-long control of glyphosate-resistant common waterhemp in glyphosate-resistant soybean.

Transgenic glyphosate-resistant oilseed rape (Brassica napus) as an invasive weed in Argentina: detection, characterization, and control alternatives.

The presence of glyphosate-resistant oilseed rape populations in Argentina was detected and characterized. The resistant plants were found as weeds in RR soybeans and other fields. The immunological and molecular analysis showed that the accessions presented the GT73 transgenic event. The origin of this event was uncertain, as the cultivation of transgenic oilseed rape cultivars is prohibited in Argentina. This finding might suggest that glyphosate resistance could come from unauthorized transgenic oilseed rape crops cultivated in the country or as seed contaminants in imported oilseed rape cultivars or other seed imports. Experimentation showed that there are alternative herbicides for controlling resistant Brassica napus populations in various situations and crops. AHAS-inhibiting herbicides (imazethapyr, chlorimuron and diclosulam), glufosinate, 2,4-D, fluroxypyr and saflufenacil proved to be very effective in controlling these plants. Herbicides evaluated in this research were employed by farmers in one of the fields invaded with this biotype and monitoring of this field showed no evidence of its presence in the following years.

Random forest and leaf multispectral reflectance data to differentiate three soybean varieties from two pigweeds

Accurate weed identification is a prerequisite for implementing site-specific weed management in crop production. Palmer amaranth (Amaranthus palmeri S. Wats.) and redroot pigweed (Amaranthus retroflexus L.) are two common pigweeds that reduce soybean [Glycine max (L.) Merr.] yields in the southeastern United States. The objective of this study was to evaluate leaf multispectral reflectance data as input into the random forest machine learning algorithm to differentiate three soybean varieties (Progeny 4928, Progeny 5160, and Progeny 5460) from Palmer amaranth and redroot pigweed. Leaf reflectance measurements of soybean, Palmer amaranth, and redroot pigweed plants grown in a greenhouse were collected with a plant contact probe attached to a hyperspectral spectroradiometer. Data were obtained at the vegetative growth stage of the plants on two dates, June 30, 2014, and September 17, 2014. The hyperspectral data were aggregated to sixteen multispectral bands (viz. coastal, blue, green, yellow, red, red-edge, near-infrared 1 and 2, and shortwave-infrared 1–8) mimicking those recorded by the WorldView-3 satellite sensor. Classifications were binary, meaning one soybean variety versus one weed tested per classification. Random forest classification accuracies were determined with a confusion matrix, incorporating user’s, producer’s, and overall accuracies and the kappa coefficient. User’s, producer’s, and overall accuracies of the soybean weed classifications ranged from 93.8% to 100%. Kappa results (values of 0.93–0.97) indicated an excellent agreement between the classes predicted by the models and the actual reference data. Shortwave-infrared bands were ranked the most important variables for distinguishing the pigweeds from the soybean varieties. These results suggest that random forest and leaf multispectral reflectance data could be used as tools to differentiate soybean from two pigweeds with a potential application of this technology in site-specific weed management programs.

Managing weeds using crop competition in soybean [Glycine max (L.) Merr.

Soybean (Glycine max (L.) Merr.) is an important crop worldwide for both protein meal and vegetable oil. Soybean accounts for more than 50% of the global oilseed production. Weed infestation is a complex and regular threat to soybean production all over the world. To combat this threat, chemical, mechanical, and cultural methods are generally used. There has been a revived interest in weed suppression through improved crop competitiveness as an alternative aid in weed management. Different approaches could be utilized to increase crop competitiveness such as adjustment of row spacing, optimum seeding rate, and use of genotypes with high weed-competitive ability. During the past several decades, adoption of narrow row spacing has become increasingly popular among soybean growers primarily because of yield advantage and early canopy closure, which directly provides greater weed suppression. Adoption of narrow rows significantly reduces the density and biomass of late-season emerging weeds and delays the critical time for weed removal compared with wide rows. An increase in seeding density/plant population also suppresses weeds by earlier canopy closure, especially when combined with narrow row spacing. Competitive abilities of different soybean cultivars against different weed species are not consistent. Interseeding cover crops after establishment of soybean also can be a viable option for weed suppression as long as cover crops do not compete with soybean, or act as weeds themselves. Integrated weed management is considered to be the most effective approach for long-term and sustainable management of weeds in soybean. The objective of this article is to provide an overview of currently known cropping practices for improving soybean competitiveness against weeds.

Associação dos herbicidas diclosulam e glyphosate na dessecação visando o controle residual de plantas daninhas na cultura da soja

A associação dos herbicidas glyphosate e diclosulam na dessecação pode diminuir a presença de plantas daninhas por maior período, favorecendo assim o desenvolvimento e a produtividade das plantas de soja. Objetivou-se verificar a eficiência do herbicida diclosulam associado ao glyphosate, na dessecação para plantio direto da cultura de soja RR, cultivada no sistema plante e aplique. A cobertura vegetal presente foi Urochloa ruziziensis com 4,4 t ha-1, distribuída uniformemente sobre a área experimental. O delineamento experimental utilizado foi o de blocos ao acaso com três tratamentos e 4 repetições. Os tratamentos constituíram-se na aplicação de glyphosate a 1,2 kg ha-1 de equivalente ácido (e.a.) + diclosulam a 25,2 g ha-1 de ingrediente ativo (i.a.) em pré-semeadura da cultura sem a aplicação complementar, glyphosate a 1,2 kg ha-1 de e.a. + diclosulam a 25,2 g ha-1 de i.a. em pré-semeadura da cultura + glyphosate a 1,2 kg ha-1e.a. em complementação e glyphosate a 1,2 kg ha-1 de e.a. em pré-semeadura + glyphosate a 1,2 kg ha-1 de e.a. em complementação. Foram avaliados os seguintes parâmetros: reinfestação inicial e densidade relativa de plantas daninhas aos 31 dias após a dessecação, reinfestação de plantas daninhas no período da colheita, dificuldade de colheita mecanizada, número de vagens por planta, peso de 1000 grãos e produtividade de grãos. A associação do herbicida diclosulam ao glyphosate auxilia no manejo inicial da comunidade infestante no cultivo da soja, sem, no entanto, dispensar a aplicação complementar do herbicida glyphosate.

Knowledge of integrated weed management practices by the farmers in Marathwada region

The present study was conducted in Marathwada region of Maharashtra state. Present study was carried out in randomly selected Parbhani district. Four talukas was selected purposely from Parbhani district by considering highest area and production of the soybean crop namely viz., Purana, Palam, Parbhani and Gangakhed. Three villages from each taluka were selected randomly, thus, the make12 villages were selected for study. Ten respondents were selected from each village with the help of those who have cultivating soybean crop on his farm was selected randomly. Thus, the total 120 respondents were selected for the study. The major soybean crops selected for study because soybean crop is infested by number of weeds like Shippi (Echinochloa crus-galli ), Kena (Commelina benghalensis ), Dudhi (Euhorbia spp.), Hazardani (phyllanthus niruri), Nagarmotha (Cyperus rotundus), Hariyali (Cynodon dactylon) etc. which causes loss of farmer upto 40 to 60 per cent in yield, weeds in soybean can be effectively controlled by using integrated weed management practices. Thus, the study was conducted for considering the problem of weed control in soybean crop. Ex-post facto research design was used for present study. The data were collected with the help of personal interview method with the help of interview schedule. It is revealed Table 1 that 69.17 per cent of the respondents were from medium farming experience, 45 per cent respondent were educated upto secondary (middle) school level, 35.83 per cent had small size land holding (upto 2 ha), 89.17 per cent of the respondents engaged in only agriculture, 78.34 per cent of the respondents were from medium income i.e. (Rs. 77103 to 409000) group, 50.84 per cent of the respondents had medium social participation, 62.50 per cent of the respondents used medium sources of information, 59.17 per cent of the respondents had medium extension contact, 59.17 per cent of the respondents had medium level of market orientation, 61.67 per cent, of the respondents had medium level of risk orientation and 62.50 per cent of the respondents had medium level of knowledge.Education, land holding, occupation, annual income, sources of information, extension contact and market orientation and risk orientation had significant relationship with adoption of integrated weed management practices.

Yield Loss and Management of Volunteer Corn in Soybean

Volunteer corn is often overlooked as a weed in soybean. To aid in management decisions, this study determined soybean yield loss attributed to volunteer corn and efficacy of various herbicides at several rates and timings. A hyperbolic equation estimated (R2= 0.88) incremental yield loss (I) of 39.7% at low density when maximum yield loss (A) was constrained to 71%, the highest yield loss observed in these trials, revealing a more competitive plant than many common midwestern weedy species. Clethodim applied at 51 g ai ha−1at V4 soybean resulted in > 90% volunteer corn control with < 5% soybean yield loss, whereas if applied at 12.7 g ai ha−1volunteer corn control was 15%, but soybean yield was 50% greater than the nontreated control. On the basis of these data, the partial volunteer corn control improved soybean yield. Timing of glufosinate application influenced volunteer corn control. Glufosinate applied to 15-cm-tall corn resulted in 33% control, whereas applications to 36- to 91-cm corn resulted in > 70% control. Glufosinate combined with grass herbicides improved control to > 85%, with concomitant yield increases. Results demonstrated that volunteer corn substantially reduced soybean yield at low densities and yield increased when volunteer corn was controlled with various herbicides. On the basis of these results, and current soybean grain and herbicide prices, soybean yield gains from volunteer corn control could increase net return by > $150 ha−1.

Glyphosate-Resistant Weed Control and Soybean Injury in Response to Different PPO-Inhibiting Herbicides

<p>In Nebraska, 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) as well as acetolactate synthase (ALS)-inhibitor-resistant weeds occur in many soybean fields where herbicides from these modes-of-action have been frequently used in the past. Currently, the protoporphyrinogen oxidase (PPO)-inhibitors are the only effective herbicides for POST control of both glyphosate- and ALS-inhibitor-resistant weeds in soybean. Greenhouse experiments were conducted in 2014 to evaluate the efficacy of PPO-inhibitors applied POST for the control of three glyphosate-resistant (GR) weeds and potential for soybean injury, when applied at two growth stages. All herbicide treatments controlled 10- and 20-cm tall GR common waterhemp ≥ 95% at 21 DAT. GR giant ragweed and kochia were controlled 86 to 99% when treated at 10-cm height and 78 to 92% at 20-cm height by 21 DAT. Herbicide treatments reduced shoot biomass in the three GR weeds 88 to 100% when treated at 10-cm height and 73 to 100% when treated at 20-cm height, at 21 DAT. Soybean injury and shoot biomass data revealed that acifluorfen and lactofen were more injurious (≥ 17%), whereas fomesafen, and fomesafen plus glyphosate were relatively safer (< 10% injury). Overall, fomesafen and fomesafen plus glyphosate caused least injury to soybean and were more effective in controlling GR common waterhemp, giant ragweed, and kochia compared with acifluorfen and lactofen.</p>

Efficacy of chlorimuron for controlling weeds in soybean

The field was infested with monocot weeds like Echinochloa colona, Cyperus iria whereas dicot weeds Alternanthera philoxiroides, Eclipta alba, Commelina benghalensis and Phyllanthus niruri were less dominant in soybean. The application of Chlorimuron-ethyl 24 g/ha as early post-emergence along with mechanical weeding was most effective in paralyzing the weed growth to that of chlorimuron-ethyl (12, 24, 36, 48 and 72 g/ha) and mechanical weeding at 20 DAS. The application of chlorimuron-ethyl herbicide at 24 g/ha as early post-emergence along with mechanical weeding was significant superior for growth parameters, yield attributes and seed yield (1.61 t/ha) of soybean than rest of the treatments without any phytotoxicity on soybean plants and was found more remunerative in terms of NMR (`20023.8) and B-C ratio (2.06) than application of chlorimuron-ethyl herbicide at 12 g/ha to 72 g/ha, as early post-emergence. Two hand weedings (20 and 40 DAS) proved to be the best in terms of yield (1.69 t/ha grain, 3.49 t/ha stover); however, NMR (`20011.7/ha) was almost at par to chlorimuron 24 g along with mechanical weeding (`20023.8/ha).

Deciphering the binding mode of dinitramine herbicide to ct-DNA, a thermodynamic discussion

Dinitramine is a herbicide that has been used to control annual grasses and broadleaf weeds in cotton and soybeans in Iran. In this study, the electrochemical behavior of dinitramine was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The interaction of dinitramine with ct-DNA was evaluated by CV, competitive fluorescence, UV-Vis spectroscopy, FT-IR spectroscopy, and viscosity titration. In addition, the thermodynamic parameters of DIN–DNA complex were calculated by spectrophotometric titration. The values of ΔHbin., ΔSbin., and ΔGbin. (T = 290.65 K) of the DIN–DNA complex were +39.25 kJ mol−1, +215.71 J mol−1, and −23.45 KJ mol−1, respectively. These data revealed that the endothermic binding has its origin in the hydrophobic interactions. Also the high positive ΔSbin was explained according to the DIN structure that optimized by mechanical quantum calculations. However, all data showed that the major groove binding between DIN and ct-DNA is more predominant than other binding modes.

RESULT OF HERBICIDES APPLIED AGAINST OF WEEDS IN SOYBEAN FIELD

Herbicides, if used properly, are safe and effective in controlling weeds in soybean. The choice of herbicide, however, depends on the predominant weed species and the availability of the herbicide. Chemical control is currently the most widely used control for soybean crops, due to its ease of control and to the small areas planted in Mongolia. In the soybean field the 15species of weeds belonging to 9 families, 12 genus including 62.5 % annual, 37.5%perennial weeds are distributed.The major grassy weeds; Common millet-(Panicummiliaceum L), Couch grass-(Agropyronrepens L), Bristlegrass-(Seteriaviridis L) sp and broadleaved weeds Redroot Pigweed-(Amaranthtusretro flexus),lambs guarters-(Chenopodium album), AristateGoosfoot-(Chenopodiumaristatum L), Black bindweed-(Polygonum convolvulus), Mallow weed-(Malvamochileviensis Down), Field bindweed-(Convolvulus arvensis), Bristhly thistle-(Cirsiumsetosum ), Dwarf bifurcate cinquefoil -(Potentillabifurca), Perennial Sowthisle-(Sonchusarvensis L) weeds have been distributed in the soybean field.In soybean field the Forward herbicide were applied in doses of 1.0-1.2l/ha have reduced the number of weeds by 90.1-91.6%, weight by 59.5-66.1% and super herbicide Gallantsuper applied in doses of 0.45-0.65l/ha have reduced the number of weeds by 91.0-95.0%, weight by 39.5-59.8% while Cobra herbicide applied in doses of 0.45-0.55l/ha used in broadleaved weed distributed field, have reduced the number of weeds by 90.2-94.6% and weight by 42.7-50.7%. The herbicide application increased of yield hectare by 3.6-9.0 center.Mongolian Journal of Agricultural Sciences Vol.13(2) 2014: 76-79

Allelopathic potential of canola and wheat to control weeds in soybean (Glycine max)

A filed experiment was done to develop management practices to reduce the use of synthetic herbicides, in the arid and semi-arid agricultural ecosystems of north east of Iran. Five treatments including I: chopped residues of canola (Brasica vulgaris), II: chopped residues of wheat (Triticum aestivum) both were separately incorporated to 25 cm depth soil, 20 days before sowing, III: shoot aqueous extract of canola, IV: shoot aqueous extract of wheat which were separately sprayed at post emergence stage and V: without any residues and spraying as control. The weed control treatments reduced the total weed cover, weed density and biomass of weed. The reduction in weed density with canola and wheat residues incorporation were up to 67.5 and 62.2% respectively, at 40 days after sowing and 65.3 and 75.6%, respectively, at 90 days after sowing, compared to control. However, post emergence spraying of shoot aqueous extract of canola and wheat, suppressed weed density up to 41.8 and 36.6% at 40 days after sowing and 54.2 and 52.7% at 90 days after sowing respectively, compared to control. Weed control treatments reduced weed cover (%), weed biomass and weeds stem length. Incorporation of canola and wheat residues in soil reduced weed cover (%) by 62.5 and 63% respectively, while spraying of shoot water extract of canola and wheat suppressed weed cover (%) by 39.6 and 40.4% respectively at 90 days after sowing. Application of canola and wheat residues increased soybean yield by 45.4 and 69.5% respectively, compared to control while post emergence application of shoot aqueous extract of canola and wheat increased soybean yield by 22 and 29.8% respectively.