Amaranthus Retroflexus Research Articles

Effect of redroot pigweed interference on antioxidant enzyme and light response of common bean (Phaseolus vulgaris L.) depends on cultivars and growth stages

Redroot Pigweed (Amaranthus retroflexus L.) is an important weed that is highly competitive with common bean. Photosynthetic pigments, the activity of antioxidant enzymes, the relative expression of a number of antioxidant enzyme and light response genes, were studied in three of common bean cultivars and in V4 and R7 stages under Redroot Pigweed free and infested. The presence of weeds reduced the content of chlorophyll, relative chlorophyll and anthocyanin of common bean leaves. With the increase of weed competition, the expression of antioxidant genes and enzymes increased, which indicates the increase of their activity in order to reduce the amount of reactive oxygen species. Among the studied antioxidant enzymes, the activity of catalase and ascorbate peroxidase produced in the leaves was higher than that of superoxide dismutase. With the increase of weed interference, the expression of phytochrome interacting factor 3 (PIF3) gene as a positive regulator of light signals is increased and the expression of phytochrome rapidly regulated1 (PAR1) gene as a negative regulator is decreased. Chlorophyll a/b-binding protein (CAB1) and auxin-responsive protein IAA8 (IAA8) genes also down-regulated with increasing competition. Along with the decrease of CAB expression in the conditions of competition with weeds, the chlorophyll a, b content also decreased. Correlation between gene expression and physiological traits related to them highlights the prominent role of CWCP in maintaining yield potential.

Exploring the Prospective of Weed Amaranthus retroflexus for Biofuel Production through Pyrolysis

Amaranthus retroflexus or redroot pigweed is a second generation lignocellulosic fuel. Each biomass sample (leaves, inflorescences and stems) was pyrolyzed in a lab-scale furnace, in a nitrogen atmosphere under non-isothermal conditions at heating rates of 10 °C/min until the furnace temperature reached 550 °C. The pyrolysis characteristics of the three major components were also studied through thermogravimetric analysis. The thermal decomposition of the biomass samples is similar to the process of pyrolysis of lignocellulosic materials and proceeds in three main stages: dehydration, devolatilization, and carbonation. The highest bio-oil yield was obtained for inflorescences (55%) and leaves (45%). Gas chromatography—mass spectrometry analysis was carried out for oil fractions of the pyrolysis liquid from Amaranthus retroflexus. The composition of the pyrolysis oil fraction from the leaves had an overbearing aliphatic hydrocarbon nature whereas the oil fraction from inflorescences and stems was composed mainly of oxygen-containing components. The use of Amaranthus retroflexus biochars can lead to slag formation in power equipment, so it is advisable to use them to produce composite fuel, for example, mixed with coal. The results would help to better understand the thermal behavior of Amaranthus retroflexus biomass and its utilization for fuels or chemicals.

Identification of the Spectral Patterns of Cultivated Plants and Weeds: Hyperspectral Vegetation Indices

The accurate recognition of weeds on crops supports the spot application of herbicides, the high economic effect and reduction of pesticide pressure on agrocenoses. We consider the approach based on the quantitative spectral characteristics of plant objects to be the most appropriate for the development of methods for the spot application of herbicides. We made test plots with different species composition of cultivated and weed plants on the experimental fields of the scientific crop rotation of the Federal Research Center of Biological Plant Protection. These plants form the basis of the agrocenoses of Krasnodar Krai. Our primary subjects are sunflower crops (Helianthus annuus L.), corn (Zea mais L.) and soybean (Glycine max (L.)). Besides the test plots, pure and mixed backgrounds of weeds were identified, represented by the following species: ragweed (Ambrosia artemisiifolia L.), California-bur (Xanthium strumarium L.), red-root amaranth (Amaranthus retroflexus L.), white marrow (C. album L.) and field milk thistle (Sonchus arvensis L.). We used the Ocean Optics Maya 2000-Pro automated spectrometer to conduct high-precision ground-based spectrometric measurements of selected plants. We calculated the values of 15 generally accepted spectral index dependencies based on data processing from ground hyperspectral measurements of cultivated and weed plants. They aided in evaluating certain vegetation parameters. Factor analysis determined the relationship structure of variable values of hyperspectral vegetation indices into individual factor patterns. The analysis of variance assessed the information content of the indicators of index values within the limits of the selected factors. We concluded that most of the plant objects under consideration are characterized by the homogeneity of signs according to the values of the index indicators that make up the selected factors. However, in most of the cases, it is possible to identify different plant backgrounds, both by the values of individual vegetation indices and by generalized factorial coefficients. Our research results are important for the validation of remote aerospace observations using multispectral and hyperspectral instruments.

Efficiency for combinations of rimsulfuron with adhesives in maize crops

Topicality. Adhesives are an integral part of the weed control system in the maize crops, because they increase the efficiency of herbicide application. They significantly reduce the cost of plant protection products and increase their efficiency, as well as increase the adhesive properties of the herbicide solution to prevent its runoff and prolong its action. Development of new herbicides, constant weather and climate changes require to study further the effectiveness of the combined action of herbicides and adhesives. Among the adhesives for maize, it is generated interest such products as Synergent SOC, Eco Oil Spray, Esterlip, etc. Purpose. To reveal the effectiveness for combinations of herbicides with adhesives in the maize crops, as well as their impact on plant growth and development. Materials and Methods. The experimental scheme included the following combinations of rimsulfuron with adhesives: 1. Control (Rimsulfuron without adhesive); 2. Rimsulforon (40 g/ha) + Trend 90 (0.15 % working solution); 3. Rimsulforon (40 g/ha) + Synergent (0.15 % working solution); 4. Rimsulforon (40 g/ha) + Eco Oil Spray (0.15 % working solution); 5. Rimsulforon (40 g/ha) + Esterlip (0.15 % working solution); 6. Rimsulforon (35 g/ha) + Esterlip (0.15 % working solution); 7. Rimsulforon (25 g/ha) + Esterlip (0.15 % working solution). Results. The combination of rimsulfuron with adhesive Esterlip had the highest technical efficiency compared to other adhesives, in particular, on the redroot pigweed (Amaranthus retroflexus L.) was 75–100% (complete destruction) and lamb’s quarters (Chenopodium album L.) – 85.7–92.9 %, slightly less on common ragweed (Ambrosia arte-misiifolia L.) – 83.3%. Common purslane (Portulaca oleracea L.) was highly resistant to almost all combinations of rimsulfuron with adhesives. The highest maize yield of 8.99 t/ha was in the variant with Rimsulfuron (40 g/ha) + Esterlip. Reduced application rate of Esterlip to 25–35 g/ha decreased the maize yield to 7.34–7.65 t/ha, or by 1.34–1.65 t/ha (14.9–18.3 %) due to increased weed infestation of crops. The application of adhesives Trend 90, Synergen, Eco Oil Spray also decreased maize yields to 8.48 t/ha, 8.07 t/ha and 8.62 t/ha, respectively, which was less by 0.51 t/ha (5.6 %), 0.92 t/ha (10.2 %) and 0.37 t/ha (4.1 %). The lowest yield was in the control – 5.30 t/ha due to significant weed infestation of grain crops, which decreased by 3.69 t/ha (41.0 %) compared to the best variant (Rimsulfuron (40 g/ha) + Esterlip). Conclusions. Considering the ongoing development of new adhesives and herbicides for maize, as well as climate changes, it is necessary to continue research in this area to determine the most optimal ratio of herbicide rates with adhesives. Key words: maize, weeds, herbicides, adhesives, yield, technical efficiency

Weed chemical control in grain sorghum at the steppe zone of Ukraine

The highest control of ragweed (Ambrosia artemisiifolia L.) in the field experiments was provided by the herbicide Primekstra TZ Gold (effect - 83%; dose - 4.5 l/ha), bent sedum (Amaranthus retroflexus L.) with herbicide Mastak (effect - 88%; dose - 0.5 l/ha), chicken millet (Echinochloa crus-galli L.) using the herbicides Varyag and Datonit Gold (effect - 57%, dose - 4.5 and 2.5, respectively), white quinoa (Chenopodium album L.) – herbicide Datonite Gold with surfactant (effect - 85%; dose - 2.5 l/ha). The greatest chemical control was provided by the application options of herbicides Varyag – 4.5 l/ha and Agent – 0.6 l/ha in the phase of 3-5 leaves of the crop in June. This treatment provide the Ponki sorghum hybrid grain yield increase 24-27% compared to the control.

Seed germination requirements of Amaranthus retroflexus L. populations exposed to environmental factors

Seed germination studies are often used to predict the potential of plants to extend their global distribution. In this research, the effect of gibberellic acid (GA3) concentrations, pre-chilling, temperature, water and salt stresses, pH, high-temperature pretreatment, planting depth, and flooding on seed germination and seedling emergence of three Amaranthus retroflexus L. populations was investigated. GA3 concentration significantly affected seed germination of all three A. retroflexus populations grown under light/dark conditions. All three populations germinated under constant (10, 15, 20, 25, and 30 °C) and alternating (20/15, 25/18, and 35/25 °C (day/night)) temperatures. The optimum alternating temperature for germination of all three populations was 18/25 °C day/night. Seed germination was severely reduced under moisture and salt stresses. Seedling emergence was reduced on the soil surface by increasing the planting depth from 2.5 to 7.5 cm, and no seedlings emerged when the planting depth of seeds was more than 10 cm . The results of this research help us to understand the germination capacity and requirements of A. retroflexus in different environments and also provide information to help better control the weed.

Confirmation and detection of novel acetolactate synthase- and protoporphyrinogen oxidase–inhibiting herbicide-resistant redroot pigweed (Amaranthus retroflexus) populations in North Carolina

AbstractComplaints of control failures with acetolactate synthase (ALS)- and protoporphyrinogen oxidase (PPO)-inhibiting herbicides on redroot pigweed (Amaranthus retroflexus L.) were reported in conventional soybean [Glycine max (L.) Merr.] fields in North Carolina. Greenhouse dose–response assays confirmed that the Camden County and Pasquotank County populations were less sensitive to ALS- and PPO-inhibiting herbicides compared with susceptible A. retroflexus populations, suggesting the evolution of resistance to these herbicides. Sanger sequencing of target genes determined the Camden County population carried a Trp-574-Leu mutation in the ALS gene and an Arg-98-Gly mutation in the PPX2 gene, while the Pasquotank County population carried a His-197-Pro mutation in the ALS gene (first documentation of the mutation in the Amaranthus genus), but no mutation was detected in the PPX2 gene. Single-nucleotide polymorphism (SNP) genotyping assays were developed to enable efficient screening of future control failures in order to limit the spread of these herbicide-resistant populations. In addition, preliminary testing of these assays revealed the three mutations were ubiquitous in the respective populations. These two populations represent the first confirmed cases of PPO-inhibiting herbicide-resistant A. retroflexus in the United States, as well as the first confirmed cases of this particular herbicide-resistance profile in A. retroflexus inhabiting North America. While no mutation was found in the PPX2 gene of the Pasquotank County population, we suggest that this population has evolved resistance to PPO-inhibiting herbicides, but the mechanism of resistance is to be determined.

Abutilon theophrasti’s Resilience against Allelochemical-Based Weed Management in Sustainable Agriculture – Due to Collection of Highly Advantageous Microorganisms?

Abutilon theophrasti Medik. (velvetleaf) is a problematic annual weed in field crops which has invaded many temperate parts of the world. Since the loss of crop yields can be extensive, approaches to manage the weed include not only conventional methods, but also biological methods, for instance by microorganisms releasing phytotoxins and plant-derived allelochemicals. Additionally, benzoxazinoid-rich rye mulches effective in managing common weeds like Amaranthus retroflexus L. have been tested for this purpose. However, recent methods for biological control are still unreliable in terms of intensity and duration. Rye mulches were also ineffective in managing velvetleaf. In this review, we present the attempts to reduce velvetleaf infestation by biological methods and discuss possible reasons for the failure. The resilience of velvetleaf may be due to the extraordinary capacity of the plant to collect, for its own survival, the most suitable microorganisms from a given farming site, genetic and epigenetic adaptations, and a high stress memory. Such properties may have developed together with other advantageous abilities during selection by humans when the plant was used as a crop. Rewilding could be responsible for improving the microbiomes of A. theophrasti.

Artemisia argyi essential oil exerts herbicidal activity by inhibiting photosynthesis and causing oxidative damage

Aromatic plant extracts, especially essential oils (EOs), can be used as alternatives to synthetic herbicides due to their effectiveness and easy degradation in environment. Rich in essential oils, Artemisia argyi is a plant that is known for both its medicinal and allelopathic properties. In this study, the chemical composition of A. argyi essential oil (AEO) was examined. Gas chromatographymass spectrometry (GCMS) revealed that relatively high amounts of monoterpenes, including eucalyptol (26.08%), thujone (10.84%), β-caryophyllene (7.46%), borneol (5.09%), and camphor (4.03%), were detected in AEO. Furthermore, AEO was found to inhibit seed germination of Echinochloa crus-galli, Setaria viridis, Portulaca oleracea, and Amaranthus retroflexus as well as kill seedlings of these plants in petri dish experiments. The IC50 values of E. crus-galli, S. viridis, P. oleracea and A. retroflexus were 5.51, 1.02, 25.41, and 0.61 μL/dish, respectively. We demonstrated that A. argyi essential oil aqueous emulsion (AEOAE) exhibited broad-spectrum herbicidal activity and significant short-term contact killing effects on weed plants in both pot and field experiments. S. viridis was taken as a model weed and various physiological indicators were assessed. The results showed that AEOAE induced excessive ROS production in the tested samples, producing an imbalance of the antioxidant system and damage to the integrity of cell membranes, which manifests as increased MDA content and electrolyte leakage. Molecular docking experiments indicated all of above components as potential binding sites with 4-hydroxyphenylpyruvate dioxygenase (HPPD) enzymes, which regulate the biosynthesis of plant tocopherols and plastid quinones to ultimately generate carotenoids. Additionally, AEOAE treatment led to the decrease of HPPD, carotenoid and chlorophyll content in target weeds, revealing that AEOAE may act as an HPPD inhibitor to impede photosynthesis in weed species. Hence, AEO has the potential to be utilized as a source for bio-herbicides that could be adapted for industrial-level production in the future, but its long-term effects should be studied further.

Characterisation of Czech arable weed communities according to management and production area considering the prevalence of herbicide‐resistant species

AbstractHerbicide resistance is a widespread issue that impacts management of conventional farms, but also has ramifications for the weed community assembly; it is therefore important to see how these species factor into the weed community assembly of farms throughout the countryside. This research analysed species richness and community diversity in 98 field relevés from 48 organic and 50 conventional farms evenly distributed between two major production regions of the Czech Republic and then evaluated the incidence of species which have been reported resistant in the Czech Republic and its neighbouring countries. Farms were selected independently of any acknowledged resistant species. Out of 164 species found in this survey, only eight species have had herbicide‐resistant biotypes reported in the Czech Republic, while a total of 19 species had herbicide‐resistant biotypes reported in neighbouring countries. Species with recorded resistance to PSII inhibitors in the Czech Republic tended to be found together and were mostly associated with the beet production region, characterised by low altitude: Amaranthus retroflexus, Chenopodium album, Echinochloa crus‐galli and Solanum nigrum. Species with reported resistance to ALS and ACCase‐inhibiting herbicides were not clearly associated with a particular region or farming type. Of the species which have had reported herbicide resistance in the neighbouring countries, several were found in conventional fields within the growing season and we recommend immediate screening for herbicide resistance in these species and more diligent action in management according to anti‐resistance strategies: Bromus sterilis resistant to ACCase‐inhibiting herbicides, A. retroflexus resistant to ALS‐inhibiting herbicides or Avena fatua resistant to ACCase and ALS‐inhibiting herbicides. This work is unique in that it is evaluating weed species diversity in organic and conventional farms and using the context to frame the prevalence of high‐risk herbicide‐resistant species; thereby putting the potential incidence of herbicide resistance into perspective at the landscape level.

Discovery of 3-(1-Amino-2-phenoxyethylidene)-6-methyl-2H-pyran-2,4(3H)-dione Derivatives as Novel Herbicidal Leads

Natural products are one of the resources for discovering novel pesticide leads. Here, by molecular hybridization between the natural enamino diketone skeleton and the reported herbicide lead compound I, a series of 3-(1-aminoethylidene)-6-methyl-2H-pyran-2,4(3H)-dione derivatives (APD) were rationally designed, synthesized and tested for herbicidal activity in a greenhouse. The bioassay results showed that most of the target compounds possessed good herbicidal activity under pre-emergence conditions, of which the analog APD-II-15 displayed good pre-emergent herbicidal activity against Abutilon theophrasti Medicus, Amaranthus retroflexus L., Echinochloa crus-galli, Eragrostis curvula (Schrad.) Nees, Avena fatua L., Cyperus difformis L., Chenopodium album L., Ixeris denticulata, Plantago asiatica L., Capsella bursa-pastoris (Linn.) Medic and Flaveria bidentis (L.) Kuntze with > 60% inhibition even at a dosage of 187.5 g ha−1, and displayed good crop safety for wheat, soybean, millet and sorghum at a dosage of 375 g ha−1. The preliminary study of the molecular mode of action by RNA sequencing suggested that a growth inhibition of weeds by APD-II-15 might result from the disruptions of carbon metabolism and formation of a cytoskeleton. The present work indicated that APD-II-15 might be used as a novel herbicidal lead compound for further optimization.

Influence of herbicide Granstar Pro 75, w.g., in vitro conditions on the seed growth of Amarantus retroflexus L.

Goal. Investigate the herbistatic properties of the herbicide Granstar Pro 75, w.g., regarding its effect on the germination of Amaranthus retroflexus L. seeds, to ensure targeted and rational use in wheat crops, with maximum preservation of the crop and minimal environmental impact.
 Methods. Laboratory, visual, computational and comparative, mathematical and statistical.
 Results. It was established that after using the herbicide Granstar Pro 75, w.g., with consumption rates of 15.0 g/ ha, 20.0 g/ ha and 25.0 g/ ha in in vitro conditions there was inhibition of the germination of the seeds of common sedum. According to research data obtained under in vitro conditions in Petri dishes on filter paper, in all repetitions of the third and fourth versions of the experiment, where the herbicide Granstar Pro 75, w.g., with consumption rates of 20.0 g/ ha and 25.0 g/ ha, respectively, the level of reduction in the germination of seeds of common sedum was 100.0%. The level of reduction of the germination of the seeds of common styrica in all repetitions of the experiment variant in Petri dishes on filter paper, where the herbicide Granstar Pro 75, w.g., with a consumption rate of 15.0 g/ ha, compared to the control was 83.8%. At the same time, 30 days after treatment in vitro on filter paper and in the soil in the variants of experiments where the herbicide Granstar Pro 75, w.g., with consumption rates of 15.0 g/ ha, 20.0 g/ ha, and 25.0 g/ ha, there were no germinated seeds at all, the level of reduction in germination was 100.0%. The total level of reduction of the germination of the seeds of common sedum in the soil was the highest in the fourth variant of the experiment, where the herbicide Granstar Pro 75, w.g., with a consumption rate of 25.0 g/ ha — 76.8%. However, compared to the total indicator of the decrease in germination of seeds of the third variant of the experiment in the soil where the herbicide was applied with a consumption rate of 20.0 g/ ha, the specified indicator of the fourth variant of the experiment improved by 4.4%.
 Conclusions. According to the data of the research, it was found that the level of germination of the seeds of the common milkweed was reduced due to the use of the herbicide Granstar Pro 75, w.g., with consumption rates of 15.0 g/ ha, 20.0 g/ ha and 25.0 g/ ha, in vitro conditions in Petri dishes both on filter paper and in soil. At the same time, herbicidal properties were better manifested in the experiments that were performed in vitro on filter paper due to direct contact of the herbicide with the object of research, which ensured 100.0% control of the germination of the seeds of common sedum in the variants where the herbicide Granstar Pro 75, w.g., with consumption rates of 20.0 g/ ha and 25.0 g/ ha. The leading fact of the in vitro research is the establishment of a clear tendency to decrease the germination of the seeds of common sedum in the soil, which is observed on the 10th day after treatment with the herbicide, which gives grounds to record the indirect effect of the herbicide Granstar Pro 75, w.g., with consumption rates of 15.0 g/ ha, 20.0 g/ ha and 25.0 g/ ha, for seed germination. Accordingly, compliance with the regulations for the use of this drug, as well as other requirements for the introduction of herbicides, taking into account the presence of herbicidal properties, can help reduce the chemical load on the environment.

DATA ON THE PRESENCE OF INVASIVE AND POTENTIALLY INVASIVE ALOGEN PLANTS IN OLT COUNTY (ROMANIA)

The research carried out in Olt County regarding invasive and potentially invasive alogen plant species is a necessary step in order to complete the information on their distribution at the national level. The data obtained will be able to be used for a careful monitoring of these plants and the adoption of the necessary management measures regarding the eradication or prevention of their introduction and spread.
 In this sense, an inventory of invasive and potentially invasive plant species identified on the territory of Olt county is presented, with information on the geographical origin, life form, biological form, an assessment of the degree of invasiveness, chorological data, habitat, as well as aspects related to the impact they exert on native vegetation, human health or the economy.
 The preliminary analysis of the list of invasive and potentially invasive alogen plants identified in Olt County highlights, in particular, the presence of some species of concern for the European Union (such as Ailanthus altissima, Asclepias syriaca and Elodea nuttallii). Besides these, the most widespread invasive species found in Olt county are Ambrosia artemisiifolia, Robinia pseudoacacia, Morus alba, Amorpha fruticosa, Acer negundo, Amaranthus retroflexus, Erigeron annuus, E. canadensis, Lycium barbarum, Sorghum halepense, Xanthium orientale subsp.italicum. It is well known that the impact of invasive species on the environment, the economy and in some situations even on human health is major and that is why these organisms must be subject to an extensive and continuous monitoring process. Also, in order to control the introduction and spread of invasive and potentially invasive species, a series of appropriate management measures are required.

Genetic variation of Amaranthus retroflexus L. and Chenopodium album L. (Amaranthaceae) suggests multiple independent introductions into Iran.

Amaranthus retroflexus L. and Chenopodium album L. (Amaranthaceae) are weedy plants that cause severe ecological and economic damage. In this study, we collected DNA from three different countries and assessed genetic diversity using inter-simple sequence repeat (ISSR) markers. Our analysis shows both weed species have low genetic diversity within a population and high genetic diversity among populations, as well as a low value of gene flow among the populations. UPGMA clustering and principal coordinate analysis indicate four distinct groups for A. retroflexus L. and C. album L. exist. We detected significant isolation-by-distance for A. retroflexus L. and no significant correlation for C.album L. These conclusions are based data from 13 ISSR primers where the average percentage of polymorphism produced was 98.46% for A. retroflexus L. and 74.81% for C. album L.These data suggest that each population was independently introduced to the location from which it was sampled and these noxious weeds come armed with considerable genetic variability giving them the opportunity to manifest myriad traits that could be used to avoid management practices. Our results, albeit not definitive about this issue, do not support the native status of C. album L. in Iran.

Secondary Metabolites from Aspergillus sparsus NBERC_28952 and Their Herbicidal Activities

Fungi have been used in the production of a wide range of biologically active metabolites, including potent herbicides. In the search for pesticides of natural origin, Aspergillus sparsus NBERC_28952, a fungal strain with herbicidal activity, was obtained. Chemical study of secondary metabolites from NBERC_28952 resulted in the isolation of three new asperugin analogues, named Aspersparin A-C (2-4), and a new azaphilone derivative, named Aspersparin D (5), together with two known compounds, Asperugin B (1) and sydonic acid (6). The structures of these compounds were elucidated based on extensive spectroscopic data and single-crystal X-ray diffraction analysis. All of the isolated compounds were evaluated for their herbicidal activities on seedlings of Echinochloa crusgalli and Amaranthus retroflexus through Petri dish bioassays. Among them, compounds 5 and 6 exhibited moderate inhibitory activities against the growth of the roots and shoots of E. crusgalli seedlings in a dose-dependent manner, while 6 showed obvious inhibitory effect on seedlings of A. retroflexus, with an inhibitory rate of 78.34% at a concentration of 200 μg/mL. These herbicidal metabolites represent a new source of compounds to control weeds.

Varijabilnost broja i mase 1000 semena korova prisutnog u naturalnom semenu lucerke sa različitih lokaliteta u Srbiji

Alfalfa is the most significant perennial and multi-crop forage legume in Serbia. Seed production has numerous problems, which causes high variability in seed yield. One of the problems in this production is the weed seeds that are in the natural alfalfa seed after harvesting. Minimum purity must be greater than 95 %, up to 2 % of other species are allowed, and up to 0.5 % of weeds, but no quarantine weeds such as dodder (Cuscuta.sp). Weed seeds were detected in natural alfalfa seeds: Sinapis arvensis L., Amaranthus retroflexus L., Rumex obtusifolius, L., Cuscuta campestris Yunk., Rumex acetosella L., Plantago lanceolata L., Plantago major L., Rumex crispus L., Galium aparine L., Convolvus arvensis L. as expected, the variability of the number of weed seeds detected from the seed lots over three years was high: CV% = 14.78 for wild sorghum - S. halepense (L.) Pers. In the 2022, to CV% = 65.47 for ribwort plantain - Plantago lanceolata L. in the 2020. For the weight of 1000 seeds of the examined weeds, the variability was determined from CV% = 5.869 for the ribwort plantain - Plantago lanceolata L. (year 2020), to CV% = 34.41 for yellow dock - Rumex crispus L. (year 2022).

Uticaj primene herbicida u trake i međuredne kultivacije na svežu masu širokolisnih korova u usevu soje

Aim of the research was to determine whether the band application of herbicides in soybean, covering a 50% smaller herbicide area, in combination with inter-row cultivation can achieve a similar or approximate weed control effectiveness, as compared to the broadcast herbicide application method in soybean crops, with and without inter-row cultivation. In three-year trials, pre-emergence (dimethenamid-P + metribuzin) and post-emergence (bentazon + imazamox) herbicides were applied using the broadcast and band (25 cm wide) application of herbicides, with and without inter-row cultivation.Inter-row cultivation was applied one week after the first and second post-emergence treatments. Impact of the tested variants on the fresh aboveground biomass of weeds was assessed, with the following species being dominant: Abutilon theophrasti Medik., Amaranthus retroflexus L., Ambrosia artemisiifolia L., Chenopodium album L., and Xanthium strumarium L. The results showed that using the band application of herbicides with inter-row cultivation can achieve approximate effectiveness in reducing fresh biomass compared to broadcast application of herbicides, with or without inter-row cultivation. The combination of pre-emergence herbicides and the two-time application of divided amounts of post-emergence band and broadcast application of herbicides with inter-row cultivation achieved the most reliable control of all weeds, with an efficiency >95%. The results indicate that under favorable conditions for the herbicide action, it is possible to omit one half of the total amount of applied post-emergence herbicides. This can further contribute to significantly reducing the total amount of herbicides used in weed control.

Innovation in agriculture and the agri-food chain: Some insights

<abstract> <p>Information on the impact of climate change on the growth of weed species and their sensitivity to herbicides could help to establish an efficient weed management strategy. Due to the excessive use of acetolactate synthase (ALS) inhibitor herbicides, resistance to those herbicides is increasing globally. It is thus crucial to find out whether the efficacy of these herbicides will change in the future due to the increase in carbon dioxide concentration and in the temperatures. This work therefore aims to evaluate the impact of temperature and carbon dioxide (CO<sub>2</sub>) changes on the growth of <italic>Amaranthus retroflexus</italic>, <italic>Bromus tectorum</italic>, <italic>Chenopodium album</italic> and <italic>Echinochloa crus-galli</italic>, including the assessment of herbicide (sulfosulfuron 75% + metsulfuron methyl 5%) (SMM) efficiency in these weeds. A factorial experiment was performed in a completely randomized design with three factors, including two CO<sub>2</sub> concentrations (400 and 700 ppm), two temperature regimes (30/20 ℃ and 34/24 ℃ day/night), and six herbicide rates (0, 25, 37.5, 50, 62.5 and 75 g a.e. ha<sup>−1</sup>) in four replications. As a result, it was seen that temperature and CO<sub>2</sub> concentration changes influenced the morphological parameters of the weeds. The main effect of the temperature regime on the herbicide's effectiveness, except for <italic>B. tectorum</italic>, was not statistically significant. The interaction of herbicide rates and temperature with the herbicide's efficacy was only significant for <italic>E. crus-galli</italic>; the highest efficacy was observed at 30/20 ℃ and at a rate 50% higher (75 g a.e. ha<sup>−1</sup>) than the recommended one (50 g a.e. ha<sup>−1</sup>). Increasing CO<sub>2</sub> concentrations enhanced the herbicide's efficiency and ALS enzyme activity inhibition in all the weed species, but had the greatest effect on C<sub>3</sub> weeds. Our results showed that temperature and CO<sub>2</sub> levels associated with climate change can interact to alter the efficacy of herbicidal weed control and that there are differences between plants with the C<sub>3</sub> and C<sub>4</sub> photosynthesis pathways. As a result, in the future, breeders and farmers could achieve the results desired by applying lower doses of this herbicide.</p> </abstract>

Pollen Micromorphology among Amaranthaceous Species from Desert Rangeland: Exine Stratification and their Taxonomic Significance

The aim of the study was to visualize the micromorphology of Amaranthaceous pollen using scanning electron microscopy collected from the Thal Desert. Field collection was conducted from July to September 2021. A total of 14 taxa of the family Amaranthaceae were collected which belong to nine genera. Achyranthes aspera, Aerva javanica, Aerva lanata, Amaranthus graecizans, Amaranthus retroflexus, Amaranthus viridis, Bassia indica, Chenopodium album, Chenopodium ficifolium, Chenopodium murale, Digera muricata, Haloxylon stocksii, Salsola tragus, and Suaeda fruticosa were studied in terms of pollen morphotypes. Pollen were acetolyzed and observed under optical and scanning microscopy. Qualitative and quantitative characters were measured to analyze the pollen to uncover its taxonomic significance. Qualitative characters observed were the shape of pollen in polar and equatorial views; the most frequent shape observed was spheroidal in the polar view, whereas in the equatorial view, prolate spheroidal was the dominant shape. Exine ornamentation is the key characteristic of pollen which is very helpful, and eight different types of ornamentations were observed in collected taxa: smooth sparsely granulate, scabrate‐spinulose, microspinulose perforate, microechinate scabrate to metareticulate, granulate, nanospinulate, granulate‐spinulose perforate, granulate‐perforate echinate, and microechinate perforate. Periporate‐type aperture was observed among all taxa. Mesoporia, ektexinous bodies, and tectum features also show variations among Amaranthaceous grains. In quantitative character, A. retroflexus recorded highest in polar view 26.3 μm and the lowest was of C. album 12.2 μm. Highest P/E index ratio was recorded in S. fruticosa (1.12) whereas the lowest for D. muricta (0.94). Exine thickness was highest in S. tragus 2.15 μm and lowest in A. graecizans 0.78 μm. The maximum number of pores was recorded as 32‐36 in D. muricata. Artificial taxonomic keys were constructed based on findings that reinforce the importance of the micromorphological ultrastructural diversity of pollen among Amaranthaceous taxa. It was concluded that the descriptions of pollen morphotypes presented greatly contribute to our understanding of desert species identification.

Amaranthus hybridus L. RESISTANT TO GLYPHOSATE AND CHLORIMURON IN PARAGUAY

Amaranthus species are extremely problematic weeds due to their aggressiveness and resistance, being Amaranthus palmeri S. Watson, Amaranthus retroflexus L., Amaranthus tuberculatus (Moq.) J. D. Sauer, and Amaranthus hybridus L. prominent worldwide. The present research aimed to study A. hybridus populations in Paraguay where the use of glyphosate and chlorimuron herbicides presented management challenges. This research was conducted in the municipalities of Corpus Christi and Hernandarias, Paraguay, in 2016, 2017, 2018, 2019, and 2020. Weed seeds with resistance indicators were collected, cultivated, and following a screening process, cultivated for seed production (heritability up to F2), and the seeds were collected to obtain the herbicide dose-response curve. The herbicides glyphosate and chlorimuron were tested in portions of 1-8, 1-4, 1-2, 1, 2, 4, and 8 times the recommended dose on the package inserts (720 g acid equivalent (ae) ha 1 and 20 g active ingredient (ai) ha1, respectively). Among the A. hybridus populations evaluated in Paraguay, biotype from Hernandarias with multiple resistance to ALS-inhibiting (HRAC 2) and EPSPs-inhibiting (HRAC 9) herbicides, and biotype from Corpus Christi with resistance to ALS-inhibiting herbicides (HRAC 2) were found. Therefore, rotation and combination of herbicides, as well as integration with non-chemical measures, are essential to control and prevent selection of resistant biotypes. Studies aimed to develop integrated weed management plans are essential for effective control. In countries like Paraguay, this becomes imperative because of the lack of research on this topic.