Abstract in English:

Abstract Background Napropamide is used to control annual grasses and broadleaf weeds. It affects root and shoot development. However, its mechanism of action is inconclusive and hence is classified in group 0 herbicides by the Herbicide Resistance Action Committee (HRAC). Objective This study focused on exploring specific endpoints which could decode some fundamental aspects leading to the inhibitory effect of napropamide on plants. Methods For rapid in vitro evaluation of morphological parameters, root and shoot length in tomato plant was measured using the International Organization for Standardization (ISO) compliant phytotox system. Indole acids were measured by Salkowski’s method and LC-MS/MS and the role of key genes involved in auxin transport was studied with qPCR. Results In this study, napropamide treatment inhibited root length by 67.6% at 50 μM, on day 8. Total indole acids content using colorimetric analysis was 13.2 ± 0.9 μg mL-1 in treated plants with respect to 10.2 ± 0.9 μg mL-1 in control. Detailed LC-MS/MS analysis revealed IAA levels to be 88.8 ± 16.2 ng mL-1 and 31.3 ± 6.1 ng mL-1 and indole butyric acid (IBA) levels to be 55.2 ± 3.4 ng mL-1 and 27.7 ± 2.5 ng mL-1 in treated and untreated plants respectively. In line with these observations, major auxin transporters AUX1/LAX, PINs showed upregulation of 1.9 to 3.6 folds upon napropamide treatment. Conclusion This study highlights the effect of napropamide on auxin levels and gene expression and presents a rapid, simple, and user-friendly model for studying inhibitory effect of herbicides in plants.

Abstract in English:

Abstract Background Horseweed (Conyza bonariensis) is an important weed species infesting soybean plantations. Some biotypes with multiple herbicide resistance have been recently reported. One way to avoid weed dispersion and spread to adjacent areas is by reducing and preventing seed germination. Objective We aimed to evaluate the effects of auxinic herbicides (2,4-D, dicamba, triclopyr and halauxifen-methyl), with or without mixing with glyphosate, on the production, germination and morphology of horseweed seeds. Methods With the recent release of the transgenic soybean event DAS-44406-6 in Brazil, we conducted three experiments with different horseweed biotypes (Canguiri, Palotina and Palmeira) and application stages (early and late vegetative, and early reproductive). Results Auxinic herbicides, applied alone or mixed with glyphosate, reduced the germination and production of horseweed seeds, regardless of the stage of application. The application of herbicides caused morphological changes in the seeds, such as darkening, damaged achenes and papillae, and absence of embryos. Conclusions For plants that produced seeds, there was a 100% reduction in germination, showing that the application of these herbicides can be a viable strategy in the integrated management of this species.

Abstract in English:

Abstract Background Barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.) is an annual weed affecting many field crops. A glyphosate-putative-resistant barnyardgrass population was found from a soybean field in southern Brazil. Objective This study aimed to confirm this resistance in Rio Grande do Sul (RS) and identify its mechanism. Methods Dose-response curves were generated using a three-parameter nonlinear regression model to assess control efficacy and shoot dry weight reduction. Resistance factors (RF) were calculated across two generations from the resistant (BR20Esp016) and susceptible (BR19Esp001) populations. cDNA was synthesized from total RNA extracted from the plants, and the EPSPS gene was sequenced from both populations. Results Based on the glyphosate required to reduce dry weight by 50% (GR50), the resistance biotype had RFs of 2.4 and 2.6 and values of 2.4 and 13.9 for the same variable for the self-fertilization generation (F2). A mutation was detected in the EPSPS gene, where proline (CCA) is replaced by alanine (GCA) at position 106, conferring resistance to EPSPS-inhibiting herbicides in barnyardgrass. Conclusion Glyphosate resistance in the barnyardgrass biotype BR20Esp016 is due to target-site resistance associated with a mutation in the EPSPS gene.

Abstract in English:

Abstract: Background Herbicide-resistant E. crus-galli poses a significant threat to rice production in direct-seeded rice systems. Objective This study aimed to confirm the presence of bispyribac-sodium-resistant (R) E. crus-galli and determine the optimal mixture ratio of propanil and quinclorac to control the R biotype. Methods E. crus-galli seeds from putative resistant and susceptible biotypes were collected from rice fields located 10 km apart in Alor Setar, Kedah, Malaysia, and screened with bispyribac-sodium, propanil, and quinclorac. Dose-response tests were conducted to confirm herbicide resistance. Propanil and quinclorac were tank-mixed at ratios of 20:80, 40:60, 60:40, and 80:20 and their inhibitory effects were evaluated under glasshouse conditions. Results Dose-response tests showed a 128-fold increase in the resistant biotype (R) compared to the susceptible (S) biotype based on the dosage corresponding to 50% inhibition of shoot growth, and a 70-fold increase based on the dosage that caused 50% mortality. The mixture ratios of propanil and quinclorac exhibited synergistic action except for the 80:20 ratio, which was antagonistic. The 40:60 mixture ratio outperformed the others, allowing the rates of propanil and quinclorac to be reduced by 2.2 and 4.7-fold, respectively, compared to their single applications to achieve 95% mortality. Conclusions: Dose-response tests revealed a high resistance level in the R biotype to bispyribac-sodium. Propanil and quinclorac at recommended rates were effective in controlling the R biotype. This study demonstrates that the ratio of propanil in combination with quinclorac is crucial in enhancing the herbicidal activity.

Abstract in English:

Abstract Background Pistia stratiotes L., is an invasive aquatic plant that forms dense mats, disrupting ecosystems and affecting waterway navigation. Although various control methods have been studied, there is no clear consensus on the best approach. Objective The goal of this study is to evaluate the efficacy of various control methods in managing P. stratiotes infestations. Methods Laboratory trials tested the efficacy of diquat, d-limonene, mineral oil, and potassium salts of fatty acids on P. stratiotes. Treatments were applied at concentrations from 10–30%, with weekly monitoring for five weeks to assess treated plants visual quality (injury symptoms), and dry biomass. Greenhouse trials replicated the most effective laboratory treatments. Results In laboratory trials, diquat at 0.89% achieved > 90% reduction in visual quality and dry biomass of P. stratiotes, making it the most effective treatment. D-limonene at 30% showed similar efficacy, while mineral oil also significantly reduced P. stratiotes populations. Combinations of d-limonene with mineral oil or potassium salts of fatty acids exhibited synergistic effects; some combinations achieved >90% reduction in visual quality and dry biomass. Treatments prepared with seawater with diquat (0.89%) and d-limonene (20% and 30%) were the most effective treatments. Greenhouse trials confirmed these results, suggesting these treatments could be effective. Conclusions In conclusion, this study underscores the effectiveness of diverse strategies in controlling P. stratiotes infestations. Further research is warranted to evaluate long-term efficacy, cost-effectiveness, and environmental impact. Integrated approaches offer a multifaceted and sustainable solution for managing P. stratiotes, mitigating its ecological and economic impacts.

Abstract in English:

Abstract Background Herbicide exposure affects the agro-histological characteristics and seed production of barnyardgrass in lowland rice fields. Objective This study aimed to assess the impact of the 2,4-D dimethylamine on the agro-histological and seed production of barnyardgrass and its effects on lowland rice plants. Methods Barnyardgrass seeds were collected from lowland rice fields in nine sub-districts of Serdang Bedagai District, Indonesia. The study was conducted in farmer fields in Medan Selayang, Indonesia, from August to December 2022. The study used a randomized block design with a single factor, 40 populations of barnyardgrass sprayed the 2,4-D dimethylamine at 1.5 fold of the recommended dose (1,080 g ai ha-1) with three replications. Results The increase in tissue size of the upper epidermis, mesophyll, and lower epidermis can be used as an indicator of the effect of higher doses of 2,4-D dimethylamine. The herbicide 2,4-D dimethylamine at a dose of 1.5 fold caused an increase in the seeds produced of barnyardgrass biotypes up to 8.20 fold and lowland rice yield until 5.98 tons ha-1. Conclusions The herbicide remained safe for the growth and yield of lowland rice and enlarge the agro-histological tissues of barnyardgrass.

Abstract in English:

Abstract Background: Acacia auriculiformis (earleaf acacia), an Australian perennial tree, is an increasingly problematic invasive species in Florida. Objective: Create a host range molecular phylogeny by generating test plant patristic distances to earleaf acacia (using rbcL sequences). Methods: DNA was extracted and sequenced from 98 Fabaceae species and an additional 28 sequences were downloaded from NCBI. Results: Molecular phylogenetics and patristic distance inform which plant species should be tested starting with closely related (usually native) plants, especially those threatened or endangered, then extending to less related plants of commercial value. Conclusions: We show the Mimosoideae clade, while monophyletic, appears within the Caesalpinioideae clade. We also suggest 33 mostly threatened or endangered species for the initial test list from the Mimosoideae and Caesalpinioideae, including nine Papilionoideae commercial species. Finally, as a secondary test list, if additional testing is required, we suggest 30 additional Papilionoideae species be added.

Abstract in English:

Abstract Background: Understanding the interactions between weed communities and chickpea crops can improve weed management practices, boost crop productivity, and promote sustainability. Objective: Assessing the interference caused by weed communities on chickpea production and to explore the relationship between weed biodiversity and chickpea yield. Methods: Random sampling was utilized to assess weed populations in 85 chickpea fields. Weed density and canopy cover, as well as indices of species richness, Shannon-Weiner, and Camargo's evenness, were recorded at two phenological stages of chickpeas: four to seven leaves and mid to early-podding. Regression methods were employed to examine the effects of weed traits on chickpea yield. Finally, principal component analysis was conducted among weed and chickpea data. Results: Chickpea yield decreased with increasing weed density and canopy cover. Increasing weed density from 0 to 50 plants m-2 decreased chickpea yield by 36.73% at the four to seven-leaf stage. In addition, an increase in canopy cover from 0 to 55% caused a yield loss of 41.70 g m-2 at the early-podding stage. Wild safflower (Carthamus oxyacantha M. Bieb.) and chicory (Cichorium intybus L.) were the most predominant weeds with a significant negative correlation with chickpea yield. Licorice (Glycyrrhiza glabra L.) had a negative correlation with chicory and wild safflower. There was a positive relationship between density and canopy cover of licorice and chickpea yield, weed diversity and evenness. Conclusions: Effective weed management should focus on both controlling dominant species and promoting weed diversity to enhance crop productivity and environmental sustainability.

Abstract in English:

Abstract Background: Swallowwort (Cynanchum acutum subsp. sibiricum) poses significant challenges in cotton fields and orchards across northwest China. Objective: Laboratory and greenhouse experiments were conducted to investigate the impact of various abiotic factors on seed germination of swallowwort. Methods: Seed germination and seedling emergence of freshly harvested seed (FS) and seed stored for six months (SS) were investigated under different temperatures, osmotic potentials, saline stresses, and burial depths. Results: The optimal germination temperature of FS was 30 to 35 °C, while that for SS was extended to 15 to 35 °C. Freshly harvested seeds germinated under alternating temperature regimes from 20/10 to 45/35 °C, but seed germination could reach to 60% at 15/5 °C after six months of storage. No germination of FS was observed at ≤ -1.0 MPa. However, seed germination remained at 44.6% at -1.0 MPa after storage. Saline stress reduced seed germination, with no germination observed at NaCl concentrations of ≥ 400 mM for the FS or ≥ 500 mM for the SS. However, pH values ranging from 5 to 10 had no significant impact on seed germination. The maximum seedling emergence (71%) was observed at the soil surface and no emergence at 10-cm burial depth. Conclusions: Six months of storage enhanced seed tolerance to sub-optimal temperature, drought and salt stress conditions, comparing with FS. This made swallowwort more adaptable to harsh environments such as drought and salinity. Therefore, timely weed control is necessary to prevent seed production.

Abstract in English:

Abstract An alternative for the control of weedy rice (Oryza sativa) and barnyardgrass (Echinochioa spp.) resistant to imidazolinone herbicides are acetyl coenzyme-A carboxylase inhibitors (ACCase) herbicides used in cultivar tolerant to these compounds. The objective was to evaluate the interaction of propaquizafop in tank mix with herbicides used in rice tolerant to ACCase inhibitors to control weedy rice and barnyardgrass. Two experiments were conducted, in the 2022/2023 season, in Dom Pedrito and Formigueiro. The hybrid XP739MA (MaxAce® technology) was used at both locations. The treatments were arranged in a 3x8+1 factorial design with factor A being rates of propaquizafop (0, 125 and 180 g ha-1), and factor B tested herbicides carfentrazone, propanil, quinclorac, penoxsulam, florpyrauxifen-benzyl, bentazon, saflufenacil, and untreated control. The additional treatment was two applications of propaquizafop (125 g ha-1). The analyzed variables were weedy rice and barnyardgrass control, rice injury, yield components and yield. The interactions were mostly additive for weedy rice and barnyardgrass control. The antagonism of the tank mixture of propaquizafop with quinclorac and florpyrauxifenbenzyl for barnyardgrass and with propanil for weedy rice reduced the yield components in Dom Pedrito. The interactions of propaquizafop with propanil were antagonistic and resulted in the lowest yield in Formigueiro. For this tank mix at the highest propaquizafop rate, yield decreased 14.6% more than at the 125 g ha-1 rate. Tank mix of propaquizafop with other herbicides used in tolerant rice with MaxAce® technology can be used, increasing the weed control spectrum.

Abstract in English:

Abstract: Background Johnsongrass (Sorghum halepense (L.) Pers.) is one of the most problematic weeds worldwide, and in recent years, control failures with herbicides inhibiting the enzyme acetolactate synthase (ALS) have been reported. Objective Determine the resistance in different biotypes of Johnsongrass to nicosulfuron, as well as elucidate its possible resistance mechanism. Methods Dose-response bioassays were conducted with four biotypes, three of them from corn fields with consecutive history of nicosulfuron applications (Veracruz-Mexico) and a susceptible biotype (Guanajuato-Mexico). A partial sequence of the ALS gene was obtained for each biotype to identify mutations conferring target-site resistance to this herbicide. Results The dose-response curves showed high rates of resistance in the biotypes from Veracruz (IR: 30, 63, and 77 times more resistant than the susceptible biotype); at the molecular level, a mutation was found, which resulted in the substitution of amino acid (Asp376Glu). Conclusions This mutation could be involved in resistance in the Oro Verde, El Marcial, and Francisco Villa populations.