Estudio fitosociológico y evaluación del banco de malezas del suelo en tres fincas maiceras del Estado Portuguesa, Venezuela

Los estudios fitosociológicos (EF) y bancos de semillas de malezas del suelo (BSMS) son una herramienta para el manejo de las malezas. El objetivo de esta investigación fue realizar un EF y evaluar el BSMS en tres fincas maiceras del estado Portuguesa, Venezuela, determinándose el índice de valor de importancia (IVI) y plántulas por superficie. Se encontraron diferencias entre la composición florística entre fincas y estudios realizados, detectándose un mayor número de especies en el EF. Las especies con mayor IVI en la finca 1 fueron Ludwigia decurrens Walter, Eclipta prostrata (L.) L., Euphorbia heterophylla L. y Amaranthus dubius Mart. ex Thell., mientras que en el BSMS las de más altas densidades fueron Torenia crustacea (L.) Cham. & Schltd., L. decurrens y Cyperus esculentus L., con 1809,95; 434,39 y 253,39 plántulas∙m-2, respectivamente. En la finca 2, Rottboellia cochinchinensis (Lour.) W.D. Clayton, E. prostrata, Eleusine indica (L.) Gaertn y Helianthus annuus L. tuvieron los más altos IVI, y en el BSMS las especies T. crustaceae, Ammannia latifolia L. y L. decurrens las densidades más altas (389,14; 181,00 y 126,70 plántulas∙m-2, respectivamente). En la finca 3, las malezas con mayores IVI fueron Murdannia nudiflora (L.) Brenan, Cyperus rotundus L. y E. indica, y el BSMS estuvo conformado principalmente por C. rotundus y E. indica con 687,78 y 171,95 plántulas∙m-2, respectivamente. En total, en los dos estudios se registraron 32 especies de malezas en 21 familias botánicas.

Influence of post-treatment irrigation timings and herbicide placement on bermudagrass and goosegrass (Eleusine indica) response to low-dose topramezone and metribuzin programs

Immediate, post-treatment irrigation has been proposed as a method to reduce hybrid bermudagrass [Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Burtt Davy] phytotoxicity from topramezone. Immediate irrigation is impractical since it would take a turfgrass sprayer 10 to 15 minutes to cover an average golf course fairway or athletic field. There is also insufficient evidence regarding how post-treatment irrigation, immediate or otherwise, influences mature goosegrass [Eleusine indica (L.) Gaertn.] control from topramezone or low-dose topramezone plus metribuzin programs. We sought to investigate bermudagrass and E. indica response to immediate, 15-minute, and 30-minute post-treatment irrigation compared to no irrigation following topramezone at 12.3 g ae ha−1, the lowest labeled rate, or topramezone at 6.1 g ha−1 plus metribuzin at 210 g ai ha−1. We also evaluated placement of each herbicide and their combination on soil, foliage, and soil plus foliage to help elucidate the mechanisms involved in differential responses between species and herbicide mixtures. Responses were largely dependent on trial due to bermudagrass injury from high-dose topramezone being nearly eliminated by immediate irrigation in one trial and only slightly affected in another. When post-treatment irrigation was postponed for 15 or 30 minutes, topramezone alone injured bermudagrass unacceptably in both trials. Bermudagrass was injured less by low-dose topramezone plus metribuzin than by high-dose topramezone. All post-treatment irrigation timings reduced E. indica control compared to no post-treatment irrigation. The herbicide placement study suggested that topramezone control of E. indica is highly dependent on foliar uptake and phytotoxicity of both bermudagrass and E. indica is greater from topramezone than metribuzin. Thus, post-treatment irrigation likely reduces topramezone rate load with a concomitant effect on plant phytotoxicity of both species. Metribuzin reduced 21-d cumulative clipping wt and tiller production of plants, and this may be a mechanism by which it reduces foliar white discoloration from topramezone.

Growth and phytoremediative capacity of Eleusine indica in a typical farmland soil under previous exposure to organochlorine pesticide

This study investigated the growth and phytoremediative response of Eleusine indica in a typical farmland soil that had been exposed to organochlorine pesticides. Different soil treatments were obtained by mixing pesticide polluted soil (P) with control soil (C) in ratios, 1P:99C, 5P:95C, 50P:50C, 25P:75C, 75P:25C, 100P and 100C. Three-leaf tillers of the test plant were sown in all the treatments for 3 months. The results revealed that there were no significant differences in all plant morphological parameters measured between plants in P impacted soils and C-soil. All the pH values were acidic, although an increase in pH and decrease in conductivity was observed with the introduction of the test plant. There was reduction in total pesticide residual (TPR) contents in the soil as a result of the plant activities. Significant reduction in q – BHC, α – chlordane and ϒ – chlordane was observed in the P1:C99 soil mix; a 90% remediation efficiency (1.663 mg kg-1 ) was registered in the all treatments. This study thus presents E. indica as a potential concentration-dependent phytoremediator of pesticide, with no significant morphological changes.

Biologia e manejo de Eleusine indica

O capim pé-de-galinha, Eleusine indica (L.) é uma gramínea C4 anual que se desenvolve espontaneamente em todo o território brasileiro. Essa espécie está entre as gramíneas mais problemáticas do mundo, tendo registro em 60 países em mais de 50 tipos de cultura. Para essa espécie existem relatos de resistência em 12 países, sendo primeiro caso no Brasil em 2003 na cultura da soja aos herbicidas cyhalofop-butyl, fenoxaprop-ethyl e sethoxydim. No ano de 2016 nas culturas de milho, soja e trigo ao glyphosate. Em 2017 foi o último caso registrado para as culturas de feijão, milho, algodão e soja aos herbicidas fenoxaprop-etil, glyphosate e haloxifop-metil, com resistência múltipla. Os fatores que favorecem a seleção de biótipos resistentes são características relacionadas às plantas daninhas, aos herbicidas e também as práticas culturais. Para o bom controle de plantas daninhas é necessário conhecer diversificadas práticas de manejo na agricultura, para reduzir as perdas de rendimento resultantes de infestações por plantas daninhas. O objetivo dessa revisão foram: identificar características morfológicas dessa espécie e de competição, mecanismo de sobrevivência e os danos que causam.

Tomato Yellow Leaf Curl Virus Infection in a Monocotyledonous Weed (Eleusine indica)

Tomato yellow leaf curl virus (TYLCV) is one of the most important plant viruses belonging to the genus Begomovirus of the family Geminiviridae. To identify natural weed hosts that could act as reservoirs of TYLCV, 100 samples were collected at a TYLCV-affected tomato farm in Iksan from 2013 to 2014. The sample weeds were identified as belonging to 40 species from 18 families. TYLCV was detected in 57 samples belonging to 28 species through polymerase chain reaction using root samples including five species (Eleusine indica, Digitaria ciliaris, Echinochloa crus-galli, Panicum dichotomiflorum, and Setaria faberi) from the family Poaceae. Whitefly Bemisia tabaci-mediated TYLCV transmission from TYLCV-infected E. indica plants to healthy tomatoes was confirmed, and inoculated tomatoes showed typical symptoms, such as leaf curling and yellowing. In addition, TYLCV was detected in leaf and root samples of E. indica plants inoculated by both whitefly-mediated transmission using TYLCV-viruliferous whitefly and agro-inoculation using a TYLCV infectious clone. The majority of mastreviruses infect monocotyledonous plants, but there have also been reports of mastreviruses that can infect dicotyledonous plants, such as the chickpea chlorotic dwarf virus. No exception was reported among begomoviruses known as infecting dicots only. This is the first report of TYLCV as a member of the genus Begomovirus infecting monocotyledonous plants.

Las arvenses como hospedantes de microorganismos en un agroecosistema de sucesión Zea mays L.-Phaseolus vulgaris L.

La competencia entre las plantas arvenses y los cultivos es un tema de gran interés, ya que esta interacción puede causar grandes pérdidas en la agricultura. A pesar de algunos estudios en este tema, poco se sabe sobre la importancia de los microorganismos. Las plantas arvenses tienden a presentar interacciones positivas con la microbiota del suelo, mientras que los cultivos presentan interacciones neutras o negativas. La competición entre las plantas arvenses y los cultivos promueven cambios en la comunidad microbiana del suelo. El objetivo del presente trabajo fue determinar los microorganismos de mayor relevancia en la rizófora de las principales especies de arvenses colectadas en los cultivos de maíz y frijol sembrados en sucesión durante tres años. Sobre un suelo Ferralítico Rojo, se condujeron seis experimentos para conocer los posibles beneficios del manejo oportuno de las arvenses en los cultivos del maíz (Zea mays L.) y del frijol (Phaseolus vulgaris L.) en un sistema sucesional para lo cual se determinaron los cambios estructurales de las arvenses e influencia de estas, sobre la presencia de microorganismos. La especie dominante de arvense fue Sorghum halepense L. en ambos cultivos. Las relaciones interespecíficas arvenses-cultivos incrementaron la biodiversidad asociada al sistema productivo. Se registraron 31 especies de arvenses (15 en maíz y 16 en frijol). Amaranthus dubius L., S. halepense y Parthenium hysterophorus L. y junto a ellas, Eleusine indica L. y Lepidium virginicum L., albergaron la mayor cuantía de microorganismos en la rizósfera. del suelo, mientras que los cultivos presentan interacciones neutras o negativas. La competición entre las plantas arvenses y los cultivos promueven cambios en la comunidad microbiana del suelo. El objetivo del presente trabajo fue caracterizar los microorganismos de mayor relevancia en la rizófora de las principales especies de arvenses colectadas en los cultivos de maíz y frijol sembrados en sucesión durante tres años. Sobre un suelo Ferralítico Rojo, se condujeron seis experimentos para conocer los posibles beneficios del manejo oportuno de las arvenses en los cultivos del maíz (Zea mays L) y del frijol (Phaseolus vulgaris L) en un sistema sucesional para lo cual se determinó los cambios estructurales de las arvenses e influencia de éstas sobre la fertilidad presencia de microorganismos del suelo. La especie dominante de arvense fue Sorghum halepense (L.) en ambos cultivos. Las relaciones interespecíficas arvenses-cultivos incrementaron los nutrientes y la biodiversidad asociada al sistema productivo. Se registraron 31 especies de arvenses (15 en maíz y 16 en frijol). Amaranthus dubius Mart., Sorghum halepense (L.) y Parthenium hysterophorus (L.), y junto a ellas, Eleusine indica (L.) y Lepidium virginicum (L.), albergaron la mayor cuantía de microorganismos en la rizofera.

Influence of different anionic charges in lead compounds in the remediation of lead by Eleusine indica (Gaertn)

The study was carried out to investigate the remediative capacity of Eleusine indica in lead-polluted soil. Soil samples were collected near student hostel (hall 5) in the University of Benin. The soil samples were sun dried to constant weight and was pulverized with wooden roller and sieved with a hand sieve of 2 mm mesh size. The sieved soil was spiked with 0.625 g lead nitrate (PbNO3), lead sulphate (PbSO4), lead carbonate (PbCO3), lead acetetrahydrate (PbC2H6) and lead chloride (PbCl2) separately in three replicate using aqueous standard solutions. Tillers of Eleusine Indica were placed in the metal polluted soil immediately and the experiment was allowed to stay for 15 weeks. The result showed that the uptake efficiency for Eleusine indica in both shoots and roots for lead nitrate was 0.016% and 0.8%, lead sulphate 0.016 % and 0.352 %, lead carbonate 0.064% and 0.496 %, lead acetetrahydrate 0.032 % and 0.688 %, and lead chloride 0.08 % and 0.72 % respectively, indicating that the plant might have sequestered the metal in the soil rather than accumulating it in the leaves. This was evident in the presentation of the metal sequestration factor of over 70 % irrespective of the nature of the metal. Microbial count of soil before and after contamination with lead nitrate was 19000 and 4000 cfu/g indicating a reduction. The study therefore revealed that Eleusine indica is a high efficient plant in sequestering lead in polluted soil.

Vegetative and Fecundity Fitness Benefit Found in a Glyphosate-Resistant Eleusine indica Population Caused by 5-Enolpyruvylshikimate-3-Phosphate Synthase Overexpression

Fitness is an important trait in weed species that have developed herbicide resistance, including resistance to the popular herbicide glyphosate. Fitness cost is commonly found in weeds with glyphosate resistance, which is caused by target-site mutations. In this study, the vegetative and fecundity fitness traits in a glyphosate-resistant (GR) Eleusine indica population caused by 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) overexpression were investigated under glyphosate-free conditions. The results showed that the resistance index of the population resistant (R) to glyphosate compared with that of the population susceptible (WT) to it was approximately 4.0. Furthermore, EPSPS expression level in the R plants was 20.1–82.7 times higher than that in the WT plants. The dry weight of the R population was significantly higher than that of the WT population at the later growth stage after planting; a similar trend was observed for leaf area. In addition, seed production in the R population was 1.4 times higher than that in the WT population. The R and WT populations showed similar maximum germination rates and T50 values. UPLC-MS/MS was performed for the metabolic extracts prepared from the leaves of R and WT populations to address changes in the metabolome. A total of 121 differential metabolites were identified between R and WT individuals. The levels of 6-hydroxy-1H-indole-3-acetamide and indole acetaldehyde, which are associated with auxin synthesis, were significantly higher in plants of the R population than in those of the WT population. However, some secondary metabolite levels were slightly lower in the R population than in the WT population. To conclude, in this study, vegetative and fecundity fitness benefits were found in the GR E. indica population. The results of metabolome analysis indicate that the increase in 6-hydroxy-1H-indole-3-acetamide and indole acetaldehyde levels may be the result of fitness benefit. Further studies should be conducted to confirm the functions of these metabolites.