Pre-emergence application of (thio)urea analogues compromises the development of the weed species Bidens pilosa, Urochloa brizantha, and Urochloa decumbens

ABSTRACT This study aimed at evaluating the physiology of maize and weeds when living under different densities. The randomized block design with 4 replications was used. The factorial scheme 5 x 2 + 1 and 5 x 3 was adopted, for maize and weeds respectively, corresponding to weed species (Bidens pilosa, Commelina benghalensis, Urochloa brizantha, Sorghum arundinaceum and Ipomoea triloba) and infestation density (control, 15 and 30 plants m-2). Weeds were kept in coexistence with the maize hybrid DKB 390 PRO 2, with an additional treatment for maize plants absent of competition. It was kept in coexistence with maize hybrid DKB 390 PRO 2 besides an additional treatment with maize plants absent of competition. On day 45 and 60 after maize planting (DAP) physiological reviews were performed within the culture, and 38 days after weed transplanting (DAT), an infrared gas analyzer (IRGA) was used. There were physiological changes in maize due to the coexistence with weeds. On day 45 DAP, the competition, regardless of the weed species, caused less photosynthetic rate in maize coexisting with 15 plants m-2; the stomatal conductance was lower in both densities. On day 60 DAP, maize in competition with 15 and 30 plants m-2 showed lower transpiration rate. U. brizantha and S. arundinaceum showed reduction in photosynthesis and transpiration, due to increased density and coexistence with maize.

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Puccinia levis var. brachiariae. [Descriptions of Fungi and Bacteria].

IMI Descriptions of Fungi and Bacteria ◽

10.1079/dfb/20093189830 ◽

2009 ◽

Author(s):

P. F. Cannon

Keyword(s):

Host Plant ◽

Geographical Distribution ◽

Conservation Status ◽

Leaf Lamina ◽

Brachiaria Brizantha ◽

Urochloa Decumbens ◽

Urochloa Brizantha

Abstract A description is provided for Puccinia levis var. brachiariae comb. nov., which causes small lesions on young stems and leaf lamina of the host plant and, where present in quantity, could significantly reduce vigour. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Malawi, Uganda, Zambia and Brazil) and hosts (Brachiaria brizantha [Urochloa brizantha], B. decumbens [Urochloa decumbens], B. humidicola [Urochloa humidicola] and an unnamed Brachiaria sp.).

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Phosphorus as a mitigator of the effects of water stress on the growth and photosynthetic capacity of tropical C4 grasses

Acta Scientiarum Agronomy ◽

10.4025/actasciagron.v38i3.28454 ◽

2016 ◽

Vol 38 (3) ◽

pp. 363 ◽

Cited By ~ 2

Author(s):

Frank Akiyoshi Kuwahara ◽

Gustavo Maia Souza ◽

Kezia Aparecida Guidorizi ◽

Ciniro Costa ◽

Paulo Roberto de Lima Meirelles

Keyword(s):

Water Stress ◽

Crop Production ◽

Photosynthetic Capacity ◽

Panicum Maximum ◽

P Deficiency ◽

Tropical Grasses ◽

Tropical Forage ◽

Productive Potential ◽

Urochloa Decumbens ◽

Urochloa Brizantha

Water deficiency during the dry seasons influences the relationship between water and gas exchange in tropical grasses, reducing their productive potential. In addition, the phosphorus (P) deficiency Brazilian soils adds to the set of factors limiting crop production. In this context, the objective of this study was to evaluate the responses of different tropical forage species to phosphorus supplementation as mitigating the damage caused by water stress. Seeds of Urochloa brizantha cv. MG-4, Urochloa decumbens cv. Basilisk, Panicum maximum cv. Áries, Panicum maximum cv. Tanzânia and Paspalum atratum cv. Pojuca were germinated in pots containing 10 liters of red-yellow Acrisol type soil. Experiments were conducted by combining levels of phosphorus, 8,0 and 100,0 mg of P dm-3, with two irrigation regimes, 100 and 40% replacement of transpired water. The biometric parameters, photosynthetic capacity, leaf water potential and soil chemical characteristics were evaluated, and the data was submitted to analysis of variance (ANOVA, p < 0.05), and subsequently the means were compared using a Tukey test (p < 0.05). The results showed for tropical grasses grown under water stress, there is a clear mitigating effect of phosphorus supplementation, especially on the maintenance of biomass growth.

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Allelopathy of aqueous Pachyrhizus erosus L. extracts on Euphorbia heterophylla and Bidens pilosa

Pesquisa Agropecuária Tropical ◽

10.1590/1983-40632018v4851117 ◽

2018 ◽

Vol 48 (1) ◽

pp. 59-65

Author(s):

Jaqueline de Araujo Barbosa ◽

Silvio Douglas Ferreira ◽

Adriana Cologni Salvalaggio ◽

Neumárcio Vilanova da Costa ◽

Márcia de Moraes Echer

Keyword(s):

Germination Rate ◽

Germination Percentage ◽

Tuberous Root ◽

Allelopathic Effect ◽

Root Extract ◽

Weed Species ◽

Bidens Pilosa ◽

Randomized Design ◽

Pachyrhizus Erosus ◽

Dry Biomass

ABSTRACT Allelopathy contributes to the sustainable management of weeds in growing areas, due to its ability to inhibit the development of weed species. This study aimed to evaluate the allelopathic effect of Pachyrhizus erosus extract on Euphorbia heterophylla and Bidens pilosa germination. The experiment was carried out in a completely randomized design, in a 2 x 2 x 4 factorial scheme, with four replications. The first factor corresponded to the plant portion (shoot and tuberous root), the second to the extract preparation method (water at room temperature and boiling) and the third to the extract concentrations (0 %, 25 %, 50 % and 100 %). Phytochemical analyses were performed to identify the presence of secondary metabolites. The variables germination percentage, germination rate index and dry biomass decreased with increasing aqueous extract concentrations for both E. heterophylla and B. pilosa. When applied a P. erosus crude shoot extract (boiling), decreases of 18 % and 92 % were observed in the E. heterophylla and B. pilosa germination, respectively, with a decrease of 91 % in the dry biomass of E. heterophylla seedlings. The tuberous root extract (boiling), on the other hand, reduced the germination percentages for E. heterophylla and B. pilosa in 18 % and 80 %, respectively. The phytochemical evaluation indicated the presence of flavonoids, coumarins and saponins in the shoot and tuberous root extracts, while tannins were only observed in the shoot extract. Thus, it can be concluded that P. erosus extracts display an allelopathic effect on the weed species evaluated.

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Interação entre volume de vaso e competição com plantas daninhas sobre o crescimento da soja

Revista CERES ◽

10.1590/0034-737x201562060003 ◽

2015 ◽

Vol 62 (6) ◽

pp. 524-530 ◽

Cited By ~ 2

Author(s):

Mirielle Oliveira Almeida ◽

Christiano da Conceição de Matos ◽

Daniel Valadão Silva ◽

Renan Rodrigues Braga ◽

Evander Alves Ferreira ◽

...

Keyword(s):

Bidens Pilosa ◽

Urochloa Brizantha

RESUMO A avaliação dos efeitos da competição das plantas daninhas sobre o crescimento da soja é efetuada por meio de ensaios em ambientes protegidos. Esses ensaios, geralmente, são feitos em recipientes (vasos) em que se testam os efeitos desejados em diferentes épocas de coleta. O tamanho (volume) dos vasos a ser escolhido depende do tipo de estudo, da espécie-teste e das variáveis que serão estudadas. Por esta razão, objetivou-se com este trabalho avaliar o efeito do tamanho de vasos na habilidade competitiva da soja com as plantas daninhas Urochloa brizantha e Bidens pilosa. O experimento foi conduzido em casa de vegetação e o delineamento foi em blocos ao acaso, em esquema fatorial 3 × 5, com quatro repetições. Os fatores considerados no experimento foram três sistemas de competição (soja cultivada isoladamente, soja + U. brizantha e soja + B. pilosa) e cinco volumes dos recipientes (2, 4, 7, 10 e 16 dm3). O crescimento das plantas de soja foi afetado tanto pelo volume dos vasos quanto pela competição com U. brizantha e B. pilosa, sendo que U. brizantha foi mais competitiva com a soja. Vasos com maiores volumes aumentam os efeitos da competição sobre o crescimento da soja.

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Germination constraints of dicarpic cypselae of Bidens pilosa L.

Brazilian Journal of Biology ◽

10.1590/1519-6984.178222 ◽

2019 ◽

Vol 79 (3) ◽

pp. 383-394

Author(s):

P. R. M. Souza-Filho ◽

M. Takaki

Keyword(s):

De Novo ◽

Growth Potential ◽

Behavioral Differences ◽

Weed Species ◽

Bidens Pilosa ◽

Hormonal Stimulation ◽

Central Type ◽

Chemical Inhibitors ◽

Peripheral Type ◽

Physical And Chemical

Abstract Bidens pilosa L. is a heterocarpic weed species with two cypselae types that present morpho-physiological differences, being the peripheral type smaller and slower to germinate than the central one. We aimed to verify how the germination mechanism varied between types. We focused on two mechanisms: (1) pericarp constraints (physical and chemical) and (2) hormonal stimulation (Abcisic acid [ABA] and Gibberellin [GA]). Both cypselae types are physically constrained by the pericarp, for when it is excised both seed types increase their germination, but behavioral differences still remain. The pericarp of the peripheral type also has chemical inhibitors that effectively inhibited germination of the intact central cypsela. To test the hormonal effects, we focused on the ABA:GA control. Both cypselae responded to an exogenous ABA concentration gradient, however there is no variation between types on the sensitivity to it. Also, both cypselae types were indifferent to Fluridone (ABA inhibitor), which indicates that the dormancy is not maintained by de novo ABA synthesis. Cypselae types had different sensitivity to an exogenous GA3 gradient, the central type being more sensitive to the treatment than the peripheral one. But when the endogenous GA synthesis was blocked by Paclobutrazol, both types responded equally to same GA3 concentrations. This indicates that endogenous GA synthesis may be related to differences observed on germination of cypselae types. To conclude, seed types differ on their growth potential to overcome the pericarp resistance: while the inhibitor in the peripheral pericarp reduces growth potential, GA increases it.

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Allelopathic effects of weed spp on the root border cells of Fagopyrum tataricum (L.) Gaertn

Allelopathy Journal ◽

10.26651/allelo.j/2021-52-1-1309 ◽

2021 ◽

Vol 52 (1) ◽

pp. 85-102

Author(s):

Y.Y. Xie ◽

L.X. Yao ◽

S. Wei ◽

S.H. He ◽

L. Chen ◽

...

Keyword(s):

Nitric Oxide ◽

Reactive Oxygen Species ◽

Mitochondrial Membrane ◽

Reactive Oxygen ◽

Aqueous Extracts ◽

Oxygen Species ◽

Weed Species ◽

Fagopyrum Tataricum ◽

Bidens Pilosa ◽

Allelopathic Effects

We studied the allelopathic effects of aqueous extracts of Galinsoga parviflora Cav., Chenopodium ambrosioides L., and Bidens pilosa L. weed species on the developmental characteristics of Tartary buckwheat RBCs. The increase in the concentration of aqueous extracts, there was increase in apoptosis rate and mucigel thickness of the RBCs, level of intracellular reactive oxygen species and nitric oxide, but decreased the mitochondrial membrane potential (P <0.05). The allelopathic effects of aqueous extracts of donor weed species on RBCs followed the order: C. ambrosioides > B. pilosa > G. parviflora. The increased levels of reactive oxygen species, nitric oxide and the reduced potential of mitochondrial membrane, further disrupted the homeostasis and normal metabolism of cells, thereby inducing the cell death. Among the three weed species, C. ambrosioides had the most significant impact

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FORAGE PLANTS AND WEEDS THAT ARE SENSITIVE TO ATMOSPHERIC CLOMAZONE RESIDUALS

Planta Daninha ◽

10.1590/s0100-83582017350100059 ◽

2017 ◽

Vol 35 (0) ◽

Cited By ~ 1

Author(s):

M.M. SILVA ◽

J.B. SANTOS ◽

E.A. FERREIRA ◽

O.G. BRITO ◽

L.M.S. DONATO ◽

...

Keyword(s):

Zea Mays ◽

Air Quality ◽

Sorghum Bicolor ◽

Chlorophyll Content ◽

Forage Plants ◽

Urochloa Decumbens ◽

Signal Grass ◽

Urochloa Brizantha ◽

Atmospheric Concentrations

ABSTRACT The use of indicator plants can be an effective alternative in monitoring the presence of toxic molecules in the air, such as herbicides. Thus, in the goal of this study is to assess the sensitivity of forage plants and weeds to atmospheric residual concentrations of clomazone. The treatments were arranged in a 6x5 factorial scheme, with the first factor corresponding to the plant species triticale (Triticosecale rimpaui), maize (Zea mays), sorghum (Sorghum bicolor), palisade grass (Urochloa brizantha), purslane (Portulaca oleracea) and signal grass (Urochloa decumbens), and the second factor to doses of 0, 90, 180, 270 and 360 g ha-1 clomazone doses (equivalent to atmospheric concentrations of 0.0, 0.05, 0.10, 0.15 and 0, 20 mg L-1). Twelve days after emergence, the plants were allocated inside experimental rectangular chambers with a volume of 500 dm3, covered by 150 uM of transparent polyethylene film. The plants remained exclusively in the chamber atmosphere with the herbicide for a period of 96 hours. After the chambers were opened, there were the first evaluation of intoxication and chlorophyll content, as well. The evaluations were repeated on day 7 and 14 after the chamber opening. The presence of clomazone in minimal concentrations in the atmosphere affected the quality of the evaluated plants. Signal grass, palisade grass, sorghum, triticale and purslane were sensitive to atmospheric residual concentrations of clomazone and they can be used to monitor the air quality when there are wastes from this molecule.

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Influence of Weeds on Yacon Initial Growth and Development

Planta Daninha ◽

10.1590/s0100-83582020380100020 ◽

2020 ◽

Vol 38 ◽

Author(s):

M.O. CABRAL ◽

F.L. OLIVEIRA ◽

L.P. DALVI ◽

A.G. TEIXEIRA ◽

L.J.F.N. ROCHA ◽

...

Keyword(s):

Leaf Area ◽

Dry Mass ◽

Cyperus Rotundus ◽

Weed Competition ◽

Initial Growth ◽

Weed Species ◽

Bidens Pilosa ◽

Smallanthus Sonchifolius ◽

Number Of Leaves ◽

Number Of Stems

ABSTRACT: The consumption of yacon has been increasing around the world due to the nutritional and pharmaceutical properties of this plant. The growing commercial interest in yacon (Smallanthus sonchifolius) generates a demand for crop management research studies, including the effect of weed competition on yacon, which was not yet studied. Thus, this study was performed with the objective of evaluating the effects of weed competition on yacon development and growth. The experimental design was completely randomized with four treatments and seven replicates. Treatments were yacon with the interference of four weed species: Cyperus rotundus L. (nutgrass), Commelina benghalensis L. (tropical spiderwort), Amaranthus viridis L. (slender amaranth) and Bidens pilosa L. (hairy beggarticks). The experiment was conducted in a greenhouse, using 10 dm3 pots. Plant height, number of leaves, number of stems, leaf area, fresh and dry mass weight (total and partial), and chlorophyll A, B and total were evaluated. The weed competition resulted in a decrease in the yacon development (height, number of leaves, number of stems, leaf area), photosynthetic rate (decreased chlorophyll content A, B and total) and yield, as also decreased the accumulation of fresh and dry biomass of tuberous roots. C. benghalensis L. and A. viridis L. were the weeds most affecting the development and growth of yacon.

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Host plants of root-knot nematodes

Anais da Escola Superior de Agricultura Luiz de Queiroz ◽

10.1590/s0071-12761975000100044 ◽

1975 ◽

Vol 32 (0) ◽

pp. 527-530

Author(s):

Luiz Gonzaga E. Lordello ◽

Luiz Carlos Fazuoli ◽

Condorcet Aranha ◽

Rubens R.A. Lordello

Keyword(s):

Coffea Arabica ◽

Host Plants ◽

Coffea Canephora ◽

Weed Species ◽

Ageratum Conyzoides ◽

Digitaria Sanguinalis ◽

Bidens Pilosa ◽

Root Knot Nematodes ◽

Eleusine Indica ◽

Solanum Americanum

Root-knot nematodes were found attacking Coffea spp. and also roots of a few weed species usually found in the coffee orchards in São Paulo. C. arabica cv. Catuaí, C. arabica cv. Mundo Novo, Timor Hybrid and a few plants of C. racemosa showed to be susceptible to Meloidogyne exigua. Roots of Ageratum conyzoides, Amaranthus viridis, Bidens pilosa, Coffea arabica cv. Mundo Novo, Coffea racemosa, Commelina virginica, Digitaria sanguinalis, Galinsoga parviflora, Gnaphalium spathulatum, Porophyllum ruderale, Portulaca oleracea, Pterocaulon virgatum and Solanum americanum were disfigured by M. incognita M. arenaria was found attacking roots of Eleusine indica and Gnaphalium spathulatum, and the presence of an unidentified Meloidogyne species was verified in roots of the following species: Vernonia ferruginea, C. arabica x C. canephora, Eupatorium pauciflorum, Coffea canephora cv. Kouillou, Coffea eugenioides, Coffea racemosa, Coffea stenophylla, Euphorbia pilullifera, Solanum americanum, Ageratum conyzoides, Phyllanthus corcovadensis, and Emilia sagittata.

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