Adaptive value of ryegrass biotypes with low-level resistance and susceptible to the herbicide fluazifop and competitive ability with the wheat culture

Ryegrass is the main weed in wheat crop, causing yield loss due to competition by environmental resources. The objectives of this study were to estimate the fitness cost of ryegrass biotypes with low-level resistance and susceptible to fluazifop and to investigate the relative competitive ability of these biotypes between themselves and against the crop. Thus, fitness cost and competitive ability experiments were conducted under greenhouse conditions. For the fitness cost experiments, the low-level resistant ryegrass biotypes and those susceptible to fluazifop were used. For competitive ability, the treatments were arranged in a replacement series, with five proportions of the wheat cultivar FUNDACEP Horizonte and the low-level resistant and susceptible ryegrass biotypes 100:0, 75:25, 50:50, 25:75 and 0:100. Competitive analysis was carried out through diagrams applied to the replacement experiments and use of relative competitiveness indices. Variables evaluated were plant height, in the fitness cost experiment, and leaf area and shoot dry biomass in both experiments. The ryegrass biotypes show overall similar fitness cost and competitive ability. The wheat cultivar FUNDACEP Horizonte is superior in competitive ability to the ryegrass biotype with low-level resistance and equivalent to the susceptible biotype.

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Initial growth and competitive ability of yellow nutsedge and irrigated rice

Planta Daninha ◽

10.1590/s0100-83582013000400007 ◽

2013 ◽

Vol 31 (4) ◽

pp. 813-821 ◽

Cited By ~ 3

Author(s):

N.R. Westendorff ◽

D. Agostinetto ◽

A.R. Ulguim ◽

A.C. Langaro ◽

L. Thürmer

Keyword(s):

Leaf Area ◽

Competitive Ability ◽

Growth Cycle ◽

Rice Crop ◽

Initial Growth ◽

Rice Cultivars ◽

Replacement Series ◽

Irrigated Rice ◽

Yellow Nutsedge ◽

Dry Biomass

Weeds cause significant reduction in the irrigated rice crop yield. Cyperus esculentus (yellow nutsedge) is adapted to irrigate environment. Information on the competitive ability of the weed to the culture, and their environmental adaptation, are scarce. In this study, we sought to determine the initial growth and competitive ability of yellow nutsedge and irrigated rice, as a function of cultivar growth cycle. Initial growth and competition studies were conducted in a randomized complete design in a greenhouse in the agricultural year 2010/11. For the initial growth study, the treatments consisted of a factorial combination of a biotype of yellow nutsedge and two rice cultivars in the function of the vegetative cycle (BRS Querência: early cycle - IRGA 424: intermediate cycle) and six evaluation times (10, 20, 30, 40, 50, and 60 days after emergence). Were evaluated: plant height, leaf area, aboveground dry biomass and root dry biomass. In the competitive ability study in the replacement series, the cultivar BRS Querência (early cycle) and yellow nutsedge were utilized and tested in different proportions of competition (100:0, 75:25, 50:50, 25:75, and 0:100). Were evaluated leaf area and aboveground dry biomass. In general, rice cultivars have an adaptive value equivalent to yellow nutsedge. IRGA 424 cultivar has less height than weed, becoming the weed control more important in this cultivar. For rice crop, intraspecific competition is more important, whereas for the weed, interspecific competition is the most pronounced.

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Criteria for Decision Making and Economic Threshold Level for Wild Radish in Wheat Crop

Planta Daninha ◽

10.1590/s0100-83582019370100004 ◽

2019 ◽

Vol 37 ◽

Author(s):

L.C. TAVARES ◽

E.S. LEMES ◽

Q. RUCHEL ◽

N.R. WESTENDORFF ◽

D. AGOSTINETTO

Keyword(s):

Dry Matter ◽

Competitive Ability ◽

Soil Cover ◽

Wheat Cultivar ◽

Wheat Yield ◽

Threshold Level ◽

Wheat Crop ◽

Wild Radish ◽

Raphanus Raphanistrum ◽

Economic Threshold

ABSTRACT: Weed competition limits wheat yield by reducing the availability of essential resources for its growth and development. In this sense, this study aimed to estimate the economic threshold level (ETL) of wild radish (Raphanus raphanistrum) in competition with wheat cultivars. Treatments were arranged in a factorial scheme. The factor wheat cultivar consisted of early (BRS 328), medium (BRS 177), and late (BRS Umbu) cycles and the factor wild radish population ranged from 0 to 564 plants m-2 (10 populations) for the cultivar BRS 328, 0 to 472 plants m-2 for the cultivar BRS 177 (11 populations), and 0 to 724 plants m-2 for the cultivar BRS Umbu (10 populations). The early-cycle BRS 328 presented a higher competitive ability when compared to the medium-cycle BRS 177 and late-cycle BRS Umbu. Yield losses of wheat grains due to wild radish interference can be satisfactorily estimated by the rectangular hyperbola model using the variables plant population, shoot dry matter, soil cover, and leaf area of the weed. ETL values varied as a function of the cultivar cycle, being higher for the cultivar BRS 328 (early) > BRS 177 (medium) > BRS Umbu (late). Wild radish is competitive in wheat crop, requiring at least 1.6 plants m-2 for control to be justified.

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RELATIVE COMPETITIVENESS OF GOOSEGRASS BIOTYPES AND SOYBEAN CROPS

Revista Caatinga ◽

10.1590/1983-21252017v30n201rc ◽

2017 ◽

Vol 30 (2) ◽

pp. 271-277 ◽

Cited By ~ 1

Author(s):

JADER JOB FRANCO ◽

DIRCEU AGOSTINETTO ◽

ANA CLAUDIA LANGARO ◽

LAIS TESSARI PERBONI ◽

LEANDRO VARGAS

Keyword(s):

Competitive Ability ◽

Total Population ◽

Dry Weight ◽

Replacement Series ◽

Genetically Modified Soybean ◽

Eleusine Indica ◽

Soybean Crop ◽

Shoot Dry Weight ◽

Control Failure ◽

Level Resistance

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.

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Fitness Cost and Competitive Ability of Ryegrass Susceptible and with Multiple Resistance to Glyphosate, Iodosulfuron-Methyl, and Pyroxsulam

Planta Daninha ◽

10.1590/s0100-83582019370100091 ◽

2019 ◽

Vol 37 ◽

Cited By ~ 1

Author(s):

J.R. HENCKES ◽

J. CECHIN ◽

M.F. SCHMITZ ◽

C. PIASECKI ◽

L. VARGAS ◽

...

Keyword(s):

Leaf Area ◽

Dry Matter ◽

Competitive Ability ◽

Acetolactate Synthase ◽

Fitness Cost ◽

Multiple Resistance ◽

Replacement Series ◽

Absolute Growth ◽

Evolution Of Resistance ◽

The Difference

ABSTRACT: Ryegrass is an important weed in wheat cultivations due to the evolution of resistance to different mechanisms of action. This study aimed to compare the phenological development, fitness cost, and competitive ability between ryegrass biotypes susceptible and with multiple resistance to 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs) and acetolactate synthase (ALS) inhibiting herbicides. Fitness cost and phenological development were evaluated from biotypes grown in pots, and morphological growth variables were determined up to 140 days after emergence. Phenological development was evaluated with a fitness cost. Competitive ability was determined in a replacement-series experiment with proportions of resistant and susceptible ryegrass. The tested proportions were 100:0 (pure resistant ryegrass stand), 75:25, 50:50, 25:75, and 0:100% (pure susceptible ryegrass stand), where the number of tillers, height, leaf area, and shoot dry matter were evaluated at 50 days after emergence. The longer tillering period of resistant ryegrass was the main factor involved in the difference in phenological development between biotypes. The resistant biotype was superior to the susceptible regarding height, shoot dry matter, and absolute growth rate, while the susceptible biotype had a higher number of tillers and leaf area ratio. Thus, the resistant biotype had no fitness cost. For competitive ability, no difference was observed between biotypes in the different tested proportions when they occupied the same ecological niche.

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Productivity and Intraspecific Competitive Ability of a Velvetleaf (Abutilon theophrasti) Biotype Resistant to Atrazine

Weed Science ◽

10.1017/s004317450008173x ◽

1995 ◽

Vol 43 (4) ◽

pp. 619-626 ◽

Cited By ~ 11

Author(s):

James A. Gray ◽

David E. Stoltenberg ◽

Nelson E. Balke

Keyword(s):

Leaf Area ◽

Seed Yield ◽

Competitive Ability ◽

Area Ratio ◽

Abutilon Theophrasti ◽

Replacement Series ◽

Relative Growth ◽

Dry Biomass ◽

Net Assimilation ◽

Over Time

Studies were conducted to determine the relative competitive ability and productivity of an atrazine-resistant biotype (WRB1) and an atrazine-susceptible accession (WSA1) of velvetleaf from Wisconsin. Noncompetitive productivity studies conducted in the field and greenhouse during 1992 and 1993 showed that instantaneous relative growth rate, net assimilation rate, and leaf area ratio of the WRB1 biotype and WSA1 accession were similar. There were no consistent differences between the WRB1 biotype and WSA1 accession in plant height, shoot dry biomass, and leaf area over time. The WRB1 biotype and WSA1 accession did not differ in noncompetitive seed yield. A replacement series experiment conducted in the field in 1992 and 1993 showed that the WRB1 biotype and WSA1 accession did not differ in shoot dry biomass or seed yield at densities of 36, 64, and 100 plants m−2. Results suggest that resistance to atrazine has not reduced the noncompetitive productivity or the intraspecific competitive ability of the WRB1 biotype relative to the WSA1 accession. Thus, even in the absence of atrazine selection intensity, the frequency of atrazine resistance gene(s) is unlikely to decrease in the velvetleaf population from which the WRB1 biotype was selected.

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Fitness Cost and Competitive Ability to Different Ploidy Levels in Ryegrass Genotypes

Planta Daninha ◽

10.1590/s0100-83582019370100115 ◽

2019 ◽

Vol 37 ◽

Cited By ~ 2

Author(s):

M.F. SCHMITZ ◽

J. CECHIN ◽

J.R. HENCKES ◽

C. PIASECKI ◽

D. AGOSTINETTO ◽

...

Keyword(s):

Leaf Area ◽

Competitive Ability ◽

Dry Weight ◽

Fitness Cost ◽

Replacement Series ◽

Ploidy Levels ◽

Shoot Dry Weight ◽

Seed Yield Components ◽

Diploid Genotype ◽

Intergenotypic Competition

ABSTRACT: The intergenotypic competition of tetraploid ryegrass with natural diploid population may be a tool to reduce the frequency of resistant individuals in an area. This study aimed to identify and compare the phenological development, fitness cost, and competitive ability between diploid and tetraploid ryegrass genotypes. Genotypes were grown in pots, and the morphological variables of genotype growth were assessed every 15 days up to 120 days after emergence to evaluate the fitness cost. Phenological development and seed yield components were measured in a single time together with the fitness cost. Competitive ability was determined in a replacement-series experiment with proportions of tetraploid and diploid ryegrass, in which the number of tillers, plant height, leaf area, and shoot dry weight were assessed at 50 days after emergence. The results of fitness cost showed that the number of tillers, leaf area, root dry weight, and the number of seeds were higher for tetraploid ryegrass, which presented a higher competitive ability than the diploid genotype regardless of the tested proportions. Tetraploid ryegrass may be useful for reducing the frequency of herbicide-resistant diploid ryegrass because of its higher competitive potential.

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Faculty Opinions recommendation of Nonmolecular test for detection of low-level resistance to fluoroquinolones in Streptococcus pneumoniae.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1030649.358710 ◽

2006 ◽

Author(s):

Gary Lum

Keyword(s):

Streptococcus Pneumoniae ◽

Low Level ◽

Level Resistance

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Competitiveness of alexandergrass or Bengal dayflower with soybean

Planta Daninha ◽

10.1590/s0100-83582010000300008 ◽

2010 ◽

Vol 28 (3) ◽

pp. 515-522 ◽

Cited By ~ 7

Author(s):

A.C.R. Dias ◽

S.J.P. Carvalho ◽

L.W. Marcolini ◽

M.S.C. Melo ◽

P.J. Christoffoleti

Keyword(s):

Competitive Ability ◽

Dry Mass ◽

Total Density ◽

Weed Species ◽

Replacement Series ◽

Commelina Benghalensis ◽

Randomized Design ◽

Full Flowering ◽

Completely Randomized Design ◽

Soybean Plants

Weeds compete with field crops mainly for water, light and nutrients, and the degree of competition is affected by the weed density and the intrinsic competitive ability of each plant species in coexistence. The objective of this research was to compare the competitiveness of alexandergrass (Brachiaria plantaginea) or Bengal dayflower (Commelina benghalensis) in coexistence with soybean, cv. M-Soy 8045. A factorial experiment (2 x 5) with two weed species and five competition proportions was carried out in a completely randomized design with four replicates. Proportions were based on a replacement series competition design, always maintaining the total density of four plants per 10 L plastic pots, which corresponded to 60 plants m ². The weed-crop proportions were: 0:4; 1:3; 2:2; 3:1; 4:0; that corresponded to the proportion of 100, 75, 50, 25 and 0% of soybean plants and the opposite for weeds, B. plantaginea or C. benghalensis plants. Leaf area, shoot dry mass of the weeds and soybean and number of soybean trifoliate leaves were evaluated when the soybean reached the phenologic stage of full flowering. B. plantaginea was a better competitor than soybean plants. Otherwise, C. benghalensis revealed a similar competitive ability that of the soybean. In both cases, there were evidences that intraspecific competition was more important.

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