Ecological Fitness of Senecio vulgaris and Amaranthus retroflexus Biotypes Susceptible or Resistant to Atrazine

Conard, S. G.; Radosevich, Steven R.

doi:10.2307/2402736

Cited by 124 publications

(117 citation statements)

References 21 publications

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“…Os valores máximos de Wt obtidos foram de 41 e 39 g planta -1 , aos 134 e 133 dias após semeadura (DAS) para o biótipo considerado resistente e o suscetível, respectivamente. A produção de matéria seca de biótipos de Senecio vulgaris e Amaranthus retroflexus, resistentes e suscetíveis ao herbicida atrazine, foi comparada por Conard & Radosevich (1979), os quais verificaram que essa característica foi maior nos biótipos considerados suscetíveis. Entretanto, a partição de assimilados destinada às partes reprodutivas, aos caules e às raízes foi semelhante entre os biótipos de cada espécie estudada.…”

Section: Resultsunclassified

Análise de crescimento de biótipos de amendoim-bravo (Euphorbia heterophylla) resistente e suscetível aos herbicidas inibidores da ALS

et al. 2001

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RESUMO -A aplicação contínua de herbicidas do grupo químico das imidazolinonas, nas mesmas áreas de produção de soja, durante anos seguidos, no município de Cafelândia, PR, favoreceu a seleção de um biótipo resistente de amendoim-bravo (Euphorbia heterophylla) aos herbicidas inibidores da acetolactato sintase (ALS). Um estudo comparativo das características do crescimento do biótipo resistente e do suscetível foi realizado em casa de vegetação da Embrapa Soja, Londrina-PR, a fim de identificar diferenças no crescimento e no desenvolvimento das plantas e de seus órgãos. A produção de matéria seca total, a área foliar, a matéria seca dos caule, das raízes e das folhas, bem como a altura por planta, foram avaliadas em 13 vezes a intervalos regulares, iniciando aos 14 dias após a semeadura. A partir desses parâmetros, foram calculadas a taxa de crescimento relativo, a taxa assimilatória líquida, a razão de área foliar, a razão de peso foliar e a área foliar específica, que decrescem com a ontogenia das plantas de amendoim-bravo, sendo similares para ambos os biótipos. A matéria seca total acumulada pelas plantas e seus órgãos, a área foliar e a altura apresentaram comportamentos semelhantes para os biótipos resistente e suscetível. O ciclo vegetativo dos dois biótipos estudados não mostrou diferença significativa quanto ao crescimento e ao desenvolvimento.Palavras-chave: resistência a herbicidas, área foliar, taxa de crescimento. Cafelândia, Paraná, Brazil, has ABSTRACT -Repetitive spraying of imidazolinone herbicides year after year to control weeds in the soybean grown areas of

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Section: Resultsunclassified

Análise de crescimento de biótipos de amendoim-bravo (Euphorbia heterophylla) resistente e suscetível aos herbicidas inibidores da ALS

et al. 2001

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“…Susceptible biotypes of redroot pigweed {Amaranthus retroflexusL.) and common groundsel produced more biomass and seeds than the résistant biotypes under non-competitive conditions (Conard and Radosevich 1979).…”

Section: Non-competitive Experimentsmentioning

confidence: 99%

“…Seed weights of the susceptible and résistant biotypes were 0.65 ± 0.01 mg and 0.60 ± 0.02 mg, respectively, and were not influenced by proportions in the mixture. Weaver and Warwick (1982) and Conard and Radosevich (1979) leaf, stem, and total above-ground biomass. The biotype effect was the most pronounced of the factors studied for any variables.…”

Section: Replacement Séries Experimentsmentioning

confidence: 99%

“…But in the absence of s-triazines, our data indicate that the susceptible biotype has a greater fitness. Résistance to s-triazines was consistently accompanied by reduced fitness when the herbicide was not used (Conard and Radosevich 1979;Holt et al 1983;Marriage and Warwick 1980;Warwick and Black 1981;Weaver and Warwick 1982). If s-triazines herbicides are no longer used in a field, the weed population will revert naturally to susceptibility because of the greater fitness of the susceptible biotype.…”

Section: Modes Of Compétition Experimentsmentioning

confidence: 99%

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Relative fitness of s-triazine susceptible and resistant biotypes of Chenopodium album

Leroux

2005

phyto

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La compétitivité relative de deux biotypes de Chenopodium album, un sensible et l'autre résistant aux s-triazines, a été comparée lors de trois expériences menées en serres. En absence de compétition, la production de biomasse sèche n'a pas différé entre les deux biotypes, mais le biotype résistant a alloué moins de matière sèche à la production de semences et a produit moins de semences que le biotype sensible. Les résultats obtenus de séries de remplacement (de Wit) menées à une densité de 400 plants m2 ont indiqué que la proportion relative de la biomasse et du nombre de semences produites par le biotype sensible était toujours plus grande que la proportion de plantes susceptibles présentes dans le mélange. Les effets de la compétition racinaire, de la compétition aérienne, et de la compétition complète (racinaire + aérienne) ont été comparés à des densités de 400, 666, 934, 1200, et 1466 plantules m-2. Les biotypes ont eu l'effet le plus marqué sur toutes les variables mesurées parmi les facteurs étudiés. Les plantules du biotype sensible atteignaient une hauteur plus grande, avaient un indice de surface foliaire (ISF) supérieur, produisaient plus de feuilles, et des rendements foliaire, caulinaire et total plus grands que les plantules résistantes, peu importe la densité de plantules ou le mode de compétition. La compétitivité du biotype sensible à l'égard du biotype résistant s'est exprimée le plus lorsque les deux biotypes rivalisaient entre eux pour la lumière. Les effets de la compétition aérienne sur le rendement, l'ISF, le nombre de feuilles, et la hauteur des plantules étaient aussi importants que la compétition complète. Les effets de la compétition racinaire, bien que significatifs, n'étaient pas aussi importants. Les résultats indiquent que s'il y a arrêt de l'utilisation des s-triazines, la population de C. album évoluera naturellement vers la susceptibilité aux s-triazines à cause de la compétitivité supérieure du biotype sensible.The relative fitness of s-triazine susceptible and resistant biotypes ofChenopodium album from Quebec were compared in three greenhouse experiments. Under non-competitive conditions, there was no difference in dry matter production between biotypes, but the resistant biotype allocated less dry matter to seed production and produced fewer seeds than the susceptible. Results from de Wit replacement series performed at 400 plants m2 indicated that the relative proportion of biomass and seeds produced by the susceptible biotype was always greater than the proportion of susceptible plants present in any given treatment. The effects of root, shoot, and full (root + shoot) competition were compared between and within biotypes at planting densities of 400,666,934,1200, and 1466 seedlings m-2. Biotype had the most pronounced effect on all variables among the factors studied. The susceptible seedlings were taller, had a greater leaf area index (LAI), more leaves, and greater leaf, stem, and above-ground dry matter yields than the resistant seedlings, regardless of the planting de...

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“…Such an hypothesis would be valid only in a few, specific circumstances; and easily the greater part of the evidence suggests that triazine-resistant weeds are competitively inferior (e.g., Conard and Radosevich 1979, Holt, 1988, Madden 1988.…”

Section: Introductionmentioning

confidence: 99%

An assessment, using a modelling approach, of inbreeding as a possible cause of reduced competitiveness in triazine‐resistant weeds

Madden

1995

Weed Research

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1.It is widely assumed that organisms which evolve resistance to a triazine suffer from a fitness deficit in the absence of that herbicide. Arguments for this view are examined, and the published evidence is discussed. 2.A simple model is developed to examine the genetics of resistance in triazineresistant plants, based on the assumption that there is a founder effect operating. The model examines the hypothesis that the extent to which plants in the sprayed population are related will increase rapidly under continual selection, even when there is a significant input of genes from non-selected populations. 3.The possible consequences of the above hypothesis on the validity of competition experiments are discussed.

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Ecological Fitness of Senecio vulgaris and Amaranthus retroflexus Biotypes Susceptible or Resistant to Atrazine

Cited by 124 publications

References 21 publications

Análise de crescimento de biótipos de amendoim-bravo (Euphorbia heterophylla) resistente e suscetível aos herbicidas inibidores da ALS

Análise de crescimento de biótipos de amendoim-bravo (Euphorbia heterophylla) resistente e suscetível aos herbicidas inibidores da ALS

Relative fitness of s-triazine susceptible and resistant biotypes of Chenopodium album

An assessment, using a modelling approach, of inbreeding as a possible cause of reduced competitiveness in triazine‐resistant weeds

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