THE BIOLOGY OF CANADIAN WEEDS.: 54. <i>Crepis tectorum</i> L.

Najda, H. G.; Darwent, A. L.; Hamilton, Greg

doi:10.4141/cjps82-067

Cited by 15 publications

(13 citation statements)

References 11 publications

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“…In contrast, Najda et al (1982) noted two flushes of narrow-leaved hawk's-beard emergence in Alberta: midMay to mid-July and early August to mid-September. They reported that it could germinate throughout the year as long as soil temperatures were above 58C and when there was sufficient soil moisture.…”

Section: Emergence In Both Fall and Springmentioning

confidence: 85%

“…For example, Blackshaw et al (2002) found that when soil water potential was (1.53 MPa, henbit germination was 11 and 83% at 10 and 208C, respectively; while at (0.03 MPa, 78 and 83% of seeds germinated at 10 and 208C, respectively. For the remainder of the species 90% non-dormant (Andersson 1990) None (Najda et al 1982) Descurainia sophia L. in this review there is little or no published information available on the impact of soil moisture levels on recruitment. Soil temperature requirements for recruitment are linked both to the dormancy characteristics and base temperature for germination.…”

Section: Recruitment Characteristics Andmentioning

confidence: 99%

“…The available literature suggests that silky bentgrass (Melander et al 2008), shepherd's purse (Roberts and Feast 1973), wild radish (Reeves et al 1981), chickweed (Bostrom and Fogelfors 1999), stinkweed (Thomas et al 2004) and field violet (Roberts and Feast 1973;Doohan et al 1991) are associated with conventional tillage. In contrast, tillage suppresses the recruitment of downy brome (Wicks 1984), Canada fleabane (Brown and Whitwell 1988), flixweed (Thomas et al 2004), narrow leaved hawk'sbeard (Najda et al 1982), American dragonhead , prickly lettuce (Weaver and Downs 2003), common groundsel (Arshad et al 1998) and bluebur (Frick 1984). For Canada fleabane, flixweed, narrow-leaved hawk's-beard, prickly lettuce, common groundsel and bluebur the negative recruitment response HR (Roberts and Feast 1973) Crepis tectorum L.…”

Section: Recruitment Characteristics Andmentioning

confidence: 99%

“…Light (Najda et al 1982) 0 cm (Andersson 1990) LR (Najda et al 1982) Conyza canadensis ( HR (Roberts and Feast 1973;Doohan et al 1991) z Abbreviations: NA, data not available; HR, higher recruitment; LR, lower recruitment.…”

Section: Recruitment Characteristics Andmentioning

confidence: 99%

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A review of the recruitment biology of winter annual weeds in Canada

Cici¹,

Acker²

2009

Can. J. Plant Sci.

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A review of the recruitment biology of winter annual weeds in Canada. Can. J. Plant Sci. 89: 575Á589. Typically, summer annual weeds have been the primary management target for field crop farmers in Canada, but with changes in cropping systems and with acknowledged global climate change there will be an increasing need to consider the management of species that are present very early in the spring, including winter annual weeds. Knowledge of weed recruitment biology and emergence patterns can be used to guide weed management practices. A review was conducted of the recruitment biology of winter annual weeds in Canada. The key finding was that all of the significant winter annual weeds in Canadian agriculture are facultative, with the majority of species emerging at two peak periods, AprilÁMay and SeptemberÁOctober. For the weed species included in this review, the information available on recruitment and seed biology was far from comprehensive, and for some species there was very little published information, in particular on specific base temperatures for germination, documented field-based emergence periods and data that could be used to create simple predictive population dynamics models, including fecundity () environment), seed longevity and overwintering probability. This is particularly true with respect to information in Canadian agricultural contexts. A number of questions result from this review, a key one being whether spring versus fall emergence creates significant differences in fundamental biological characteristics of winter annual weeds including seed dormancy status, microsite requirements, phenology, plant vigour and competitive ability. Given that none of the winter annuals in Canada are constitutive and given ongoing climate change, farmers in Canada should be careful not to encourage summer annuals to become winter annuals. Movement away from fall weed management, including tillage and repeated sowing of winter annual crops will encourage facultative winter annual behaviour. In addition, farmers should be wary of invasion by populations of persistent winter annuals including stinkweed, chickweed and American dragonhead. Habituellement, quand ils ge`rent leurs cultures, les agriculteurs canadiens prennent surtout pour cible les adventices annuelles d'e´te´. Cependant, l'e´volution des syste`mes agricoles et le changement climatique exigeront qu'on se penche de plus en plus sur les espe`ces pre´sentes tre`s toˆt au printemps, notamment les adventices annuelles d'hiver. Mieux connaıˆtre la biologie du recrutement des mauvaises herbes et la leve´e de ces dernie`res pourrait nous guider dans les me´thodes de lutte. Les auteurs ont passe´en revue ce qu'on sait sur la biologie du recrutement des adventices annuelles d'hiver au Canada. Leur principale constatation est que les grandes adventices annuelles d'hiver canadiennes sont toutes de type facultatif, la majorite´levant durant deux pe´riodes, soit d'avril a`mai et de septembre a`octobre. En ce qui concerne les adventices examine´es dans le cadr...

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Section: Emergence In Both Fall and Springmentioning

confidence: 85%

Section: Recruitment Characteristics Andmentioning

confidence: 99%

Section: Recruitment Characteristics Andmentioning

confidence: 99%

Section: Recruitment Characteristics Andmentioning

confidence: 99%

See 2 more Smart Citations

A review of the recruitment biology of winter annual weeds in Canada

Cici¹,

Acker²

2009

Can. J. Plant Sci.

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“…Therefore, in the remainder of this discussion, it is necessary to assume that many seeds germinate in sites that are markedly different from the sites of the parent plants, a likely scenario in the wind-dispersed Crepis tectorum considering the wide range of habitats occupied by the species (Babcock, 1947), the great colonizing ability of the weed ecotype (e.g. Najda et al, 1982) and the sharp environmental gradients characterizing many outcrop sites (Andersson, 1992).…”

Section: Discussionmentioning

confidence: 99%

Phenotypic plasticity in Crepis tectorum (Asteraceae): genetic correlations across light regimens

Andersson

Shaw

1994

Heredity

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Inbred F3 and F4 families from a cross between two contrasting ecotypes of Crepis tectorum were replicated in two regimes in a glasshouse to determine whether genetic tradeoffs within the reaction norm favour genetic differentiation over phenotypic plasticity in this species. There was no tradeoff in reproductive fitness (flower production) across light regimes but genetic cross-environment correlations approached unity for a wide range of characters subject to divergent selection across habitats, suggesting little genetic variation in plasticity and a limited opportunity for selection to favour broadly adapted genotypes capable of attaining the optimum phenotype in every environment. The presence of genotype-environment interaction without large changes in the ranking of genotypes over light regimes indicates a greater potential for evolutionary change in environmental sensitivity although developmental constraints may limit the range of phenotypes that can be expressed in a character. A selection analysis was conducted to determine how the average reaction norm would evolve in this system. Whereas the relationship between each trait and reproductive fitness was environment-specific, there was no change in the direction of selection between light regimes. Given the genetic correlation structure observed, one would expect some of the genetic response in one environment to carry over to the other environment.

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