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Titre :
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Neighbour Effects in the Genus Avena. I. Comparison of Crop Species
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Auteurs :
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B.R. Trenbath ;
John Lander Harper
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Publisher :
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Journal of Applied Ecology, 10(2)
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Type de document :
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Article
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Année de publication :
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1973
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Format :
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379-400
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Langues:
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Anglais
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Résumé :
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[A comparison is made of the relative advantages of interspecific mixture experiments using `additive' and `substitutive' designs. This paper describes the results of growing Avena sativa var. Blenda, A. strigosa and two weed species A. fatua and A. ludoviciana in an additive design under glass on very fertile, irrigated field-soil. Although the two indicator species differed markedly in their pattern of growth, the effects of infestations of four added species were similar in each. A higher level of infestation simply produced intensified effects. The effects of added species were not always quantitative variants of the indicator's own density response and were qualitatively different in the cases of stem extension and weight per seed. The differences were related to the degree of shading suffered by the indicator. For A. sativa, the adaptive value of increased stem extension in the presence of A. ludoviciana was calculated to be about 20% extra weight in each seed. Canonical variates were calculated using observations of seven primary characters made on the individual plants in each plot. The most important canonical variate in each indicator species was identified as weight of panicles. In A. sativa three axes represented neighbour effects but in A. strigosa only the first and third axes were concerned with these; the second axis represented experimental error.]
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En ligne :
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https://www.jstor.org/stable/2402288
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