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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730 EISSN: 1021-9730
Vol. 4, No. 1, 1996, pp. 19-27
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Bioline Code: cs96036
Full paper language: English
Document type: Research Article
Document available free of charge
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African Crop Science Journal, Vol. 4, No. 1, 1996, pp. 19-27
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Diallel Analysis for Reaction to Exserohilum Turcicum of Maize Cultivars and Crosses
Ojulong, H.F.; Adipala, E. & Rubaihayo, P.R.
Abstract
The effectiveness of a diallel cross in initiating recurrent
selection as a breeding procedure for concentrating genes for
resistance to Exserohilum turcicum (Pass) Leonard and
Suggs was studied in maize single and double cross F1's during
the first rains of 1993. Resistance was expressed as reduced
percentage leaf area blighted, area under disease progress
curve of percentage leaf area blighted (AUDPC-S) and lesion
numbers (AUDPC-L), and apparent infection rate (r), indicating
presence of rate-reducing resistance. General combining
ability effects differed with the genotype, cross and disease
indices, resistant cultivars giving the highest negative
values, and the single cross giving higher negative values
than their corresponding double cross gemstypes. High
heritability values were obtained for both types of crosses,
signifying the highly heritable nature of this polygenic
resistance and the low level of resistance present in the
parent cultivars.
Keywords
Combining ability, diallel cross, disease progress, northern leaf blight, Zea mays
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fr |
Ojulong, H.F.; Adipala, E. & Rubaihayo, P.R.
Résumé
L'efficiencience d'un croisement diallele en selection
recurrante comme procedure d'amelioration en vue de concentrer
des genes de resistance a l'Exserohilum turcicum etait etudiee
en croisement simple et double de mais de F1's durant la
premiere saison pluvieuse en 1993. La resistance etait
exprimee en fonction de la reduction du pourcentage de
feuilles attaquees, de la courbe de progression de la surface
malade, du pourcentage de feuilles attaquees (AUDPC-S) et du
nombre de lesions (AUDPC-L), ainsi que du rapport d'infection
apparante (r) indiquant la presence d'un rapport de reduction
de resistance. Les effets generaux d'habilite combinee etaient
differents selon le genotype, le croisement et les incidences
de la maladie. Les cultivars resistants donnent des hautes
valeurs negatives tandis les croisements simples donnent les
valeurs negatives plus elevees que leurs correspondants
genotypes a croisements doubles. Des valeurs elevees
d'heritabilite etaient obtenues pour les deux types de
croisement, ce qui explique la nature hautement heritable de
cette resistance polygenique et le faible niveau de resistance
present chez les parents de cultivars.
Mots Clés
Habilite combinee, croisement diallele, progression de la maladie, Zea mays
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© Copyright 1996 - African Crop Science Society
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