Genotype × environment interaction and yield stability in a cowpea-based cropping system |
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Authors: | Francis Kwame Padi |
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Institution: | (1) Savanna Agricultural Research Institute, CSIR, P.O. Box 52, Tamale, Ghana |
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Abstract: | Twenty-four cowpea genotypes were evaluated under sole cropping or additive series intercropping with sorghum from 2004 to
2005 at four sites representative of the Guinea and Sudan savannah ecologies in Ghana. The aim was to determine whether cowpea
breeding programs that emphasize selection under sole-crop conditions have the potential to produce cultivars that are effective
under additive series intercropping. Genotype × cropping systems interaction was significant for days to 50% flowering but
not for grain yield, biomass and other studied traits. Genotypic yield reaction to cropping systems indicated that bridging
the yield gap between sole cropping and intercropping systems is best addressed by agronomic interventions that reduce stress
on intercrop cowpea rather than by selecting for specifically adapted genotypes for intercropping. Significant genotype × environment
interactions were observed for all traits when data was pooled over cropping systems. Partitioning of the genotype × environment
interaction variance indicated that days to 50% flowering was dominated by heterogeneity of genotypic variance, whereas genotype × environment
interactions for grain yield and biomass was mainly due to imperfect correlations. Large differences in genotypic yield stability
were observed as estimated by the among-environment variance, regression of yield on the environmental index, Kataoka’s index,
and by partitioning of genotype × environment interaction sum of squares into components attributable to each genotype. The
results suggest that in regions where genotype × environment interaction for yield frequently causes re-ranking across environments,
genotypes with the least contribution to the interaction sum of squares are likely to be most productive. On the whole, the
results support the contention that breeding under sole-crop conditions has the potential to produce cultivars effective under
intercropping conditions. |
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Keywords: | Cowpea Genotype × environment interaction Intercropping Stability |
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