Genotype × environment interaction and yield stability in a cowpea-based cropping system

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.

Stability analysis of components characters in cowpea (Vigna unguiculata (L.) Walp)

“…These results indicated that cowpea genotypes responded differently to different environmental conditions, suggestion the importance of assessment of genotypes under different environments in order to identify the best genetic make up for particular environment. These results appeared to be in harmony with those obtained by Nwofia et al (2007), Padi (2007), Peksen (2007, De Rocha et al (2007 a,b), Sarutayophat et al (2007) and Taiwo (2007).…”

Evaluation of Planting Dates on Growth and Yield of Three Cowpea [Vigna unguiculata (L) Walp.] Genotypes in Northern Ghana

“…Songotra produce the highest pod per plants, followed by T 2 T 4 and Padi-tuya recorded the least pods per plant. This result is in conformity with [18][19][20] who reported that the number of pods per plant is the most important component in determining yield in several legume crops.…”

Response to selection for grain yield and correlated response for grain size and earliness in cowpea based on early generation testing

“…A caution with the early generation section approach is, however, that strong genotype  environment interaction for grain yield has been documented in cowpea in the northern savannah belt of West Africa (Padi, 2007b), and the probability of obtaining families with broad adaptation to the target production belt is higher when a high proportion of elite families are tested in advanced multilocation evaluations. Although this has been achieved mainly based on the single-seed descent breeding approach, retrospective selection in the F 3 suggests that a pedigree breeding approach would have been effective as well, with less transaction costs related to the number of families that are screened in replicated tests.…”

“…Although this has been achieved mainly based on the single-seed descent breeding approach, retrospective selection in the F 3 suggests that a pedigree breeding approach would have been effective as well, with less transaction costs related to the number of families that are screened in replicated tests. A caution with the early generation section approach is, however, that strong genotype  environment interaction for grain yield has been documented in cowpea in the northern savannah belt of West Africa (Padi, 2007b), and the probability of obtaining families with broad adaptation to the target production belt is higher when a high proportion of elite families are tested in advanced multilocation evaluations. A low selection pressure is, therefore, necessary in early generation selection for these production regions.…”