Evaluation of cowpea (Vigna unguiculata L. Walp.) genotypes for phosphorus use efficiency

S. Gyan Ansah, H. Adu-Dapaah, F. Kumaga, V. Gracen, F.K. Nartey
Cowpea is an inexpensive vegetable protein for humans and livestock and contributes to the sustainability of cropping systems in sub-Saharan Africa. Phosphorus (P) deficiency affects the productivity of legumes such as cowpea. Smallholder farmers do not have the resources to purchase P fertilizers. A pragmatic solution to the problem of P deficiency is the development of cowpea genotypes with the ability to perform well in P-deficient soils as well as respond to P fertilization. A pot experiment was conducted to screen 100 cowpea genotypes for their P-use efficiencies at two levels of phosphorus: triple superphosphate, 60 kg P2O5 ha-1, applied to the pots (8.2 kg soil pot-1) and no P application (control). Tap root length, total root length, root dry weight, shoot dry weight, total dry weight, shoot P content, P utilization and P uptake efficiency were measured. These traits were highly heritable based on the ratio of genotypic coefficient of variation (GCV) to phenotypic coefficient of variation (PCV). Data for the 14 variables measured from these accessions were subjected to multivariate analysis using principal component analysis (PCA) and clustering criteria. Characters that contributed most to variability based on the first five principal components (Eigenvalue>1) were shoot dry weight, shoot P content, lateral root number and nodule dry weight. The pruned dendrogram generated through agglomerative hierarchical clustering based on the similarity matrix revealed two main groups of genotypes. Group (A) had 10 accessions, which were P-use efficient. These are being introgressed in adapted cultivars. Implications of the results on cowpea improvement for farmers and other end-users are discussed.
Gyan Ansah, S., Adu-Dapaah, H., Kumaga, F., Gracen, V. and Nartey, F.K. (2016). Evaluation of cowpea (Vigna unguiculata L. Walp.) genotypes for phosphorus use efficiency. Acta Hortic. 1127, 373-380
DOI: 10.17660/ActaHortic.2016.1127.58
phosphorus, deficiency, P-uptake, efficiency, principal component analysis, heritability, productivity, yield, accession

Acta Horticulturae