Genetic Architecture of Some Leaf Yield and Quality Attributes in Dual-purpose Cowpea (Vigna unguiculata L. Walp.)
Jean-Baptiste Tchiagam Noubissié *
Department of Biological Sciences, Faculty of Science, University of Ngaoundéré, P.O. Box 454 Ngaoundéré, Cameroon.
Emmanuel Youmbi
Unit of Genetics and Biotechnology, Department of Plant Biology, Faculty of Science, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon.
Nicolas Yanou Njintang
Department of Biological Sciences, Faculty of Science, University of Ngaoundéré, P.O. Box 454 Ngaoundéré, Cameroon.
Ange Ndogonoudji Alladoum
Department of Biological Sciences, Faculty of Science, University of Ngaoundéré, P.O. Box 454 Ngaoundéré, Cameroon.
Marcel Richard Nguimbou
Department of Food Sciences, Higher School of Agro-industrial Science, University of Ngaoundéré, P.O. Box 455 Ngaoundéré, Cameroon.
Joseph Martin Bell
Unit of Genetics and Biotechnology, Department of Plant Biology, Faculty of Science, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Aims: Cowpea’s use as leafy vegetable has been widely neglected in research. The present study was aimed at finding out the nature and magnitude of genetic variability in dual-purpose cowpea for leaf yield and quality attributes.
Place and Duration of Study: Ngaoundéré University (Cameroon), from 2008 to 2009.
Study design and Methodology: Fourteen pure lines and ten F1 hybrids derived from a 5 x 5 half-diallel cross were grown in Randomized Complete Block Design (RCBD) with three replications to assess the genetic mechanism of leaf yield index (LYI), leaf area (LA), leaves per plant (NLP), leaf protein (LN) and phosphorus (LP) content.
Results: Analysis of variance indicated significant differences (p<0.01) among genotypes for all traits. Moderate to high heritability in broad-sense (0.49-0.90) was recorded for the characters indicating major role of genetic variance in the expression of these polygenic traits. Diallel analysis showed significance (p<0.05) of the effects of general combining ability (GCA), specific combining ability (SCA), the involvement of additive and dominance genes. These genes were asymmetrically distributed among the parental genotypes. Dominant genes had an overall positive effect for leaves per plant, leaf yield index and phosphorus content while high protein content and surface area appeared to be associated mostly with recessive genes. Correlations between the leaf attributes and seed yield components were significant only for leaves per plant and seeds per pod (-0.73), pods per plant (-0.69); leaf yield index and seed weight (0.69); leaf protein content and pods per plant (-0.77).
Conclusion: These results could be exploited in breeding programs to develop nutritional superior cowpea varieties which could be used for harvesting of both leaves and seeds.
Keywords: Vigna unguiculata, leaf yield, leaf protein and phosphorus, diallel analysis, genetic improvement, Guinea savannah zone