Genetic divergence in cowpea genotypes with upright growth and early cycle

F.T.C Dias,C.H.C.M Bertini,A.P.M Silva

doi:10.12702/1984-7033.v09n03a07

Abstract

The objective of this study was to group cowpea genotypes with upright growth and early maturity using multivariate techniques to estimate the relative contribution of the response variables to genetic divergence studied. Twenty- eight lines of the Genbank of the Universidade Federal do Ceara and Embrapa Meio Norte were used. For the analysis of genetic divergence the canonical variables, Mahalanobis' distance and the Tocher cluster method were used. Most of the maximum distances were observed when combined with CE-46 genotypes. The crosses between the groups VIII and XI and groups VII and VIII may result in new gene combinations. The variables beginning of flowering and crop cycle contributed most to the genetic divergence among the genotypes.

Highlights

Cowpea (Vigna unguiculata (L.) Walp) is one of the most important and strategic food sources in tropical and subtropical regions of the world (Freire-Filho et al 2005) and is one of the most adapted, versatile and nutritive Fabaceas among the cultivated species.The species is well-adapted to the climate and soil conditions in the North and Northeast of Brazil
In recent years the yield of this crop has gradually declined in the state of Ceará, to yields as low as 75 to 473 kg ha-1 (CONAB 2008), which does not represent the full genetic potential of the cultivars used in the state
In view of the importance of cowpea in the North and Northeast of Brazil, the purpose of this study was to group cowpea genotypes with upright growth and early maturity according to the genetic dissimilarity, for the formation of cross blocks and indicate the relative contribution of the studied response variables to the genetic divergence, to increase the efficiency of the selection process

Summary

Introduction

The species is well-adapted to the climate and soil conditions in the North and Northeast of Brazil. Unlike common bean (Phaseulos vulgaris L.) and other Fabaceas, cowpea can be grown in Brazil in both the dry climate of the Northeast as well as the humid climate in the North, from latitudes 5 ° N to 18 S. In recent years the yield of this crop has gradually declined in the state of Ceará, to yields as low as 75 to 473 kg ha-1 (CONAB 2008), which does not represent the full genetic potential of the cultivars used in the state. A number of factors are responsible for the low yields, including: use of cultivars with low genetic potential and extensive intercrop cultivation, in rotation with other crops, mainly maize, cassava and cotton (Teófilo et al 2003)

Objectives

Methods

Results