Abstract
ABSTRACT The objective of this study was to evaluate genetic divergence among cowpea genotypes and to select parents for crosses aimed at the fresh pod and grain market. Two experiments were carried out during 2014, corresponding to two sowing times, in the municipality of Mossoró, State of Rio Grande do Norte. Twenty-three cowpea genotypes were evaluated in a randomized complete block design with four replicates. Fifteen descriptors were used to quantify divergence, using the Mahalanobis distance as a measure of dissimilarity, obtained from the genotypic mean predicted by the Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP) method. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) hierarchical method was used to group genotypes and the Singh criterion to quantify the contribution of traits to genetic divergence. The genotype × environment interaction (G × E) influenced divergence, both in the contribution of traits and in the grouping of genotypes. In the experiment 1, the genotypes were distributed among four groups. In the experiment 2, less discrimination occurred and the genotypes were represented by only two groups. When joint analysis of two evaluations was carried out based on two sowing times, genotypes were represented by six groups. The G × E interaction influences the contribution of traits and the grouping of cowpea genotypes in the study of divergence. The genetic divergence of the set of cowpea genotypes evaluated is mainly due to green grain and pod yield. BRS Aracê and BRS Xiquexique cultivars are the most divergent among the genotypes studied, representing 75% of the recommended crosses.
Highlights
This work aimed at studying genetic divergence among cowpea genotypes and the selection of parental crosses suitable for the marketing of green pods and grains
Soil samples were collected from the area for fertility analysis, which was carried out at the Plant Nutrition Laboratory of the Plant Research Center of the Semi-Arid at the Department of Plant Sciences (DPS)
The following results were obtained from soil samples: experiment 1; experiment 2
Summary
Walp) is an important food crop which is widely cultivated in several parts of the world and represents an essential component of cropping systems in the driest regions of the tropics (SINGH, 2007). It is able to reach high levels of productivity when well nodulated (ALMEIDA et al, 2010; COSTA et al, 2011; SOARES et al, 2006) and is less reliant on good soil fertility compared to other food crops. In Brazil, cowpea cultivation has an important socioeconomic role, mainly in the North, North-East and Center-West regions. In the North and North-East regions, it represents a staple food for rural populations, as well as providing employment in the field. In the Center-West region, it has been incorporated into production systems such as safrinha or main culture, predominantly in the state of Mato Grosso (FREIRE FILHO, 2011)
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