Selection of Cowpea Lines for Multiple Traits by GYT Biplot Analysis

Cowpea is an African legume that was introduced to Brazil by Portuguese settlers in the mid-16th century. The productive potential of this crop may fluctuate depending on its environment. The objective of the present study was to select cowpea lines with high grain yield coupled with other traits of agronomic interest, such as good adaptability and stability, by the GYT biplot methodology. Twelve lines were evaluated in the years 2016 and 2017 in the municipality of Bom Jesus de Itabapoana, Brazil, in a randomized-block design with four replicates and two cultivars, which were used as controls. The following variables were evaluated- number of days to flowering, final stand, crop value, lodging, pod weight, pod length, seed number per pod, seed weight per pod, 100-seed weight (100SW), and grain yield. Analysis of variance was performed and GYT biplots were constructed using R software and the ggplot2 package. The GYT biplot graph analysis allowed for the selection of superior cowpea genotypes. In the combinations of traits observed, lines L1, L3, L5, L6, L8, and L9 were superior and cultivar Imponente stood out as one of the controls. The yield combinations GY*CV, GY*NDF, GY*LDG, GY*CV, GY*PW, GY*SNP and GY*P100G were positively correlated with each other but showed negative to highly negative correlations with GY*SWP and GY*TS.