Abstract

Drastic changes in random environment and lack of cultivar evaluation and multiple trait assessment across years are major constraints to pepper breeding in derived savanna agro-ecology. Ten genotypes of aromatic pepper grown in randomized complete block design were used to investigate the genotype by trait (GT) biplot analysis and to examine its effectiveness in visualizing fresh fruit yield and yield components relationships and its application in cultivar evaluation, comparison and selection across years. Twenty-two traits including fresh fruit yield were studied using GT biplot analysis.Results of the analysis of variance show signigicant genotypic, year and genotype byyear interactions (GEI) for yield and yield components. GT biplot analysis showed that the genotypes were affected diversely by different environmental stresses prevalent in each of the years. G4 (Shombo) was outstanding in the first year of assessment havingsignificantly the highest value in eighteen traits including fresh fruit yield, however, in the second year of assessment, G1 (UNS₂) and G3 (Nsky-lp), not varying significantly (P = 0.01) from each other, had the highest yield. The combined analysis biplot polygon showed that G4 (Shombo) had significantly the highest values in eleven traits. Thegenotype by year GE biplot show G4 (Shombe) as the most outstanding genotype inyears 1 and 3 assessment seasons in both fresh fruit yield and major yield components as number of nodes per plant, canopy diameter, number of fruits per plant among other traits as shown in the biplot. G7 (Tatase) is the vertex genotype having the highest value in, single fruit weight in all the years of assessment and pericarp thickness in years 2 and 3. Genotype evaluation and selection of parents for high fresh fruit yield and yield components were facilitated by GT biplot, as a result, G4 could be selected as the best genotype for high fresh fruit yield and G7 for high single fruit weight value and pericarp thickness. Equally, selection for number nodes per plant, canopy diameter, number of branches per plant, number of fruits per plant among other traits offers a wide scope for improving fresh fruit yield in Capsicum annuum. 

Key words: Capsicum annuum, genotype by trait, biplot, selection, year.