Morphological characterization and distinctness of seven pepper (Capsicum annuum L.) varieties

Consistent morphological descriptors in crop-specific DUS guidelines support cultivar identification, yet empirical validation of their discriminating power remains scarce. This study assessed the morphological distinctness of seven Capsicum annuum L. varieties using UPOV TG/76/8 descriptors over two growing seasons (2023-2024) at the National Agricultural Seeds Council field in Nigeria. Of 42 traits evaluated, 34 (81%) were polymorphic and used in multivariate analysis; 8 (19%) were monomorphic and excluded. Principal component analysis of the polymorphic traits showed the first three components explained 74.6% of total variation (PC1: 33.0%, PC2: 26.8%, PC3: 14.8%). Fruit apex shape, locule number, fruit length/diameter ratio, fruit shape in longitudinal and cross-section, and leaf margin undulation emerged as the primary discriminating traits on PC1. Hierarchical clustering grouped the varieties into three clusters: elongated-fruited types (Serenade, PS Pepper 1, PS Pepper 2); thick-peduncled, broad-leaved types (Commandant, Efia); and compact-fruited, sinuate-pericarp, tall types (Piquante, Spicy). PS Pepper 1 and PS Pepper 2 were the least distinct pair (Gower distance = 0.178), while Commandant and PS Pepper 1 were most distant (0.622). Seedling and floral traits contributed little discriminatory value. These results support the UPOV TG/76/8 descriptor set's effectiveness and suggest a reduced eight-trait subset could reliably determine distinctness in Capsicum annuum.