Identification of unique black pepper (Piper nigrum L.) hybrids using multivariate analysis

Abstract

Black pepper is the most important spice crop in terms of cultivation area, production, and export earnings. The development of improved varieties mainly focuses on three aspects: overcoming biotic and abiotic stresses, as well as achieving higher yield potential. A study was conducted to identify unique hybrids using the evaluation of 52 black pepper (Piper nigrum L.) hybrids along with the standard check var. Panniyur-1. Principal Component Analysis (PCA) of four traits (leaf length, leaf width, specific leaf weight, and collar diameter) showed that the first two components explained 83.5% of the total variance (PC1 = 55.78%, PC2 = 27.75%). Leaf length and width loaded most strongly on PC1, whereas specific leaf weight (SLW) and collar diameter dominated PC2. Clustering partitioned the genotypes into six distinct groups. Cluster-V contained hybrids with exceptionally large leaves (mean ≈17.9 × 14.4 cm), while Cluster VI, consisting of a single hybrid (SPH-49), recorded the highest SLW (≈9.70 mg/cm²) and thickest collar (≈8.69 mm). The check variety Panniyur-1 fell into an intermediate cluster (IV) with moderate trait values. These results demonstrate that multivariate trait analysis effectively uncovers phenotypic diversity in black pepper and identifies unique hybrids that can be targeted in breeding programs.