Genetic Divergence and Strategic Parental Selection for Hybridization in Black Pepper (Piper nigrum L.) Germplasm

Abstract

Aims: To quantify genetic divergence among 25 black pepper (Piper nigrum L.) genotypes using Mahalanobis D² statistics, classify the germplasm by Tocher’s method, identify the traits underlying divergence and translate cluster-specific agronomic profiles into a strategic framework for parental selection. Study Design: Field evaluation in a Randomised Complete Block Design, followed by multivariate divergence analysis. Place and Duration of Study: Field genebank at Haalugudde village, Anandapura taluk, Shivamogga district, Karnataka, India (14.15° N, 75.32° E; 640 m above mean sea level), between November 2024 and March 2025. Methodology: Twenty-five genotypes, comprising local landraces, a traditional cultivar, released and hybrid varieties, and farmer selections on six-year-old, stable-bearing vines, were evaluated in three replications. Twenty quantitative agro-morphological, yield and quality traits were subjected to Mahalanobis D² analysis; genotypes were grouped by Tocher’s method, and the relative contribution of each trait to divergence was estimated. Results: The genotypes resolved into six clusters (Cluster III, 9 genotypes; Cluster II, 8; Clusters I and IV, 3 each; and Clusters V and VI, one genotype each: Panniyur-1 and V-2, respectively). Maximum inter-cluster divergence (D² = 6,870.80) occurred between Cluster V and Cluster VI; Clusters II and III were closest (D² = 682.26). Dry berry yield per vine (27.00%), spikes per plagiotropic shoot (17.67%) and laterals m⁻² (16.33%) jointly accounted for 61.00% of divergence. Cluster V combined the highest fresh (32.77 kg) and dry (11.46 kg) berry yields with the longest spikes (21.50 cm); Cluster VI led in plant architecture (27.33 laterals m⁻²; 65.00 spikes m⁻²); Cluster IV combined 105.00 berries per spike with the heaviest fresh berries (16.01 g). Conclusion: Substantial, cluster-structured divergence exists in this germplasm, but the most divergent pair did not automatically coincide with the pair offering the most useful complementarity. Integrating Mahalanobis D², cluster-specific complementarity and defined breeding objectives is proposed as a more defensible basis for prioritising crosses than divergence alone, with Panniyur-1 × V-2 identified as a high-priority combination for experimental hybridisation and progeny evaluation.