Uncovering Indigenous Diversity and Farmer Preferences in Pigeon Pea (Cajanus cajan): Insights from Germplasm Exploration, Ethnobotanical Surveys, and Digital Phenotyping for Climate-Smart Breeding

Pigeon pea ( Cajanus cajan [L.] Millsp.) remains an underutilized legume in most African countries despite its potential for climate-resilient farming systems, food diversification, and nutritional value. Limited knowledge of its indigenous diversity and farmer trait preference constrains wider adoption, particularly in the West African sub-region. Between February and June 2025, a germplasm exploration was conducted across 18 Nigerian states, complemented by accessions from the International Institute of Tropical Agriculture (IITA) genebank, Ghana, the Republic of Benin, and the Gambia, bringing the total to 273 accessions. Ethnobotanical surveys captured farmer preferences, cultural uses, and local nomenclature while seed morphometric traits were assessed using Videometerlab4 multispectral imaging. Farmer surveys revealed cooking time (58.3%), commercial value (27.0%), and maturity cycle (14.7%) as preferred varietal traits. Gender and age differences were evident; women and older farmers prioritized cooking time, while men and youth emphasized the maturity cycle as a preferred trait. Vernacular names (e.g., Otili , Fiofio , Waken Gwari ) highlighted deep cultural integration and cross-border exchange in Ogun State and the Republic of Benin, indicating transboundary diversity. Morphometric analyses revealed moderate variability in seed size, shape, and pigmentation. Seed area (14.2–46.0mm ² ), Compactness (0.590–0.998), and eccentricity (0–0.808) differentiated rounded from elongated seeds, while CIELab_A values (–0.04–29.98) captured pigmentation differences. The first two PCA axes explained 67.1% of total variation, and cluster analysis grouped accessions into four morphotypes. By integrating genetic and morphometric information, as well as farmer varietal preference insights, this study provides a robust foundation for the conservation and development of climate-resilient, fast-cooking, and market-preferred varieties for sub-Saharan Africa.