Phenotypic Diversity and Multivariate Characterization of Opuntia ficus-indica from the Inter-Andean Dry Valleys of Northern Ecuador

Opuntia ficus-indica (L.) Mill. is a crassulacean acid metabolism (CAM) xerophyte whose intraspecific morphological diversity remains poorly documented in Andean agroecosystems. This study characterized the phenotypic diversity of 55 accessions collected along an altitudinal gradient in the dry inter-Andean valleys of northern Ecuador. Twenty morphological descriptors were used to analyse the data. Quantitative descriptors showed moderate to high variability, with reproductive and defensive characters exhibiting greater variation than vegetative descriptors. MCA revealed substantial chromatic diversity, with fruit peel and pulp color emerging as the strongest qualitative discriminators among morphotypes. Cluster analysis identified three statistically distinct groups: a small-fruited, highly spinescent morphotype restricted to the most arid sites; an intermediate and phenotypically diverse morphotype distributed across all provinces; and a large-fruited, low-spinescence morphotype with the highest seed numbers, consistent with a more advanced domestication trajectory. The primary differentiation axis reflected a trade-off between spine investment and reproductive output. Five discriminant descriptors—fruit weight, spine length, seed number, peel color, and pulp color—provide a robust baseline for germplasm characterization and support conservation, breeding, and nutraceutical valorization in Andean drylands. The findings of this research contribute to filling a critical knowledge gap regarding Andean cactus pear germplasm, providing a scientific basis for conservation, sustainable management, and future breeding and agro-industrial initiatives.