Agromorphological Characterization of Quinoa (Chenopodium quinoa Willd.) Under Andean–Amazonian Region of Peru

Quinoa (Chenopodium quinoa Willd.) is an Andean pseudocereal of high nutritional value and remarkable phenotypic diversity, recognized as a strategic crop for food security under increasing climatic variability. In this study, the agromorphological diversity of 158 accessions cultivated in the Andean–Amazonian region of Peru was evaluated with the aim of identifying superior materials for conservation and breeding programs. The experiment was conducted using an augmented design that included three check cultivars (INIA 415 Pasankalla, INIA 420 Negra Collana, and Blanca Juli). Diversity in eleven qualitative traits was quantified using the Shannon–Weaver (H′) and Nei (He) indices, whereas twelve quantitative traits were analyzed through principal component analysis (PCA) and hierarchical clustering. The results revealed substantial intra- and inter-accession variability, with He values ranging from 0.21 to 0.76 and H′ values from 0.40 to 1.79, reflecting marked differences in growth habit, panicle morphology, stem pigmentation, and tolerance to Peronospora variabilis and Epicauta spp. Multivariate analyses identified three contrasting groups and enabled the selection of outstanding accessions, including UNTRM-367-1149, UNTRM-367-1107, UNTRM-367-1078, UNTRM-367-1079, UNTRM-367-1081, UNTRM-367-1095, and UNTRM-367-1104, characterized by high yield potential, favorable reproductive architecture, early or intermediate maturity, and low downy mildew severity. These accessions represent promising genetic resources for developing quinoa varieties adapted to transitional Andean–Amazonian environments, contributing to improved crop productivity and resilience.