Validating a core collection of Peruvian quinoa germplasm

A Peruvian quinoa core collection, containing 103 chosen ecotypes or landra ces, was defined on a geographically stratified non-overlapping sampling pr ocedure. The objective was to determine whether this protocol was correct. Hence, a phenotypic distance matrix among 76 accessions from this core coll ection was created by calculating the difference between each pair of acces sions for each characteristic. These 76 accessions were chosen because they had complete data for eight morphological descriptors. The diversity index was calculated by averaging all the differences in the phenotypic value fo r each quantitative descriptor divided by the respective range, and conside ring a matching coefficient for the qualitative descriptors, i.e., 0 for ch aracteristics that matched, and 1 if they did not. The total sum of squares from the analyses of variance for the phenotypic diversity index, based on morphological descriptors, was partitioned between and within Peruvian Dep artments. The between Department cluster variance was smaller (0.0022) than the within Department cluster variance (0.0144), because accessions with t he same stem colour or similar inflorescence type and colour were grouped t ogether irrespective of their Department. This was further corroborated by the average linkage cluster analysis, which was performed on the phenotypic diversity matrix to study the pattern of variation and the relationship be tween the quinoa landraces of this core subset according to their geographi cal origin. Within each sub-cluster (based on above qualitative descriptors ) accessions were ranked by their Department of collection, which indicated that the sampling method was appropriate for choosing accessions for the P eruvian quinoa core collection.