Objective To construct primary core collection of Phalaenopsis based on phenotypic traits to provide theoretical basis for the conservation and utilisation of Phalaenopsis resources and species selection.

Methods Using 210 Phalaenopsis germplasm resources as materials, 32 phenotypic traits were investigated, including 13 qualitative traits and 19 quantitative traits. Three sampling methods (random sampling method, preffered sampling method, deviation sampling method), two genetic distances (Euclidean distance, Mahalanobis distance), three sampling ratios (20%, 25%, 30%) and eight clustering methods (single, complete, median, centroid, unweighted, weighted, flexible and ward) were used to explore the best sampling strategy to construct core collection. The alternative core collection was evaluated using the mean difference percentage (MD), variance difference percentage (VD), range coincidence rate (CR) and variation coefficient change rate (VR), and the core collection was confirmed using mean and extreme comparative analyses and principal component analysis.

Results Preffered sampling method can make the core collection more representative, Euclidean distance is better than Mahalanobis distance, 25% is the optimal sampling ratio, and the optimal clustering method is the complete method, so that the primary core collection of 52 materials was finally sampled. The constructed core collection was excellent in all evaluation parameters, representative of the genetic diversity of the original collection, the principal component information was retained, and the genetic redundancy of the original collection was well removed.

Conclusion The constructed primary core collection of Phalaenopsis can be prioritised as material for subsequent Phalaenopsis germplasm resource research, providing a theoretical basis for germplasm conservation and utilisation.