Genetic diversity and comprehensive evaluation of physicochemical traits in Phyllanthus emblica L. for breeding and resource utilization

Phyllanthus emblica L. is a nutritionally and medicinally valuable fruit tree with extensive germplasm diversity. This study evaluated 61 genetically diverse accessions collected from China and South Asia for 27 physicochemical traits, including 13 physical and 14 chemical attributes, to assess genetic diversity and identify elite germplasm for breeding. Substantial phenotypic variation was observed, with coefficients of variation (CV) ranging from 5.13 to 98.09% for physical traits and 1.51-59.82% for biochemical traits. Notably, single fruit weight (CV: 98.09%), flesh stickiness (63.65%), crude fat (59.82%), and polysaccharide content (50.12%) exhibited high variability. Fifteen traits conformed to a normal distribution and were categorized into five probability-based grades. Correlation analysis showed that pericarp strength was significantly positively correlated with soluble solids, titratable acid, total flavonoids, polyphenols, and tannin content, while flesh hardness correlated positively with crude fiber and total sugar. Principal component analysis (PCA) reduced the 27 traits to 12 representative indicators, accounting for 82.54% of total variation. Hierarchical clustering grouped the germplasms into three classes: Class I (19 accessions) with high antioxidant contents and strong textures; Class II (2 accessions) with the largest fruit size and high flesh toughness; and Class III (40 accessions) with high moisture content and lower values for most traits, suitable for juice processing. A comprehensive biochemical evaluation model was constructed using PCA-derived weights, and the top-performing accessions-PEF30, PEF41, PEF35, PEF17, and PEF31-demonstrated superior nutritional quality based on total sugar, polyphenols, vitamin C, and flavonoid contents. These accessions are promising candidates for functional food development, fresh consumption, and cultivar improvement. This study provides a robust analytical framework and theoretical foundation for the classification, conservation, and targeted utilization of P. emblica germplasm in breeding programs.