Phenotypic and biochemical diversity of indigenous apricot (Prunus armeniaca L.) genetic resources

Apricot is a globally cultivated temperate fruit with high nutritional and economic value. Gilgit Baltistan (GB), Pakistan, is a major apricot-producing region with unique geographic surroundings and rich germplasm diversity. However, the indigenous apricot accessions in this area have not yet been scientifically explored. This study provides the first integrated evaluation of 19 local apricot accessions using multivariate statistical analysis, including descriptive statistics, principal component analysis, correlation analysis, and hierarchical cluster analysis, to comprehensively assess morphological, pomological, and biochemical diversity among indigenous apricot accessions for conservation and crop improvement, and to identify elite accessions with promising horticultural and nutritional traits. The results revealed substantial variations in morphological traits, skin cracking susceptibility (56.270%), followed by texture of flesh (55.110%), flesh color (52.830%), over color pattern (49.970%), and harvesting maturity (49.430%). In correlation analysis, significant positive correlations were observed among key morphological and quality traits, including suture size with overcolor (r = 0.67) and fruit color with flesh color (r = 0.65), while harvesting maturity showed a negative correlation with color pattern (r = - 0.61), and stone separation was negatively associated with flesh juiciness (r = - 0.60). In biochemical assessments, notable diversity was recorded in total soluble solids (11.393-24.267 °Brix), titratable acidity (0.438-0.698%), total phenolic contents (27.721-121.078 mg GAE/100 g), total flavonoid contents (80.738-154.075 mg QE/g), reducing sugar (5.432-13.452%), total sugar (7.775-19.578%), and non-reducing sugar (2.172-6.448%). Furthermore, total lycopene contents (TLC), total anthocyanin contents (TAC), antioxidant activity (AOA), and total tannin contents (TTC) showed varied amounts from 2.880-19.720 mg/kg, 77.941-122.412 mg L⁻¹, 50.340-94.100%, 1.660-20.609 mg TAE/100 g, respectively, highlighting the unique nutraceutical potential. Principal Component Analysis (PCA) exhibited 78.582% of the total variability, highlighting fruit size, sugar composition, antioxidant-related traits, and color attributes as major contributors to diversity. In the biochemical correlation analysis, the strongest positive correlation was observed among total sugars, reducing sugars, non-reducing sugars, lycopene content, and crude fiber. Based on agronomic and biochemical quantitative traits, hierarchical cluster analysis divided these accessions into three clusters, and 'Yakyar' and 'Hawalpa' were identified as the most diverse accessions in biochemical characteristics. This study is novel in providing the first comprehensive phenotypic and biochemical characterization of GB apricot germplasm, revealing highly diverse and nutritionally valuable accessions that can be targeted for breeding, conservation, and functional food development.