Multi-trait evaluation of almond germplasm using the MGIDI method: optimizing yield and nutritional quality

Almond (Prunus dulcis) is a nutrient-rich tree nut of global economic and dietary importance, with Iran serving as a key center of genetic diversity. This study evaluated 78 Iranian almond genotypes for pomological traits and major biochemical constituents to identify genotypes combining high yield potential with superior nutritional quality. Measured attributes included kernel and nut weight, oil and protein content, soluble and total sugars, phenolic compounds, and fatty acid profiles. Almond nut weight (NW) showed considerable variation (0.90–9.56 g), while kernel weight (KW) ranged from 0.53 to 3.38 g, with a mean of 1.34 g. Oil content ranged from 41% to 62%, and protein content from 27% to 55%. Among fatty acids, oleic acid (OA) was predominant (mean 74.35%), whereas linoleic acid (LA) and palmitic acid (PA) ranged from 11.65% to 31.18% and 1.00% to 9.03%, respectively. The Multi-Trait Genotype-Ideotype Distance Index (MGIDI) identified 12 superior genotypes displaying complementary profiles across morphological and compositional traits. Principal Component Analysis indicated that the first five components accounted for 74.2% of total variance, with PC1 primarily associated with morphological attributes and PC2 with lipid-related traits. Nut and kernel weights were strongly and positively correlated (r = 0.85***), whereas oleic and linoleic acids showed a strong negative association (r = -0.98***). No significant correlations were found between physical and biochemical traits, underscoring the potential for concurrent improvement of yield and nutritional composition. The substantial genetic variability within Iranian almond germplasm offers valuable opportunities for breeding programs to develop high-quality cultivars for diverse markets.