Morphological diversity and early growth performance of F ₂ populations of barberry ( Berberis spp.) from interspecific hybridization

This study assessed morphological and genetic diversity in twelve Berberis F 2 populations. Seeds were collected from selected F 1 hybrids resulting from crosses between Berberis integerrima , B. crataegina , and ‘Zereshk Bidaneh’-a commercial seedless barberry cultivar. Initial evaluations compared seed germination and seedling survival on three substrates: perlite, cocopeat, and peat moss. Germination rates varied widely among F 2 populations, ranging from 17% to 95.48%. A 1:1 mixture of cocopeat and perlite significantly enhanced germination. Twelve morphological and vegetative traits were subsequently measured, revealing substantial phenotypic variability across F 2 populations. Correlation analyses identified strong positive associations among key traits such as leaf number, plant height, and leaf morphology characters. Factorial analysis indicated that the first two factors explained 35.5% of the total variance, primarily differentiating populations based on leaf pigmentation and leaf-spine architecture. Heatmap clustering grouped the F 2 genotypes into six distinct phenotypic clusters. Notably, traits such as leaf margin spine (CV = 33.89%) and leaf pigmentation (CV > 43%) exhibited high coefficients of variation, suggesting the potential for transgressive segregation and providing a wide basis for selection. These findings establish a robust framework for early-stage selection in barberry improvement programs.