Variability of acorn anatomical characteristics in Quercus robur L. genotypes

The aim of this study was to examine variability of acorn anatomical characteristics in seventeen Quercus robur L. genotypes. Acorns were collected in clonal seed orchard Banov Brod (Srem, Vojvodina, Serbia). Microscopic measurements were done for pericarp (total thickness, thickness of exocarp and mesocarp), seed coat (total thickness, thickness of outer epidermis, parenchyma, and inner epidermis), and embryo axis (diameter, thickness of cortical region, and diameter of stellar zone). Obtained results revealed certain divergence between genotypes. The thickness of pericarp varied from 418 to 559 mm (genotypes 20 and 22, respectively). On average, the participation of exocarp in the total thickness of pericarp was 36.3%, of mesocarp 61.0%, while of endocarp 2.6%. The thickness of seed coat for individual genotypes ranged from 71 mm (genotype 28) to 157 mm (genotype 38). In addition, anatomic parameters of embryo axis varied among studied genotypes. The lowest cortical zone thickness and stellar zone diameter were measured in genotype 40, while the highest values in genotype 33