ABSTRACT In Brazilian apple breeding ( Malus domestica Borkh.), Active Germplasm Banks are providing the genetic diversity required for selecting genotypes with low chilling requirements, high yield and superior fruit quality. This study estimated genetic parameters and perform genotype selection based on phenotypic traits from the IDR‐Paraná breeding programme. Fifteen promising genotypes and the cultivar ‘Eva’ (check) were evaluated on M7 or Marubakaido/M9 (MM9) rootstocks. The evaluated traits were canopy volume, number of brindilles and spurs, yield (kg plant −1 ), soluble solids (SS), titratable acidity (TA) and fruit flesh firmness across four growing seasons (2021/22 to 2024/25). Data were analysed via REML/BLUP methodology, principal component analysis (PCA), hierarchical clustering and adaptability/stability analysis using the GGE biplot method. Broad‐sense heritability was low for most traits due to high meteorological variability across seasons, except for TA ( h 2 = 0.57). BLUP values highlighted PR2.60/MM9 presented higher predicted genetic values for SS and firmness, representing a favourable combination for selection. Hierarchical clustering revealed high similarity among most combinations, except for PR2.10/M7, being distinct due to its higher titratable acidity and lower soluble solids and fruit firmness. In the principal component, the three postharvest traits contributed the most to variability; thus, selection should focus on these traits to discriminate the superior genotype/rootstock combinations. The genotypes PR2.70 and PR2.47, grafted onto MM9, were ranked as the top two combinations by the Smith–Hazel selection index. According to the adaptability/stability, the PR2.70/MM9 combination exhibited the highest yield potential and adaptability, whereas the PR2.47 genotype showed the greatest yield stability on both rootstocks across the four seasons. These two genotypes, when grafted onto MM9, can be advanced to further testing as potential new apple cultivars for the IDR‐Paraná breeding programme, primarily due to their superior performance in the three postharvest traits (higher firmness and SS, and lower TA).
Ribas et al. (Fri,) studied this question.