Mechanical Resistance of New Apple Genotypes for Automated Harvesting.

Mechanical damage to apples that occurs without visible skin rupture represents a significant issue during handling and harvesting. The aim of this study was to evaluate the potential for detecting initial internal tissue failure using parameters derived from the deformation curve obtained during a quasi-static penetration test. Particular attention was given to the parameter Pa, defined as the pressure at the yield point, which indicates the onset of structural failure in the tissue. The occurrence of Pa was monitored across five apple genotypes, and the results demonstrated the parameter's sensitivity to latent internal damage. The parameter Pc, characterising resistance in the later phase of penetration, also showed a strong correlation with fruit bulk density. Significant differences in all mechanical characteristics were observed between the genotypes. The results highlight the potential of these parameters for assessing varietal suitability for mechanised harvesting and sorting. The proposed methodology is readily applicable in the selection of new genotypes within breeding programmes as well as in post-harvest situations.