Suitability for machine harvesting of 6 red raspberry (Rubus ideaus L.) varieties grown in Italy.

In order to apply machine harvesting on red raspberry (Rubus ideaus L.) varieties grown in Italy, preliminary trials have been conducted to obtain an objective estimate of the effect of cultivar and ripeness stage on harvest. Suitability for machine harvesting was determined by measuring the force necessary to remove the berry from the receptacle and fruit firmness of 6 varieties of red raspberries: Chilliwack, Fairview, Glen Lyon, Glen Moy, Rusilva and Titan. Subjective determination of ripeness categories has been solved proposing CIEL*a*b* space colour co-ordinates as objective and numerically expressed measurements of the stage of maturity. Analysis of data demonstrates that hue and lightness have the most useful relation with mechanical characteristics of red raspberry fruit. According to the findings of this trial, mechanical harvesting could be successfully applied to Chilliwack and Glen Moy. Chilliwack has a large differential in fruit-from-core detachment force between fully ripe and unripe fruit. Its fruit resistance to deformation is high in every stage of ripeness. If mechanical harvesting is applied to this cultivar, a large number of harvesting operations will be a necessary. Glen Moy associates low fruit retention force with a good resistance to deformation in every maturity stage. Mechanical harvesting applied to this variety would require lower number of harvesting operations, but more labour for sorting.