A Comparison of Two Methods for Measurement of Fruit Strength in Red Raspberry

Abstract

Abstract Fruit strength in red raspberry was measured using a cohesion method that determines the force required to pull a fruit apart. This method was compared to the compression method, which measures the force required to flatten the fruit. Fruit maturity significantly affected accuracy; the cohesion method was most variable for ripe fruit. A relatively low coefficient of variation across all maturity types indicates that the compression method is preferable for between-maturity comparisons, using a log transformation to produce variance homogeneity. With both methods, red ripe-stage raspberries showed significant differences between clones; the coefficients of variation for each method were similar within each clone. Variances were homogeneous using either method. The cohesion method gave relatively low absolute measurements that were highly correlated with those obtained using the compression method. Therefore, either method should be acceptable for measurements made within one maturity type.