Impact of tree training system, branch type and position in the canopy on the ripening homogeneity of 'Abbé Fétel' pear fruit.

In pear, fruit ripening is not homogeneous, which leads to problems in harvest and storage management. To identify factors affecting the ripening homogeneity, structural, biochemical and molecular parameters were investigated. Fruit were sampled from trees trained with three different systems, spindle, V-shaped and bi-axis, and were further grouped on the basis of canopy position (top or bottom) and branch type (short-old-spurs, 3-year-old or older branches, 2-year-old branches and twigs). This study confirmed that the position in the canopy plays a crucial role in fruit ripening in V-shaped and bi-axis training systems. Fruit on the spindle training system was unaffected by the position of the canopy, albeit showing a large variability within the fruit of each part of the canopy. Such variability is much lower in the bi-axis and V-shaped systems. The spindle training system had no similarity in homogeneity indices between the molecular and physiological measurements. Partial Least Square Discriminate Analysis (PLS-DA) showed differences in training system, branch type and canopy position separated by the different physiological and molecular parameters. Short-old-spurs and twigs had the highest homogeneity and least variability in all training systems and branch types. In addition, Partial Least Square Path Modelling (PLS-PM) was able to identify a high correlation between physiological measurements and ripening compared to that of molecular data.