Evaluating Fruit Quality and Maturity in Large Open Vase-trained ‘D’Anjou’ Trees

Commercial pear trees in the Pacific North West are still primarily low density systems with multi-leader, globe shaped canopies usually with an open center to allow light penetration. Rootstocks are limited to mainly seedlings, leading to highly vigorous trees. Trees height can reach 5 m with a very large canopy volume where fruit are mostly in the upper-medium portion of the canopy. Fruit characteristics inside such a vigorous tree can be very diverse because their exposure to light is variable within the canopy.  This system has several disadvantages including highly variable maturity and internal quality within the canopy of the same tree.  A ‘d’Anjou’ pear commercial orchard located in WA and grafted on Bartlett seedlings in the 1970s with a planting density of 278 trees/ha was object of this study. A portable spectrometer was used to quantify light intensity in the different horizontal layers within 15 similar canopies in the same orchard. Fruit were classified into two canopy positions as internal (<30% light) and external (70-100% light) and were harvested separately. Fruit were further sorted according to the I_AD index and classified into 5 classes. Fruit maturity distribution within I_AD classes at harvest was different within each canopy position.  Nearly 28% of external fruit were from the most ripe category, while only 0.7% of internal fruit were in that class. Fruit from each class were randomized and subdivided into 4 groups: T0 (= after harvest, no storage) and three pull outs (3, 6, and 8 months) from controlled atmosphere (CA, 0.5°C, 2 kPa O₂ and 0.8 kPa CO₂) storage. Fruit quality was assessed at each pullout including percentage of blush over-color surface, background color, exogenous ethylene, weight, firmness, fruit diameter, cork spot incidence, dry matter %, soluble solid content, acidity and pH.  External fruit were larger, more ripe and had a higher dry matter % and SSC than internal ones after 8 months of CA storage. The results indicate fruit position within these trees has a considerable impact on d’Anjou’ pear internal quality and storability.