Combined effects of irrigation, crop load and fruit position on size, color and firmness of fruits in an extra-early cultivar of peach

Experiments were conducted on a very early-maturing peach (Prunus persica) cv. ‘Flordastar’ in 2006 in order to study the influences of irrigation, fruit load and fruit location within the leafy shoot and the canopy on fruit growth and several fruit-quality attributes. Trees were subjected to full irrigation (FI) and regulated deficit irrigation (RDI, consisting in 25% of FI during stages I and II of fruit development) under two crop loads: commercial and low (half of the commercial crop load). Fruit position on the shoot, height in the crown, their exposure to sunlight and orientation were recorded. Fruit diameter, fresh weight, firmness, and flesh and skin color attributes were determined for each fruit. Water stress and crop load had a high impact on all the variables studied. Fruits from trees under RDI were smaller, lighter and had a higher firmness than those from FI trees. Thinning was not able to counteract the negative effects of water stress on peach fruit size. Exposure to sunlight strongly influenced fruit size, weight, and skin color. Fruits highly exposed to sunlight in water stressed trees were larger. Therefore, leaving a certain fruit distribution on the tree, with fruits more exposed to sunlight, may compensate for the negative effects of water stress on fruit size. Further research is needed on peach-fruit distribution under water restriction conditions.

► Irrigation and crop load exerted a great influence on all the attributes studied.
► Thinning was unable to counteract the negative impact of regulated deficit irrigation on fruit size.
► Position on the shoot affected more variables than height and orientation in the crown.