Dry matter accumulation and seasonal partitioning in mature Opuntia ficus-indica (L.) Mill. fruiting trees

Aim of this study was to understand the allocation of biomass into different canopy and root components and to measure the stem area index and its partitioning by cladode functionality (age), for fruiting Opuntia ficus-indica (OFI) Gialla trees, spaced 6x5 m apart and trained to a globe. The net primary productivity (NPP), calculated taking into account dry weight gain for above-ground vegetative components of OFI trees was 3.6 t C ha^–1. Including the fruit component and 1^st flush current-year cladodes, NPP of above-ground components becomes 12 t ha^–1, equivalent to 5.4 t C ha^–1. Current-year cladodes were the highest C sink (49% of total annual C fixed in the canopy), secondary growth accounted for 22% of C fixation and the fruit component for 29%. This study demonstrated that OFI trees, grown in a commercial fruit orchard, couple high productivity, in terms of fruit yield and harvest index, with relevant C fixed in the canopy.