XVI International Botanical Congess

The olive fruit mesocarp is composed principally of parenchymatous cells with occasional isolated sclereids. We quantified cell number and size during mesocarp development using transverse equatorial sections. At flowering, mesocarp area was less than 1% that at fruit maturity, cell size was 2.5% and cell number was 12%. Cell division was highest the first six weeks after flowering, but continued at a lesser rate until maturity. Cell expansion was continuous during fruit growth, following a pattern similar to mesocarp size. Measurements in different parts of the mesocarp and in different sectioning planes reflected similar patterns, yet revealed that cell expansion was greatest in the radial dimension. Comparisons between cultivars indicated that cell number was the principal factor determining varietal differences in fruit size.