Lavee, S., Institute of Horticulture, Volcani Center, Bet-Dagan 50-250, Israel, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
Wodner, M., Institute of Horticulture, Volcani Center, Bet-Dagan 50-250, Israel

The oil content in olive fruits of different sizes from irrigated high ('on') and low ('off') yielding olive trees of cvs. Barnea and Manzanillo were determined at different stages of fruit maturation. The fruit size range at all stages of maturation is significantly higher on low yielding 'off' trees than on high yielding 'on' trees. The oil content in the mesocarp of olive fruits is not yield or fruit size dependent. Only in young fruit at early stages of green maturation is the oil content in the fruit's mesocarp higher in the low yielding 'off' trees than in the high yielding 'on' ones. At full black maturation, the relative oil content in the mesocarp is uniform in all fruits regardless of size and level of yield. The final oil content in the fruits is dependent on the interaction between the growing conditions and the genetic potential of the variety. The amount of oil produced by an olive tree seems to be regulated mainly by the amount of mesocarp available for oil biosynthesis. The ratio of mesocarp/endocarp (flesh/pit) within each cultivar is strongly related to fruit size, and thus affected by high and low yields. © 2003 Elsevier B.V. All rights reserved.