Olive seedling first-flowering position and management

The prolonged length of the juvenile period represents a substantial obstacle in olive (Olea europaea) breeding programs, delaying both the possibility for analyzing the fruit, the harvest unit, and the capacity for sexual recombination. In both olive and other fruit tree species, the juvenile-adult transition has been successfully hastened by forcing and formation procedures designed to rapidly achieve a minimum height. Precise knowledge of the position within the tree canopy where the juvenile-adult transition occurs, identified by the location of the first flowers, offers further potential for manipulating tree structure in order to hasten that transition. The occurrence of the juvenile-adult transition has been described spatially within the canopy as the formation of a juvenility cone, which we report here for olive plants from seed, and for the first time quantitatively describe its position based on the added trunk and branch distances from the soil. In canopies of seedlings from open pollination of cv. Arbequina olive the first-flowering position was consistently located, in our conditions, at an average distance of 200 cm from the trunk base. Based on that evidence, that first flowering can occur at lower positions, and on the values we obtained, three canopy-formation heights (100-130 cm, 130-160 cm and >160 cm) were compared for their effect on the length of the juvenile period and the vigour of olive seedlings. Canopy heights of 100-130 cm, much lower than the 160 cm previously reported by the olive tree breeding program of Córdoba, produced the highest number of flowering plants in the first two flowering years and also provided easier management. © 2009 Elsevier B.V. All rights reserved.This study was partly funded by project P05-AGR-0649, Junta de Andalucia, Spain.Peer Reviewe