Optimizing Early Flowering and Pre-selection for Short Juvenile Period in Olive Seedlings

In recent years, the juvenile period of olive seedlings has been reduced by diverse forcing and pruning-formation techniques, but it is still a major drawback for breeding. Plant height at the time when seedlings are transplanted to the field has been found effective for obtaining earlier flowering, but the value of this parameter varies widely among olive breeding programs. We evaluated different transplant dates, taking into account mean plant height and age, with the aim of determining the optimum parameters for achieving early flowering and easy plant management and, at the same time, for the early elimination of genotypes with a long juvenile period. A mean seedling height of approximate to 100 cm at the time of planting in the field provided the best results in terms of shortening the juvenile period and facilitating handling of the seedlings. For all dates tested, seedling height at transplanting was effective as a pre-selection criterion for the early elimination of genotypes with long juvenile periods, with slight improvement in effectiveness with advancing transplant date.