Early bearing and vegetative growth of 153 Sicilian olive accessions

In 2014, an olive germplasm collection was established in south-western Sicily, Italy. The collection included 153 Sicilian accessions and 3 international varieties (reference), each with 7 trees, spaced at 5×2 m and trained to hedgerow system. The aim of the trial was to study early growth and yield responses of the accessions to super-high planting density (SHD). Trunk cross sectional area, tree height, pruning weights, shoot positioning, blooming and fruit yield (kg tree-1) were measured in 2015 and 2016. Based on trunk growth and amount of prunings, the 153 accessions were separated into four categories of vigor as it follows: very high vigor (6 accessions), high vigor (13), medium vigor (131), and low vigor (3). In 85% of the accessions, the majority of shoots were born on the central part of the main stem, indicating prevalent mesotony. Constant early blooming (100% of trees in trial in both years) was recorded in 7 accessions (‘Nebba 1’, ‘Nocellara di Licata’, ‘Olivo di Monaci’, ‘Olivo di Monaci 1’, ‘Olivo di Mandanici’, ‘Verdella’, and ‘Calatina’), with ‘Nocellara di Licata’ and ‘Verdella’ bearing no fruit at the end. Accessions in the very high and low vigor categories produced no fruit, determining a lack of relationship between early bearing and tree vigor.