## 3 Results and Discussion
'Calatina' lost efficiency in the last year in FPx3, GVx4, and PVv5 systems (Figure 5B-D). On the contrary, 'Abunara' and 'Nocellara' increased their efficiency at the end of the trial in GVx4 and PVx5 systems (Figure 5C,D), finally reaching the levels of 'Calatina'. The latter is primarily due to the greater canopy size and yields of the two vigorous cultivars at greater in-row spacing. On the contrary, the poor performance of 'Abunara' and  
Figure 4: Trends of fruit yield per hectare across the seven years of trial for ‘Abunara’, ‘Calatina’, and ‘Nocellara del Belice’ olive trees grown as central leaders at \(2\times 5\) m (CLx2, (**A**)), free palmette at \(3\times 5\) m (FPx3, (**B**)), globe vase at \(4\times 5\) m (GVv4, (**C**)), and polyconic vase at \(5\times 5\) m (PVx5, (**D**)). Error bars represent standard errors of the means. Mean separation by [PERSON]’s honestly significant difference (HSD, \(p<0.05\)). 'Nocellara' under the reduced in-row distances of CLx2 and FPx3 systems may be due to canopies saturating the full allotted space and intercepting less light due to some reciprocal shading. In the PVx5 system, 'Calatina' trees were the most efficient in the first two years and at the end (Figure 5D), and this is primarily due to marked changes in yield per tree. These results confirm previous findings of high yield efficiency and low vigor of 'Calatina' trees grown under the same conditions [38]. In a high-density trial, [PERSON] et al. [31] also obtained high yield efficiency with low-vigor, compact 'Arbequina' trees. For all three cultivars, fruit yield per hectare was higher in CLx2 and FPx3 systems than in the other two. 'Calatina' had the highest cumulated fruit yield in CLx2, FPx3, and GVx4 systems, and the highest cumulated yield across cultivars and planting systems was obtained with 'Calatina' under CLx2 (Figure 6). In addition, 'Abunara' had its highest cumulated fruit yield per hectare in CLx2 but the absolute lowest across cultivars and  
Figure 5: Trends of yield efficiency across the seven years of trial for ‘Abunara’, ‘Calatina’, and ‘Nocellara del Belice’ olive trees grown as central leaders at 2 \(\times\) 5 m (CLx2, (**A**)), free palmette at 3 \(\times\) 5 m (FPx3, (**B**)), globe vase at 4 \(\times\) 5 m (GVx4, (**C**)), and polyconic vase at 5 \(\times\) 5 m (PVx5, (**D**)). Error bars represent standard errors of the means. Mean separation by Tukey’s honestly significant difference (HSD, \(p<\) 0.05). planting systems in GVx4. 'Nocellara del Belice' exhibited similar cumulated yields in all planting systems, with a tendency to perform better under the PVx5 system. In agreement with [PERSON] et al. [36], in CLx2, 'Abunara' and 'Calatina' had both higher oil yield than 'Nocellara' (Figure 7A). In FPx3 and PVx5, all the three cultivars had similar oil yield (Figure 7B,D), while in GVx4, 'Nocellara' had a higher oil yield than 'Abunara', with 'Calatina' showing an intermediate level (Figure 7C). Overall, in terms of oil yield, 'Abunara' and 'Calatina' performed best under higher densities with compact trees (in CLx2), while 'Nocellara' performed best with open center trees (\(5\times 4\) and \(5\times 5\) m) under wider spacings. This further confirms that high densities and compact forms penalize growth and productive performance of 'Nocellara' trees, which have the tendency to grow open with wide croch angles. To give a reference with a global cultivar such as Arbequina, the levels of oil production exhibited by 'Calatina' in all the four pedestrian systems  
Figure 6: Cumulated fruit yield per hectare across the seven years of trial for ‘Abunara’, ‘Calatina’, and ‘Nocellara del Belice’ olive trees grown as central leaders at \(2\times 5\) m (CLx2, (**A**)), free palmette at \(3\times 5\) m (FPx3, (**B**)), globe vase at \(4\times 5\) m (GVx4, (**C**)), and polyconic vase at \(5\times 5\) m (PVx5, (**D**)). Error bars represent standard errors of the means. Mean separation by Tukey’s honestly significant difference (HSD, \(p<0.05\)).