Effect of row spacing on vegetative structure, fruit characteristics and oil productivity of N–S and E–W oriented olive hedgerows

• Three row spacings were evaluated in N–S and E–W olive oriented hedgerows.
• In N–S hedgerows spaced at 2.5 out yield 5.0m by 52%, after four first harvests.
• In E–W, oil production was not significantly affected by reducing row spacing.
• Increasing the row spacing reduced fruit traits differences among canopy positions.

The effect of row spacing on fruit characteristics and production was studied in two super-high density olive hedgerow orchards planted at three row spacings (5.0, 4.0 and 2.5 m) with the same intra-row tree spacing, one with rows N–S and the other E–W. For both row orientations, reduction of spacing from 5.0 to 4.0 and 2.5 m added on average 39 and 107% more canopy volume and external surface area per hectare, respectively. In N–S hedgerows, cumulative oil production per ha during the first five years increased significantly by 14 and 52% in 4.0- and 2.5-m relative to 5.0-m spacing. In E–W hedgerows, accumulated oil production per ha did not respond to row spacing. The explanation was found in significantly fewer fruits per unit length of hedgerow and smaller oil content at 2.5 m than 5.0 m spacing in E–W but not in N–S. In N–S hedgerows, there were no differences in oil production and fruit characteristics between opposing sides in all row spacings. In E–W hedgerows spaced at 5.0 m, fruit characteristics were similar between opposing sides, but at 4.0 m and 2.5 m spacings, fruits on S sides were heavier and more mature than on N sides, revealing the impact of lower transmission of irradiance through the hedgerow in closer spacings. Optimal spacing for maximum production depends on row orientation. In N–S hedgerows, the most productive orchard, during the first five years was that planted at 2.5 m, but in E–W hedgerows 5.0 m spacing was the more profitable option.