Yield characteristics of N–S oriented olive hedgerow orchards, cv. Arbequina

Profiles of yield (g oil m−2) and yield components, fruit density (m−2), size as dry weight (DW) (g), and oil% DW were measured in 11 N–S oriented hedgerow orchards, cv. Arbequina, of various height and alley width combinations in Spain. Profiles of daily shortwave solar radiation incident vertically on the canopy walls (MJ m−2) calculated by a canopy illumination model were weakly exponential, revealing the importance of alley width in determining the diurnal persistence of sunlit canopy wall to depth. Strong positive linear relationships were established between radiation incident on canopy walls and fruit size and oil% over the entire canopy depth in all orchards. In contrast, fruit density was closely related to incident radiation on canopy walls only in the lower profile where incident daily solar radiation was <6 MJ m−2 during oil production in October. The consequence was a weaker relationship between yield (g oil m−2) and incident radiation on canopy walls than between the size and oil% components. Explanation is found in the impact of pruning applied to maintain hedgerow height that removes fruit in the current year. Results emphasize the importance of alley width:height relationships in determining complete illumination of canopy walls in hedgerow orchards giving guidance to questions of optimal orchard structure for maximum yield. They also demonstrate importance and need for work on canopy management to maintain yield in upper canopies of hedgerows where fruit are large and also have high oil%.