# Tree Planting Density and Canopy Position Affect 'Cerasuola' and 'Koroneiki' Olive Oil Quality
###### Abstract  
To maximize orchard production and tree crop efficiency, optimization of both maximum orchard light interception and radiation distribution within the tree canopy are important strategies. To study the influence of planting density and fruit position within the canopy on oil quality from 'Cerasuola' and 'Koroneiki' olive (_Olea europaea_ L.), fruits were harvested from the upper and lower canopy layers of trees in hedgerow planting systems at two densities: High at 1000 trees ha\({}^{-1}\) (HD) and Medium at 500 trees ha\({}^{-1}\) (MD). Tree crop efficiency and fruit weight, water and fat content were measured together with olive oil standard quality parameters, phenolic and volatile composition. Fruits in the upper layers of the canopy always showed a higher maturity index, 6% more fat content, and 4% less water content than lower layers. Upper layers of HD trees showed the highest phenol content, whereas lower layers of MD trees showed the lowest phenol content (36% less than the upper layers of HD). HD trees showed the largest differences in fruit maturation, water and fat content between upper and lower canopy positions, increasing quality and oil yield variability at harvest. 'Koroneiki' showed more stable oils with a 28% higher MUFA/PUFA ratio and 12% higher phenol content than 'Cerasuola' oils. This study provides further evidence of the fact that cultivar, planting density, and canopy architecture may be strong determinants of olive oil yield and composition in hedgerow planting systems. Olea europaea; fat content; fatty acid profile; phenolic content; volatile compounds; hedgerow planting systems +
Footnote †: journal: _Horticultural_  
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Footnote †: journal: _Horticultural_  
and sweet [3]. Recently, the international cultivar 'Koroneiki' has been introduced in Sicily. 'Koroneiki' is a cultivar of high vigor with an upright growth habit that partially satisfies requirements for super-intensive planting systems. Its fruits are rather small, and the olive oil produced by 'Koroneiki' has excellent quality and fragrance, classified as a very fruity oil with green-apple notes, medium level aroma of leaves and grass, bitter and pungent. It is also asringent with a touch of almond, fig, and bark [4]. Due to its nutritional and health-promoting effects, the consumption of olive oil has been increasing worldwide, even in countries where it is not produced [5]. The nutritional and health promoting effects of olive oil have been associated with the optimal balance between saturated, mono, and polyunsaturated fatty acids as well as to minor components such as chlorophyll, polyphenols, and tocopherols [6]. Marketing of high quality olive oils is based on the chemical and sensory attributes, which are strongly affected by genotype, environment, fruit maturity at harvest, and their interaction among other factors [7; 8; 9]. Previous studies evidenced that high quality olive oil requires harvesting olive fruit at the optimum time [10; 11; 12]. The rate of oil synthesis and the length of the oil accumulation period can be responsible for the final oil content in the olive fruit [13; 14]. High production costs, especially for harvest, have played a key role in the redesigning of olive orchards during the last 30 years [15]. For an optimal yield and maximum light interception, optimum planting density should be determined [16]. In addition to tree spacing, cultivar, climate, harvest method, tree training system, fertilization, irrigation management, and soil conditions should be properly considered. It was reported that along with the reduction of row spacing (ranging from 7 to 3 m), the management of orchard light interception should be taken into consideration [16; 17; 18]. Moreover, increasing tree planting density alters interception of solar radiation and distribution of radiation within the tree canopies during the orchard development [17; 18]. This allows for managing the efficiency of solar radiation used for different processes including photosynthesis, flower bud formation, growth, and fruit quality.