Elsevier

Scientia Horticulturae

Volume 193, 22 September 2015, Pages 240-248
Scientia Horticulturae

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

https://doi.org/10.1016/j.scienta.2015.07.013Get rights and content

Highlights

  • 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.

Abstract

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.

Introduction

The olive hedgerow system has expanded in area significantly in the last two decades in both traditional and new olive-production zones (Spain, Argentina, Australia, Spain, USA and Tunisia; e.g., Larbi et al., 2011, Rallo et al., 2013, Connor et al., 2014) and even more recently has attracted considerable scientific attention (Connor, 2006, Ferguson, 2006). Two types of hedgerows have emerged suited to available mechanized over-row, canopy-contact harvesters. The first are narrow hedgerows (as used in the experiment reported here) planted at super high density (1500–2000 trees/ha) and maintained around 2.5 m high and 1.0–1.5 m wide to suit the dimensions of modified grape harvesters. The second are large hedgerows planted at 250–500 trees/ha and maintained around 4.5 m high and to 4 m wide for which a special harvester, the “Colossus”, was developed (Connor et al., 2014). In commercial practice, olive hedgerow spacing varies over range of 4.0–4.5 m and 6.0–8.0 m for narrow and large hedgerows, respectively (Vossen, 2007, Gómez-del-Campo et al., 2010).

The intended dimensions of hedgerows must match those of the harvester and row spacing must allow the machines access, but the design should also meet the objectives of oil productivity (Connor, 2006). The evident advantage of reducing the distance between rows is to increase row length and canopy external area per unit orchard area, both of which are known to increase yield in early years after planting (León et al., 2007). This early yield advantage can, however, be lost with time as trees fill their allotted space and light limitation intensifies (Moore et al., 1993, Lavee et al., 2012). Experimental information on the effects of hedgerow spacing on olive production is limited. León et al. (2007) reported the oil production of olive hedgerows planted with tree density ranging from 780 to 2580 trees/ha, obtained by reducing alley width (from 5.7 to 3.1 m) and tree spacing (from 2.25 to 1.25 m). After 7 years from planting, cumulative oil production per ha increased linearly with density, consistent with oil production per tree. This report did not include data on hedgerow vegetative structure, so the contribution of the individual factors, spacing between trees and/or between rows, to the hedgerow productivity cannot be determined.

The ratio (D/A) of canopy depth to free alley width (i.e., row spacing minus hedgerow width) is widely used in orchard design to select row spacing because it controls contrasting effects on canopy illumination. As D/A increases so does canopy surface area per ha but at the cost of decreasing penetration of radiation within alleys to lower canopy layers (Hadari, 2004). Cain (1972) developed a light model for solid hedgerows that proposed optimal irradiance on solid hedgerows with D/A = 2, while Smart et al. (1990), Robinson (2011), and Hadari (2004) recommend a design value for D/A near to 1 for high production and fruit quality in grape, apple, and avocado, respectively. Connor and Gómez-del-Campo (2013), who simulated radiation-limited yield response of various N–S oriented rectangular olive hedgerows, also found maximum oil yield with D/A = 1, with decrease at lower values due to shorter length of productive hedgerow per unit orchard area and slight oil yield increase at values greater than 1. There are many reports in fruit crops suggesting that light limitation in lower parts of overcrowded canopies (i.e., high D/A) reduces yield (Wheaton et al., 1995, Farina et al., 2005, He et al., 2008). In olive, Pastor et al. (2007) found significant reduction of fruit number and fruit oil content in lower canopy layers of narrow olive hedgerows when D/A exceeded 1.25. In this case the positive effects of more row length per unit orchard area was reduced by yield loss in bottom layers.

In a previous paper, Trentacoste et al. (2015a) presented the results of a field experiment with four hedgerow orientations, each with the same D/A (0.7), to explore the role of light relations in the determination of oil yield. Here, we study, the effect of hedgerow spacing (varying D/A) on oil yield in hedgerows oriented either N–S or E–W. The impact of hedgerow spacing in combination with row orientation on radiation capture has been analysed previously in a range of crops using interception models (Cain, 1972, Palmer, 1989, Olesen et al., 2007). These authors estimated that (i) wider row spacing reduces annual interception of solar radiation more in E–W than N–S hedgerow orchards, and (ii) wider spacing improves radiation distribution within individual hedgerows in N–S more than in E–W orientations. Given these simulated effects of hedgerow spacing and orientation on interception of solar radiation, there is reason to propose a significant effect of row spacing on olive oil production and the need for experimentation to assist hedgerow design. The aims of the work reported here were to determine the impact of hedgerow spacing on overall oil production and the contributions from opposing sides of hedgerows in experimental hedgerows oriented N–S and E–W. To better understand the overall response, the contributions to yield from individual sides of the hedgerows were evaluated as vertical profiles of the fruit-yield components (density, size and oil content) and fruit characteristics (fruit water concentration and ripening).

Section snippets

Site and orchard

The trials were conducted in olive (cv. Arbequina) hedgerow orchards planted in 2008 near La Puebla de Montalbán (39°53′N, 4°27′W, 479 meters above sea level), Toledo, central Spain. Two experimental orchards, separated by approximately 100 m, were established with rows oriented North–South (N–S) and East–West (E–W), each planted at three row spacings (5.0, 4.0 and 2.5 m). Each row-spacing treatment comprised 3 contiguous rows of 48 trees spaced at 1.3 m. The corresponding orchard densities and

Hedgerow structure

The average tree height from planting increased similarly in both orientations across spacing treatments. In the N–S hedgerows, trees that were 0.63 ± 0.04 m tall at planting in 2008 grew markedly to 1.42 ± 0.15 m in 2009, 1.95 ± 0.06 m in 2010 and 2.35 ± 0.08 m in 2011 when trees achieved the target height (i.e., ∼2.5 m) compatible with the intended harvester. In the E–W hedgerows, trees were 0.72 ± 0.05 m tall in 2008, 1.50 ± 0.18 m in 2009, 1.80 ± 0.17 m in 2010 and 2.43 ± 0.09 m in 2011. Importantly, tree canopies

Hedgerow structure

In spring 2008, olive trees were planted at row spacings of 5.0, 4.0 and 2.5 m in N–S and E–W orientations at neighboring sites. The trees were then on average 0.65 m tall and reached the target height of 2.5 m, appropriate for the harvester, in winter of the 4th growing season. During spring of the 4th season, the trees filled their allotted space and formed continuous fruit-bearing canopies. In 2012 and 2013, all hedgerows were restricted to the same dimensions (2.5 m height × 1.0 m width) by

Acknowledgements

We gratefully acknowledge “Casa de Hualdo” for access to olive orchards where this research was conducted. The companies Todolivo, Regaber and Agromillora financed the installation of the experiments. We also thank Antonio Hueso and Valeria Albarracín for assistance in olive collection. E. Trentacoste holds a pre-doctoral fellowship from ERASMUS-Mundus.

References (28)

  • C. del Río et al.

    Whole, unmilled olives can be used to determine their oil content by nuclear magnetic resonance

    HortTechnology

    (1999)
  • V. Farina et al.

    Vertical distribution of crop load and fruit quality whitin vase- and Y-shaped canopies of ‘Elegant Lady’ peach

    Hortic. Sci.

    (2005)
  • L. Ferguson

    Trends in olive harvesting

    Grasas Aceites

    (2006)
  • M. Gómez-del-Campo et al.

    Olive growing in the arid valleys of Northwest Argentina (Provinces of Catamarca and La Rioja)

    Olivae

    (2010)
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