Influence of Light Availability on Fruit and Oil
P. Proietti, L.Nasini, F. Famiani,
Characteristics in Olea europa L.
P. Guelfi and A. Standardi
T
Dipartemento di Scienze Agrarie e Ambien-
he influence of light availability on olive
Materials and Methods
fruit development, oil accumulation and
The trial was carried out in 2006 and 2007, in
Agenzia Regionale Umbra per lo Sviluppo e
the qualitative characteristics of the oil were
central Italy in Deruta (PG) latitude 43 deg
l’Innovazione in Agricoltura,Italy.
studied. The trial was carried out in central
North, in a non-irrigated olive grove (350 m
Italy, on non-irrigated trees of cultivars ‘Fran-
a.s.l.) growing in slightly sloping with a light
toio’ and ‘Leccino’. In October and Novem-
soil. The 20 year old trees, cultivars ‘Fran-
ber, samples of olives grown under conditions
toio' and ‘Leccino’, were spaced 5 x 5 m and
of low or high light availability (about 400 and
trained to the vase system. Ten uniform trees
1100 umol of photons m-2s-1) were collected
per cultivar with harvest of about 20 kg of
and analysed. (Added comment-Correspond-
olives per tree were selected. In correspond-
ing months in SA April and May)
ence to the four compass points, for each
tali, Universita degli Studi di Perugia,Italy
the external part of the canopy and 400 umol of
photons m-2s-1 for those in the internal (shaded) part of the canopy. Fruit ripening Pattern.
In October and November of 2006, the
olives of the cultivar 'Leccino' grown in the
well-lighted parts of the canopy had a slightly
higher pigmentation and lower pulp consistency than those grown in the shaded parts of
Fruit ripening was slightly affected by high
cultivar 100 fruiting branches (10 per tree)
availability of light (higher pigmentation and
on the external part of the canopy, well ex-
detachment force and lower pulp consistency).
posed to the light, and 100 fruiting branches
Olives grown under well lighted conditions,
(10 per tree ) in the internal shaded part of
with respect to those grown at low light inten-
the canopy were selected and labelled. In
sity, were heavier, had a higher percentage of
September, around 11:00 am on a cloudless
oil and a lower water content. The oils extract-
day, the light intensity was the sensor for tak-
ed from olives grown under high light condi-
ing the measurements and was positioned in
tions had a higher polyphenol content and
the middle part of the branches. At the end of
better sensorial characteristics than those ob-
October and November, in both years (2006
tained from olives grown at low light intensity.
and 2007) the following parameters were
The results highlight the importance of good,
measured on olive samples from both cul-
uniform illumination of the entire crown by
tivars (‘Frantoio’ and ‘Leccino’), from well-
making optimal choices at the moment of the
lighted and shaded branches Detachment
olive orchard establishment and rationalizing
force. Fresh and dry fruit weight.
a longer time. The results indicate that the pa-
1. Fruit pigmentation index.
such as pigmentation, pulp consistency and
system and spacing, pruning intensity, etc.).
2. Pulp consistency. Oil and water content
detachment force, evolve in relatively dif-
3. Ratio between the dry weight of the pulp
ferent ways depending on the conditions in
Introduction
and that of the pit in 20 fruits / treatment.
which the fruit develops (i.e., less coloured
4. Free acidity, peroxide number, total poly-
olives can have a lower detachment force than
phenol content,fatty acid composition and
more coloured ones if the latter had developed
chlorophyll content (the latter only in 2007)
under good light conditions
all techniques that affect light availability at the
crown level (planting area exposition, training
To date, the research has been done to determine the effects of shading on olive, has
shown that limited light availability reduces
floral bud induction, fruit set and growth
and oil accumulation of the fruit (Ortega
Nieto,1969; Proietti et al., 1996; Tombesi et
al., 1999). The aim of this study was to evaluate the effects of the availability of different
levels of natural light in different portions of
the canopy on olive growth and oil accumulation in the fruit and on the main chemical
and sensorial characteristics of the oil.
the canopy; In 2007, no differences for those
parameters were recorded. The olives grown
in well lighted parts of the canopy always had
a higher detachment force, even though there
were differences related to the cultivar and the
year, the high availability of light seems to intensify the olive ripening process (higher pigmentation and lower pulp consistency) and at
the same time, to lengthen the ripening period
(higher detachment force). This indicates that
olives in well lighted portions of the canopy
can reach a higher ripening level because the
ripening process is more intense and lasts for
rameters frequently used as ripening indexes,
and the oils extracted from the olives of each
treatment, using the Official Methods of
Fruit growth
Analysis for their determinations.
In both cultivars and years, the dry weight
5. Sensorial characteristics.
value of fruit grown under good light conditions was higher than that of fruit grown in
Results and discussion
Light intensity at fruit level
shaded portions of the canopy.
The maximum light availability was, on aver-
Fruit Pulp/Pit Ratio
age, about 1100 umol of photons m-2s-1 for
The pulp/pit ratio did
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not show differences
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due to the light availability. In general, the fruit
weight and pulp/pit ratio values were higher for
the cultivar 'Leccino' than 'Frantoio'.
Fruit water content
In both cultivars the water content of fruits
grown in the shaded portions of the canopy
was higher than that of olives grown in parts
that were well exposed to light.
Fruit Oil Content
In both years and cultivars, the olives grown
in the well-lighted portions of the canopy
had higher oil content, with greater differences in October.
Oil quality
tritional, health and sensorial characteris-
The free acidity and peroxide number of the
tics of the oil. The polyphenols also strongly
oils were not significantly affected by the
light availability. All of the oils extracted
from olives grown in the well-lighted portions of the canopy had higher total polyphenol and chlorophyll contents than those
extracted from olives grown in shaded parts
affect the sensorial profile of the oils; they
are responsible for the 'bitter' and 'spicy'
taste, that are considered positive qualitative attributes of the oils, provided that they
are not too intense.
of the canopy. The polyphenols have an im-
Conclusion
portant positive role in determining the nu-
The light availability slightly affected the rip-
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