Download Biological characteristics

Click on markers
Click off markers
BIOLOGICAL CHARACTERISTICS
28
GENERAL SETTINGS
The olive tree belongs to the oleaceae. It's got a short, thick and twisted, sometimes
tortuous trunk and a wide top with many branches which is 4 or 5 metres high in our
country (*).
Their leaves are opposed, persistent and coriaceous; they are in one piece with an
eliptical shape, very narrow and sharp. The are also green and gloss on the surface
although their tonality changes depending on the variety, and they are whitish on the back
because of the presence of starry hairs.
The flowers are very white and small, appearing in underarm bunches.
Its fruit, the olive, is an ovoid “drupa” from 2 to 4 centimetres long, depending on
the varieties. Its colour is yellow green becoming purple when mature.It tastes bitterly.
SYSTEMATICS
The oleaceae family includes trees and bushes with pinned or entire leaves,
normally opposed and without stipulae. The flowers have got a bell-shaped, tubular calyx
with four or five lobes and corollas with similar characteristics although, in rare occasions,
they can have free petals.
The “androceo” is made by two stamens and the “gineceo” shows supero and
bilocular ovary. They may have a dry and freshy fruit.
(*) Their hight and general aspect vary depending on their pruning. If there is no pruning, they could become
bushes. When they are trees they have a pyramid shape and about 12 to 15 metres high.
29
Apart from the olive tree, there are other species that belong to the same family
such as ash trees, lilac, “agracejos”, “aligustres” and jasmine.
The type of Olea can be found all over the world since they can be found in all
continents. Among them, one of the most important of them is the Olea Europaea which
corresponds to the olive tree.
30
Distribution map of the type of Olea
This type includes 30 species among which we can find the olive tree “Olea
europaea”, with numerous subespecies, series and varieties.
Summary of the main subdivisions from the species Olea europaea. (Cifferi y
Breviglieri 1942).
31
Among all of them we'll mention the followings:
* Olea europaea euromediterranea var. oleaster,
O.oleaster u O.sylvestris Mill (acebuche)
* Olea europaea euromediterranea var. Sativa
u O.sativa (cultivated olive)
According to some authors, the “acebuche” might come from the wild growing of
cultivated olives; in that case, they could be considered within the O. sativa group.
Almost all researchers agree that the domestic olive growing started in certain
zones in Syria, Iran and minor Asia and spreading towards the west along the two
mediterranean shores.
We' ll finish this section with a list of the main varieties of olive growing as well as
their characteristics and application. (Information given by C.O.I.- International oleic
conseil.
32
Varieties found in Spain
33
Varieties found in Spain (cont.)
34
Most common varieties: main characteristics.
Footnote: The most frequent applications are shown.
35
MORPHOLOGY
The trunk and the brunches
In the olive tree we can normally distinguish the main trunk and the primary,
secondary and fruit-bearing ramifications or branches
THE MAIN TRUNK
The olive trunk is easily recognizable because of its dark and cracked bark often
showing thick cords and cavities that sometimes get to the centre of the tree.
This may happen in mature-aged specimen but in young trees, the trunk is much
smoother, lighter-coloured and regular shape.
The general aspect of the tree depends on the way it is pruned; therefore, it
changes depending on the zone as well as their variety.
The most characteristic types of olive trees: a) candelabra shaped, b) three feet shape
36
PRIMARY RAMIFICATIONS
Starting from the trunk there are thick branches that constitute the general shape of
the tree. The number of branches vary depending on their prune and they are very
important to regulate the production and the simplicity for the harvest.
When the tree gets older, these branches are pruned, or even cut, so that the
growing of the young branches keep the vitality of the fruit-bearing ramifications and,
therefore, the production of the olive tree.
SECONDARY RAMIFICATIONS
From the primary ramifications there come other branches that, by new divisions,
make the top of the tree and where fruit-bearing branches are hold.
FRUIT-BEARING RAMIFICATIONS
The flowers and, therefore, the fruit, don´t grow on any branch of the olive tree; they
appear in the shoots put out the previous year. These shoots use to be 50 cm long and the
harvest depends on their number and position. If the number is too low, the harvest will be
poor but if the number is high, there will be a great deal of small fruit and, therefore, less
valuable.
The leaves
The olive tree leaves are complete and
lance-shaped. They are laid on the branches
through a petiole short. Like all the Oleaceae,
they are opposing. Although their general shape
is lance-shaped, their proportion may vary from
oval to almost lineal depending on the variety.
37
It’s colour may also change. There are some varieties with light green leaves and
others with darker tones. At the back side, the colour vary among silver grey and other
more brown because of the presence of starred hair in this position.
They are persistent leaves with an average duration of 2 or 3 years. Their size vary
between 3 and 8 cm long, and 1 to 2.5 cm wide, depending on the variety. They are
normally very hard and have a very marked central nerve.
In a cross section we can find the elements which are common to all leaves,
showing a thick cuticle on the upper epiderm and the starred hair at the back. Its fenceshaped parenchyma is made by two or three cell layers and are frequently the fibres in the
lagunar parenchyma.
In the section of “applications in class” we will describe the process of preparation of
the leaves for their observation as well as the suitable diagram.
The roots
The olive tree normally shows fasciclated roots. Nevertheless, if we observe the
germination of a seed, we can see that there is only one pivotant root from which we can
observe secondary small roots. The reason for this is the way of planting them. That way,
the roots grow in a fasciclating way from an “estacón” (stick) and when the tree seedling
come from seeds, the pivotant roots blunt to let the secondary roots appear.
The definite aspect of the radicular system depend on the physical characteristics of
the ground and the depth of the freatic layer. Furthermore, we can also find variety
differences that justify the graftings on the feet which develope better roots.
38
The flowers
The flowers of the olive tree are
small and white. They could be unseen
if they were not
gathered in axilar
inflorescencies (picture 2.3). These are
long-shaped compound bunches
in
which there are dozens of flowers. The
flower is “tetrámera”, although it is not
very difficult to find “pentámera” flowers
with welded petals and two stamen, with
a very short filament and an ovary with
two carpels (picture 2.4)
The fruit itself
The olive is a “drupa”, whose mesocarpo represents about 2/3 of the fruit. This is
very rich in lipids.
Its shape is not constant since there
are some varieties such as the “manzanilla”,
with a small and almost rounded fruit, la
“cornicabra” with a longer, slightly bended
fruit, etc.
Its size may fluctuate between a bit
more than a centimetre (“arbequina”) and
more than three centimetres (“gordal”).
The endocarpio is woody and its morphology depends on its variety.
The epicarpio is welded to the mesocarpio, its colour is green but it changes to
purple when mature,gloss (because of the presence of wax) and very soft (picture 2.5)
39
DEVELOPMENT AND GROWING UP
We all know the olive tree longevity since we can often find millennial trees.
Nevertheless, from the agricultural point of view, we must concentrate in the period from its
birth to the notorious diminishing of its productivity. Therefore, depending on its
productivity we can divide the life of the olive tree into three stages:
•
Youthful stage, from 1 to 7 years old ( with no production)
•
Production stage, from 7 to 150 years old.
•
Senile stage, from 150 years old onwards (little production)
Youthful stage
When the seed germinates, or when the seedlings start to take root, the plant starts
to develop its roots and brunches.
Like in all trees, the formation of new tissues implies the use of bio-elements that
will be part of the new plant. The carbon is incorporated to the leaves as CO2; the nitrogen
travels through the roots as nitrates mainly. That´s why the quotient C/N (proportion
between the quantity of carbon in the elaborated sap glucids and the nitrogen in the brute
sap) is useful to evaluate the relative importance of the aerial system with respect to the
radicle system.
There is a close relationship between all this and the development of the plant and
this allows us to know the plant growing point.
During the initial stage there is an important development in the branches and
mainly in the roots and that's why the relationship C/N keeps low.
Apart from its size, there are other characteristics that allow us to distinguish a
young plant such as the intense ramification, leaves which are wider than those in an
40
adult plant, and other less evident characteristics.
Within this stage,some authors can see a youth stage (until the first blooming) and a
final stage in which there are already flowers and even fruit although it isn't real
production.
Production stage
This second stage starts with a transition periodthat goes until its full production
period. During this transition there is a progressive growing of C/N approaching to the
equilibrium.
When the tree has reached that equilibrium, about 35 years old, it is the most
productive period, which can get to 150 years if the farming conditions are adequate. The
pruning, fertilization and parasite elimination are particularly important as we can see in
the corresponding chapter.
Senile stage
From 150 years old onwards the production starts to diminish and at this point the
substitution or renewal of the tree is advisable; nevertheless, this period is not always
constant depending mainly in the attention they have received in the previous stages.
Among the main characteristics at this stage are the diminishing of the production,
the increase of the “vecería” (alternation between good and bad harvest) and progressive
degeneration of the wood.
Annual cicle
Like almost all trees, the olive tree starts its cicle in spring, by developing its leaf
bud, apicals and axilars. The axilar leaf buds can originate new ramifications o bunches,
called “esquimo” in many places.
41
When the temperature rises, approximately in May, the flowers bloom and
pollination starts. The starting of that blooming may vary depending on the annual weather
peculiarities.
During the summer there is a growing of the fruit and a hardening of the stone,
reaching its ripening point at the end of summer or in autumn.
The harvest takes place between September and October, for the grazing olive
(greenish), and between November and January for the mill olive. After this, the tree starts
a rest phase until the following spring.
During this rest period, the cold action is necessary for the flowering. That's why, in
countries in which there are constant warm temperatures, the olive tree can develop
properly but the is no flowering.
Later on we will see a simplified diagram of the annual cycle. We will also see in
pictures 2.6 to 2.9 some details corresponding to different stages of the olive tree.
42
REQUESTS
Although the olive tree is a tough, resistant tree that can be grown in almost any
kind of ground even in adverse water conditions, its profitability in these conditions is
affected negatively.
To be profitable, the olive tree needs at least one metre thick ground and it doesn't
tolerate grounds with a high level of CINa. As for pH, develops better with a slightly
alkaline ground. They resist the limy ground perfectly.
All this makes that its geographical distribution is rarely under 30ºN; therefore they
are rarely found in the southern hemysphere.
The olive tree looks for the light, so they grow better in the southern orientated
sides. In elevated zones, they can grow at 800 metres high, in the south sides, and at 600
metres high, in the north sides. Nevertheless, they can grow at higher altitudes in tropical
zones.
In the olive groves next to the Sahara desert, we can find that they can resist
extreme dry conditions thanks to their six metres long roots. If water is not very deep, the
radicle systems are poor and therefore, the stability and dry season resistance.
To end up with all these requests we must say that the environmental humidity,
mainly fog, damages the tree making fungus and parasites appear.
In the chapter corresponding to the the growing techniques we will develop the concrete
necessities and the adequate fertilizing.
43
PICTURES
44
45
Go back to the main page
46