OIL
PALM (Elaeis guineensis)
The
oil palm tree is a tropical plant which commonly grows
in warm climates at altitudes of less than 1,600 feet
above sea level. The species, Elaeis oleifera (H.B.K)
Cortes is native of America; and the species Elaeis guineensis
Jacq. which originated in the Gulf of Guinea in West Africa
(hence its scientific name) is better known as the African
oil palm.
This tree produces one of the most popular edible oils
in the world - a versatile oil of superb nutritional value.
It is the most prolific of all oil plants and in commercial
terms the one which offers major prospects of development.
Primary roots grow downwards from the base of the palm
and radiate outwards in a more or less horizontal direction
close to the surface of the ground. Their length and depth
depend on the type of soil.
Its stem stands straight in the form of an inverted cone.
In the wild it may grow to heights of one hundred feet
and more. The stems of young and adult plants are wrapped
in leaves which give them a rather rough appearance. The
older trees have smooth stems apart from the scars left
by the leaves which have withered and fallen off.30-40
leaves are seen on the crown of the palm.
Each leaf has short thorns at its base and about 250 leaflets
in an irregular pattern on both sides of the petiole.
Oil palm has both male and female flowers on the same
tree. It produces thousands of fruits, in compact bunches
whose weight varies between 10 and 40 kilograms. Each
fruit is almost spherical, ovoid or elongated in shape.
Generally the fruit is dark purple, almost black before
it ripens and orange red when ripe. The fruit has a single
seed - the palm kernel - protected by a wooden endocarp
or shell, surrounded by a fleshy mesocarp or pulp. This
fruit produces two types of oil: one extracted from the
pulp (palm oil) and the other from the kernel (palm kernel
oil).
Oil palm grows best in areas with a mean maximum temperature
of 30-32 ºC and on an average of at least five hours
of sunlight. It can be grown in areas, which receive well-distributed
annual rainfall of 200 cm or more. However, it can tolerate
two to four months of dry spell. The oil palm grows on
wide range of tropical soils. The adult palms can withstand
occasional waterlogging, but frequently waterlogged, extremely
sandy and hard lateritic soils should be avoided.
Nursery practices
The
fruits are separated from the bunch and seeds are extracted
by scraping off the exocarp and mesocarp with a knife,
or by retting in water. The seeds are then dried by
spreading them on concrete or wooden floors under shade
for two days. Such seeds can be stored for 3-9 months
at about 27 ºC without much reduction in viability.
Seeds are soaked in water for five days, changing the
water daily. Thereafter, the seeds are spread out to
dry for 24 hours. The dried seeds are put in polythene
bags and placed in germinator maintained at a temperature
of 40 ºC. After 80 days, the seeds are removed
from polythene bags, soaked in water for 5 days changing
the water daily and dried in the shade for two hours.
The seeds are then put back into bags and kept in a
cool place in order to maintain the moisture content.
Germination commences in about 10-12 days. The percentage
of germination obtainable by this method is 90-95.
Raising
nursery
Polybags
(preferably black) of 400-500 gauge measuring 40 x 35
cm are used. The bags are filled with topsoil and compost
and are arranged at a spacing of 45 x 45 cm and one
sprouted seed is dibbled per bag. A good mulching during
summer is desirable. Watering the seedlings weekly thrice
is recommended. A fertilizer mixture containing 15 g
N, 15 g P2O5 and 6 g K2O at the rate of 8 g in five
litres of water for 100 seedlings may be applied when
the seedlings are two month and eight month old.
The
only variety recommended for commercial cultivation is
Tenera, which is a hybrid between Dura and Pisifera.
Planting
Oil
palm is planted in the main field in triangular system
at spacing of 9 m accommodating 140 palms per ha. Planting
is preferably done at the onset of monsoon during May-June.
The polythene bag is torn open and the entire ball of
earth is buried in the pit (50 x 50 x 50 cm) and levelled.
Leaf pruning
Dead
and diseased leaves and all inflorescences should be
cut off regularly up to three years after planting.
When the palms are yielding, judicious pruning to retain
about 40 leaves on the crown is advocated. It is necessary
to remove some of the leaves while harvesting. In such
cases, care should be taken to avoid over pruning. In
addition, all dead and excess leaves should be cut off
and crown cleaned at least once in a year, usually during
the dry season.
Pollination
Oil
palm is a cross-pollinated crop. Assisted pollination
is done to ensure fertilization of all female flowers.
However, this is not necessary if the pollination weevil
Elaedobius kamerunicus is introduced in the plantation.
They congregate and multiply on male inflorescence during
flower opening. The weevils also visit the female flowers
and pollinate them effectively.
Manuring
The
following fertilizer schedule is considered satisfactory
for oil palm.
N:P2O5:K2O |
g/palm/year |
First
year |
400:200:400
|
Second
year |
800:400:800
|
Third
year onwards |
1200:600:1200 |
Mg application is necessary only if deficiency symptoms
are noticed. Fertilizers are preferably applied in two
equal split doses (May and September), within 2 m diameter
around the palm and forked in. Supply of sufficient
quantities of green leaf or compost is advantageous,
especially where the soil is poor in organic matter.
The
field has to be regularly maintained to allow access
for harvesting and palm inspection. The weeded circle
should be sufficiently kept clear of vegetation for
loose fruit collection. It is also extremely important
to reduce direct weed competition in young palms. This
can be controlled manually or chemically using herbicide.
Pests
Rhinoceros
beetle
The
pest causes severe damage to emerging fronds and spindle.
The adult beetle feeds on the softer tissue of the rachis,
resulting in snapping off of the fronds and spears at
the feeding sites. Field sanitation and elimination
of breeding sites are essential components of the pest
management operation. This pest can be suppressed by
using the virus Baculovirus oryctes.
Red
palm weevil
This
is a major pest of oil palm in India. These weevils
lay their eggs at the cut end of petioles or other wounds.
The emerging larvae tunnel into the crown and feed on
the growing tissues. Palms infested by red palm weevil
start wilting and leaves show gradually increasing chlorosis
and fracture in strong winds. If detected early, treatment
of affected palm with 0.2% solution of
1% carbaryl would save the palms.
Birds
Many
birds such as the forest crow, the house crow and the
common Indian myna cause severe damage to oil palm fruit
bunches. These birds feed on the mesocarp of the oil
palm fruits. The damage can be minimized by scaring
the birds and covering the ripe bunch with wire net,
150 days after fruit set.
Diseases
Anthracnose
This
disease occurs in the nursery. It is recognized by regular
or irregular brown to black leaf blotches surrounded
by yellow haloes, which develop along the margin, centre
or tip of the leaves. It causes heavy seedling loss.
The disease can be controlled by spraying mancozeb or
captan at the rate of 200 g/100 litres of water. Copper
fungicides should not be used because of the extreme
susceptibility of oil palm seedlings to copper burn
(scorching).
Spear
rot
This
is noticed to affect oil palms of all ages. The incidence
is less than one per cent. Yellowing starts from tip
of the innermost whorl of leaves. Small lesions occur
at the distal portions of spear and rotting extends
downwards. As the disease advances, new leaves become
rudimentary and show rotting. General decline in vigour
and production is then noticed. Occurrence of spear
rot without yellowing has also been noticed. Distinguishable
marginal yellowing of leaflets and sudden drying of
leaves showing yellowing are other symptoms. Rouging
of all the affected palms may be adopted to prevent
further spread of the disease. In early stages of the
disease, the affected portions of leaves may be removed
and burnt.
Bunch
failure
Sparse
or no fruit set followed by complete drying or rotting
of the affected bunches are the typical symptoms. The
extent of incidence can be up to 20%. This malady is
generally attributed to excess pruning, mutual shading,
underpollination, moisture stress and unhygienic conditions.
The situation can be improved by assisted pollination
as well as by adopting hygienic measures like removal
of infected bunches and dry male inflorescence.
First
harvest can be taken 3.5 to 4 years after planting.
When a few ripe fruits are loose / fall off, the bunch
is ready for harvesting. Processing over-ripe fruits
reduces quantity and quality of oil.
A chisel is used for harvesting bunches from young palms.
The stalk of the bunch is struck hard with the chisel
to cut off and push the bunch out. When the palms become
taller (from 10 year onwards) a harvesting hook has
to be used. When the palms are too tall, it is necessary
to climb the palms for harvesting.
For
mature plantations not exceeding 40 ha, a hand-operated
hydraulic press will be enough for extraction of oil.
In the case of large-scale plantations, the hydraulic
press will not be economical and as such, mechanically
driven oil mills have to be established. The fruit bunches
brought to the factory are first quartered by means
of a chisel. They are then sterilized in steam or boiling
water for 30-60 minutes. The objective of this process
is to inactivate the fat splitting enzymes, which are
present in the fruit, which may raise the free fatty
acid content of the oil and also to soften the fruits
for easy pounding. The sterilized fruits are stripped
off from the bunch and then pounded. The pounded fruit
mass is then reheated and squeezed using a hydraulic
press. It is then boiled in a clarification drum where
the sludge will deposit and pure oil float over the
water. The oil is then drained out.
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