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BOTANY OF THE COCONUT PALM

Chapter 1: BOTANY OF THE COCONUT PALM

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Coconut (Cocos nucifera L.) is the only species of the
genus Cocos belonging to the subfamily Cocoideae which incorporates 27 genera
and 600 species. It’s a diploid with 32 chromosomes (2n=32). As such,
hybridization is especially intraspecific.

The most important classification of coconut primarily based on stature or peak
is as follows:

(1) Tall palms, generally known as
var. typica (Nar). They’re broadly planted each for family and
industrial use and develop to a peak of 20-30 m. They’re sluggish maturing and
flower 6-10 years after planting. They’re long-lived with an financial lifetime of
about 60-70 years, though a lot older palms are identified to exist and yield effectively.
They’re usually cross-pollinating and subsequently thought of to be
heterozygous.

(2) Dwarf palms, generally known as var. nana
(Griff). These are believed to be mutants from tall varieties with brief
stature, 8-10 m when 20 years outdated. They start bearing in regards to the third yr at
lower than 1 meter excessive. They’ve a brief productive lifetime of 30-40 years. They
are usually self-pollinating and subsequently thought of to be
homozygous.

The Roots

The palm has adventitious roots regularly produced from the
basal 40 cm or so of the trunk, which is the swollen half or what’s termed
‘bole’, in tall varieties and in some dwarf hybrids. It has no taproot or root hairs
however has numerous major roots which bear massive portions of rootlets.

The primary roots develop out considerably horizontally from the bole
and are principally discovered throughout the topsoil. The primary branches develop deeper and will
prolong laterally to as a lot as 10 m.

The roots, having no cambium, are noticeably uniform – the
important roots reaching a most diameter of about 1 cm. The basis tip is the
actively rising area and behind it’s the absorbing space whose dermis is a
single layer of thin-walled cells that progressively thicken and change into impervious
with age. In outdated roots, the dermis disintegrates and exposes the arduous
hypodermis which is mostly purple.

The basis centre has a stele surrounded by a single-celled
pericycle sheath from which rootlets and aerenchymatous (respiratory change)
protuberances or pneumatophores come up. The respiratory change happens extra
abundantly nearer the soil floor to permit straightforward diffusion of oxygen into and
carbon dioxide out of the foundation.

The Stem

The stem develops from the only terminal bud referred to as the
‘cabbage’ which is the palm’s solely vegetative rising level. Below beneficial
situations, the muse of the trunk of a younger palm reaches full improvement
inside 3-Four years.

Within the tall varieties, the bottom of the trunk is as much as 0.Eight m in
diameter, tapering shortly to about 0.Four m (Little one 1974). As soon as shaped, the trunk
doesn’t change a lot in diameter. If variation happens from base to crown, this
shouldn’t be brought on by organic components however by weather conditions and cultural
practices.

Stem development is quickest at early levels, which could be as a lot
as 1.5 m per yr. The incremental development fee ranges off because the palms develop outdated;
as much as 10-15 cm per yr at in regards to the 40th yr and over.

The coconut stem has no cambium. Therefore, it can’t regenerate
broken tissues. Nonetheless, a mature palm might have as a lot as 18 000 vascular
bundles which assist it to face up to vital bodily injury to its trunk,
offered pest entry is prevented.

The Leaf

The primary leaves of a coconut seedling have the pinnae fused
collectively and seem as complete leaves. After eight to 10 have been shaped,
subsequent leaves have a tendency to separate into leaflets. After about 3-Four years, the stem
begins to type with a single terminal rising level the place new leaves develop.
Typically, a standard grownup palm produces 12-16 new leaves yearly, every bearing
a corresponding flower cluster (inflorescence). There are about 30-40 leaves in
a wholesome crown with an identical variety of leaf primordia, every differentiated
about 30 months earlier than it emerges as a ‘sword leaf’. A mature leaf is 3-Four m lengthy
and has 200-250 leaflets. A leaf stays on the palm for about Three years and
thereafter, shed leaving a everlasting scar on the trunk.

The age of an grownup palm is correlated with the variety of leaf
scars. The variety of scars on the stem, divided by 13, provides the approximate age
of the palm in years (Mahindapala 1991). This can be necessary in estimating the
age of current palms used as father or mother supplies in breeding.

The Inflorescence

The coconut inflorescence is enclosed in a double sheath or
spathe, the entire construction often called a ‘spadix’ which is borne singly within the
axil of every leaf. The palm is monoecious, i.e. its inflorescence carries each
female and male flowers. The male flowers are extra quite a few than the feminine
flowers. The previous are borne on the highest portion of spikelets that are hooked up
to a important axis or peduncle. The feminine flowers are located on the base of the
spikelets.

The inflorescence primordium could be detected about Four months
after the primary leaf primordium is differentiated; the female and male flowers,
22 months thereafter. The opening of the absolutely grown spathe happens 1 yr
later.

The male flowers are the primary to open, starting on the high
of every spikelet and continuing in direction of the bottom. After every flower opening, the
pollen is shed, and male flowers abscise, the entire course of taking simply 1 day.
The male part, nonetheless, takes about 20 days in most palms however this may increasingly differ
in response to season and selection.

A feminine flower stays receptive from 1 to three days. Relying
on the environmental situations and selection, the feminine part might start a couple of
days or later after the spathe has opened and lasts 3-5 days in tall palms and
about 8-15 days in dwarfs. A standard inflorescence might have 10-50 feminine flowers.
With pure pollination, 50-70% normally abort and fall off, particularly these
which emerge throughout extreme dry climate. The remaining flowers turn into
fruits, which take about 12 months to mature.

The size of the female and male phases is affected by
climatic setting and normally don’t overlap within the tall varieties, such that
self-pollination hardly ever happens. In some dwarfs, significantly the Malayan Dwarf,
overlapping of the female and male phases and between spadices normally takes
place, selling selfing. Therefore, these dwarfs are fairly
homozygous.

The Fruit

As soon as pollination and fertilization happen, fruits set and
develop to maturity in about 12 months, or lower than 1 yr for some dwarf
cultivars. A rely of bunch and fruit set may give an inexpensive estimate of
yield.

The fruit is a fibrous drupe however with a clean exterior pores and skin
(exocarp), which can differ from inexperienced to purple brown and even ivory. The coat
(mesocarp) within the younger coconut is white and agency. Alternatively, the ripe
nut has a fibrous mass, the husk, from which coir is obtained. Inside this
fibrous mass is the nut with a tough shell (endocarp) enclosing the kernel
(endosperm). Between the shell and the kernel is a skinny brown seed coat (testa).
It adheres firmly to the kernel which is the white flesh, about 12 mm thick
lining the central cavity containing the nut water. In direction of the top of
maturation, the amount of water within the cavity decreases significantly which can
be as a consequence of absorption by the endosperm tissue or to evaporation. Matured nuts
have a sloshing sound of water inside when shaken. Yield is normally estimated in
phrases of the variety of nuts produced per palm or unit space and weight of
equal copra.


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