Expert answer:re-write the assignment only in different words
Expert answer:Rewrite the assignment in different words only, you just need to make sure the meaning is not distorted and the grammar is perfect since it is key for this assignment, thank you. Its only 4 pages
the_cocos_nucferia_1.docx
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The Cocos Nucferia
Coconut palm, (Cocos nucifera), tree of the palm family (Arecaceae). It is one of the
most important crops of the tropics. The slender, leaning, ringed trunk of the tree rises to a height
of up to 25 m (80 feet) from a swollen base and is surmounted by a graceful crown of giant,
featherlike leaves. Mature fruits, ovoid or ellipsoid in shape, 300–450 mm (12–18 inches) in
length, and 150–200 mm in diameter, have a thick, fibrous husk surrounding the familiar singleseeded nut of commerce. A hard shell encloses the insignificant embryo with its abundant
endosperm, composed of both meat and liquid.
Coconut fruits float readily and have been dispersed widely by ocean currents and by
humans throughout the tropics; they probably originated somewhere in Indo-Malaya. Marco Polo
was among the first Europeans to describe coconuts.
Coconut palms flourish best close to the sea on low-lying areas a few feet above high
water where there is circulating groundwater and an ample rainfall. Most of the world’s coconuts
are produced on small native plantations. Propagation is by unhusked ripe nuts. These are laid on
their sides close together in nursery beds and almost covered with soil. After 4 to 10 months the
seedlings are transplanted to the field, where they are spaced at distances of 8–10 m. Palms
usually start bearing after 5 to 6 years. Full bearing is obtained in 15 years. Fruits require a year
to ripen; the annual yield per tree may reach 100, but 50 is considered good. Yields continue
profitably until trees are about 50 years old.
The harvested coconut yields copra, the dried extracted kernel, or meat, from which
coconut oil, the world’s ranking vegetable oil, is expressed. The Philippines and Indonesia lead in
copra production, and throughout the South Pacific copra is one of the most important export
products. The meat may also be grated and mixed with water to make coconut milk, used in
cooking and as a substitute for cow’s milk.
Although the coconut finds its greatest commercial utilization in the industrial countries
of the Western world, its usefulness in its native areas of culture is even greater. Indonesians
claim that coconuts have as many uses as there are days in a year. Besides the edible kernels and
the drink obtained from green nuts, the husk yields coir, a fibre highly resistant to salt water and
used in the manufacture of ropes, mats, baskets, brushes, and brooms.
The palm has adventitious roots continually produced from the basal 40 cm or so of the
trunk, which is the swollen part or what is termed ‘bole’, in tall types and in some dwarf hybrids.
It has no taproot or root hairs but has lots of primary roots which bear large quantities of rootlets.
The main roots grow out somewhat horizontally from the bole and are mostly found within the
topsoil. The main branches grow deeper and may extend laterally to as much as 10 m.
The roots, having no cambium, are noticeably uniform – the main roots reaching a maximum
diameter of about 1 cm. The root tip is the actively growing region and behind it is the absorbing
area whose epidermis is a single layer of thin-walled cells that gradually thicken and become
impervious with age. In old roots, the epidermis disintegrates and exposes the hard hypodermis
which is generally red.
The root centre has a stele surrounded by a single-celled pericycle sheath from which rootlets
and aerenchymatous (respiratory exchange) protuberances or pneumatophores arise. The
respiratory exchange occurs more abundantly nearer the soil surface to allow easy diffusion of
oxygen into and carbon dioxide out of the root.
The stem develops from the single terminal bud called the ‘cabbage’ which is the palm’s
only vegetative growing point. Under favourable conditions, the foundation of the trunk of a
young palm reaches full development within 3-4 years.
In the tall types, the base of the trunk is up to 0.8 m in diameter, tapering quickly to about 0.4 m
(Child 1974). Once formed, the trunk does not change much in diameter. If variation occurs from
base to crown, this is not caused by biological factors but by climatic conditions and cultural
practices.
Stem growth is fastest at early stages, which can be as much as 1.5 m per year. The
incremental growth rate levels off as the palms grow old; up to 10-15 cm per year at about the
40th year and over.
The coconut stem has no cambium. Hence, it cannot regenerate damaged tissues.
However, a mature palm may have as much as 18 000 vascular bundles which help it to
withstand significant physical damage to its trunk, provided pest entry is prevented.
The first leaves of a coconut seedling have the pinnae fused together and appear as entire leaves.
After eight to ten have been formed, subsequent leaves tend to split into leaflets. After about 3-4
years, the stem starts to form with a single terminal growing point where new leaves develop.
Generally, a normal adult palm produces 12-16 new leaves annually, each bearing a
corresponding flower cluster (inflorescence). There are about 30-40 leaves in a healthy crown
with a similar number of leaf primordia, each differentiated about 30 months before it emerges as
a ‘sword leaf’. A mature leaf is 3-4 m long and has 200-250 leaflets. A leaf remains on the palm
for about 3 years and thereafter, shed leaving a permanent scar on the trunk.
The age of an adult palm is correlated with the number of leaf scars. The number of scars on the
stem, divided by 13, gives the approximate age of the palm in years (Mahindapala 1991). This
may be important in estimating the age of existing palms used as parent materials in breeding.
he coconut inflorescence is enclosed in a double sheath or spathe, the whole structure known as a
‘spadix’ which is borne singly in the axil of each leaf. The palm is monoecious, i.e. its
inflorescence carries both male and female flowers. The male flowers are more numerous than
the female flowers. The former are borne on the top portion of spikelets which are attached to a
main axis or peduncle. The female flowers are situated at the base of the spikelets.
The inflorescence primordium can be detected about 4 months after the first leaf
primordium is differentiated; the male and female flowers, 22 months thereafter. The opening of
the fully grown spathe occurs 1 year later.
The male flowers are the first to open, beginning at the top of each spikelet and proceeding
towards the base. After each flower opening, the pollen is shed, and male flowers abscise, the
whole process taking just 1 day. The male phase, however, takes about 20 days in most palms
but this may vary according to season and variety.
A female flower remains receptive from 1 to 3 days. Depending on the environmental
conditions and variety, the female phase may begin a few days or later after the spathe has
opened and lasts 3-5 days in tall palms and about 8-15 days in dwarfs. A normal inflorescence
may have 10-50 female flowers. With natural pollination, 50-70% usually abort and fall off,
especially those which emerge during severe dry weather. The remaining flowers develop into
fruits, which take about 12 months to mature.
The length of the male and female phases is affected by climatic environment and usually do not
overlap in the tall types, such that self-pollination rarely occurs. In some dwarfs, particularly the
Malayan Dwarf, overlapping of the male and female phases and between spadices usually takes
place, promoting selfing. Hence, these dwarfs are reasonably homozygous.
Once pollination and fertilization occur, fruits set and develop to maturity in about 12
months, or less than 1 year for some dwarf cultivars. A count of bunch and fruit set can give a
reasonable estimate of yield.
The fruit is a fibrous drupe but with a smooth outside skin (exocarp), which may vary
from green to red brown or even ivory. The coat (mesocarp) in the young coconut is white and
firm. On the other hand, the ripe nut has a fibrous mass, the husk, from which coir is obtained.
Within this fibrous mass is the nut with a hard shell (endocarp) enclosing the kernel
(endosperm). Between the shell and the kernel is a thin 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. Towards the end of maturation, the volume of water in the cavity decreases
considerably which may be due to absorption by the endosperm tissue or to evaporation.
Matured nuts have a sloshing sound of water inside when shaken. Yield is usually estimated in
terms of the number of nuts produced per palm or unit area and weight of equivalent copra.
Whereas there are usually some visible signs of insects and their damage, the coconut is also
prone to several fatal diseases, the symptoms of which remain invisible for a long time after
infection, until no countermeasures are possible.
The most worrying disease of coconut, worldwide, is known generically as lethal yellowing
disease and, in Africa, by many local names that distinguish some of its variants. Although lethal
yellowing does not usually appear in palms before their rst owering, it is listed in this chapter for
convenience. Symptoms include premature fruit drop from all bunches, followed by blackening
of the newly emerged in orescence. ere is distinct yellowing and then death of the older fronds
rst, progressing through the younger ones until there is a complete collapse of the crown period
between rst symptoms and death is 6–12 months.
Lethal yellowing was first recognized as a disease in Jamaica around the mid-20th century and
was eventually found to be caused by an pathogen characterized as a mycoplasma. More
complex than a virus but lacking the cell development of a bacterium, this type of organism is
somewhere between the two in terms of size and biological complexity. Transmission is most
likely due to leaf-hoppers, coincidentally related to those that transmit foliar decay (see below),
but there may be other vectors. The spread of the disease within
the past 50 years has been alarming. It has appeared for the first time in many countries of
Central America and the Caribbean, and even among ornamental coconut palms in southern
Florida and date palms in Texas. The crisis continues in Jamaica, despite extensive planting of
Dwarfs (found to be at least partially tolerant) and of hybrids between Dwarfs and some
promising Talls, notably Panama Tall. A disease similar to lethal yellowing has been known for
many decades in various coconut populations on the coast of West Africa, in Tanzania (East
Africa), in parts of southern India (where there is usually a slower decline of the a ected palm
than elsewhere), and more recently in some islands o the coast of Kalimantan, Indonesia. There
seems to be an important connection between the expression of lethal yellowing disease
symptoms and the stresses of extreme weather: symptoms often appear during drought, but also
after severe flooding events (for example, flooding associated with intense hurricanes).
Uncertainty exists about the strength of some coconut varieties’ observed tolerance to lethal
yellowing disease, and about the ability of the pathogen to spread
to previously disease-free areas. A concerted, long-term research e ort is needed, especially in
Jamaica, Mexico, Florida and West Africa. Molecular investigation of the variant forms of the
mycoplasma in
different parts of the world is under way, along with research into the tolerance found in some
coconut varieties. Improving the ‘security of production’ of the coconut might ultimately depend
on this work. The size and weight of a mature fruit varies from 600 g to 3 kg between different
types of palm. Fruit is usually larger on Talls than on Dwarfs, and its size often varies according
to the ‘load’ or number of fruits in the bunch. e fruits of a particular palm maintain a very
similar shape and color, varying only in size when there are more or fewer fruit in the bunch.
A large fruit, falling more than five meters, can seriously injure or kill humans or other
creatures. Mature fruits are most likely to be released when the palm is shaken by the wind, but
can also fall without warning, especially when there has been little wind for a few weeks. e
damage done to an immature fruit, small or large, by a feeding rat will usually bring it down. e
high moisture content of the husk at the immature stage makes a large fruit heavy and
particularly dangerous. The incidence of serious injury from falling fruit in coconut countries
is low because local people are well aware of the risk, and have a seemingly instinctive ability to
avoid the hazard. e iconic or cartoon- like aspect of falling coconuts attracts the attention of
the media, inducing a perception that such injuries are commonplace. There is however, more
risk at tourist resorts and in the parks of cities where ‘coconut consciousness’ is low and citizens,
especially children, are often not fully aware of the danger of a falling coconut fruit.
…
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