The coconut odyssey - the bounteous possibilities of the ... - ACIAR

and of trunk, there is sufficient
energy to generate a long vertical gap,
or ‘internode’, between fronds on the
trunk (100 mm or so). Because each
frond then has a substantial portion
of trunk to itself, the lower stem
(petiole) of the frond maintains a
position closely hugging the trunk,
free of any contact with fronds higher
up. �ere is a gentle curving out or
drooping of the top ends of these
fronds, under the influence of gravity.
�e overall shape of the crown is that
of an inverted cone, which achieves
high and efficient light interception,
and therefore rapid growth.
Fruiting begins: a
competition for resources
Once fruiting begins, the energy
need of fruit growth is met at the
expense of the trunk, resulting over a
few years in a significant shortening
of the internodes. As the internode
space decreases, the base of each frond
is subjected to increasing outward
pressure from the thick basal part of
the two fronds immediately above
it, tending to force it away from the
trunk and weakening its attachment
or ‘grip’ on the trunk. �e base of each
frond also experiences the increasing
weight of its bunch of fruit, which also
tends to pull it away from the trunk.
�e result is that the attitude, or
angle of display (in a vertical plane),
of each frond evolves gradually
from vertical upon first emergence
through 45 degrees around
10 months of age, 100 degrees
(horizontal) at 18 months and
135 degrees (pointing somewhat
downwards) when the frond is two
years of age or older. �e combined
effect of 20 or more fronds, each
angled a little further from the
vertical than its next, younger
neighbour, is a spherical shape in the
palm crown—a shape that is typical
of Tall palms older than 20–30
years (and Dwarf palms older than
10 years), and which constitutes the
classical ‘loose, languid and relaxed’
image of the coconut palm.
A palm crown with this spherical
display of fronds intercepts less light
than it did with a similar number of
fronds in a more hemispherical or
inverted conical shape. Downward
hanging fronds receive little light,
while only a few fronds are held
in the horizontal position to
intercept the maximum available.
�e productivity of the ageing palm
gradually diminishes, because of the
reduction in photosynthesis that
goes with reduced light interception.
�ere is often some compensation
apparent, however: fruit yield can
50
be sustained by allocating fewer
resources to the growth of the trunk.
In turn, this increases the crowding
of the fronds on the trunk and the
length of the fronds themselves also
begins to diminish, contributing to a
further decline in light interception.
Palms can live to 100 years and
more, but at that age the crown is
very small, the trunk has tapered to
a ‘pencil point’, and nut production is
close to nil.
Figure 3-8. Crowded frond bases of a
mature palm, which has developed
a spherical crown shape. �e internode
space on the trunk here is only
5 to 10 mm compared with 50 mm
in Figure 3-7 above. (Simon Foale)