Coconut Research Institute Repository

Peiris, T.U.S.

Peiris, T.S.G.

Arrival dates of Southern monsoon rains

Samarajeewa, S.

A production function approach in coconut cultivation

Siriwardena, P.H.A.P.

Development of a new technique to estimate the population of coconut mite Aceria guerreronis (Keifer) (Aceri: Eriophyidae) in a single nut

Dasanayake, P.N.

Everard, J.M.D.T.

Genetic relatedness of coconut germplasm in Sri Lanka as revealedby Random Amplified Polymorphic DNA (RADP)

Waidyanatha, U.P.de.S.

Pol welenda pola jayaganna aluth krama soyagannata barida?

Fernando, M.T.N.

Dassanayake, K.B.

Joseph, P.G.

Economic feasibility of growing gliricidia under coconuts as an energy source for dendro-thermal power plants

Import duty reduction for substitute oils and its implications on Coconut oil industry in Sri Lanka

Some economic consideration of coconut production and processing

Ranasinghe, C.S.

Mathes, D.T.

Silva, L.R.S.

Kularatne, J.D.J.S.

cocos (2000-2002), 14 1-5
Prillted ill Sri Lanka
A NON-DES.TRUCTIVE METHOD FOR DETERMINING THE AREA OF
UNSPLIT LEAVES OF COCONUT SEEDLINGS
C S RANASINGHE, D T MATHES, L R S SILVA AND J D J S KULARATNE
Coconut Research Institute, Lunuwila, Sri Lanka
ABSTRACT
A rapid, non-destructive and accurate method for determining the leaf area
of unsplit leaves of coconut seedlings (var. CRIC 60 and CRIC 65) is
proposed using two regression models y =25.85 + 0.99 x (for CRIC 60) and
y = 38.36 + 1.04 x (for CRIC 65) with reliabilities of 99.3% and 96.9 %,
respectively, where y is the area of the leaf and x = (c + d) {(e + ...j (f 2 + 9 2 /
4)) /2}, c, d, and g are the breadths while e and f are lengths at different
positions of the leaf.
INTRODUCTION
Leaf is the major plant organ responsible for photosynthesis, transpiration
and consequently, the total plant productivity (Linder, 1985). Therefore, it is
of utmost importance to study the leaf area development of a plant. The
vigor of a coconut (Cocos nucifera L.) seedling is also to some extent
indicated by the length and width of a leaf and the number of leaves. These
parameters are in effect related to the total leaf area of a seedling. In
studies done by the plant physiologists, botanists and agronomists, leaf area
of a young coconut seedling is frequently used as an index of the plant's
response to environmental changes (Ranasinghe et al., 1999).
Coconut seedlings are often used in research studies. Very often destructive
sampling is not possible. For such situations, the most common method of
determining the leaf area is by mathematical regression equations using
easily measurable leaf parameters. Several acceptable non-destructive
methods are available for determining the leaf area of split leaves in coconut
seedlings (Mathes et al., 1989; Satheesan et al., 1983) and adult coconut
palms (Jayasekara and Mathes 1992; Ramadasan and Jacob Mathew
(1987). However, a method to determine the leaf area of seedlings with
unsplit leaves in which the leaflets are not separated is yet to be developed.
Hence it has become necessary to find a method of estimating the leaf area
of such seedlings by a non-destructive method. '
There is a large variation in the morphology of leaves among the cultivars
and hybrids of coconut (Ramadasan and Kasturi Bai , 1999). Th is may
necessitate developing different regression equations to determine the leaf
I
area of seedlings of Tall and Dwarf -Green x Tall varieties. The aim of this
study wa·s to develop a common equation or different equations to estimate
leaf area of unsplit leaves of seedlings of Tall Dwarf Green x Tall varieties .
MATERIALS AND METHODS
Eight-month-old seedlings from Tall x Tall (CRIC 60) and Dwarf Green x Tall
(CRIC 65) varieties were randomly selected for the study from two coconut
nurseries, Kirimatiyana and Thabbowa. From each nursery, 15 seedlings of
each variety were selected and six unsplit leaves from each seedl ing were
taken for measurements. The most mature leaf of each seedling was
numbered 1 and the other leaves were numbe red in the descending orde r of
maturity. Measurements were taken at different posit ions of each leaf in
order to develop a suitable equat ion to estimate the total area of a unsplit
leaf. The measurements finally used for the development of the most
efficient regression equation or equations were c, d, e, f and g (Fig. 1).
Fig. 1: Diagram of an unsplit leaf showing the measured parameters c. d, e,
f and g.
The model takes the form ;
Where, Yi is the actual area of the leaf and Xi to describe later , a and bare
constants. The actual area of each leaf was measured destructively using
an electronic leaf area meter (L1-COR 3000 , USA).
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Statistical analytical procedure
Consider the area ABC of the unsplit . leaf in Fig. 1. This area is best
described as proportional to one half the area def ined by,
c {(AB +BC) 12}
ie; c {{AB +BC) 12}= c {(e + " (f 2 + e 2/4)) 12}.
Similarly the area of ABO is proportional to, d {(e +" (f 2 + g2/4)) 12}
Thus the total area x = (c + d){(e + " (f 2 + g 2/4)) 12}
Let x = (c + d) {(e +"(f 2 + g 2/4)) 12)
Let y = the actual leaf area of each leaf measured by leaf area meter
Thus for each leaf, the leaf area (Yi) and calculated value (Xi) will be
available and the regression equation developed accordingly.
RESULTS
Separate regression equations were developed for the varieties CRIC 60
and CRIC65 and are described below .
CRIC 60 : y =25.85 + 0.99 x,
CRIC 65 : y =38.36 + 1.04 x,
Where y = actual leaf area
x = (c + d) {(e + " (f 2 + g 214)) 12}
r2 =99.3%
r2 =96.9 %
The regression coefficients showed significant (p=0 .001) dependency of y
on x. The high r2 values indicate the prediction value of the two equations
and the extent to which the variation in y is explained by x.
A further test was carried out to see whether a common equation could be
fitted for the two var ieties. The test however showed that there is a
significant difference between the 'a ' values and the 'b' values. This
suggests that leaf area of the seedlings of the two varieties is best described
by the two regression equations.
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DISCUSSION
Leaves are the most important organs for plant production due to the ir role
in intercepting and absorbing radiant energy and building this energy into
organic substances through the processes of photosynthesis. The
physiological aspects such as rates of photosynthesis and transpiration of a
plant are commonly expressed as CO2 uptake and H20 loss per unit leaf
area. The value of leaf area in the study of plant growth and other
physiological aspects is so significant that researchers from time to time had
tried various methods in evaluating the leaf area of coconut seedlings by
non-destructive methods. Mathes et al (1989) developed a regression
equation to est imate area of the leaves of coconut seedlings up to three
years of age and observed that the third leaf could be used as the
representative leaf to measure the total leaf area of seedlings. However ,
their method could not be applied for seedlings with unsplit leaves. Based
on results of the present study, the following non-destructive method could
be proposed for obtaining the area of the unsplit leaves of seedlings in the
'field planting stage'. The measurements of c, d, e, f and g of each unsplit
leaf have to be taken , irrespective of the age of the leaf, and used in the
equation developed to estimate the area of each leaf. Total leaf area of the
seedling can thus be estimated by adding individual leaf areas.
In conclusion , the equations developed from this study could be used to
determine the leaf area of unsplit leaves of Tall and Dwarf Green x Tall
seedlings and applied to studies of growth analysis and in the evaluation of
cultivars at the seedling stage for the ir potential to adopt to different
environmental conditions.
REFERENCES
Jayasekara C and Mathes D T (1992) . A method to determine leaf area of
a frond and the whole canopy of an adul t coconut palm . Indian Coconut
Journal 23, 7-13.
Linder S (1985) Potential and actual production in Australian forest stands.
In: Landsberg J J, Parson W (Eds.) Research for Forest Management,
CSIRO, Melbourne, 11-35 .
Mathes D T, Liyanage L V K, Randeni G (1989). A method for
determining leaf area of one, two and three year old coconut seedl ings (var .
CRIC60). Cocos 7,21-25.
Ramadasan A, Jacob Mathew (1987). Leaf area and dry matter
production in adult coconut palms. Journal of Plantation Crops 15 (1), 59-
63.
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Ramadasan Ii., Kasturi Bai K V (1999). Leaf area, dry matter production
and yield. In: Advances in plant physiology and biochemistry of coconut
palm (Eds. Rajagopal V and Ramadasan A). Publisher APCC, PP 30-35.
Ranasinghe C S, Weerakoon L K, Liyanage Y M H, Mathes D T (1999) .
Physiological aspects of in vitro-grown coconut (Cocos nucifera L.) plants
during acclimatization. CORD XV (2),46-67.
Satheesan K V, Narasimhayya G, Ramadasan A (1983). A rapid method
for estimation of leaf area of one-year-old seedlings of tall variety of coconut
palms. Journal of Plantation Crops 11 (1), 47-49.
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A non-destructive method for determining the area of unsplit leaves of coconut seedlings

Fernando, L.C.P.

de Moraes, D.J.

Wickramananda, I.R.

Proceedings of the international workshop on coconut mite (Aceria guerreronis)

National Science Foundation of Sri Lanka

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