Coconut Research Institute Repository

Bandaranayake, C.K.

Fernando, W.M.U.

Progeny evaluation as an effective method of selection in coconuts

Everard, J.M.D.T.

Use of molecular markers for the enhancement of the coconut breeding strategy at the Coconut Research Institute

Jayasekara, K.S.

Peries, R.R.A.

Jayasekara, C.

Drought response and efficient water management in coconut (Cocosnucifera L.)

Twenty five commercial copra kilns in Sri Lanka were studied for variations of their dimentions and copra curing practices in relation to the "Standard Ceylon Copra Kiln" and the quality of copra produced.  Changes in the height and the width of the platform resulting in probable changes in drying conditions of copra was noted.  The use of powdered charcoal appeared to improve the quality of copra produced and more cost effective than use of coocnut shells.  Addition of sulphur dust to the fuel further improved the quality of copra

Rodrigo, M.C.P.

Amarasiriwardene, B.L.

Samarajeewa, U.

COCOS (1996), 11, 21 - 3 1 
Printed in Sri Lanka 
SOME OBSERVATIONS ON COPRA DRYING 
IN SRI LANKA 
M C P Rodrigo, B L Amarasiriwardene1 and U Samarajeewa 
Department of Food Science and Technology, 
University ofPeradeniya, Peradeniya, Sri Lanka 
ABSTRACT 
Twenty five commercial copra kilns in Sri Lanka were studied for variations of 
their dimensions and copra curing practices in relation to the "Standard Ceylon 
Copra Kiln" and the quality of copra produced. Changes in the height and the width 
of the platform resulting in probable changes in drying conditions of copra was 
noted. The use of powdered charcoal appeared to improve the quality of copra 
produced and more cost effective than use of coconut shells. Addition of sulphur dust 
to the fuel further unproved the quality of copra. 
INTRODUCTION 
Extraction of coconut oil by converting the coconut kernels to copra continues to 
be the most economical and efficient method in spite of several disadvantages 
(Samarajeewa, 1993). The production of copra is labour intensive, results in under 
dried and over dried kernels at times, uses most of the valuable coconut shells as 
fuel, and also results in deposition of polycyclic aromatic hydrocarbons (PAH) on 
the surface of kernels. Some of the PAH are carcinogenic and pass into, edible oils 
on extraction (Wijeratne et al . , 1996). 
The kilns used to dry coconut kernels vary from country to country in the South-
East Asian region (Timmins, 199S). The capacity, the methods of operation, the fuel 
used and the quality of coconut kernels used depends on the types of drying 
processes although they all basically operates on the direct drying principles. The 
quality of the copra produced varies widely depending on the types and operational 
conditions of the kilns. Some of the existing kilns (dryers) and the operational 
conditions are reviewed by Patel (1985). 
In Sri Lanka, coconut kernels were dried using the "Chula dryer" introduced in 
1923 for copra manufacture. The "Chula dryer" operates on indirectly heated air 
generated by a furnace. This dryer was replaced by the direct air heated "Standard 
Ceylon Copra Kiln" (STD) designed in 1960s. This model is still considered to be 
the most economical and drying is practiced following the guidelines stipulated with 
1
 Coconut Development Authority, Colombo, Sri Lanka. 
21 
the design of the kiln (The Ceylon Copra Kiln, 1965). The drying operation reduces 
the moisture content in the kernels from 43% to 8% (Nathanael, 1962). However, 
the design of the kiln and the drying procedure has got modified over the years in 
the hands of the copra manufactures. A study of 25 copra kilns was carried out to 
understand the modifications and the resulting effects on copra quality processed in 
the present kilns. Currently there is a need to improve the copra production methods 
to meet the demand for a quality copra - white in appearance and containing no 
smoke deposits, thus avoiding PAH. 
MATERIALS AND METHODS 
Twenty five copra kilns in the Marawila-Chilaw area were visited. The 
measurements of the copra kilns and the copra drying chambers were made. The 
method of copra drying in relation to the type of fuel used (coconut shells, coconut 
charcoal, other) the pattern of spread of the fuel on the surface (number and spacing 
of rows or other spreads) were examined. A breakdown of the quality of copra based 
on the commercial grading system (white edible, edible, milling superior, milling 
ordinary) was carried out in relation to each of the mills. 
RESULTS AND DISCUSSION 
General Information 
The general information on the over all dimensions of the copra kilns, the 
locations of the ventilation openings in the firing chamber and the operational 
procedure practiced in copra drying are summarized in the tables 1 to 3 respectively. 
All parameters show a wide range of variation compared to the kiln at the. Coconut 
Research Institute. With regard to the over all size of the kilns there are differences 
between the "Standard Ceylon Copra Kiln" (STD) described in the advisory leaflet 
and the one used at the Coconut Research Institute (CRI) too. The mean dimensions 
of the kilns in the field lie between that of the CRI and STD kilns. 
Of the different parameters, the width of the drying chamber and the distance 
between the floor and the drying platform are critical in the drying process. The 
mean width of the platform in commercial mills is 2.8 ± 1.2 m as against the widths 
of 1.1 and 1.5 m recommended and used in the STD and CRI kilns (Table 1). To 
compensate for the doubling in the width in commercial mills the copra producers 
lay two or more rows of shells to be burned instead of a single row recommended 
(Table 3). The variations in gaps between the rows of shells laid down in the 
different kilns and the number of lines of shells per row can result in overlap of heat 
cones and heat intensities or unheated gaps at the drying platform leading to uneven 
drying of copra. 
Most kilns operate with a much lower height (mean 2 ± 0.4) m as against 3 m 
22 
recommended in the STD kiln and 2.4 m used in CRI kiln (Table 1). The heights of 
the drying chambers are reduced, perhaps with the intention of catching the heat 
early, thus economizing on the fuel. However, it is not known whether the reduced 
height results in increased scorching of copra or the burning is adjusted in such a 
way to overcome possible scorching. The combination of wider platform and reduced 
height in the drying chamber would certainly affect the quality of copra. 
Overlap of Heat Cones 
It is assumed that the design of the "Standard Ceylon Copra Kiln" and construction 
of the CRI kiln have taken into consideration the most efficient heat distribution in 
each chamber. On the basis of the design of the drying chambers of CRI and STD 
kilns, one could assume the presence of an inverted heat cone with apex at the 
burning point of shells and base overlapping with the surface of platform containing 
copra to be dried. The angle at the apex of the inverted cone works out to be 26° 
and 28° for the CRI and STD kilns. 
When the concept of heat cone is extended to the commercial kilns examined, the 
drying appears to occur with overlapping of the base of heat cones in most of the 
kilns, sometimes resulting in 100% overlap on the basis of the diameter of the cone 
(Table 4). In situations with 30% to 50% overlap one could expect areas of higher 
temperatures and increased rates of drying. The high temperature areas on the drying 
platform may. result in case hardened and scorched copra. On the other hand if the 
rows of shells are too far apart leaving unheated or low temperature areas outside 
the heat cones during drying, copra may become slimy due to bacterial growth on 
the surface. It is. important to adhere to stipulated dimensions in the drying chamber 
and laying of the rows of fuel for uniform and efficient drying. The temperatures of 
the kernels at drying need to be monitored to understand the performance of the 
modified commercial mills. An examination of the percent distribution of under-dried 
or over-dried copra produced in the modified kilns may provide necessary 
information for required adjustments. 
Ventilation 
In addition to the door which allows entry of plenty of air during burning of 
shells, windows are kept for ventilation in most of the kilns in keeping with the 
requirements laid down in the CRI leaflet (Table 2). During drying of copra the door 
is normally kept closed for controlled burning of shells. 
The ratio of total volume of the copra drying chamber to the area of the 
ventilation openings (window or the window and the door together) varied widely, 
in the commercial kilns showing a very high standard deviation (Table 5). It is not 
known whether such variations do effect the quality of copra. The possible effects 
are worth examining. 
23 
Table 1. Overall measurements of copra kilns (m). 
Parameter CRI STD Commercial 
Length of copra kiln mean 21.6 30.2 20.4 ± 10.7 
range 6.0 - 40.8 
Width of copra kiln mean 6.0 3.8 3.8 ± 0.7 
range 2.7 - 5.8 
Width of the veranda mean 1.7 1.8 2.4 ± 0.9 
range 0.8 - 5.5 
Height of roof (lowest) mean 2.0 2.3 2.2 ± 0.4 
range 1 .2 - 3.0 
Height of roof (top) mean 4.0 4.6 3.8 ± 1.1 
range 3.0 - 7.0 
Number of drying chambers mean 16 18 8 ± 4 
range 3 - 16 
Depth of drying chamber below ground level mean 1.1 0.9 0.5 ± 0.4 
range 0 . 0 - 1.9 
Height of the drying chamber mean 2.4 3.0 2.0 ± 0.4 
range 1 . 7 - 3 . 1 
Width of the drying chamber mean 1.1 1.5 2.8 ± 1.2 
range 1.1 - 5.4 
CRI - Copra kiln used in the Coconut Research Institute 
STD - 'Standard Copra Kiln' recommended in the CRI Leaflet No. 15. 
24 
Table 2. Location of ventilation openings in copra kiln. 
Parameter CRI STD Commercial 
Windows per chamber mean 1 1 2 ± 0.6 
range 0 - 6 
Distance between two windows mean n.a. n.a. 0.5 ± 0.6 
range 0 - 2 . 1 
Height of window from floor mean 1.2 0.3 0.6 ± 0.5 
range t 0.1 - 1.4 
Distance of window from the wall mean 0.5 0.7 . 0.5 ± 0.3 
range 0.1 - 1.1 
Width of window mean 0.1 0.2 0.1 ± 0.1 
range 0 . 1 - 0.3 
Height of window mean 0.4 0.6 0.2 ± 0.2 
range 0.1 - 0 . 6 
Height of the door mean 0.8 1.2 0.8 ± 0.1 
range 0 . 6 - 1.2 
Width of the door mean 0.8 0.8 1.1 ± 0.2 
range 0 . 7 - 1.6 
CRI - Copra kiln used in the Coconut Research Institute 
STD - 'Standard Ceylon Copra Kiln' recommended in the CRI Leaflet No. 15. 
n.a.- not applicable 
25 
Table 3. Operations of copra drying (all lengths in m). 
Parameter CRI STD Commercial 
Sun drying + + + in 22 
- in 3 
Fuel shell shell shell in 18 
shell + S in 1 
char in 2 
char + S in 4 
Number of firings mean 
range 
8 8 5 ± 1 
2 - 8 
Number of double rows mean 
range 
1 2 3 ± 1 
1 - 8 
Width of a row mean 
range 
0.4 n.a. 0.3 ± 0.1 
0 . 3 - 0 . 4 
Distance between rows mean n.a. n.a. 0.8 ± 0.9 
range n.a. n.a. 0.3 - 1 
CRI - Copra kiln used in the Coconut Research Institute 
STD - 'Standard Ceylon Copra Kiln* recommended in the CRI leaflet No. IS 
char - charcoal powder 
S - sulphur powder 
+ - sundried prior to drying in the kiln 
directly kiln dried (no sundrying) 
n.a. - not applicable 
26 
Table 4. Overlap of heat cone during drying of copra in the individual drying chambers of the kilns. 
Mil l No. Platform of chamber Height No. of rows % Overlap by 
width (m) area (sq.m) (m) diameter of the cone 
STD 1.5 5.7 3.0 
CRI 1.1 6.6 2.4 1 
. 1 4.3 19.0 2.1 2 42 
2 1.7 5.9 2.2 2 25 
3 1.4 5.9 1.7 2 33 
4 4.9 21.6 2.1 4 52 
S 2.4 8.9 1.9 3 13 
6 4.4 14.5 2.0 4 46 
7 3.9 15.2 1.8 2 10 
8 1.9 6.2 2.4 2 35 
9 2.4 9.3 1.8 2 11 
10 3.4 11.2 3.1 5 100 
11 1.3 5.5 2.0 2* 30 
12 3.8 16.7 1.7 2 0.1 
13 4.0 15.6 2.1 4 0.1 
14 4.6 26.7 2.0 4 00 
IS 5.4 17.8 3.1 8 100 
16 3.1 8.7 2.3 4 00 
17 2.1 8.2 1.9 3 30 
18 2.1 7.3 1.8 3 6 
19 3.0 12.0 1.8 3 33 
20 1.9 8.2 1.9 2 0.14 m gap 
21 1.1 3.5 1.0 2 00 
22 3.0 9.6 2.1 2 36 outside cone 
23 2.3 8.3 1.7 2 9 
24 1.5 5.7 2.2 2» 30 
25 2.2 5.3 2.1 3 39 
Mean 2.8 10.1 2.0 3 
± 1.2 5.1 0.4 1 
* - Triple rows 
Table 5. The ventilation cavities of the chamber in relation to total area/volume of drying chamber. 
Parameter CRI STD Commercial 
Height of the chamber mean 2.4 3.0 2.0 ± 0.4 
range 1.0 - 3.1 
Volume of the chamber (v) mean 1S.S 17.1 22.8 ± 14.0 
(cubic meter) range 3 . 5 - 15.2 
Area of the window/s (w) mean 0.04 0.05 0.03 ± 0.03 
(square meter) range 0 - 0 . 1 5 
Area of the door (d) mean 0.6 1.0 0.9 ± 0.3 
(square meter) range 0 . 5 - 1 . 5 
v/w mean 395 342 546 ± 695 
range 0 - 3280 
v / (w+d) mean 23 16 25 ± 15 
range 6 - 5 6 
CRI - Copra kiln used in the Coconut Research Institute 
STD - 'Standard Ceylon Copra Kiln' recommended in the CRI Leaflet No. 15. 
28 
Table 6. Quality of copra in relation to the fuel used. 
Fuel Mill No. Grade of copra 
Coconut shells 
1 M 0 4 & 5 
2 M 0 4 & 5 
3 MS 1 & 2, 
5 M 0 4 & 5 
7 M 0 4 & 5 
8 M 0 4 & 5 
9 MO 4 & 5 
11 MO 4 & 5 
f2 M 0 4 & 5 
13 MO 1 
15 MS 1,2 & 
16 MO 1 & 2 
17 MS 2, MO 
18 MS 2, MO 
19 MS 2, MO 
24 MS 3, MO 
25 M 0 4 & 5 
Coconut shells and Sulphur dust 
14 
23 
MS 1 & 2, MO 
MS 1 & 2 
Charcoal and Sulphur dust 
4 
6 
10 
20 
21 
22 
MS 1, MS 2 
Edible, MS 1 & 2 
MS 1 & 2 
Edible, MS 1 
Edible, MS 1, MS 2 
MO 1-5 (only for oil) 
The presence of wide openings above the drying platform is necessary to 
allow outward flow of moist hot air. If the moist air is not removed the moisture 
tend to condense on the roof and drop back on copra. In six of the kilns observed 
there was no open walls to allow a cross wind above the drying platform. Two kilns 
contained only windows for air movement, which may be inadequate. 
29 
Fuel Used 
There are two types of fuel used in the copra kilns. While most of the kilns use 
shells as fuel, a few use charcoal. Addition of sulphur dust to the fuel is also 
becoming popular (Table 6). Judging by the over all grades of copra produced as 
determined by an expert on quality, the use of charcoal provides a distinctly 
improved quality in copra (MS and edible grades) and the use of sulphur dust 
(100 g per row) produces a white copra which could fetch better prices in the 
market. The use of sulphur is probably not. objectionable as sulphur dioxide is 
commonly used in fumigating the ship on carrying copra in bulk (Salunke et al., 
1992). 
The use of charcoal is coupled with certain advantageous modificaitons of the 
drying practices and cost effects. The charcoal dust, used is a low cost fuel (Rs. 
1500/- per ton) compared to the shells. It appears that one could increase the profit 
margin by converting the shells to high value charcoal and using the residual 
charcoal powder as a fuel. The copra producers using charcoal as fuel have also 
done away with initial sun-drying of kernels, but have introduced selection of only 
well matured kernels and arranging the kernel cups inverted on the drying platform. 
CONCLUSION 
It is important to investigate further, the effect of different layouts of shells for 
burning on the percent distribution of quality and moisture content of the copra. 
Since the use of charcoal and sulphur appears to carry a distinct advantage in relation 
to quality, shifting of the present drying method to use of charcoal powder may be 
worth giving consideration. 
ACKNOWLEDGEMENT 
The authors thank the Coconut Development Authority, the Coconut Research 
Institute of Sri Lanka and the copra manufacturers for assistance in this study. 
REFERENCES 
Nathanael, W R N (1962) Report of the chemist, Ceylon Cocon. Q., 14: (1/2) 21-24. 
Patel, R T (1985) Copra drying process and equipments. J. Plant. Crops, 13: (2) 
78-87. 
Rodrigo, M C P and Samarajeewa, U (1995) Production and utilization of coconut 
kernel products in Sri Lanka. Proceedings of the European Community Project 
Seminar on polyaromatic hydrocarbons in copra and derived products, 24-26 July, 
1995, Bogor, Indonesia. 
30 
Salunke, D K, Chavan, J K, Adsalf, R H and Kadam, S S (1992) World Oil 
Seeds: Chemistry, technology and utilization. AVI, Van Nostrand Reinho, New 
York. 
Samarajeewa, U (1993) Improvements in coconut processing in the South-East 
Asia. Proceedings of the Third International Food Convention. 7-12 September, 
1993. Mysore, India, pp. 166. 
The Ceylon Copra kiln (1965) Coconut Research Institute Leaflet No. 15. 
Timmins, W H (1994) Polycyclic aromatic hydrocarbons and copra. 
Proceedings of the European Community Project Seminar on Potyaromatic 
Hydrocarbons in Copra and Derived Products. 24-26 July, 1995, Bogor, 
Indonesia. 
Wijeratne, M C P, Samarajeewa, U and Rodrigo, M C P (1996) Polycyclic 
aromatic hydrocarbons in coconut kernel products. / . Nat. Sci. Council of Sri 
Lanka, (in press) 
31 


Some observations on copra drying in Sri Lanka

Tennakoon, N.A.

Somasiri, L.L.W.

O R G A N I C M A N U R E S : A P O T E N T I A L 
M I C R O N U T R I E N T S O U R C E F O R C O C O N U T 
The elements which are required in 
very small amounts but essential for plant 
growth are known as micronutrients or trace 
elements. Eight such elements viz manganese 
(Mn), iron (Fe), boron (B), zinc (Zn), copper 
(Cu), molybdenum (Mo), cobolt (Co) and 
chlorine (Ci) have been recognized as micro-
nutrients for plant growth. 
The coconut palm takes up nitrogen 
(N), phosphorus (P) and potassium (K) in 
large quantities as primary nutrients and the 
magnesium (Mg) and sulphur (S) in moderate 
quantities as secondary nutrients. Chlorine (CI) 
is also removed by the coconut palm in a large 
quantity which is comparable to potassium. 
The soil may get rapidly depleted of these nu­
trients due to prolonged coconut cultivation. 
Therefore potassium and magnesium defi­
ciency symptoms are often visible in coconut 
plantations. Such deficiencies can be corrected 
by application of common NPK and Mg fer­
tilizers. 
Micronutrient deficiency symptoms in 
coconut plantations have not been observed 
so far except boron (B) in very few sites. In 
1980's, the boron deficiency symptom first ap­
peared in coconut palms on a heavily leached 
soil at Pujapitiya, in Kandy district. Later the 
boron deficiency symptoms appeared in 
Kegalle and Peradeniya areas in 1993, where 
coconut has been planted in uprooted rubber 
lands. 
"Visible symptoms occur in the leaf 
only when the deficiency is severe. When the 
N A Tennakoon 
L L W Somasiri 
Coconut Research Institute of Sri Lanka 
deficiency is mild, symptoms are not visible 
but yield limiting conditions would occur. In 
such circumstances, deficiencies should be 
diagnosed by special techniques. Nutrient de­
ficiencies of the coconut palm can be diag­
nosed easily by analysing the leaf nutrient con­
centration of the 14th frond. Sufficiency 
ranges of concentrations of primary and sec­
ondary nutrients are well established. Suffi­
ciency ranges for few micronutrients have 
been determined by some workers and those 
for other micronutrients are under investiga­
tion. 
The sufficiency ranges of micronutri­
ents for the coconut palm are as follows. 
Mn - 60 mg/kg 
B - 8-10 mg/kg 
Fe - 40 mg/kg 
Cu - 5-7 mg/kg 
Zn - 15-24 mg/kg 
CI - 3000-6000 mg/kg 
(Manciot et al., 1979; Eschbach and Manciot, 
1981; ANON, 1989). 
The leaf analysis of coconut palms 
grown on some predominent soil types in the 
major coconut growing areas, such as 
Madampe series, Sudu series, Andigama se­
ries, Kuliyapitiya series, and Kurunegala se­
ries indicated that Fe and Mn concentrations 
were above the respective sufficiency ranges 
in all five soil series. The study further showed 
that leaf Cu concentration of coconut in all 
1 
five soil types was marginal. The leaf zinc 
concentration was also marginal in 
Kuliyapitiya and Kurunegala soil series. Low 
concentrations of leaf boron were randomly 
observed in all soils irrespective of the soil 
type (Somasiri, 1994). Therefore, the situa­
tion is not alarming to the extent that micro-
nutrient fertilizers to be applied to coconut. 
But the current situation suggests that appli­
cation of organic manures to coconut could 
be a successful preventive measure against oc­
currence of micronutrient deficiencies of co­
conut plantations in the future. 
Organic manures are rich in micronu-
trients as shown in Table 1. Trace elements in 
organic manures occur in complex forms. 
They are released to the soil at a slow rate de­
pending on the rate of decomposition of or­
ganic matrix (Tennakoon, 1994). Most or­
ganic sources are applied to the coconut palm 
at the rate of 30 kg per palm per year, except 
goat dung which is applied at the rate of 15 kg 
per palm per year (Anon, 1987). 
Obviously, organic manures can be success­
fully used for replenishing the soil micronu­
trient pool. Although the current recommen­
dations on organic manures for coconut (eg. 
Table 1 Micronutrient concentrations in different types of organic sources 
(Tennakoon, 1994) 
Organic source Micronutrients ppm (mg/kg) 
Fe Mn Cu Zn B 
Goat dung 1449-2174 246-505 20-38 112-184 29-66 
Cow dung 690-1518 167-389 24-40 128-183 13-30 
Poultry manure 
Broiler Litter 
Layer Litter 
723-1565 
1144-2215 
213-421 
287-450 
27-40 
22-38 
166-271 
182-329 
15-27 
12-23 
Pig dung . 1020-1990 180-207 45-48 186-575 4-13 
Farm yard manure 
(FYM) 
Compost 
1135-3515 
2090-4064 
229-668 
201-505 
17-29 
11-25 
83-128 . 
75-169 
12-27 
12-20 
Biogas residues 1097-1644 402-616 37-53 300-412 22-46 
Sewage sludge 2275-3322 100-287 7-11 69-177 3-5 
Gliricidia 212-450 85-156 4-5 57-70 41-69 
Acacia 870-994 78-92 7-9 54-61 46-49 
Pueraria 117-280 82-120 4-6 64-70 20-24 
2 
A p p l i c a t i o n o f o r g a n i c m a n n u r e 
35 kg of cattle manure, or 30 kg of poultry ma­
nure or 15 kg of goat dung) are aimed at meet­
ing the N demand of the palm. The same 
amount would be sufficient to enrich the soil 
micronutrient pool. It is important to note that 
accumulation of micronutrients in the soil 
would become toxic to plants. Such an accu­
mulation could result from liberal application 
of micronutrients. Therefore, much care is 
needed in using micronutrient chemical fertil­
izers. Whereas addition of micronutrient 
through organic would not cause such an ac­
cumulation due to their slow decomposition. 
Therefore organic manure application would 
be safer and more beneficial than chemical 
fertilizer application to the coconut palm be­
cause it supplies the required amount of pri­
mary and secondary nutrients along with mi­
cro nutrients. Improvement of soil quality 
around the coconut palm is another impor­
tant benefit of organic manuring. 
R e g i s t e r w i t h C R I 
C o c o n u t c u l t i v a t i o n i s v e r y p r o f i t a b l e i f y o u d o i t c o r r e c t l y w i t h n e w t e c h n o l ­
o g y . T h e C o c o n u t R e s e a r c h I n s t i t u t e h a s d i f f e r e n t p r o g r a m m e s t o a s s i s t c o c o ­
n u t g r o w e r s t o i m p r o v e t h e i r k n o w l e d g e o n c u l t i v a t i o n a n d p r o c e s s i n g . C o c o ­
n u t g r o w e r s a r e r e q u e s t e d t o r e g i s t e r w i t h t h e i n s t i t u t e t o o b t a i n t h e s e s e r v i c e s . 
P l e a s e s e n d y o u r i n f o r m a t i o n t o t h e D i r e c t o r , C o c o n u t R e s e a r c h I n s t i t u t e , 
L u n u w i l a . 
3 


Organic manures. a potential micronutrient source for coconut

Katz, M.

Use of RAPDs for estimation of genetic distances between populations of the coconut palm, Cocos nucifera

COCOS (1996), 11, 01 -06 
Printed in Sri Lanka 
G E N E T I C C O N T R O L O F H U S K E D 
N U T W E I G H T I N COCONUTfCocos nucifera) 
W M U Fernando 
Coconut Research Institute, Lunuwila, Sri Lanka 
A B S T R A C T 
The genetic control of husked nut weight in Coconut (Cocos nucifera) was 
investigated using a full-diallel cross including eight parents. The parents were a 
selected sample of palms which gave an annual mean yield of 23 kg of copra per 
palm with 713 gm of husked nut weight over five years. An average of five 
progenies per cross planted in a fully randomised design were evaluated for five 
years. Husked nut weight of five nuts per palm was recorded at each pick. 
Analysis of variance of mean husked nut weight confirmed the presence of 
additive and non additive genetic variance. The non additive genetic component was 
found to be higher in magnitude than the additive component. The heritability 
expressed as the ratio of the genetic variance to the total phenotypic variance was 
0.45. Of the dominance components, directional dominance was non significant. 
Neither the presence of heterosis nor inbreeding depression was consistent among the 
selfed and crossed progenies elucidating the fact that not only crossing but seifing 
could also improve the trait, depending on the genetic constitution of the individual. 
Reciprocal differences were evident in the crosses suggesting the importance of the 
direction of cross. 
INTRODUCTION 
With the exception of a few progeny tests, mass selection based on the phenotype 
followed by hybridisation is the rule in most coconut improvement programmes 
(Liyanage 1967). The theory on quantitative genetics highlights the risk of this 
procedure unless the heritability of the character of interest is very high where a high 
score for a character of interest in an individual actually mirrors its genotype 
(Falconer 1981). Therefore accurate estimates of the heritability of characters used 
as selection criteria is imperative before embarking on any major selection 
procedure. Liyanage and Sakai (1961) using the progenies of 9 high yielding palms 
estimated the heritability of the husked nut weight of coconut as 0.95 and concluded 
'Paper presented at the International Symposium on Plantation Crops (PLACROSYM 
XI) 30 November - 03 December, 1994, Calicut, Kerala, India. 
1 
that mass selection for copra/nut ought to be very effective. Bourdeix (1988) 
estimated the heritability of copra/nut (estimated as 32% of the husked nut weight) 
in the range of 0.73 using parent-offspring regression with data extracted from 
parents and progeny planted in two separate blocks and for varying periods. 
However, an estimate of heritability of a character depends on the method of 
partitioning of the genetic and environmental components of variation and therefore 
the attempt of comparing the estimates obtained in two different situations is 
worthless. Furthermore the above procedures do not provide any information on the 
type of gene action controlling the yield characters in coconut which is a necessary 
pre-requisite in planning the breeding procedures. 
The objective of the present study is to determine the type of gene action 
responsible for the husked nut weight in coconut and estimate the heritability of the 
above character. Diallel cross analysis was introduced as one of the strategic 
methods of determining the genetic control of quantitative traits and one that partition 
the genetic and environmental components of variation most efficiently (Mather and 
Jinks, 1982). 
MATERIAL AND METHODS 
The selection of parent palms for the diallel crossing programme was based on the 
nut yield/palm/year and mean husked nut weight for a period of five years after 
attaining yield stability. Yield data of the selected palms appear in Table 5. The 
pollinations were carried out in all possible combinations among the best 8 palms and 
the progeny was transplanted at Pothukulama Research Station in December 1964 in 
a fully randomized design with 10 plants per family (CRI, 196S). Although all 
progenies derived from 8 x 8 diallel crosses were planted originally, high casualty 
rates in the field resulted in only 40 progeny families surviving which could provide 
data for the present analysis. Average weight of 5 husked nuts were recorded at each 
pick for S years (1976 - 1980). An analysis of variance was carried out to test for 
differences between the reciprocal families for parents which they were available. 
The loss of many families over time and the reduction in family size of others 
resulted in the situation that data could be used only as a half diallel with selfs. A 
maximum of 5 individuals per family was used in the analysis. The half diallel 
analysis of the mean husked nut weight over a 5 year period was carried out 
according to the method of Jones (196S). The general combining ability (G.C.A.) 
and specific combining ability (S.C.A.) effects were further analysed equating the 
additive component to G.C.A. and the sum of the dominance components to the 
S.C.A. effect. 
RESULTS AND DISCUSSION 
The analysis of variance between and within the reciprocal families revealed 
2 
significant differences between the reciprocal crosses (Table 1) indicating the 
importance of the direction of a cross. A possible reason for the above occurrence 
is the influence of the maternal parent in contributing more alleles to the triploid 
state of the endosperm. 
Table 1. Analysis of variance of reciprocal families. 
Source df SS MS P 
Between reciprocal families 10 0.9292 0.0929 o.or 
Within families 375 12.6258 0.033 
The variance for husked nut weight between the families as partitioned by the half 
diallel analysis is summarised in Table 2.. The additive component (a) was highly 
significant, of the dominance components (b,) was not significant indicating the 
absence of directional dominance among the loci controlling nut weight.. The 
significance of the (bj) item indicated that there were differences between parents 
with respect to the relative proportions of dominant and recessive alleles at these' 
loci, while residual dominance (b 3) was also significant. 
Table 2. Results of half diallel analysis of mean husked nut weight (a = 
additive, b, = directional dominance, b2 = mean dominance b3 = 
residual dominance). 
Source df SS MS P 
a 6 1.625 0.270 o.ooor* 
bl 1 0.014 0.014 ns 
b2 6 0.880 0.146 0.0001-
b3 14 1.175 0.084 o.or 
within family error 545 16.022 0.029 
The mean squares of (a) was equated to mean squares of general combining ability 
whilst the pooled mean squares (b,) (bj) and (b,) was equated to the mean squares 
of the specific combining ability. The components general combining ability ( o 2 ^ , 
specific combining ability (o z g e J and the environmental component (o2e) appearing 
in Table 3 were computed from the relevant mean squares. The variance component 
analysis revealed that additive genetic variation was available for selection but the 
non additive component was also of significant importance in controlling the husked 
nut weight. The ratio of the genetic variance to the total variance was 0.45. The 
value estimated by Liyanage and Sakai (1961) for heritability of husked nut weight 
using data from half sib families appear to be too high due to the reason that 
3 
dominance variance was assumed to be negligible. 
The means of selfed and crossed progenies of the seven parents averaged over the 
five year period is shown in Table 4. A higher progeny mean was observed (586 gm) 
in the selfed families than in the crossed families (553 gm). However certain 
individuals produced improved progenies when crossed than selfed, elucidating the 
fact that either the presence of heterosis or the inbreeding depression was determined 
by the genetical constitution of the individual. Moreover the extent of inbreeding 
depression is controlled by the triploid nature of this tissue and the flow of genes 
brought by the pollen restores heterozygosity limiting inbreeding depression. 
Table 3. Results of the general and specific combining ability variance and 
heritability. 
Source df MS EMS 
GCA 6 0.2708 o 2 . + 5 ^ + 35 o 2 ^ 
SCA 21 0.0997 o 2 . + 5 o 2 „ 
within error 545 0.029 o\ 
o 2 g c , = 0.004 o2m = <0.014 h
2
 = 0.45 
Table 4. Husked nut weight means of half diallel families averaged over 5 
years (1976-1980) (kg). 
Parent 418 283 183 96 69 337 78 
418 0.5657 
283 0.6126 0.6053 
183 0.6328 0.3840 0.5084 
96 0.6050 0.3660 0.4350 0.5914 
r»<* n S7(V. ft n < w 0.563"! 
337 0.6236 0.5794 0.6133 0.6012 0.6470 0.6316 
78 0.5995 0.5681 0.4783 0.5935 0.4913 0.6468 0.5860 
A comparison of the performance of the diallel parents on which the selection was 
carried out and the progeny performance (both self and crossed) are shown in Table 
5. (total copra for the present experiment was calculated using the mean number of 
nuts/palm/year multiplied by the estimated copra/nut). The parent No 337 with an 
intermediate husked nut weight has produced the progeny with the highest husked 
nut weight and total copra exhibiting its general combining ability. Eventhough, 
parent no 78 with the highest husked nut weight (768 gm ; Table 5) showed low 
general combining ability, this palm produced the best progeny when crossed to palm 
337 elucidating the importance of specific combining ability in controlling the husked 
nut weight (Table 4). 
4 
Table 5. Details of parental performance (which the selection was based) and 
diallel progeny (selfed and crossed) performance. 
Parent Progeny 
Parent Mean husked Total Mean husked Total 
wt/nut copra wt/nut copra 
gm kg gm kg 
418 736 23.78 601 13.07 
283 690 22.90 515 8.24 
183 745 27.65 509 12.86 
96 613 21.70 536 13.21 
69 709 23.31 557 12.47 
337 713 ' 22.50 620 15.87 
78 768 20.64 566 11.41 
CONCLUSION 
The heritability of husked nut weight in coconut is estimated to be 0.45 suggesting 
that the improvement in the trait through mass selection is limited. The importance 
of both additive and non-additive genetic variance is evident in controlling the 
character indicating the possibility of not only crossing among individuals but also 
selfing the selected individuals for improving the character. A top cross or a test 
cross progeny testing method which would provide estimates of the general 
combining ability is suggested as a useful tool in determining the best parents for a 
crossing programme. 
ACKNOWLEDGEMENTS 
The author wishes to thank Dr D V Liyanage former Botanist of the Coconut 
Research Institute for initiating this trial and former Head of the Genetics & Plant 
Breeding Division D r M R T Wickramaratne for monitoring and co-ordinating the 
long term trials and documenting the data. Thanks are due to the Technical and field 
staff of Genetics & Plant Breeding Division for data collection and recording. 
REFERENCES 
Bourdeix R, (1988). Effectiveness of mass selection based on yield components in 
coconut. Oleagineux 43 no 7 : 283-295. 
CRI , (1965y Report of the Coconut Research Institute for 1964. Coconut Research 
Institute, Lunuwila, Sri Lanka. 
Falconer D. S., (1961).Introduction to Quantitative Genetics 2nd edit. Longman 
Scientific Gp London. 
Jones, R. M. , (1965). Analysis of variance of half diallel table. Heredity 20: 117-
121. 
Liyanage, D. V. and K. I. Sakai, (1961).Heritabilities of certain yield characters of 
the coconut palm. J. Genetics 57: 245-252. 
Liyanage, D. V., (1967). Identification of genotypes of coconut palms suitable for 
breeding. Expt. Agric. 3: 210-215. 
Mather K. and Jinks J. (1982).Biometrical Genetics 3rd edit. Chapman and Hall 
Cambridge. 
6 


Genetic control of husked nut weight in coconut (Cocos nucifera)

Perera, L.

Patterns of segregation in the F2 generation of dwarf x tall crosses of Cocos nucifera with special reference to reproductive characters

Jayasundara, M.G.F.S.

Abbott, L.K.

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Coconut research in Sri Lanka

National Science Foundation of Sri Lanka

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