Coconut Research Institute Repository

Everard, J.M.D.T.

Molecular markers a new tool in crop improvement

Jayasekara, C.

Photosynthesis and assimilate partitioning characteristics of the coconut palm as observed by 14C labelling.

Coconut Research Institute

De S.Liyanage, M.

Jayasekera, C.

Report of the coconut research institute for 1997

Junper, S.

Abbott, L.K.

Jayasundara, M.G.F.S.

Approaches to the study of interactions between VA mycorrhizalfungi

Fernando, W.M.U.

Rhode, W.

Genetic diversity of the form San Ramon var Typica of Cocosnucifera L detected by the novel ISTR DNA marker technology using coconut specific PCR primers

Vidhana Arachchi, L.P.

An evaluation of different mulches used in soil moistureconservation of coconut lands

Identification of basic design parameters of a drip irrigationsystem for coconut (Cocos nucifera L.) in gravelly soils

Appuhamy, P.A.H.N.

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Katz, M.

Gregg, K.

Inheritance of RAPD markers in the coconut palm Cocos nucifera

Bandaranayake, C.K.

COCOS (1996), 11, 32 - 39 
Printed in Sri Lanka 
EFFECT OF PLANTING DENSITY 
ON THE YIELD OF COCONUT 
W M U Fernando and C K Bandaranayake 
Coconut Research Institute, Lunuwila, Sri Lanka 
ABSTRACT 
An analyses is presented of the yield components of coconut established under 
densities varying from 128 palms/ha to 239 palms/ha from a spacing trial conducted 
by the Coconut Research Institute. Analysis of yield data during 1976-1980 from 24 
palms from 4 replicates analysed for each density treatment revealed significant 
differences in nuts/palm and copra/palm for the densities tested. The nuts/palm 
decreased with increasing density but the yield/ha maximised at a density of 171 
palms/ha and decreased beyond 171. Significant differences were absent in yield of 
copra/nut for the densities tested. The differences in copra/palm were due to the 
effect of nut number/palm. At a density of 179 palms/ha, copra/ha maximised to 
2260 kg and decreased beyond 179. The results of the present analysis indicate that 
a density ranging from 171-179 palms per hectare is the optimum for planting 
coconut in dry-intermediate zone where the study was conducted. 
INTRODUCTION 
Coconuts are generally planted at spacings determined from past experience 
influenced by traditions which have been developed in particular countries. As a 
result, a variety of plant- to- plant spacings are used for planting in different coconut 
growing countries mainly determined on a hypothetical basis. In Sri Lanka the range 
of plant population density for commercial tall variety varies from 123 to 210 
palms/ha (SO to 85 palms/ Ac) and different systems of planting such as square, 
rectangular and triangular are adopted to obtain the relevant densities. 
However, experimental evidence on optimum spacing for coconut is meagre and 
the available information leads to contradictions (Smith 1972). The first systematic 
experiment on coconut densities was initiated at the Pothukulama Research Station, 
Coconut Research Institute, Sri Lanka in 1964 (Manthriratne 1976) and an interim 
analysis of data revealed that spacings that were experimented with had no significant 
influence on total leaf production or time taken for initial flowering but had a 
significant effect on the length of fronds and girth of the trunk. Subsequently 
Manthriratne (1979) using nut yield data during 1973-1976 from the same trial 
32 
showed that significant differences exist in the mean yield per palm for both between 
and within row spacings. Further the number of nuts/palm decreased with increasing 
density but a high yield per unit area was obtained from high density systems. 
However, Manthriratne (1979) highlighted the necessity of a complete examination 
of the yield components and total yield of palms, giving a reasonable duration of 
time for yield stability for different densities before a final judgement is made on 
optimum densities. Therefore it was considered to use the past experimental data on 
spacings to reach consensus on optimum densities.for future plantings. This paper 
elaborates on yield data under different densities after yield stabilization of the trial 
at the Pothukulama Research Station, with the objective of recommending the 
appropriate plant population density for the grower under specific agroecological 
conditions. 
MATERIALS AND METHODS 
A set of experimental data has been selected from the planting distance trial 
initiated in 1964 at the Pothukulama Research StationfPRS). The site is located in 
the dry-intermediate zone of north-western Sri Lanka. The soil type is a sandy-loam 
(regosol), and the average rainfall at the site during the period of study was 1399.4 
mm/yr (Estate Management Division, PRS). 
The design of die experiment was 4*4 strip plot, where within each replicate the 
columns were allotted the within row spacings. There were two replicates with 6 
palms per plot (Fig 1). The spacings and resulting number of palms are given in 
Table 1 . The planting material used for the experiment were selected hand pollinated 
Table 1. Between-row and within-row spacings and number of palms per 
hectarefin bold) (densities used for data analyses are underlined). 
Between-row spacing (m) 
7.6 9.1 10.6 12.2 
Within-row 4.6 290 232 2fi§ 122 
spacing 5.3 232 199 m 15Q 
(m) 6.3 171 146 m 
7.3 122 150 121 112 
F I seedlings of Typica x Pumila (CRIC65) hybrids.The crop yield for the 5 year 
period 1976-1980 were used for the analysis. Planting densities ranging from 128 to 
33 
239 palms/ha were only considered for the present analysis. Moreover data from a 
dual set of planting systems (each with 2 replicate plots) commmon to a single 
density were pooled together resulting in 24 palms for each density, eg. data from 
plots with spacings 6.3 x 9.1 and S.3 x 10.6 resulting in 171 palms/ha were 
considered together. Based on the earlier results, the effect of densities was 
considered important than the planting systems (Manthriratne, 1979) since the yield 
per/palm of a specific density did not vary significantly with the planting system 
whether it was a square or a rectangular. Data from systems 5.3 x 9.1 and 6.3 x 
10.6 were excluded from the analyses since they resulted in densities which were 
almost similar to the densities under consideration. Densities 290 palms/ha and 112 
palms/ha were not considered as these densities were believed to be too high and too 
lower respectively on empherical evidence. 
RESULTS AND DISCUSSION 
The analysis of variance on the plot means for the 6 densities, revealed significant 
differences for nuts/palm/yr and husked nut wt/palm/yr (Table 2). However, 
significant differences were absent among the 6 planting densities for mean husked 
nut wt indicating that the differences in husked nut wt/palm/yr were due to the 
control exercised by number of nuts. It was obvious that the total assimilate 
available for the formation of a bunch of nuts is partitioned between number of nuts 
and weight of nuts. The present investigation shows that for the range of densities 
tested, only the number of nuts/palm/yr varied significantly due to differences in 
densities and the variation in total husked nut wt/palm and copra weight/palm is a 
consequence of the latter phenomenon. 
The mean number of nuts on the basis of per palm and per ha during the period 
1976 to 1980 appear in Table 3. A steady increase in nut yield/palm is observed 
from the closest spacing to the widest (Fig 2) but the per hectare yield maximised 
at the density of 171 palms/ha for number of nuts (Fig 3). The mean husked nut 
weight/palm decreased steadily with increasing density, with the yield stabilising in 
the plant population density range 171 to 179 palms/ha (Fig 4). 
In parallel with the results for nut yield, mean husked nut weight/ha maximised 
at 179 palms/ha. The mean husked nut weight/ha varied between 6230 kg for the 
density of 239 palms/ha and 7065 kg for the density of 179 palms/ha (Table 03). 
Copra yield was estimated as 32% of the husked nut weight (Pieris, 1935) and 
copra/ha/yr varied from 1993 kg to 2261 kg for densities of 239 palms/ha and 179 
palms/ha respectively (Fig 5). 
In contrast to the previous analysis of nut yield data (1973-1976) of Manthriratne 
(1976) indicating a linear increase in yield of nuts/ha with increasing density of 
palms, the present analysis of yield of nuts and copra showed an increase in the 
nuts/ha and copra/ha upto 171 palms/ha and 179 palms/ha respectively and then 
34 
I 
Pt 4 0 40 40 40 25 25 25 25 30 30 30 30 35 35 35 35 t 
24. X X X X X X X X •x X X X • 
24. u • X X X X X X X X X X X . 
21. X X X • X X X X X X X X X . 
M X X X X X X 
• X X X • X X X 
i i s - X X X • X X X • X X X • X X X 
15. X X X X X X X X X X x. X . 
18.. X X X • X X X X X X X X X • 
18. X X X X X X X ' X X X X X • 
30 10 30 30 35 35 35 35 40 40 40 40 25 25 25 25 I 
18. X X X • • x • X X X X X X X X 
18. X X X X X X X X X X X X . 
24. X X X • X X X • X X X X X X 
24. X X X X X X X X X X X X . 
a 24. # • • • . . . • 
. 
•• « - • • 
'X X X • X X X X X X X X X • 
1 1 S* X X X X X X X X X X X X . 
21. X X X X X X X X X X X X • 
21. X X X X X X X X X X X X • 
. GUARD ROW'PALMS 
X BCPOUMENZM, PALMS 
Figure 1. Spacing trial (Potbthukulama) (Strip plot design) 
Extracted from Manthriratne (1979) 
35 
100 
128 160 171 170 206 239 
Plant d a M R y (Palm/ha) 
Figure 2~ V a r i a t i o n in. n u t y i e l d / -
palm wi th p l a n t d e n s i t i e s . 
126 160 171 179 206 230 
Plant danattr (Palma/tta) 
Figure 3 - V a r i a t i o n i n nu t y i e l d / 
ha wi th p l a n t d e n s i t i e s 
F igure 5 - V a r i a t i o n i n copra y i e l d / F igure 4 - V a r i a t i o n i n husked n u t 
ha wi th p l a n t d e n s i t i e s weight /palm wi th p l a n t 
d e n s i t i e s 
36 
Table 2 . Results of the analysis of variance tests far yield components. 
Between MS Within MS F P 
Nuts/palm/yr 839.202 11.995 7.49 OJ0006++* 
HNW/palm/yr 335.624 59.269 . S.66 0.0026** 
HNW/ha/yr 78905.59 249980.47 0.32 0.8971 
Cop.wt/nut/yr 0.00033 0.00059 0.56 0.7296 
Cop.wt/palm/yr 34.368 6.069 5.66 0.0026** 
Table 3. Mean annual nut yield, husked nut weight and copra yieldof the different densities. 
Plant density Nut yield Husked nut wt (kg) Copra wt (kg) 
(Palms/ha) per palm per ha per palm per ha per ha 
128 82.83 10602 51.23 6557 2098 
ISO 77.53 11595 46.09 6913 2212 
171 74.12 12674 40.56 6936 2219 
179 66.93 11980 39.47 7065 2260 
205 53.13 10892 31.94 6548 2095 
239 45.91 10972 26.07 6230 1993 
37 
decreased with increasing density without a compensation for the loss of yield/palm 
due to increase in population density. Results indicate that eventhough the palms at 
higher density produced a higher yield at the early stage of growth, the competition 
over time has caused a reduction in yield leading to a lower total yield for densities 
above 179 palms/ha. 
Eventhough the husked nut weight per ha varied from 6230 kg for 239 palms/ha 
to 7065 kg for 179 palms/ha, the differences were not significant (Table 2). 
Furthermore based on the argument of Smith(1972), that the fertile moisture rich 
soils can accomodate more palms than the less fertile moisture stressed soils, 
growers opting for higher densities and within the moisture rich soils of the wet and 
wet-intermediate zones, a maximum density of 200 palms per ha could be used 
following the tradition of using an optimum spacing of 7.6m (25 ft) in a triangular 
system. 
Experimental evidence on root biomass studies of different planting densities in 
coconut show that there is a greater tendency for lateral root expansion particularly 
in the form of primary roots in lower density systems and the development of more 
feeder roots in the higher density systems (Mohd et. al., 1982). Planting at a high 
density, however, is likely to result in intense competition between the young palms 
as they approach maximum leaf area, resulting in an extended period of rapid stem 
elongation, to the detriment of yield (Foale, 1993). 
CONCLUSION 
The choice of spacing and resultant density for coconut is influenced by the 
decision whether to grow the crop in monoculture or to grow it in association with 
intercrops. According to the results of this study, it is beneficial to plant at high 
plant population density, but within the range 171-179 palms per hectare if grown 
in monoculture in dry-intermediate zone. 
ACKNOWLEDGEMENTS 
The authors wish to thank Dr.D V Liyanage former Botanist who initiated this 
field trial on a design prepared by Mr. V Abeywardena, former Biometrician, 
Coconut Research Institute. Thanks are due to the former staff, Genetics and Plant 
Breeding Division for maintenance of the trial and data collection and Dr. R R A 
Peries, Head Genetics & Plant Breeding Division for his helpful comments in 
preparation of this manuscript. 
38 
REFERENCES 
Foale, M. A. (1993).Prospects for future coconut research in the South Pacific: 
Personal view. Coconut Improvement in the South Pacific. AGAR Proceedings. 
No.53: 74-77. 
Manthriratna, M. A. P. P. (1976). Planting densities and planting systems for 
coconut. Cocos nucifera L. 1. A study of vegetative characters. Perak Planters' 
Journal for 1976: 57-59. 
Manthriratna, M. A. P. P. and Abeywardena, V. (1979)< Planting densities and 
planting systems for coconut. Cocos nucifera L. 2. Study of yield characters and 
the economics of planting at different densities.Ceylon Cocon. Q. 30: 107-115. 
Mohd, J. B., Wazir, S. K. S. and Tahir, M. (1982).Early performance of MAWA 
under different planting densities in Hilir Perak, Malaysia. In National Coconut 
Conference, Kuala Lumpur, Malaysia : 12p. 
Pieris, W. V. D. (1935)-Studies on the coconut palm - ii. Trop. Agric. 85: 208-220. 
Smith, R. W. (1972). The optimum spacing for coconuts. Oleagineux 27: 73-86. 
39 


Effect of planting density on the yield of coconut

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