Coconut Research Institute Repository

Fernando, S.C.

Weerakoon, L.K.

Karunaratne, S.M.

Santha, E.S.

cocos (2002-2002), 1445-52
Printed in Sri Lanka
A COST EFFECTIVE MEDIUM FOR PRODUCING EMBRYO CULTURED
COCONUT PLANTS
S C Fernando, L K Weerakoon, S M Karunaratne* and E S Santha
Coconut Research Institute, Lunuwila, Sri Lanka
* University of Queensland, Brisbane, Australia
ABSTRACT
Zygotic embryo culture of coconut is a useful research tool employed
in various fields of crop science. In the present study, the feasibility of
reducing the production cost of embryo-cu ltured coconut plants was
explored . In separate experiments, Analar grade potassium chloride,
sucrose and double distilled water in the Y3 medium were substituted with
Muriate of Potash (fertilizer grade potassium chloride), table sugar and tap
water, respectively. Furthermore, embryos were cultured in a growth
medium devoid of hormones (BAP and 2,4-0).
The results indicated that low cost ingredients can be used in culture
media without affecting the germination and subsequent growth of coconut
embryos. The results also revealed that incorporation of hormones to the
culture medium is not essential. The findings will contribute to reducing the
cost of producing coconut plants in vitro.
INTRODUCTION
Zygotic embryo culture of coconut (Cocos nucifera L.) is a useful tool
for research in various fields, such as germplasm collection, exchange and
storage (Assy-Bah et al., 1987; Karunaratne, 1988), embryo rescue (De
Guzman, 1970; Balaga and De Guzman, 1971; Karunaratne, 1987), disease
transmission (Orense and Pacumbabba, 1988), screening for disease
resistance (Rillo et al., 1988) and drought tolerance (Karunaratne et al.,
1991 ).The first published research on coconut zygotic embryo culture was
carried out by Cutter and Wilson (1954). Since then much work has been
carried out by a number of scientists to improve in vitro culture of coconut
zygotic embryos and the technique has been perfected. Accord ing to our
knowledge, in most of the investigations on zygotic embryo culture of
coconut, culture media contained analytical grade chemicals, which are
costly . Low cost ingredients such as fertilizer grade chemicals and table
sugar have been used in several tissue culture systems to reduce the
production cost (Ganapathi et al., 1995; Purnima, 1997; Sujatha and
Chandran, 1997). In coconut embryo culture, the possible use of tap water
instead of glass distilled water (Areza et al., 1995) and refined table sugar
instead of Analar grade sucrose (E Rillo personal communication) in the
culture medium, was reported recently. These findings encouraged further
45
work on cost reduction in producing embryo cultured coconut plants. The
aim of the present study was to determine the feasibility of reducing the
production cost of embryo cultured coconut plants by using low cost
ingredients and eliminating hormones in the growth medium.
MATERIALS AND METHODS
Mature zygotic embryos were collected from freshly harvested nuts
(12-13 months postanthesis) of Sri Lanka Tall coconut. The embryos were
ste rilized , cultured and incubated as described by Karunaratne et al. (1985).
In separate experiments, Analar grade potassium chloride (KCI), sucrose
and double distilled water in Y3 medium (Eeuwens, 1978) were substituted
with Muriate of Potash (fertilizer grade KCI), table sugar and tap water
respectively. All the other chemicals used for media preparation were of
Analar grade. The possibility of eliminating hormones (BAP and 2,4-0) in
the growth medium was also tested by growing embryos in the growth
medium devoid of hormones. The standard growth medium containing
Analar grade chemicals and hormones was used as the control.
During the course of germination and development of the cultured
embryos, the numbers of germinated embryos, developing into plants,
photosynthetic leaves per plant, primary roots per plant and plant height
were recorded.
Eight replicates each consisting of 20-25 embryos were used for
each treatment. A completely randomized design was used in all the
experiments. The data was analyzed using the analysis of variance. The
percentage data was analyzed using inverse sine transformation.
RESULTS AND DISCUSSION
The results indicated that quality of KCI, sucrose and water (Tables 1
& 2) did not affect the germination and subsequent growth of coconut
embryos. It is note worthy that although commercial grade chemicals were
used in similar quantities as analytical grade, it did not have any negative
effect on embryo germination and plant growth indicating that any impurities
present in commercial grade material had no deleterious effect. Reduction
of production cost of many crops including Melia azedarach L. (Sujatha and
Chandran, 1997), Brassica campestris (Okuno et aI., 1996), Musa spp.
(Ganapathi et aI., 1995) and Zingiber officinale (Sharma and Singh, 1995)
has been achieved by substituting Analar grade sucrose with table sugar.
Furthermore, Malemngahha et al. (1994) have tested a medium prepared by
using a commercial fertilizer formulation, table sugar and coconut water for
Dendrobium spp. embryo culture. The successful use of tap water instead of
46
distilled water in micropropagation of Musa spp. (Ganapathi et al., 1995),
Solanum tuberosum (Purnima, 1997) and Cocos nucifera .(Areza et al.,
1995) has also been reported . Thus the above studies have shown that
commercial grade chemicals could be used successfully in in vitro culture
and the production cost of in vitro-raised plants could be reduced
significantly. The results of the present study are in agreement with these
find ings.
The use of non-ionic water instead of double distilled water and
refined table sugar instead of Analar grade sucrose has resulted in slight
decrease in secondary metabolites content of cell cultures (Zheng et el.,
1982; Jianping et a/., 1996). However, the decrease was not significant
when compared to the cost reduction achieved by using cheaper chemicals.
The results of the present study revealed that coconut embryos
could be germinated and grown successfully in media devoid of hormones.
Furthermore, the number of leaves per plant developed in hormone-free
medium was significantly higher than that of plants developed in the control
medium (Table 3). This would be beneficial as plants having more leaves
will have a better chance of survival during acclimatization. The control
contained 0.1 f.l.M 2,4-0, 5 f.l.M BAP and 0.25 % activated charcoal. Activated
charcoal is added to the culture medium to reduce necrosis as it adsorbs
toxic components released from tissues. However the presence of activated
charcoal in a culture medium results in the reduction of freely-available
hormones due to the adsorption of hormones by activated charcoal (Ebert
and Taylor, 1990). As the adsorption capacities of different types of charcoal
differ, the level of freely-available hormones present in the medium depends
on the type of the activated charcoal. However, Banaobra III et al. (1998)
reported that any brand of activated charcoal could be used satisfactorily for
in vitro culture of coconut embryos. This indicates that the level of hormones
is not critical in coconut embryo culture . Considering the above facts, and
the results of the present study , it can be concluded that incorporation of the
hormones (2,4-0 and BAP) to the culture medium is not essential for growth
of coconut embryos and a hormone-free medium can be recommended for
coconut embryo culture.
The results of the present study indicated the feasibility of using low
cost ingredients in culture media and using media devoid of hormones for
coconut embryo culture. Thus, the findings will contribute to reduction of
cost in producing coconut plants through embryo culture .
ACKNOWLEDGEMENTS
We would like to thank the staff of the Tissue Culture Division for
their assistance in carrying out the experiments. Thanks are also extended
47
to the Head and the staff of the Biometry Division for their assistance in
statistical analysis of data.
REFERENCES
Areza, M. B. B., Rillo, E. P., Cueto , C. A, Ebert, A W. and Orense, O. D.
(1995). Effects of water quality, pH and state of the medium on growth
and development of coconut embryos in vitro. Cord XI(1) , 1-12.
Assy -Bah , B., Durand-Gasselin, T. and Pannetier, C. (1987). Use of zygotic
embryo culture to collect germplasm of coconut (Cocos nucifera L.).
FAOIIBPGR Plant genetic Resources Newsletter 71, 4-10.
Balaga, H. Y. and De Guzman, E. V. (1971). The growth and development
of coconut 'Makapuno' embryos in vitro. II Increased root incidence and
growth in response to media composition and to sequential culture from
liquid to solid medium . Philippine Agriculture 53(10) ,551-565.
Bonaobra III, Z. S., Rillo, E. P. and Orense, S. D. (1998). Effect of different
brands of activated carbon on growth and development of coconut
(Cocos nucifera L.) embryos in vitro. Cord XIV(2) , 1-11.
Cutter, V. M. and Wilson, K. S. (1954). Effect of coconut endosperm and
other growth stimulants, upon the development in vitro of embryos of
Cocos nucifera. Botanical Gazette 115, 234-240.
De Guzman, E. V. (1970). The growth and development of coconut
'Makapuno' embryos in vitro. I The induction of rooting. Philippine
Agriculture 53(2) , 65-78 .
Ebert, A and Taylor, H. F. (1990). Assessment of the changes of 2,4-
dichlorophenoxyacetic acid concentration in plant tissue culture media in
the presence of activated charcoal. Plant Cell Tissue and Organ Culture
20,165-172.
Eeuwens, C.J . (1978). Effects of organic nutrients and hormones on growth
and development of tissue explants from coconut (Cocos nucifera) and
date (Phoenix dactylifera) palms cultured in vitro. Physio!. Plant 42, 173-
178.
Ganapathi, T. R., Mohan, J. S. S., Suprasanna, P., Bapat, V. A and Rao, P.
S. (1995). A low-cost strategy for in vitro propagation of banana. Current
Science 68(6) ,646-650.
48
JianPing, L., GuangZhi, Z., Gan-Fan, Y., LiPing , P., Luo, J. P., Zheng , G. Z.,
Gan, F. Y. and Peng, L. P. (1996). Cost reduction in cell culture of Panax
ginseng for production of oligosaccharins. Acta Botanica Yunnanica
18(2),139-144.
Karunaratne, S. M. (1987). Tissue culture towards better coconut. Coconut
Bulletin 4(1),6-10.
Karunaratne, S. M. (1988). Short-term in vitro preservation of coconut seed
material: A method to facil itate field collection and transport of coconut
germplasm. Cord IV(2), 40-47.
Karunaratne, S. M., Kurukularachchi, C. and Gamage, C. (1985). A report
on the culture of embryos .of dwarf coconut, Coconut nucifera L. var.
nana in vitro. Cocos 3,1-8.
Karunaratne, S. M., Santha, S. and Kovoor, A. (1991). An in vitro assay for
drought-tolerant coconut germp lasm. Euphytica 53, 25-30 .
Malemnganba, H. Bhattacharya, S. and Deka, P. C. (1994). A new cost
effective embryo culture medium for orchids. Journal of the Orchid
Society oflndia 8(1-2), 67-71.
Okuno, K., Matsumoto, K. and Hisajima, S. (1996). A trial of improvement of
micropropagation of Brassica campestris cv. Kukitachina by cost
simulation. Journal of Society of High Technology in Agriculture 8(4),
253-263.
Orense, J. C. and Pacumbaba, E. P. (1988). Transmission of cadang-
cadang by insects and mites. Annual Report of Philippine Coconut
Authority-Albay Research Center 1988,26-27.
Purnima, H. S. (1997). Manipulation of culture requirements for low cost in
vitro tuberization in potato. Journal of the Indian Potato Association 24(3-
4),128-131.
Rillo, E. P., Paloma, M. B. F., Rodrigues, B. J. and Ignacio, M. T. R. (1988).
Screening of coconut populations for resistance to cadang-cadang
disease using in vitro cultured embryos. Annual Report of Philippine
Coconut Authority-Albay Research Center 1988, 39-40.
Sharma, T. R. and Singh, B. M. (1995) . Simple and cost effective medium
for propagation of ginger (Zingiber ' officinale). Indian Journal of
Agricultural Sciences 65(7),506-508.
49
Sujatha, M. and Chandran, K. (1997). A commercially feasible
micropropagation method for Melia azedarach L. Indian Journal of
Experimental Biology 35(7) ,787-791.
Zheng, G. Z., He, J. B. and Wang , S. L. (1982). Studies on tissue culture of
medicinal plants. VI. Costs in the cell culture of Anisodus acutanggulus.
Acta Botanica Sinica 24(3), 209-215.
50
Table 1: Effect of low cost chemicals on growth of in vitro-cu Itured
coconut zygotic embryos
Treatment Germination Plant Plant height Number of Number of
(%) development (em) leaves per primary
(%) plant roots per
plant
Control 78.9 54.1 9.6 1.4 2.4
Se 83.9 53.0 8.9 1.4 2.3
Kf 79.8 45.0 9.7 1.4 2.2
Se + Kf 79.8 62.8 9.4 1.4 2.1
LSD (p=0.05) NS NS NS NS NS
CV(%) 16.2 20.9 21.7 19.2 21.1
Growth measurements of plants were recorded after four and a half months
of culture. Control = Growth medium with Analar grade chemicals, Sc =
Growth medium with table sugar, Kf = Growth medium with Muriate of
Potash (fertilizer grade KCI), Sc-iKf = Growth medium with table sugar and
Muriate of Potash (fertilizer grade KCI) NS = Not significant.
51
Table 2: Effect of water quality on growth of in vitro-cultured coconut
zygotic embryos
Treatment Germinat ion Plant Plant Number of Number of
(%) . development .height leaves per primary
(%) (em) plant roots per
plant
Control 73.4 75.8 24.8 1.8 2.0
(deion ized
water)
Tap water 73.8 70.4 23.9 1.9 1.8
LSD (P=0.05) NS NS NS NS NS
CV (%) 18.5 28.6 7.7 8.4 9.9
Growth measurements of plants were taken after 6 months of culture.
NS =Not significant.
Table 3: Effect of hormones on growth of in vitro-cultured coconut
zygot ic embryos
Treatment Germ inat ion Plant Plant Number of Number of
(%) development height leaves per primary roots
(%) (em) plant per plant
Control (with 68.2 78.5 26.2 1.9 2.0
0.1 ~M 2,4-0
and 5 11M
SAP)
Medium 81.9 76.6 29.4 2.2 2.0
without
hormones
LSD{p=0.05) NS NS NS 0.2 NS
CV (%) 21.9 8.8 10.4 8.7 11.8
Growth measurements of plants were taken after six months of culture.
NS = Not significant, S = Significant.
52


A cost effective medium for producing embryo cultured coconut plants

Everard, J.M.D.T.

Perera, S.A.C.N.

Conservation of coconut genetic resources in Sri Lanka

Fernando, M.T.N.

Peiris, T.S.G.

Tariff changes and its implications on coconut industry

Gamage, C.K.A.

Abscisic acid induced somatic embryogenesis in immature embryoexplants of coconut (Cocos nucifera L.)

Nainanayake, A.D.

Bandara, D.C.

Ranasinghe, C.S.

The impact of soil type, soil compaction and water stress on above and below ground components of coconut (Cocos nucifera L.) seedlings

Fernando, K.S.K.S.

Tennakoon, N.A.

Widanapathirana, S.

COCOS (2000-2002),14 6-18
Printed in Sri Lanka
IDENTIFICATION OF SOIL MICROORGANISMS (BACTERIA ANDFUNGI)
IN DIFFERENT COCONUT GROWING SOILS IN SRI LANKA
Fernando", K.S.K.S., Tennakoon ' , N.A. and Widanapathirana2 , S.
1. Coconut Research Institute, Lunuwila, Sri Lanka
2. University of Kelaniya, Kelaniya, Sri lanka
ABSTRACT
Bacteria and fungi present in the manure circles (rhizosphere) of twenty
selected soil series in coconut growing areas were studied . Bacilli spp were
the dominant bacteria in all soil series. In addition, Micrococcus,
Staphylococcus, Enterobacter, Serratia, Corynebacterium, Pseudomonas and
Actinomycetes were also identified. Among the fungi Penicillium, Aspergillus
and Curvularia were common in most of the soil series.
INTRODUCTION
In Sri Lanka , coconut is grown in different agro-ecological regions of the main
agro-climatic zones, namely the Dry zone, the Intermediate zone and the Wet
zone. Coconut plantations in the Puttalam , Kurunegala, Colombo, Gampaha
and Kalutara Districts comprise the coconut triangle (Somasiri, et al., 1993).
The performance of coconut depends mainly on physical , chemical and
biological properties of soils such as, moisture availability, rooting depth,
aeration, fertility, organ ic matter content, microbial activity etc. (Somasiri , et
el., 1993). The various biochemical processes associated with nutrient
cycling are mediated by soil enzymes which are derived from microorganisms
and plant roots (Tabatabai, 1982). Bacteria, actinomycetes and fungi are the
organisms most actively involved in the decay of organic materials. The
bacteria are the most numerous and most diverse with each species having
specific functions such as cellulose users, pectin decomposers, protein
decomposers, ammonifiers, nitrifiers etc. There are also bacteria with
different adaptation to various environmental conditions. Therefore
identification of microorganisms is very important in determining the soil
quality. The objective of this study was to identify bacter ia and fungi present
in the different coconut growing soils.
METODS
Site selection
Twenty different coconut growing soils within the coconut triangle were
selected for this study. Three locations were selected in each soil series,
where fertil izer or manure has not been applied at least for the last three
years.
6
The selected soil series, locations, major soil types, agro-ecological regions
and mean annual rainfall (mm) are given in Table 1.
Table 1 Selected soil series, major soil types agro-ecological regions
and rainfall of the studied locations (IL - Intermediate Low
Country, WL - Wet Low Country, DL - Dry Low Country)
Soil series Major soil type Locations Agro- 75% of theecological
expected rainfall
region
Rathupasa Latosols and regosols on Dummaladeniya ILl 1000
old red and yellow sands Mahawewa ILl 1000
Koswadiya ILl 1000
Madampe Latosols and regosols on Tummodara ILl 1000
old red and yellow sands Kirimetiyana ILl 1000
Madampe ILl 1000
Sudu Latosols and regosols on Suduwella IL1 1000
old red and yellow sands Karukkuwa ILl 1000
Maradawella ILl 1000
Wilattawa Colluvial members of red Wannirasnayakapura IL3 750-875
yellow podzolics with soft Mahagama ILl 1000
or hard laterites Mudalakkuliya IL3 750-875
Andigama Red yellow podzolics Mudalakkuliya IL3 750-875
Weerakodiyana ILl 1000
Wadumunnegedara ILl 1000
Boralu Red yellow podzolic with Divulapitiya WL3 <1875 >1500
soft or hard laterites Alabodagama WL3 1500
Bogamuwa WL3 >1500
Ambakelle Alluvial soils Sedawatta DLl 750-875
Arachchi kattuwa ILl 1000-1125
Pottukulama IL3 875-1000
Wariyapola Non calcic brown soils Kobeigane IL3 <875
Awulegama IL3 <875
Wariyapola IL3 <875
Maho Non calcic brown soils Alahena IL3 >875
Wannigama IL3 <875
Wariyapola IL3 >875
Melsiripura Reddish brown latosolic Galwarama ILl >1000
soils Adirillawatta WL2 >1875
Panliyadda DLl >750
Warakapola Red yellow podzolic soils Arangalakanda WL2
Wewaldeniya WL2 1500-1875
Neligama WL2-WL3
7
Soil series Major soil type Locations Agro- 75% of the
ecological
expected rainfall
region
Kurunegala Red yellow podzolic soils Metiyagane IL, 750-875
Yaggapitiya ILl 750-875
Ambanpola DL, <875
Kuliyapit iya Red yellow podzolic soils Amangalla ILl >1000IL,
Metiyagane ILl 750-875
Katupotha 1125>1000
Pallama Colluvial members of red Alabodagama W L3 >1750
yellow podzolic with soft Divulapitiya W L3 <1875>1500
or hard laterites Bogamuwa WL3 >1500
Weliketiya Sandy regosols Karambe DG 500-750
Kadiyamutte DL3 500-750
Marawila ILl 1000
Tambarawa Non calcic brown soils Koorikulama IL3 875-1000
Kadigawa IL3 875- 1000
Welipennagahamula ILl 1000
Kalpitiya Sandy regosols Kurunchipitiya DL3 500-750
Palakudawa DL3 500-750
Nawakkad uwa DL3 500-750
Negombo Sandy regosols Kandatoduwawa DL, 500-875
Karukapana IL, 875-1000
Modarawella ILl 1000
Gamb ura Red latosols Vijayapura DL3 575-750
Bodhirajapura DL3 575-750
Sirambiadiya DL3 575-750
Katunayaka Latosols and regosols Welihena WL, >1500
Ekala WL 4 >1500
Kadirana WL, >1500
Sampling procedure:
Soil samples were taken from the manure circles (within 1.75 m radius from
the base of the palm) . Four samples of soil from 0 - 15 cm were drawn from
four positions of each manure circle and mixed and prepare a composite
sample. Sampled soils were passed through 2 mm sieve and mixed well to
get a composite sample and were stored at 0-4 °C in polythene bags until
isolation of microorganisms.
Isolation of Microorganisms
For the isolation of both fungi and bacteria , first, the Dilution Plate technique
was carried out under asept ic conditions using Potato Dextrose Agar and
Nutrient Agar , respectively (Parkinson, et al., 1971). Colon ies of different
external appearance, from mixed populat ion, were streaked on separate
Nutrient Agar media. Pure cultures were then obtained by re-strea king those
8
colonies several times in same media. Bacterial identification was carried out
using pure cultures obtained from morphologically different bacterial colonies
grown in nutrient agar. Later they were subjected to basic morphological
tests (colony morphology, pigmentation, staining characteristics, shape and
arrangement of cells, motility, presence or absence of spores) and thereafter
bio-chemical characteristics were tested (Cowan and Steel , 1974, Sneath,
1986). Identification of fungi was carried out following the keys and by the
microscopic examinations of the structures (Onions, et al., 1981).
RESULTS AND DISCUSSION
Identification of bacteria
The bacteria identified in different soil series are presented in Table 2.
Different types of bacteria i.e, Bacillus spp, Micrococcus spp, Staphylococcus
sp, Enterobacter sp, Serratia sp, Corynebacterium sp, Pseudomonas sp and
Actinomycetes sp were found . Most of these bacteria are commonly found in
tropical soils. Bacillus spp were the dominant bacteria in all the soil series. In
addition to Bacillus species, Micrococcus luteus, Enterobacter cloacae and
Pseudomonas aeruginosa were also prominent in most of the soil series.
Some of bacteria were specific to some soil series, i.e. Bacillus thuringiensis
was found only in Katunayake soil series; Aerococcus viridans was found in
only Weliketiya soil series; Bacillus pasteurii was found in only Pallama soil
series. A greater number of bacterial species was found in soil series such as
Rathupasa, Kalpitiya, Ambakelle, Boralu , Katunayaka and Melsiripura which
can be considered as fertile or soil series with high nutrient availability.
ldentlflcatlon of fungi
Fungal species identified in different soil series under investigation are shown
in Table 3 and some common fungi species are shown in Plates 1 to 8.
Fungal species such as Penicillium, Aspergillus, Mucor, Rhizopus, Absedia,
Syncephalastrum, Mortierella, Curvularia, Humicola, Ulocladium, Fusarium
and Trichoderma were present in most of the soil series and Penicillium spp,
Aspergillus spp and Curvularia spp were the most abundant species in the
coconut growing soils. Aspergillus japonicus and Aspergillus niger were found
in all soil series while Penicillium frequentans was the next most common.
9
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Some fungi species present in the soil
Penicillium species
Aspergillus species
12
Rhizopus species
Mortierella species
13
Curvularia species
Humicola species
14
Fusarium species
Trichoderma species
15
Some fungi species were specific to some soil series i.e. Trichoderma sp in
Pallama, Boralu and Melsiripura soil series. Ulocladium sp in Rathupasa and
Madampe soil series; Rhizopus sp in Rathupasa, Kurunegala and Melsiripura
soil series; Penicillium citreonigrum in Rathupasa and Katunayaka soil series;
Penicillium oxalicum in Negombo , Warakapola and Pallama soil series;
Aspergillus terreus in Weliketiya and Wariyapola soil series ; Fusarium
moniliforme in Wariyapola and Thambarawa soil series; Aspergillus
ochraceus in Weliketiya and Gambura soil series.
More fungal species were found in Rathupasa, Madampe and Ambakelle soil
series which can be considered as fertile soils or having more available
nutrients than the other soil series.
Soil microorganisms are of critical importance in nutrient cycling processes ,
and also as sources and sinks of plant nutrients. Bacteria are the most
prominent among the soil microbes usually more numerous than the others
(Alexander, 1977). Bacillus were the predominant bacteria isolated from
every soil series in the present study. The soil series considered in this study
are from various agro-climatic zones and vary in their physical and chemical
properties. Some of the soil series had favourable properties for microbial
growth while others did not. But Bacilli were found in both categories. This is
probably because Bacilli has the ability to persist in unfavourable conditions
by the formation of endospores. These endospo res show resistance to both
prolonged desiccation and high temperature.
In addition to Bacilli, bacteria such as Micrococci, Staphylococci,
Enterobacter, Serratia, Corynebacterium, Pseudomonas, Aerococcus,
Erwinia and Actinomycetes were also commonly in coconut growing soils.
These types of bacteria are capable of utilizing various organic compounds
present in the soil. Pseudomonas and Bacilli are capable of utilizing cellulose ,
hemicellulose, starch and proteins; Serratia and Micrococcus have the ability
to use starch; Corynebacteria proteins; Bacilli and Pseudomonas have the
phosphate solubilization ability (Verma, 1998; Wani and Lee, 1995).
Some soil series e.g. Rathupasa, Kalpitiya, Ambakelle, Boralu, Katunayake
and Melsiripura had more bacterial species than the other soil series. This
may be due to the presence of favourable conditions for microbial growth in
these soils. Most of these soils have a higher amount of organic C content
than the other soil series.
Fungi are also an important biological factor in the soil. Among the identified
fungi, Penicillium, Aspergillus and Curvularia were common as reported by
Cosico (1994). Fungi such as Mucor, Rhizopus, Absedia , Syncephalastrum,
Mortierella, Humicola, Ulocladium and Trichoderma were also found in this
study. Anderson and Anderson (1986) reported that fungi are the main
16
cellulose decomposing organisms and these include Trichoderma, Fusarium,
Penicillium , Aspergillus and Curvularia .
Some soil series have shown more fungi species. This may be due to the
favourable environmental conditions of these soils which affect the growth of
fungi.
CONCLUSION
Some bacteria and fungi were specific to certain coconut growing soils i.e.
Bacillus thuringiensis only in Katunayake series, Staphylococcus epidermidis
in Kuliyapitiya and Ambakelle and Melsiripura series, Alcaligenes odorans
only in Negombo and Melsiripura series; Serratia marcescens only in
Madampe soil series. Fungal species Trichoderma species in Pallama,
Boralu and Melsiripura soil series; Uloc/adium sp only in Rathupasa and
Madampe series; Rhizopus species in Rathupasa, Kurunegala and
Melsiripura soil series. Growth of bacteria and fungi are mediated by
environmental condition. Therefore certain type of microorganisms grow in
environments where they have favourable conditions. Soil series differ from
each other in chemical and physical properties . Therefore according to their
physical and chemical properties specific microorgan isms were found in
specific soil series.
REFERENCES
Alexander, M. 1977. Introduction to soil microbiology. John Willey & Sons,
New York.
Anderson and Anderson, 1988. The Philippine Agriculturist. 77 (1): 67-76.
Cosico, W.C. 1994. Are microbial innoculants necessary in composting . The
Philippine Agriculturist 77(1): 67-76.
Cowan, S.T. and Steel, 1974. Identification of Medical Bacteria. Cambridge
University Press.
Medoza, N.S. and Joson, L.M. 1986. Isolation, selection and characterization
of cellulose degrading fungi. Philippine Journal of Science 115(1): 31-41.
Onions, A.H.S., Allsopp, O. and Eggins, H.O.W. 1981. Smith's Introduction to
Industrial Mycology. (Seventh edition), Edward Arnold Publishers Limited,
41, Bedford Square, London, WCLB 300.
17
Parkinson, D., Gray, T.R.B. and Williams, S.T. 1971. Methods for studying
the ecology of soil microorganisms. p 36-51,64-66,71-101. IBP
Handbook No. 19. International Biological Programme, London, NWI.
Sneath, P.H.A. 1986. Bergy's Manual of Systemic Bacteriology 2: 1104-1125.
Somasiri, L.L.W., Nadarajah, N., Amarasinghe, L. and Gunethilaka, H.A.J.
1993. Land Suitability Assessment of Coconut Growing Lands in the
Coconut Triangle. Coconut Research Institute, Lunuwila, Sri Lanka.
Tabatabai, M.A. 1982. Soil enzymes. In: Methods of Analysis. Part II 2nd
edition (eds. Page et al.,) Agronomy 9: 903-947.
Verma, L.N. 1995. Cibservation and efficient use of organic sources of plant
nutrients. In: Organic Agriculture (ed. P.K. Thampan) Peekay Tree Crops
Development Foundation. Cochin - 682020, Gandhi Nagar, Kerala, India.
Wani, S.P. and Lee, K.K. 1995. Microorganisms as biological inputs for
sustainable agricu lture. In: Organic Agriculture (ed. P.K. Thampan)
Peekay Tree Crops Development Foundation. Cochin - 682020, Gandhi
Nagar, Kerala, India.
18


Identification of soil microorganisms (Bacteria and fungi) in different coconut growing soils in Sri Lanka

Perera, L.

Russell, J.R.

Provan, J.

Powell, W.

Use of microatellite DNA markers to investigate the level ofgenetic diversity and population genetic structure of coconut(Cocos nucifera l.)

Daw, M.E.

Edwards, I.E.

Adoption of coconut-based intercropping systems in Sri Lanka: The fallacy of conventional wisdom on economic profitability

Gunathilake, H.A.J.

Senarathna, S.H.S.

Samarajeewa, A.D.

Weed management in coconut lands

Genetic diversity of coconuts (Cocos nucifera L) assessed by microsatellite DNA markers.

National Science Foundation of Sri Lanka

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