Title: TropicLine
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Permanent Link: http://ufdc.ufl.edu/UF00089450/00009
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Title: TropicLine
Series Title: TropicLine
Physical Description: Serial
Language: English
Creator: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Ft. Lauderdale, Fla.
Publication Date: May/June 1994
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Bibliographic ID: UF00089450
Volume ID: VID00009
Source Institution: University of Florida
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TropicL ineVolume 7, Number 3, May-June, 1994


Editor: Alan W. Meerow
Christine T. Stephens, Dean, Cooperative Extension


Coir (Coconut Mesocarp Pith) as a Peat Substitute

Alan W. Meerow

Palm and Tropical Ornamentals Specialist

Peat used in soilless container media for commercial plant production is harvested from
wetland ecosystems at rates considered non-sustainable by wetland ecologists (Barber,
1993; Barkham, 1993; Buckland, 1993). While the peat industry argues that peatlands can
be managed at sustainable levels (Robertson, 1993), it recognizes that alternatives to peat
must be developed in order to meet environmental concerns of consumers and contend
with increased regulation of peatland exploitation (Bragg, 1990; Robertson, 1993).

Previously (TropicLine 6(2): 1-4), I reported on the potential of coir dust (the short fibers
and dust left behind after the industrially valuable long fibers of coir are extracted from the
coconut husk) as a peat substitute. Here, I report on tests of coir dust as a 40% constituent
in media for four oramental crops: ixora, pentas, majesty palm, and anthurium.

Materials and Methods

In the first experiment, 30 liners of Ixora coccinea 'Maui' and Pentas lanceolata 'Starburst
Pink,' and 20 liners of Anthurium 'Lady Jane' were potted into 3.7 liter containers of 5:4:1
(v:v) non-composted pine bark, either sedge peat or coir pith and sand on 13 Apr 1993.

Twenty-five liners of Ravenea rivularis (Majesty palm) were potted into 7.4 1 containers of
the same medium. In the second experiment, 15 liners of the same species were potted into
3.7 liter containers of 5:4:1 (v:v) non-composted pine bark, either sphagnum peat or coir
pith and sand on 8 Aug 1993. All media were amended with 9.5 kg.m-3 Osmocote
17N-2.3P-10K, 4.16 kg.m-3 dolomite, and 1.2 kg.m-3 Micromax. Fifteen to thirty replicate
plants, respectively for the two experiments, of each treatment were arranged in a
completely randomized design in full sun (max PPF=2100 umol.m-2.sec-1; ixora and
pentas), 50% shade (majesty palm) or 63% shade (anthurium) and irrigated as necessary.
Height and width measurements were taken at inception and again at termination from
which a growth index was calculated (net change in height + net change in width). At
termination, tops and roots were harvested, dried, and weighed. For the ixora and pentas,
the first trials were terminated on 27 Jul 1993 (Pentas) and 7 Sep 1993 (Ixora); the second


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on 8 Nov 1993 (Pentas) and 4 Jan 1994 (Ixora). The anthuriums and majesty palms were
harvested on 15 Dec 1993 (coir/sedge trials) and 4 Apr 1994 (coir/sphagnum trials).

Data were analyzed using ANOVA and Tukey's Studentized Range test. Physical
parameters, pH and conductivity (eC) of the media were determined at inception and again
at termination for three replicate samples of each medium exposed to the same conditions
as the plants, but in which no plant was grown. Measurement of pH and eC used the
saturated paste extract method (Bunt, 1988).

Results

Pentas, ixora and majesty palm grown in coir-based media were superior in all growth
parameters measured to those grown in sedge peat-based media (Table 1). The ixora in
particular averaged nearly a fourfold, sixfold, and fivefold increase in growth index, top
dry wt and root dry wt, respectively, in the coir-based medium as compared to sedge peat.
The anthurium had significantly better top weight and growth index in the coir-based
medium, but root dry weight equal in both sedge and coir-based medium. However, the
differences in growth between sedge-grown anthurium and coir-grown anthurium were not
as significant as with the other crops.

The sedge peat-based medium had the greatest per cent air space and the lowest
water-holding capacity of the three media at the initiation of the trials but at termination,
showed considerable reversal of these parameters (Table 3). The coir-based medium
showed the least change in these parameters over time.

There were no significant differences between growth, top or root dry weight of anthurium
or majesty palm in coir-based vs. sphagnum peat-based media. Growth and top dry weights
were similar for coir- and peat-grown pentas, but root dry weight was greater for
coir-grown pentas plants (Table 2). The ixora had significantly greater growth and top dry
weight in the sphagnum peat-based medium versus coir, but no difference in root dry
weight (Table 2). These differences were not as large as observed between coir and sedge
peat.

The better growth of ixora in sphagnum-based medium as compared to coir-based medium
could have been due to nitrogen drawdown in the coir-based medium.

Conclusions

On the basis of plant growth parameters, coir pith was superior to sedge peat as a medium
component (though only marginally for the anthurium) and at least equal to sphagnum peat
for all crops tested except ixora. In this latter case, higher rates of nitrogen fertilization
might have overcome the difference. The physical characteristics of coir pith appear more
stable over time than either sedge peat or sphagnum peat.

For most plant producers in the United States, the primary decision on whether to use this


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material as a substitute for peat will likely be economic, and secondarily environmental.
Sedge peat, despite its disadvantages, is very inexpensive relative to sphagnum. If high
quality coir dust can be brought into the United States at a price competitive with
sphagnum peat, it should find a ready market among users of the latter.

Literature Cited

Barber, K. E. 1993. Peatlands as scientific archives of past biodiversity. Biodiv. Conserv. 2: 474-489

Barkham, J. P. 1993. For peat's sake: conservation or exploitation? Biodiv. Conserv. 2: 556-566.

Bragg, N. C. 1991. Peat and Its Alternatives. Horticultural Development Council, Petersfield.

Buckland, P. 1993. Peatland archaeology: a conservation resource on the edge of extinction. Biodiv. Conserv.
2: 513-527.

Bunt, A. C. 1988. Media and Mixes for Container-Grown Plants. Unwin Hyman, London.

Cresswell, G. C. 1992. Coir dust a viable alternative to peat? Pp. 1-5 in: Proceedings of the Australian
Potting Mix Manufacturers Conference, Sydney.

Pryce, S. 1991. Alternatives to peat. Pro. Hortic. 5: 101-106.

Robertson, R. A. 1993. Peat, horticulture and environment. Biodiv. Conserv. 2: 541-547.


Table 1. Growth of Pentas lanceolata 'Starburst Pink,' Ixora coccinea 'Maui,' Anthurium
'Lady Jane,' and Ravenea rivularis in coir- and sedge peat-based media.

Species Medium Growth Index' Top dry wt. Root dry wt.
( ll c ) ( ) (l2)
'//ih/ li//n ie l//hi 'Sttlbui bi. .. Pink' Coli ._ 51 i1a lj 311

Sedge ,101b 2819b 5.07b

,l\i C /L / /L 1 /1'i 'N Iaill' Col 2 44 211 II 11

Sedue 1 ob ,b (Ib

Anthurium 'Lady Jane' Coir 58.30a 18.49a 10.61a

Sedue 53 148 1 233

Ravenearivularis Coir ,.16az 120.83a 53.35a

Sedue b 3_ -43 35- )


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ZNet increase in leaf number was used as the growth index for Ravenea rivularis

YMean separation by Tukey's Studentized Range Test. Means within each comparison with the same letter
are not significantly different


Table 2. Growth of Pentas lanceolata 'Starburst Pink,' Ixora coccinea 'Maui,' Anthurium
'Lady Jane,' and Ravenea rivularis in coir- and sphagnum peat-based media.


Species


Pentas lanceolata 'Starburst Pink'


~lIedltum GCo\\ th Inlde\

(cm)
Coir 59.40ay


Sp~haulnuiu ~~ll


1\'i / C Lt / I/t'/ 'NT lLII'


Colr


43 V3
24 stb


4n( 3b


Sphagnum 54.91a


.A4/!whilnlm 'Lad\ Jane'


Coln


52 -3


Sp)haMUHnuiu 5- fij,"


Ravenea rivularis


24 "13a


12 ~3a

12 ii


Coir


Sp~haulnuiu -~~


-. -1a


22" Sil 1


ZNet increase in leaf number was used as the growth index for Ravenea rivularis

YMean separation by Tukey's Studentized Range Test. Means within each comparison with the same letter
are not significantly different


Table 3. Physical characteristics of coir-, sedge peat- and sphagnum peat-based media. Mean of three
samples (std dev).


% Air space %
Atier 5 iios.
11.0 (0.2)
9. (1.0)
8.5 (0.8)


After 8 inos.
9." (0.5)
8.5 (0.8)
8.1 (1.1)


Initial
35." (1.2)
29.8(1.4)
36.9(1.1)


Water-holding capacity
After 5 inos.
39.2 (1.0)
45.4 (2.0)
43.4 (0.6)


After 8 inos.
39.8(1.2)
46." (0.6)
45.3 (0.5)


Table 4. pH and eC of coir-, sedge peat- and sphagnum peat-based media. Mean of three samples (std dev).


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Top dr \\ t

(g)
4-16.13a


Root d \\ t

(g)
".00a


Nledilumi


(oir
Sedge
Spl )ha .


Initial
13." (0.")
23.1 (2.")
14.5 (1.5)


1) Illb
(14'
,_ l4ob


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Initial After 5 mos. A\ter 8 mos.
5.6(0.1) 6.3 (0.1) 6.3 (0.1)
5.6 (0.2) 6.6 (0.3) 6." (0.2)
4.9(0.1) 6.1 (0.0) 6.3 (0.2)


eC (dIS 'n)
Initial .Afer 5 Imos. .Afer 8 mos.
3.1 (1.3)) 1.6(0.6) 0.31 (0.13)
2.4 (1.5) 1." (1.2) 0.40 (0.0")
2.6 (0.9) 1.4(0.9) 0.36 (0.20)


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Coii
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