H
O R T
S
CIENCE
26(11):1395-1397. 1991.
Cold Storage of Selected Members of
the Proteaceae and Australian Native
Cut Flowers
Rod Jones and John Faragher
Institute of Plant Sciences, Knoxfield, Department of Agriculture,
Victoria, PO Box 174, Ferntree Gully 3156 Australia
Additional index words. Leucospermum spp., Protea spp., Leucadendron, Thryptomene
calycina , Telopea speciosissima , Chamelaucium uncinatum , Vertcordia spp . ,
Anigozanthos spp., postharvest physiology, vase life
Abstract. Five members of the Proteaceae and 13 Australian native cut flower culti-
vars were stored for 35 days under standard conditions at 1C to assess their ability to
withstand long-term storage and transport. Protea cynaroides L., Leucadendron ‘Silvan
Red’, Leucospermum ‘Firewheel’, Thryptomene calycina (Lindl.) Stapf., Telopea spe-
ciosissima R. Br., and Verticordia grandtiflora Endl. retained a vase life of at least 7
days after 21 days of storage. Leucospermum cordifolium Salisb. ex Knight, Protea
neriifoli R. Br., Chamelaucium uncinatum ‘Alba’, C. uncinatum ‘Purple Pride’, Ver-
ticordia monadelpha Turcz., Verticordia plumosa (Desf.) Druce, and Verticordia nitens
(Lindl.) Schau. suffered a decline in vase life ranging from 31% to 100% after 14 to
21 days of storage. Species of Verticordia and Chamelaucium were particularly suscep-
tible to fungal infection. Anigozanthos pulcherrimus Hook. and the Anigozanthos cul-
tivars Ruby Delight, Bush Harmony, Bush Haze, and Gold Fever all showed a significant
reduction in vase life after 14 days of storage compared with unstored controls.
Early research on the postharvest handling
of cut flowers demonstrated the potential of
dry storage in the rose, carnation, and chry-
santhemum (Fischer, 1952; Hauge et al.,
1947; Neff, 1939; Thornton, 1930). Recent
studies have also concentrated on storage
protocols for traditional flower crops (Gosz-
czynska and Rudnicki, 1988; Hardenburg et
al., 1986) The rapid expansion of the Aus-
tralian cut flower industry has resulted in a
marked increase in the export trade of Aus-
Received for publication 21 Mar. 1991. This work
was partially- funded by a grant from the Rural
Industry Research Development Corn. We thank
Ausflora Pacific Pty. Ltd.; The Australian Protea
Growers Assn., Australian Flower Exporters Ply.
Ltd, and Growth Industries Ltd. for supplying the
flowers used in this study. We are also greatly
indebted to Janyce Truett for her skilled technical
assistance and Peter Franz for assistance with sta-
tistical analysis. The cost of publishing this paper
was defrayed in part by the payment of page
charges. Under postal regulations, this paper
therefore must be hereby marked advertisement
solely to indicate this fact.
H
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. 26(11), N
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1991
tralian native cut flowers, particularly Cha-
melaucium uncinatum (Geraldton waxflower),
Anigozanthos cultivars (kangaroo paw), and
members of the Proteaceae. In the few stor-
age trials conducted using these crops, the
vase life of Telopea speciosissima (waratah)
was reduced by 25% after 28 days of storage
at 1C (Faragher, 1986), while vase life in
Anigozanthos rufus and Chamelaucium un-
cinatum was significantly reduced by 14 days
of storage at 1C (Joyce, 1988; Seaton and
Joyce, 1989). P. cynaroides and L. cordi-
folium withstood 42 days of dry storage at
2C without reduction in vase life (Haasbroek
et al., 1973; Ireland et al., 1967; Meynhardt,
1976). During a transient period of high air-
freight costs, successful seafreight of cut
Protea flowers from Cape Town, South Af-
rica, to Rotterdam, Holland, was completed
by several South African Protea growers in
1980 using refrigerated containers, but no
data exist on storage and transport protocol
(J. Wood, personal communication). Stor-
age protocols and conditions differed widely
between these trials, and in many cases the
criteria for determining the end of vase life
were not cited. The aim of this study was to
assess the storage capacity of a wide range
of commercial Australian native cut flowers
and members of the Proteaceae family using
specific vase life criteria and under a stan-
dard storage protocol. Cultivars that were
suited to long-ten dry storage were deter-
mined to be those that retained a vase life of
at least 7 days after 21 days of storage.
Verticordia spp. were obtained from
Western Australia and airfreighted to Knox-
field within 30 h of harvest. The Chamelau-
cium and Anigozanthos cultivars were
harvested from commercial flower growers,
cooled for 6 h, and transported dry for 6 to
12 h to the laboratory. All other flowers were
harvested locally and transported in water,
arriving at the laboratory within 3 h of har-
vest. Control, unstored flowers were sprayed
with 1 g iprodione/liter (wettable powder,
50% a.i.; commercial name: Rovral, Rhone
Poulenc, Melbourne, Australia) and placed
in water at 1C for 24 h, then removed to 20C
for vase life assessment. Stored blooms were
thoroughly sprayed with 1 g iprodione/liter,
allowed to dry, and kept at 1C for 24 h while
standing in distilled water. Preliminary trials
indicated that a pre- and poststorage treat-
ment in water lasting at least 24 h was most
effective (data not shown).
Flowers were bunched and tightly wrapped
in two layers of newsprint and placed in low-
density polyethylene bags (~38 µm thick).
These were then placed in fiberboard flower
boxes (1030 x 370 x 160 mm) and stored
in a room set at 1 ± 1C and 80% ± 5%
relative humidity (RH). A nonstored control
group was placed directly into the evaluation
Table 1. Criteria used for determining end of
vase life.
1395
Fig. 1. Fitted curves representing changes in vase
life after dry storage at 1C in members of the
Proteaceae. 1) L. cordifolium ( r ); Y =
10.66
–
0 . 1 2 9 X
–
0.00596X; Adj. R
2
=
60.4. SE = 0.128X; 0.00353X
2
. 2) Firewheel
(
t ); Y = 9.68 + 0.033X - 0.00756X
2
; Adj.
R
2
= 39.4.
S E
= 0.137X; 0.00378X
2
. 3) P.
cynaroides
(◊);
Y = 7.83 - 0.0883X; Adj.
R
2
= 17.9.
SE
= 0.0389X. 4) P. neriifolia
(∆);
Y = 6.58 – 0.374X + 0.00542X
2
; Adj.
R
2
= 76.4. SE = 0.0508X; 0.004X2. Where
Y = vase life (days); X = storage time (days).
room. After storage, the flowers were un-
wrapped, the stems recut and rehydrated at
1C in distilled water for 24 h, with flower
heads covered with a polyethylene bag sim-
ilar to that used in packing to increase rela-
tive humidity in the air surrounding the flower
heads. Vase life was evaluated at 20C and
55% to 65% RH under constant light (10
µmol·m
-2
·s
-1
) supplied by cool-white flu-
orescent lamps. Criteria used to specify the
end of vase life for each species and cultivar
were defined (Table 1).
Each treatment (storage time) consisted of
10 replicate stems, and each storage trial was
repeated twice. Regression analysis was per-
formed on the data. Those stems infected
with fungal growth during storage were ar-
bitrarily assigned a vase life of zero, and
these values were included in the calculation
of mean vase life.
Proteaceae. Leucadendron ‘Silvan Red’,
Leucospermum ‘Firewheel’, and Protea cy-
naroides retained a vase life of at least 7 days
after 21 days of storage (Figs. 1 and 2). The
vase life of ‘Silvan Red’ had decreased by
only 11% (25 days compared with 28 days
in unstored controls) after 28 days of storage
Fig. 4. Fitted curves representing changes in vase
life in Verticordia spp. after dry storage at 1C.
1) V grandiflora (o); Y = 13.67 + 0.1049(X)
– 0 . 0 1 4 9 9 ( X
2
); Adj. R
2
= 9 2 . 9 . S E =
0.0587(X); 0.0016(X
2
). 2) V. nitens (
t );
Y =6.503 – 02012(X); Adj R
2
= 72.0.
SE
= 0.0178(X). 3) V monadelpha
(◊).
N o
regression equation. 4) V. pulmosa (A). No
regression equation. Where Y = vase life (days);
X = storage time (days).
Fig. 2.
Fitted curve representing change in vase
life in Leucadendron ‘Silvan Red’ after dry
s t o r a g e a t 1 C . Y = 2 7 . 7 2 + 0 . 1 5 6 X –
0 . 0 0 6 2 6 X
2
, Adj. R
2
= 25.2.
SE
= 0.182X
2
,
0.00321X
2
. Where Y = vase life (days); X =
storage time (days).
(Fig. 2), and storage was therefore continued
for an additional 21 days. ‘Silvan Red’
maintained a commercially acceptable vase
life of 19 days even after 49 days of storage
(Fig. 2).
Poststorage vase life of Leucospermum
cordifolium declined rapidly after 14 days of
storage, mainly due to fungal infection (data
not shown). A more effective anti-fungal
treatment than we used probably would dra-
matically improve poststorage vase life in
this flower. Preliminary trials with L. cor-
diforium indicated that stems not infected with
fungal rot during storage had a vase life of
at least 7 days after 21 days of storage.
Cold storage-induced leaf blackening after
14 days of storage in P. neriifolia resulted
in a short poststorage vase life. Storage-in-
duced leaf blackening was not observed in
P. cynaroides.
Australian native cut flowers. Generally,
Australian native cut flower species stored
in these trials did not withstand the rigors of
dry storage as well as members of the Pro-
teaceae family (Figs. 3,4, and 5). However,
vase life in Thryptomene calycina and Tel-
opea speciosissima did not change signifi-
cantly after 21 days of storage (11 and
7
Fig. 5. Fitted curves representing vase life in
kangaroo paw cultivars after dry storage at 1C.
1) ‘Gold Fever’ ( r ); Y = 13.3 – 0.578X +
0 . 0 0 6 5 9 X
2
. Adj. R
2
= 83.5.
SE
= 0.0757X;
0.00208X
2
. 2)A. pulcherrimus (
t ); Y = 12.17
– 0.521X + 0.0059X
2
. Adj. R
2
= 72.0. S E
= 0.0941X; 0.0826X
2
. 3) ‘Bush Harmony (0);
Y = 6.45 – 0.01X – 0.0042X
2
. Adj. R
2
=
69.5. SE = 0.0498X; 0.00138x2.4) ‘Bush Haze’
(∆);
Y = 7.1 – 0.1726X; Adj. R
2
= 80.8.
SE = 0.012X. 5) ‘Ruby Delight ' ); Y = 6.53
– 0.162X; Adj. R
2
= 73.6.
SE
= 0.014X.
Where Y = vase life (days); X = storage time
(days).
Fig. 3.
Fitted curves representing changes in vase
life in selected Australian native cut flowers after
dry storage at 1C. 1) T. speciosissima ( r );
Y = 8.273 + 0.1744X – 0.00566X
2
. Adj.
R
2
= 8.3.
SE
= 0.0847X; 0.00234X
2
. 2) T.
calycina (
t ); Y = 6.622 + 0.1341X –
0 . 0 0 4 8 2 X
2
. Adj. R
2
= 19.0.
SE
= 0.0552X;
0.00153X. 3) C. uncinatum ‘Alba’
(◊);
Y =
8.847 – 0.4657X + 0.00756x2. Adj. R
2
=
81.7. SE = 0.0489X; 0.00135X
2
. 4) C. uncin–
atum ‘Purple Pride’ (
∆
);Y = 7.8 – 0.4582X
+ 0.0069X
2
. Adj. R
2
= 83.8.
SE
= 0.0478X,
0.00132X
2
. Where Y = vase life (days); X =
storage time (days).
days, respectively; Fig. ,3).
Verticordia grandiflora maintained a vase
life of 10 days after 21 days of storage (Fig.
4), after which vase life declined severely,
whereas the vase life of all other species of
Verticordia declined significantly after 14 days
of storage. No regression analysis was per-
formed on V. monadelpha and V. plumosa
as no stems survived after 14 days of stor-
age.
Significant floral abscission occurred in T.
calycina after 28 days of storage
(≈15%
to
20% of flowers). As there was no further
abscission during vase life assessment, these
stems were rated in a similar manner as con-
trol stems. Observations during preliminary
trials indicated that abscission became a ma-
jor problem during storage only when flow-
ers are harvested late in the season and in
full flower.
The vase life of stored T. speciosissima
was 8 days after 35 days of storage, similar
to the vase life of unstored control stems
(Fig. 3). Faragher (1986) reported that war-
atah vase life was reduced by 50% (from 6
to 3 days) if stems were stored at 4C, or if
flowers were stored unwrapped, indicating
the importance of low temperature (1C) and
the need to maintain flower hydration during
storage with adequate wrapping.
Quality in both C. uncinatum ‘Alba’ and
‘Purple Pride’ declined rapidly after 14 days
of storage (Fig. 3). Stems of C. uncinatum
were stored with a similar reduction in vase
life by Seaton and Joyce (1989). C. uncin-
atum suffered from fungal attack (identified
as Botrytis cinerea Pers.) in these trials, de-
spite a prestorage spray with 1 g iprodione/
liter, resulting in poor poststorage vase life.
Fungal infection was also prevalent in all
Verticordia spp. and kangaroo paw cultivars
after 21 days of storage. When present, it
effectively ended vase life immediately after
storage. The Veticordia spp. were not treated
with an antifungal agent before air transport
from Western Australia to Victoria, and con-
ditions during transit (high temperature, high
1396
H
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1991
relative humidity) possibly were conducive
to fungal attack. Subsequent spraying with
1 g iprodione/liter was not sufficient to pre-
vent further fungal infection.
The evaluation of other anti-fungal agents
and spraying/dipping techniques has estab-
lished the anti-fungal potential of a mixture
of 1 g iprodione/liter and 1 g mancozeb/liter
(wettable powder, 80% a.i.; commercial
name: Mancozeb, suggested by D. Joyce;
data not shown). An effective anti-fungal
treatment that can be applied immediately
after harvest to improve the storage perform-
ance of C. uncinatum and Verticordia spp.
possibly will be developed.
Kangaroo paw cultivars with a long con-
trol vase life (Anigozanthos pulcherrimus and
the cultivar Bush Fever) suffered a substan-
tial reduction in vase life after 14 days of
storage (Fig. 5), leaving all kangaroo paw
cultivars with a vase life of <7 days after
14 days of storage. Seaton and Joyce (1989)
reported a dramatic decrease in vase life when
Anigozanthos rufus cut flowers were stored
for 2 weeks at 0C. Vase life significantly
increased in unstored kangaroo paws pulsed
with sucrose solutions of up to 30% (Carter
et al., 1989; Manning et al., 1989), and it
is possible that pre- and poststorage treat-
ment with a sucrose solution might extend
vase life significantly.
The vase lives cited in this study represent
a minimum value. Further improvements of
this storage protocol, including more ad-
vanced packaging techniques and the use of
solutions containing a germicide and sucrose
in the precooling and rehydration phases,
should improve the length of storage possi-
ble and the condition of flowers after stor-
age.
Our results suggest that Leucospermum
‘Firewheel’, Protea cynaroides, Leucaden-
dron ‘Silvan Red’, Thryptomene calycina,
Telopea speciosissima , and Verticordia
grandiflora can be stored for at least 21 days
and retain a commercially acceptable vase
life of at least 7 days. Vase life of stored
Leucospermum cordifolium, Chamelaucium
uncinatum ‘Alba’ and ‘Purple Pride’, Ver-
ticordia monadelpha, Verticordia plumosa,
Verticordia nitens, Anigozanthos pulcherri-
mus, and the Anigozanthos cultivars Ruby
Delight, Bush Harmony, Bush Haze, and
Gold Fever declined significantly compared
with unstored controls. Australian native
species were susceptible to fungal attack
during storage. Effective anti-fungal treat-
ments may extend the storage period and vase
life of these species.
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