Economically Sustainable Sphagnum Moss Products Grant No. 03/087

Transcription

Economically Sustainable Sphagnum
Moss Products
Grant No. 03/087
Yu J
August 2006
Report to the West Coast Development Trust and the MAF Sustainable
Farming Fund
HortResearch Client Report No. 13386
HortResearch Contract No. 19046
Yu J
The Horticulture and Food Research Institute of New Zealand Ltd
HortResearch Ruakura
Private Bag 3123
Waikato Mail Centre
Hamilton 3240
NEW ZEALAND
Tel: +64-7-858 4650
Fax: +64-7-858 4700
© The Horticulture and Food Research Institute of New Zealand Ltd 2007
DISCLAIMER
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Private Bag 92 169, Auckland Mail Centre, Auckland 1142, New Zealand.
This report has been prepared by The Horticulture and Food Research Institute of New Zealand Ltd
(HortResearch), which has its Head Office at 120 Mt Albert Rd, Mt Albert, AUCKLAND. This report has been
approved by:
_____________________________
Researcher
___________________________
Group Leader, Quality Systems
Date: 21 December 2006
Date: 21 December 2006
CONTENTS
Page
EXECUTIVE SUMMARY........................................................................................................ 1
INTRODUCTION...................................................................................................................... 3
Objectives and milestones...................................................................................................... 3
MATERIALS AND METHODS ............................................................................................... 5
Nashi....................................................................................................................................... 5
Kiwifruit ................................................................................................................................. 5
Chestnuts ................................................................................................................................ 5
Cherries .................................................................................................................................. 6
Avocados ................................................................................................................................ 6
Stonefruit................................................................................................................................ 6
Feijoas .................................................................................................................................... 7
Animal bedding trials ............................................................................................................. 7
Disease suppression trials....................................................................................................... 7
RESULTS................................................................................................................................... 8
Nashi....................................................................................................................................... 8
Kiwifruit ............................................................................................................................... 10
Chestnuts .............................................................................................................................. 13
Cherries ................................................................................................................................ 17
Avocados .............................................................................................................................. 17
Stonefruit.............................................................................................................................. 18
Feijoas (see also appendix 2) ............................................................................................... 20
Animal bedding trials ........................................................................................................... 21
Disease suppression.............................................................................................................. 22
DISCUSSION AND CONCLUSIONS.................................................................................... 24
ACKNOWLEDGEMENT ....................................................................................................... 25
LIST OF TALKS/SEMINARS/ARTICLES PRESENTED .................................................... 26
APPENDIX 1. RAW DATA FOR YEAR 1 AND 2 EXPERIMENTS ON STORAGE OF
CHESTNUTS IN SPHAGNUM MOSS. ................................................................................. 27
APPENDIX 2. EFFECT OF SPHAGNUM MOSS ON STORAGE LIFE OF FEIJOA FRUIT
.................................................................................................................................................. 33
1
EXECUTIVE SUMMARY
Economically Sustainable Sphagnum Moss Products
Grant No. 03/087
Report to the West Coast Development Trust and the MAF Sustainable Farming Fund
August 2006
Yu J
This project aimed to develop economic opportunities for the New Zealand sphagnum moss
industry through the development of new sphagnum moss-based products. We determined
the effectiveness of sphagnum moss in several potential applications. Two notable
characteristics of sphagnum moss are its ability to absorb and retain moisture (up to 20 times
its own weight) and its alleged anti-microbial properties. This proposal focused on these two
attributes as a premise to develop new commercial and industrial applications. We focused on
several areas of research.
1. Packaging. We used sphagnum moss to package fruits to reduce postharvest infection,
and to extend storage and shelf life in fruits and chestnuts
2. Veterinarian services. Materials that are highly absorbent and reduce odour are in
demand in a variety of areas involving animal husbandry. We evaluated the
effectiveness of sphagnum moss in this application
3. Disease suppression. Anecdotal observations from some plant growers indicated that
sphagnum moss was effective in reducing “damping off” in seed germination. We
evaluated how effective sphagnum moss was in decreasing incidences of fungal
infection in soil.
PACKAGING
We tested chestnuts and a wide range of fruits.
•
Chestnuts packed in sphagnum moss maintained good nut quality and had a
significantly extended storage life compared with chestnuts not packed in sphagnum
moss. Chestnuts packed in sphagnum moss had up to a six-month extension of
effective storage life and exhibited a reduction in premature germination
•
Kiwifruit showed a tendency to stay firmer for longer and did not mature as quickly
when packed in sphagnum moss. ‘Hort16A’ kiwifruit showed about a one-month
extension of storage life
•
‘Dawson’ cherries showed about a one-week extension of storage life
•
‘Unique’ feijoas packed in sphagnum moss showed some improvements of storage
compared with the controls, though these were probably not commercially significant
•
Other fruit tested (avocados, nashi, summerfruit) showed no significant improvements
in storage and shelf life when stored in sphagnum moss.
2
•
Based on trials evaluating various forms of sphagnum moss, it is concluded that “dust”
and “petal” usually worked just as well as whole, intact sphagnum moss strands.
However, sphagnum moss dust had a tendency to compress and cake which
sometimes caused problems with aeration unless carefully handled and packed
•
Laboratory trials showed that improved storage results were not due to the fruit or
chestnuts drying out, nor were they due to ethylene production/absorption or other
modified atmosphere effects. In the case of chestnuts, the beneficial effects seemed to
be mainly the result of inhibition of surface moulds due to absorption of free water by
sphagnum moss.
VETERINARIAN SERVICES
•
Testing compressed sphagnum moss sheet as an animal bedding gave very good
results compared with the more usual alternatives of wood-shavings or synthetic
IsopadTM mats
•
The water-holding capacity and ammonia-absorbing properties of sphagnum moss
compressed sheet were superior to those of the wood shavings and IsopadTM.
Furthermore, sphagnum moss sheets lasted longer and produced less dust than wood
shavings
•
Irradiation for sterilization slightly reduced the water-holding capacity of the
compressed sphagnum moss sheet, but this reduction was not significant.
DISEASE SUPPRESSION
•
No beneficial results were obtained from the use of sphagnum moss as a growing
medium for seedlings exposed to test levels a common fungal pathogen (Pythium).
For further information contact:
Yu J
The Horticulture and Food Research Institute of New Zealand Ltd
HortResearch Ruakura
Private Bag 3123
Waikato Mail Centre
Hamilton 3240
NEW ZEALAND
Tel: +64-7-858 4650
Fax: +64-7-858 4700
3
INTRODUCTION
Sphagnum moss (Sphagnum cristatum, S. subnitens, S. falcatulum) is a New Zealand native
plant found growing naturally in swampy conditions, mainly on the West Coast of the South
Island. It is harvested by hand, sorted, graded, dried and sold commercially around the world,
particularly in Asia, where it is used for orchid production and similar applications.
Significant tonnages are exported annually (up to $20 million/year).
For commercial purposes, long intact strands (characteristic of S. cristatum) are the most
sought-after material. The less dense strands of S. subnitens and S. falcatulum are less
desirable but are often intermingled with S. cristatum when harvested. After harvest, the moss
is hand sorted and graded over a mesh sorting table. The longer strands are packed as top
grade, while mixed species and shorter strands are sometimes packed separately. The sorting
process generates a lot of moss petal (detached leaves and fragments of strand), and moss
“dust” (finely crushed bits of sphagnum moss), which has a similar consistency to that of
sawdust. While long intact strands are always in high demand, there is a more limited use for
petal or “dust”.
OBJECTIVES AND MILESTONES
The aim of this project was to identify and develop new economic opportunities for the New
Zealand sphagnum moss industry through the development of sphagnum moss-based products.
It should be noted that the objectives and milestones were revised several times throughout
the course of the project in response to discussions held between participants.
The following is the latest revised list of milestones.
Milestone 1:
• Industry-wide meeting and discussion
• Collection of materials
Milestone 2:
• Set up preliminary experiments involving nashi, chestnuts, summerfruit and kiwifruit
• Evaluate susceptibility to at least five major pathogens: Phomopsis, Penicillium,
Botrytis, Sclerotinia, and bacterial rots.
Milestone 3:
• Collation of all results to date
• Industry-wide meeting to discuss results and decide on future directions
Milestone 4:
• Carry out expanded packaging trials including new crops (cherries, feijoas, avocados)
and additional grades of sphagnum moss (petal and dust as well as strand moss)
4
Milestone 5:
• Collation of results
• Industry-wide meeting to discuss results and decide on future directions
Milestone 6:
• Animal bedding trials with laboratory mice
Milestone 7:
• Final meeting with participants
• Presentation of final results and report.
5
MATERIALS AND METHODS
Chestnut cultivar 1005 and 1015, the nashi pear cultivars ‘Hosui’ and ‘Dae Bae’, the avocado
cultivar ‘Haas’ and the feijoa cultivar ‘Unique’ were sourced directly from commercial
growers or packhouses and prepared, graded, packed, stored and evaluated according to
standard commercial practice. The cherry cultivars ‘Primavera’, ‘Sonet’ and ‘Dawson’, and
the apricot cultivar ‘Clutha Gold’ were sourced from HortResearch’s experimental orchard in
Clyde, and the kiwifruit cultivars ‘Hort16A’ and ‘Hayward’ were obtained from the Ruakura
and Te Puke Research Orchards. Sphagnum moss was sourced direct from the processors in
standard grades.
Fruit packing trials were carried out over two years.
NASHI
Forty-four boxes of ‘Hosui’ nashi pears with 12 fruit in each box, and 44 boxes of ‘Dae Bae’
with 23 fruit in each box were used. Fruit in 21 treatment boxes were covered with 25 g of
strand sphagnum moss and were compared with fruit in 21 control boxes (no moss). At the
start of the trial, fruit from one treatment box and fruit from one control box were weighed,
tested for sugar content (SSC) with a refractometer and tested for fruit firmness (kgf) with a
penetrometer. Fruit from one treatment box and one control box were then tested at regular
intervals (every two weeks after the first month) over the course of eight months of storage.
As fruit became softer, two to three treatment and control boxes were assessed for each time.
Fruit were stored at 2-4ºC. Four temperature monitors were placed randomly through the
stacked boxes to record temperature and humidity during the experiment.
KIWIFRUIT
In our pilot experiment (Year 1), at harvest ten bags containing 10 randomly selected fruit of
either ‘Hayward’ or ‘Hort16A’ kiwifruit were packed in plastic bags. Treatment fruit were
packed with enough loose sphagnum moss to cover the fruit (approx. 25 g) while control fruit
had no sphagnum moss. The plastic bags had small holes punched through for ventilation and
when the fruit were packed, the bags were lightly twisted and placed in a large plastic
container. The bags of treatment and control fruit were randomly placed in the container
before being stored at 2-4ºC.
In Year 2, standard, single-layer kiwifruit trays with 30 fruit in each tray were used. Kiwifruit
were packed with 45 g of sphagnum moss underneath and on top of the fruit (90 g of moss
total). Fruits were stored at 20ºC. Fruit from each of one tray of treated and one tray of
control were assessed as described for nashi pears before the start of the experiment and then
at regular intervals (every two weeks after three months) over six months of storage. The
percentages of rots, blemishes and spoilage were noted. At each sampling, a sub sample of
sphagnum moss was weighed, dried to constant weight, reweighed, and the percentage
moisture content was calculated.
CHESTNUTS
In Year 1, two pilot trials were carried out. In the first trial, 60 bags of 1 kg each of chestnuts
(a mixture of export grade cultivars 1005 and 1015) were packed in ventilated plastic bags.
Twenty bags of treated chestnuts, containing either 10 or 25 g of sphagnum moss, were
6
compared with twenty bags of control chestnuts that had no sphagnum moss. In the second
trial, we assessed whether lower grade sphagnum moss dust, petals, or strands were as
effective as the higher grade strand sphagnum moss. Ten bags with 25 chestnuts per bag were
packed with either 10 or 20 g of sphagnum moss dust, petals or strand and compared with
10 bags of control chestnuts.
In Year two, we repeated the second experiment from Year 1, but increased the number of
chestnuts to 1 kg that were packed in sphagnum moss dust, petals or strands.
To mimic a commercial environment, 20 kg of chestnuts were packed in each of six standard
industry bags, three bags with sphagnum moss petal or dust and three with no sphagnum moss
(control chestnuts), before being placed in storage at 2ºC. The amount of sphagnum moss
petal or dust used was 30 litres. At three time intervals during storage, chestnuts from one bag
of each treatment and from controls were weighed and scored for presence or absence of
surface mould, colour (normal or blackened), and whether each chestnut was hard or soft
(dehydrated). The number of chestnuts that germinated and the percentage of internal fungal
rots (based on a sub sample of 50 nuts cut open and examined visually) were noted. At each
sampling, a sub sample of sphagnum moss and a sub sample of 10 chestnuts were removed
and dried for moisture content determination.
In Year 1, chestnuts were stored for six months with a total of 6088 chestnuts were assessed.
In Year 2, assessment continued through to nine months (“testing to destruction”), with a total
of 1631 chestnuts assessed.
CHERRIES
In Year 1, 12 industry-supplied cardboard boxes with 50 no-spray grown ‘Dawson’ cherries
in each box were used. Six boxes of cherries were packed with moss and six were not. In
Year 2, three cultivars of cherries - ‘Sonet’, ‘Primavera’ and no-spray ‘Dawson’ - were
packed in compressed sphagnum moss sheets inside industry-supplied boxes. All fruit were
stored at 2ºC and after four weeks of storage, the fruit were evaluated at regular intervals.
Fruit from each treatment and from controls (without sphagnum moss) were graded into either
“marketable” or “reject” based on visual appearance and the incidence of bacterial or fungal
rots.
AVOCADOS
Ten bags of avocados, with 10 fruit in each bag, were used. Five bags of fruit were packed in
ventilated plastic bags containing either 50 g of sphagnum moss strands or dust and were
compared with five bags of controls (no sphagnum moss). Fruit were stored at 4ºC but were
allowed to come to room temperature for seven days before being assessed. All fruit were
then graded on the basis of ripeness, surface blemish and stem end rot; then peeled and cut in
half and scored for internal quality, according to standard industry practice.
STONEFRUIT
Ten bags, with 10 fruit per bag, of ‘Clutha Gold’ apricots were used. Five bags of fruit were
packed in sphagnum moss (strands) in ventilated plastic bags and compared with five bags of
controls (no sphagnum moss). Fruits were cool stored at 2oC for two weeks before being
returned to room temperature and assessed for the incidence of surface rots after 24 and 48 h.
7
FEIJOAS
Eight hundred ‘Unique’ feijoas were picked from a commercial organic orchard and packed
into plastic polyliners in industry cardboard boxes containing sphagnum moss (strand), before
cool storage at 4oC. At regular intervals, fruit from each treatment and from controls (without
sphagnum moss) were graded according to the incidence of surface rots or blemishes and as
Grade A, B, C, D or E according to the industry standard for colour and ripeness. After five
weeks in cool storage, all fruit were transferred to room temperature for a further five days
before final assessment. A sub sample of fruit was removed at the end of the trial period and
was also tested for sugar content and firmness, and separate sub samples of fruit and
sphagnum moss were used for moisture content determination.
ANIMAL BEDDING TRIALS
All trials were carried out at the AgResearch small animal colony, using standard mouserearing facilities and procedures and received prior AgResearch Animal Ethics Committee
approval. Six cages with three male mice in each cage and six cages each with three female
mice were used. Each cage was a standard Perspex cage with food and water, containing
either a measured/weighed amount of wood sawdust, synthetic IsopadsTM (the main
commercially available alternative) or compressed Sphagnum moss sheet (10 cm x 5 cm x
1 mm thick, either irradiated or non-irradiated). The mice were reared under controlled
conditions. At regular intervals each mouse was weighed (to check for any adverse effects on
health) and the bedding was removed, weighed, and tested for ammonia levels (using a VRAE
Multigas Monitor PGM-78000 at 1.7 L/min., APC Services); for water absorption (by
weight); and for dust produced when shaken in a sealed plastic bag (using a DustTrak 8520
aerosol monitor, TechRentals). Dust readings were also taken from wood shavings, whole
sphagnum moss strands, dust and petal, as a comparison.
DISEASE SUPPRESSION TRIALS
Yates Potting Mix was mixed with the soil pathogen Pythium such that 50% of cucumber
seedlings would be affected with “damping off”. Once this ratio had been determined, a wide
variety of seeds was tested. Capsicum, sweet pea, snow pea, cauliflower and lettuce were
used. Pythium inoculum was grown in potato dextrose extract at 28oC for two days. Two
Petri dishes of inoculum were mixed with 5 L of potting mix. The mixture was placed in 15 x
5 cm containers before 10 test seeds were planted. Germination rates were compared with
those in inoculated potting mix that had 25 g/5 L of sphagnum moss added.
8
RESULTS
Following is a summary of key results. Complete data sets for some of the experiments are
attached in Appendix 2.
NASHI
Early in the nashi trials, both ‘Hosui’ and ‘Dae Bae’ fruit showed on average a slight tendency
towards lower soluble solids content (% SSC; Brix), higher firmness (kgf) and lower weight
after packing and storage in sphagnum moss than the control fruit (Table 1). In practice,
however, any beneficial effects were negated by the high incidence of surface infection (from
what mostly looked to be Trichoderma) coming from the sphagnum moss onto the fruit e.g.,
in ‘Hosui’ (Figures 1 to 3). In both cultivars there was a high incidence of core breakdown
due to the natural physiological disintegration of the fruit. As a result, no effective increase in
storage life of fruit quality was obtained overall. Only data from ‘Hosui’ are shown. ‘Dan
Bae’ normally has a tendency to store better than ‘Hosui’, although no effect was seen for
fruit that were packed in sphagnum moss, before all fruit regardless of treatment disintegrated.
Table 1. Comparison between ‘Hosui’ nashi pears packed in standard fruit trays (controls)
and those packed in sphagnum moss.
Date
2005
Avg. wt
(g)
Avg.
firmness
(kgf)
Avg. %
soluble
solids
content
Surface
mould
(%)
Internal
rot (%)
Control
March 20
Aug. 29
Sept. 24
Oct. 19
345.0
323.0
258.4
239.3
2.47
2.35
2.00
2.00
12.2
12.8
12.7
13.0
0
0
0
0
0
0
37
66
Sphagnum
moss
March 20
Aug. 29
Sept. 24
Oct. 19
345.0
326.7
256.1
232.1
2.47
2.40
2.0
2.1
12.2
12.5
12.6
12.5
0
0
0
25
0
0
37
42
9
Figure 1. ‘Dae Bae’ nashi pears after eight months of storage. Externally, the fruits packed
in sphagnum looked marketable; however internally, the fruits had started to break down.
Figure 2. ‘Dae Bae’ nashi pear previously packed in moss.
breakdown of the fruit.
Internal physiological
10
Figure 3. ‘Hosui’ nashi pears. High incidence of surface infection by (probably)
Trichoderma that transferred from the sphagnum moss to the fruit. The motley appearance
seen here is not a disorder that normally occurs on nashi. It appears that the presence of
Trichoderma, not normally so extensive, was facilitated by the breakdown of the fruit.
KIWIFRUIT
In Year 1, packing ‘Hayward’ kiwifruit into sphagnum moss extended the storage life,
reducing and delaying the development of fungal rots (Table 2). ‘Hort16A’ showed no similar
response, but this may have been because the fruit were much riper than Hayward when
packed (Table 3 and Figure 4). In Year 2, both cultivar of kiwifruit packed in sphagnum moss
also stayed firmer for slightly longer and developed fewer surface blemishes, giving an
approximately one-month increase in effective storage life (compared with the standard
industry benchmark). However, after five months, fruit quality of all treatments, including
controls, declined rapidly (Table 4).
11
Table 2. Comparison of fruit quality between ‘Hayward’ kiwifruit stored in ventilated plastic
bags (controls) and kiwifruit packed in sphagnum moss (Year 1, 2005).
Control fruit
May 13
Aug. 13
Aug. 16
Aug. 31
Sept. 21
Oct. 12
Sphagnum
moss packed
fruit
May 13
Aug. 13
Aug. 16
Aug. 31
Sept. 21
Oct. 12
Avg. wt (g)
Avg. soluble
solids content
(%)
Avg. firmness
(kgf)
% rots
107.2
104.6
103.6
103.6
101.6
-
8.1
12.5
13.1
13.3
13.4
13.4
7.1
0.9
0.6
0.6
0.5
0.3
0
0
20
100
100
100
107.2
100.2
101.4
101.6
90.5
90.0
8.1
13.7
12.9
13.0
13.8
12.3
7.1
0.9
0.8
0.7
0.8
0.4
0
0
0
0
0
10
Table 3. Comparison of fruit quality between ‘Hort16A’ kiwifruit stored in ventilated plastic
bags (controls) and those packed in sphagnum moss (Year 1, 2005).
Controls
May 13
July 23
Aug. 13
Aug. 31
Sphagnum
moss-packed
fruit
May 13
July 23
Aug. 13
Aug. 31
Avg. wt (g)
Avg. soluble
solids content
(%)
Avg. firmness
(kgf)
% rots
89.0
86.2
86.4
84.6
13.5
15.6
15.8
15.9
4.4
<0.5
<0.5
<0.5
0
0
0
0
89.0
87.8
83.2
78.9
13.5
15.5
15.6
15.5
4.4
0.6
0.6
0.6
0
0
0
0
12
Figure 4. Year 2 (2006). ‘Hort16A’ kiwifruit in our pilot experiments, which initially
suggested that sphagnum moss storage might be beneficial to fruit.
13
Table 4. Comparison of fruit quality after five months between kiwifruit stored in trays with
and without sphagnum moss (Year 2, 2006).
‘Hayward’
control
‘Hayward’ in
sphagnum
moss
‘Hort16A’
control
‘Hort16A’ in
sphagnum
moss
Avg.
Firmness
(kgf)
Avg.
soluble
solids
content(%)
Soft/rotten
(%)
Blemished
(%)
Marketable
(%)
0.3
13.2
4
9
89
0.3
13.3
5
7
90
0.3
14.5
18
20
78
0.4
13.0
5
9
88
CHESTNUTS
In our pilot experiment in Year 1, packing chestnuts in 25 g of sphagnum moss decreased the
number of chestnuts affected by surface mould by 10% (Table 5 and Figures 5 and 6). In our
second experiment, chestnuts packed in sphagnum moss (either strand, petal or dust) showed
a significant reduction in premature germination, incidence of soft rots and surface mould, but
no significant change in internal rots or chestnut moisture content over time (Table 6).
Doubling the amount of sphagnum moss packed around the nuts helped to reduce germination
and some spoilage.
Table 5. Comparison of nut quality between chestnuts stored in 1-kg ventilated plastic bags
with and without sphagnum moss for six months (Year 1, 2005).
Control chestnuts
10 g sphagnum moss
strands and 1 kg
chestnuts
25 g sphagnum moss
strands and 1 kg
chestnuts
Total Nuts
% mouldy
1537
62
% nonmouldy
37
1477
69
32
1574
51
49
14
Figure 5. 1 kg of chestnuts packed in sphagnum moss (left) compared with chestnuts without
moss (right).
Figure 6. At regular intervals during storage, chestnuts are taken out and scored for fungal
infection, internal rots, and germination.
15
Table 6. Comparison of quality of chestnuts stored in either lower grade sphagnum moss or
standard sphagnum moss strands (Year 1, 2005).
Control
chestnuts no
sphagnum moss
10 g of dust
sphagnum moss
and chestnuts
10 g of petal
sphagnum moss
and chestnuts
20 g of strand
sphagnum moss
and chestnuts
20 g of dust
sphagnum moss
and chestnuts
20 g of petals
sphagnum moss
and chestnuts
Total
nuts
250
%
mouldy
6.4
% soft
nuts
6
%
germination
40
Moisture
content
54.2
250
0
2.4
20
Not done
250
0
2.4
14
Not done
250
0
4.4
3
54
250
0
4.8
9
53.7
250
0
4.8
2
53
In Year 2, chestnuts packed in 20-kg ventilated plastic bags stored significantly better when
packed in either sphagnum moss petal or dust, effectively extending the storage life by about
50% (from six months to nine months), despite a higher-than-normal incidence of internal
fungal rots, due to a warm wet season (Table 7, Figure 7).
16
Table 7. Comparison of nut quality between chestnuts stored in 20-kg ventilated plastic bags
for six to nine months and those packed in sphagnum moss.
6 months
Chestnut
controls
Chestnuts in
sphagnum
moss petals
7 months
Chestnut
controls
Chestnuts in
sphagnum
moss petals
9 months
Chestnut
controls
Chestnuts in
sphagnum
moss dust
Germination
(%)
Usable
nuts
(%)
Nut
moisture
content of
nut (%)
52
12
31
54.2
737
7
8
47.6
56
1152
78.5
9.5
9.6
56.3
762
12
10
45.2
55.1
1073
83.9
13.1
0.3
56.6
769
13
11
38.6
57.8
Total
nuts
assessed
Surface
mould
(%)
1218
Figure 7. 20 kg of chestnuts stored in ventilated bags. The plastic bag helps to keep the
chestnuts from drying out, but can also encourage surface mould, germination, fungal and
bacterial rots.
Weed seed (gorse) in the sphagnum moss (coming from the swamp) germinated as well as
seeds that we sowed (data not shown).
17
CHERRIES
In Year 1, no significant differences were noted in cherry storage life or quality. No
treatments maintained acceptable quality of cherries for more than four weeks (possibly
because many cherries were hail-damaged and predisposed to fungal rots and spoilage)
(Figure 8). In Year 2, no-spray ‘Dawson’ cherries stored slightly better when packed in the
sphagnum moss, with only 26% being unmarketable after six weeks, compared with 59%
unmarketable in the controls. By eight weeks, there was no difference between treatments and
fruit quality declined rapidly. The use of sphagnum moss packaging effectively increased the
storage life of ‘Dawson’ cherries by approximately one week. No significant effects were
observed on other cherry cultivars, ‘Primavera’ or ‘Sonet’.
Figure 8. No-spray ‘Dawson’ cherries after about four weeks in storage. Sphagnum moss
packed cherries (top) and controls (bottom).
AVOCADOS
There was no significant improvement in avocado fruit quality when fruit were packed in
sphagnum moss strands compared with control fruit. Avocados packed in sphagnum moss
dust showed a reduction in the incidence of fungal stem and body rots, but subsequent
examination suggested that this could have been related more to the ripeness and maturity of
the fruit than to the presence or absence of sphagnum moss. There was therefore no effective
increase in storage life observed.
18
STONEFRUIT
When first assessed after two weeks in cool storage, significantly more of the control fruit
(five out of 10) showed surface blemish and fungal rots than did the fruit packed in sphagnum
moss (zero out of 10) (Figure 9). After 48 h at room temperature, eight out of 10 control fruit
showed blemish and rots compared with only one out of 10 fruit packed in sphagnum moss.
However, all fruit deteriorated quickly at room temperature, so that there was no effective
improvement in quality, storage or shelf life resulting from the use of sphagnum moss.
19
Figure 9. ‘Clutha Gold’ apricots after two weeks of storage and 24 h at room temperature,
packed with (bottom) or without (top) sphagnum moss.
20
FEIJOAS (SEE ALSO APPENDIX 2)
After seven weeks in cool storage, the percentage of rots (~1%, or less than one fruit in every
five boxes) was lower in fruit packed in sphagnum moss than in the controls, but this trend
rapidly reversed when fruit were returned to room temperature, resulting in no overall benefit
(Figure 10). Fruit packed in sphagnum moss showed a significantly lower level of ripeness by
the end of the trial, compared with controls, and this was reflected in their slightly higher fruit
firmness and lower % SSC readings. Some fruit packed in sphagnum moss lost more weight
over time than did the controls, but this was not significantly different in either fruit or moss
dry weights or % moisture contents at the end of the trial.
Figure 10. ‘Unique’ feijoa after seven weeks of storage. Fruits packed with sphagnum moss
(top) compared with fruit packed without sphagnum moss (bottom).
21
ANIMAL BEDDING TRIALS
Sphagnum moss performed well as mouse bedding, showing increased absorbency and
increased ammonia absorption compared with IsopadsTM (Table 8). Water-holding capacity
was approximately six times greater than that of IsopadsTM and ammonia levels were
approximately 25 times lower. Maximum dust production from the sphagnum moss (when
shaken in a plastic bag) was higher than from the IsopadsTM, (0.8 mg/m3 compared with 0.4
mg/m3), but much lower than that for wood shavings (6.4 mg/m3) and loose sphagnum moss
strands, petal or dust (4.0, 3.1 and 8.0 mg/m3 respectively) (Figure 11).
A wood shavings
B Isopad™
C compressed sphagnum moss
D loose sphagnum moss
E sphagnum moss petal
F sphagnum moss dust
Figure 11. Different materials used in the animal bedding trial.
Table 8. Comparison between compressed sheets of sphagnum moss (irradiated and nonirradiated) and commercial Isopad™ synthetic animal (laboratory mice) bedding.
Sphagnum moss
sheets nonirradiated
Sphagnum moss
sheets irradiated
Isopad
Dust production
(mg/m3)1
[NH3] after 14-21
days (ppm)
0.8
6-9
Water holding
capacity (times
100%)
26.9
0.8
6-9
24.1
0.4
200
4.3
1
(NB: the background level of dust, without shaking, was only 0.013 mg/m3, well below the
standard definition of a “clean environment” of 0.1 mg/m3).
Sterile, irradiated moss showed a slight reduction in performance compared with nonirradiated moss, but still performed better than wood shavings or IsopadsTM. The use of
sphagnum moss gave an approximately 1-2 week increase in effective life of the bedding. The
22
effectiveness of the sphagnum moss depended on whether male or female mice were used,
male mice being significantly larger and more difficult to house for as long. This is a
significant extension, considering that the bedding is usually changed every 1-2 weeks. The
compressed moss sheets were also easier to handle and use. The animals themselves “fluff it
up” for bedding use after its introduction, thereby reducing dust production during handling
and storage and providing “occupational therapy” for the mice (Figure 12). The reduction in
the ammonia smell was readily apparent even to casual users of the facility.
Figure 12. Male mice cages after four weeks of use. Isopad™ (green card) started to
disintegrate after the first week. The compressed sphagnum moss sheets performed the best
with the non-irradiated sphagnum moss (purple card) being slightly more absorbent then the
irradiated sphagnum moss sheet (yellow card).
DISEASE SUPPRESSION
We tested whether sphagnum moss could protect germinating seeds from “damping off”.
Control soil was inoculated with Pythium such that about 50% of the cucumber seeds sown
germinated. The number of cucumber seeds germinated in the control soil was compared with
the treated soil that contained Pythium and 20 g of sphagnum moss. Results showed that soil
containing Pythium and sphagnum moss had almost no germination, compared with the
control soil that had slightly fewer than half the seeds germinated (Figure 13). The treated
soil showed that sphagnum moss in Pythium-infected soil was more detrimental to
germination in all seeds tested.
23
Figure 13. Seedlings germinating in potting mix containing pythium (top) and seedlings
germinating in potting mix containing pythium and sphagnum moss (bottom).
24
DISCUSSION AND CONCLUSIONS
In the past, sphagnum moss has been used in various applications such as wound dressing and
orchid growing, which exploited its high water-holding capacity and alleged antimicrobial
activity. This is the first time it has been used to address practical fruit and nut handling and
storage applications.
High value fruits as well as emerging crops were chosen for the storage trial with sphagnum
moss. We wanted to determine whether the use of sphagnum moss could help to expand or
extend the market share of these crops, by making fruits available that are normally out of
season in the northern hemisphere. Furthermore, higher prices are paid for spray-free and
organic produce and the use of sphagnum moss fits well with the “clean and green” image,
especially for the Asian markets.
Storage trial results were either variable, as in the case of kiwifruit, or showed no significant
benefits of sphagnum moss in extension of the normal shelf life of the fruits tested. The trials
highlighted two main challenges. The first challenge was that fruits such as apricots and
avocados have systemic rot infection that is initiated in the field. We found that sphagnum
moss can inhibit rots in cool store but once fruits were brought back to room temperature, as
in a supermarket, or with the consumer, dormant infections such as stem rot and brown rot
proliferated. How well sphagnum moss performed as a postharvest storage material depended
greatly on how well the orchard in which the fruits were grown controlled fungal and bacterial
inocula. The second challenge we encountered was physiological breakdown of the fruit.
Perishable fruits such as cherries and feijoas do not last long. During the course of these
storage trials, some of the fruits were used for informal taste evaluation. Apricots and
cherries started to lose taste after about 3-4 weeks even though they looked marketable. In an
extreme case, as seen in ‘Hosui’ nashi pear, the breakdown of the fruit facilitated the growth
of fungus and bacteria that normally do not affect the fruit.
Results with chestnuts were good. When sphagnum moss was used to pack and store
chestnuts, there was less surface mould and less premature germination, in a linear
relationship with the amount of sphagnum moss used. Lower grade sphagnum moss (moss
dust and “petals”) seemed to be as effective as sphagnum moss strands in reducing the
number of chestnuts with surface mould. After seven months, the percentage of usable
chestnuts was 45.2% compared with 9.6% of the controls.
The chestnut industry is not as large as that of cherries or kiwifruit, but it does have
significant storage issues. There are very few domestic sales and therefore the emphasis is
very much on export. The New Zealand chestnut season is six months out-of-phase with the
northern hemisphere chestnut marketing season. Therefore, marketing fresh nuts early in the
season (November-December) will reap a premium price. Results from our trials certainly
demonstrated that sphagnum moss can improve storage of chestnuts long enough to enhance
opportunities for premium prices in the northern hemisphere.
The storage trials with chestnuts also yield an unexpected result. Packing chestnuts in
sphagnum moss had a reduced number of chestnuts that germinated. Normally, there is a
high percentage of premature germination and as a result nuts become much more susceptible
to rots and decay. In Year 1 of our trial, chestnuts packed in 20 g of sphagnum moss petals
had 2% germination, compared with 40% germination in the control.
25
It has to be noted that results will vary from year to year depending on the weather and
growing conditions in the orchard. In Year 2 of our trial, the chestnut growing season was
unusually wet, resulting in very high incidences of internal rots. This reduced the number of
usable or marketable chestnuts irrespective of the use of sphagnum moss.
In our seed germination experiment, results showed that sphagnum moss was ineffective in
reducing the incidence of “damping off”. In fact, seeds sown in Pythium-inoculated soil
faired better than seeds that were sown in Pythium-inoculated soil and with sphagnum moss
added. Some growers have previously noticed that they had fewer incidences of “damping
off” when they used sphagnum moss. However, this may have been due to a change of media
for seed germination, which could have removed the source of fungal inoculum. It might also
be possible that seeds were sown directly onto sphagnum moss without soil. If this were the
case, it is not surprising that seeds germinated quite well, because of high water content and
an environment in which Pythium or other soil pathogen (e.g., Phytophthora) would normally
not be present.
We trialled the effectiveness of sphagnum moss as animal bedding. Animals used in research,
such as mice, are required to be treated ethically. Since animals can sometimes be caged for
long periods, one of the requirements is that their environment must be “enriched”. This
means that the environment must be sufficiently stimulating that the animal does not hurt
itself out of boredom. Results from our animal trials showed that compressed sphagnum
moss sheets as bedding performed better than all currently available commercial alternatives.
Not only were the sphagnum moss sheets better at absorbing urine and ammonia smells, they
also engaged the mice in their nesting instincts. There is a potential worldwide market for
commercially produced animal bedding, and this would seem to be a relatively easy product
to be developed further. The main drawback was the need for sterilization, (by irradiation),
which added cost and slightly reduced absorption, although not significantly.
This project has demonstrated that sphagnum moss can be used effectively in some
applications, such as storing chestnuts and bedding material for mice, while in other
applications it is less effective, such as packaging fresh fruits or preventing “damping off” in
seed germination. Commercial viability and industry willingness to continue to develop and
pursue these applications remains to be proven. Future work should be based on focused
evaluations and the development of a business case that should demonstrate clear market
opportunities and financial returns.
ACKNOWLEDGEMENT
HortResearch is grateful for the invaluable help and support of David Klinac, Rick Broadhurst,
Pia Rheinlander and Jill McLaren.. HortResearch is also grateful for the financial assistance
of the MAF Sustainable Farming Fund and the West Coast Development Trust.
26
LIST OF TALKS/SEMINARS/ARTICLES PRESENTED
•
2006. Evaluating new uses for NZ sphagnum moss. Poster. NZ Tree Crops
Association Conference. Masterton.
•
2006. New and novel uses for NZ sphagnum moss and meadowfoam. Presentation.
NZ Tree Crops Association Conference. Masterton.
•
2006. Sphagnum moss and other new and novel horticultural crops. Presentation. NZ
Horticultural Society meeting. Hamilton.
•
2005. Use of sphagnum moss for storing chestnuts. Popular article. “Chestnutz News”
(Journal of the NZ Chestnut Council).
•
2005. New and novel tree crop applications: Sphagnum moss. Popular article. “The
Tree Cropper” (Journal of the NZ Tree Crops Association).
•
2005. Research update 2005-2006. Presentation. NZ Chestnut Council Annual general
Meeting (R&D report).
27
APPENDIX 1. RAW DATA FOR YEAR 1 AND 2
EXPERIMENTS ON STORAGE OF CHESTNUTS IN
SPHAGNUM MOSS.
28
29
30
31
32
33
APPENDIX 2
EFFECT OF SPHAGNUM MOSS ON STORAGE LIFE OF FEIJOA FRUIT
Pia Rheinlander & Janet Yu
June 28, 2006
Background
The recommended storage (ripening) time for feijoa fruit is three to a maximum of five weeks
at 4°C. This short storage life presents a major export constraint to the New Zealand feijoa
industry because transport to the international market has to be by airfreight. The limited
storage time also leads to oversupply and lower prices at the peak of the season. It is
therefore highly desirable to extend the storage life of this fruit crop. Previous trials within
this SFF project have shown that sphagnum moss has preservative properties in some fruit
crops. In this study we tested whether packaging of feijoa fruit in sphagnum moss would
prolong their storage life.
Methods
Photos: Pia Rheinlander
A total of 800 fruit of the cultivar ‘Apollo’ was harvested in early May 2006 in an orchard in
South Auckland. In the orchard, half the fruit were distributed among 20 commercial
avocado storage boxes (20 fruit per box) packed with a ~7 cm thick layer of sphagnum moss
below and on top of the fruit (Figure A1a). Each box with the fruit packed in sphagnum moss
was lined with a polythene sheet to reduce evaporation. The remaining fruit were wrapped in
polythene sheets alone in groups of 20 fruit (Figure A1b) and placed in cardboard boxes (20
boxes, each with 20 fruit). These boxes functioned as controls. The fruit was transported
directly to a 4°C storage facility at HortResearch Mt Albert Research Centre.
A
B
Figure A1. A: Feijoa fruit were packed in a ~7 cm thick layer of sphagnum moss below and
on top of the fruit in commercial avocado storage boxes lined with a polythene sheet. B:
Control fruit were placed directly in the boxes wrapped in a polythene sheet.
34
To ensure that any preservative effect of the sphagnum moss would be detectable, the fruit
were stored for seven weeks, which is two weeks longer than the prescribed storage duration.
They were thereafter assessed as follows:
(1)
The preservative properties of sphagnum moss in other fruit crops observed in previous
trials is believed to be related to uptake of moisture by the moss, thereby reducing the
growth conditions for the fungi. However, sphagnum moss may also uptake moisture
from the fruit. It was tested whether fruit stored in sphagnum moss would have a
greater weight loss than control fruit by weighing the fruit from two boxes per treatment
(40 fruit per treatment) prior to and after storage
(2)
The number of fruit with storage rots per box was recorded twice: immediately after
seven weeks of cool storage, and again after five days of storage at room temperature
(3)
The green skin colour of feijoa fruit typically yellows in storage because of the
degradation of chlorophyll. The proportion of fruit per box that had turned yellow was
recorded
(4)
The ripeness was estimated for five fruit randomly selected per box using the indices
(Figure
A2)
from
the
Feijoa
Retailer
Handling
Guide
(http://www.feijoa.org.nz/retailer.html). For analytical purposes, the index letters were
changed to numbers (i.e. A = 1; B = 2; C = 3; D = 4; E = 5).
A Will never ripen properly. Pulled too hard in picking.
B
Touch picking maturity. Jellied sections half white/half clear. Not yet ready to eat.
C
Retail Display. D Jellied sections clear. E The beginning of optimum eating maturity.
Figure A2.
The indices from the Feijoa Retailer Handling Guide
(http://www.feijoa.org.nz/retailer.html) were used to estimate the ripeness after seven weeks
of cool storage. For analytical purposes, the index values A, B, C, D and E were changed to 1,
2, 3, 4 and 5, respectively.
Differences in weight loss between fruit stored in sphagnum moss and the control fruit were
tested using one-way ANOVA. The effect of storing feijoa fruit in sphagnum moss on the
development of rots at the two assessment times (i.e. after cool storage and after additionally
five days at room temperature) was tested using two-way ANOVA on absolute numbers, with
assessment times as repeated measures (STATISTICA). Differences in fruit yellowing and
ripeness between treatments were tested using the Student’s t-test on absolute numbers.
Results and discussion
35
The weight loss of feijoa fruit packed in sphagnum moss was significantly greater than in the
control fruit (F df=1 = 215.3, P < 0.001). On average, individual fruit packed in sphagnum
moss lost 6.0% ± 0.2% of their weight after seven weeks, which was nearly three times the
weight loss of 2.4% ± 0.2% recorded for the control fruit.
The mean number of rots for both the fruit stored in sphagnum moss and the control fruit
increased significantly from <1% after cool storage to ~7% after additional five days at room
temperature (Figure 3; F df=38 = 23.2, P < 0.001) (Figure A3). However, storing feijoa fruit in
sphagnum moss did not decrease the development of rots significantly (F df=38 = 0.6, P =
0.05).
Mean % rots per box ± SE
Sphagnum
10
Control
5
0
7 wks cool
storage
extra 5 days
room temp.
Figure A3. Mean frequency of rots in feijoa fruit stored with and without sphagnum moss
after seven weeks of storage at 4°C and after an additional 5 days at room temperature.
Values are mean % of fruit with rots per box ± standard error (20 boxes per treatment, each
with 20 fruit per box).
Storing fruit in sphagnum moss had no effect on the yellowing of the fruit skin (t = -0.61, P >
0.05) (Figure A4). However, the ripeness of fruit stored in sphagnum moss was significantly
reduced compared with that of the control fruit (t = -3.91, P < 0.001) (Figure A5).
Nevertheless, the differences in ripeness were only marginal (4.5 = D-E for the fruit stored in
sphagnum moss; 5 = E for the control fruit) and would not warrant the extra expense of
storing feijoa in sphagnum moss.
36
Fruit yellowing
Mean % per box ± SE
50
40
30
20
10
0
Sphagnum
Control
Figure A4. Yellowing in feijoa fruit stored with and without sphagnum moss after seven
weeks at 4°C. Values are mean % of yellow fruit per box ± standard error (20 boxes per
treatment, each with 20 fruit per box).
Fruit ripeness
Mean ripeness ± SE
5
4
3
Sphagnum
Control
Figure A5. Ripeness of feijoa fruit after seven weeks of storage at 4°C with and without
sphagnum moss. The ripeness was estimated using the indices described in Figure A2.
Values are mean ripeness ± standard error per storage box (20 boxes, 5 fruit per box).
Conclusions
Feijoa fruit stored in sphagnum moss exhibited a greater weight loss after seven weeks of
storage than did the control fruit. The enhanced weight loss is likely to be due to uptake of
moisture by the moss. The reduced dampness of fruit stored in sphagnum moss is thought to
reduce the growth conditions and thereby inhibit or slow down the decay by fungi. However,
no effect of storing feijoa fruit in sphagnum moss was found on reducing the development of
rots. The lack of effect suggests that the storage rots of feijoa originated from latent
infections (i.e. fungi established in the skin during fruit development) rather than from
infections occurring during storage. Although there was an effect of storing feijoa fruit in
sphagnum moss on the ripeness, the difference was only marginal and would not be
financially viable.
37

Economically Sustainable Sphagnum Moss Products Grant No. 03/087

Transcription

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