Bitter Melon in Australia A report for the Rural Industries Research and Development Corporation
by Dr Wendy Morgan and Professor David Midmore Plant Sciences Group Central Queensland University Rockhampton Qld 4702
November 2002 RIRDC Publication No 02/134 RIRDC Project No UCQ-10A
© 2002 Rural Industries Research and Development Corporation. All rights reserved. ISBN 0642 58533 4 ISSN 1440-6845 Bitter Melon in Australia Publication No. 02/134 Project No. UCQ-10a The views expressed and the conclusions reached in this publication are those of the author and not necessarily those of persons consulted. RIRDC shall not be responsible in any way whatsoever to any person who relies in whole or in part on the contents of this report. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186.
Researcher Contact Details Professor David Midmore Plant Sciences Group Central Queensland University Rockhampton QLD 4702 Phone: 07 49 309770 Fax:07 49 309255 Email:
[email protected] Internet: http://science.cqu.edu.au/psg/ In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 1, AMA House 42 Macquarie Street BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: Fax: Email: Website:
02 6272 4539 02 6272 5877
[email protected]. http://www.rirdc.gov.au
Published in November 2002 Printed on environmentally friendly paper by Union Offset
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Foreword While Australian rural industries and research institutions are typically based more on a competitive spirit than on active cooperation and coordination, there are a number of instances where a particular industry or section of an industry has adopted a successful collaborative approach to the development of new export or domestic industries Collaborative research amongst groups of specialists located across the length and breadth of Australia has the potential to be an effective catalyst to the development of cooperative arrangements for continuous supply of perishable vegetables to satisfy domestic and export markets. This publication, one of a number arising from the RIRDC project UCQ-10a, presents data from cooperative trials on bitter melon run in the Northern Territory, Queensland and New South Wales, and illustrates how various institutes can cooperate in such ventures. This project was funded from RIRDC Core Funds which are provided by the Federal Government, with varying levels of co-funding from the cooperating institutes. This report, a new addition to RIRDC’s diverse range of over 800 research publications, forms part of our Asian Foods R&D program, which aims to support industry in its drive to develop new products and markets and to gain competitive advantage through improving productivity in, and achieving price premiums for, Australian production. Most of our publications are available for viewing, downloading or purchasing online through our website:
· downloads at www.rirdc.gov.au/reports/Index.htm · purchases at www.rirdc.gov.au/eshop
Simon Hearn Managing Director Rural Industries Research and Development Corporation
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Acknowledgements The sub-project team members: CQU, Rockhampton, Qld. Rachel Brimblecombe Tom Osborne D. BIRD, Darwin, NT
Mark Traynor Peter Hopkinson Emma Maroulis Greg Owens NORADA, NSW David Hicks Craig Harman Dr David Gallagher, for most of the Literature Review (current knowledge) and Peter McLaughlin for his practical information generously contributed to the review. Mr Tony Byrne, RIRDC Asian Food Program Manager for continued interest and support of the project and its aims. Dr Nguyen Quoc Vong, for practical advice to NORADA and DBIRD, Darwin. Participating institutions in UCQ-10a
Contact person:
Agriculture WA, Bunbury Ms Vynka McVeigh Central Queensland University, Rockhampton Professor David Midmore Northern Rivers Agricultural Development Association, Murwillumbah Mr Peter McLaughlin Northern Territory Department of Business Industry and Resource Development, Darwin Ms Melinda Gosbee NRE, Institute for Horticultural Development, Knoxfield Dr Wendy Morgan NSW Agriculture, Gosford Dr Nguyen Quoc Vong Queensland Department of Primary Industries, Mareeba Lester Loader Tasmanian Institute for Agricultural Research, Dr Frank Hay Burnie University of Queensland, Gatton Assoc. Prof. Alan Wearing
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Contents Foreword ............................................................................................................................................... iii Acknowledgements.............................................................................................................................. iv Contents ................................................................................................................................................. v Tables and Figures............................................................................................................................... vi Executive Summary ............................................................................................................................ vii 1. Introduction........................................................................................................................................ 1
1.2 Current Knowledge ...................................................................................................................... 2 2. Materials and methods ................................................................................................................... 12
2.1 Replicated field trials................................................................................................................... 12 2.2 Observation trials ........................................................................................................................ 13 3. Results.............................................................................................................................................. 15
3.1 Replicated field trials................................................................................................................... 15 3.2 Observation field trials ............................................................................................................... 20 4. Discussion ...................................................................................................................................... 24 5. References ....................................................................................................................................... 27 6. Appendix 1 ....................................................................................................................................... 29
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Tables and Figures Table 1.
Bitter melon market preferences.
Table 2.
Seasonal margins for bitter melon planting in Australia.
Table 3.
Respiration and ethylene production of selected Asian vegetables.
Table 4.
Northern Territory production and value of selected Asian vegetables.
Table 5.
Bitter melon cultivars: average fruit weight, size and Brix 0 over a five week harvest, Northern Territory, 1999.
Table 6.
Bitter melon cultivars: fruit appearance over a five week harvest period, Northern Territory, 1999.
Table 7.
Bitter melon cultivars: fruit appearance rated with BMPDL, Northern Territory, 1999.
Table 8.
Bitter melon cultivars: yield parameters, Northern Territory, 2000.
Table 9.
Bitter melon cultivars: yield and quality characteristics, Burringah NSW, 1998/99.
Table 10.
Fruit characteristics and water use of bitter melon cultivars grown hydroponically on two trellis types, Rockhampton, Qld., 2000.
Figure 1.
Price of bitter melon at Flemington Markets, Sydney, January 1996- June 1999.
Figure 2.
Weekly harvest yields, Northern Territory, 2000.
Figure 2.
Cumulative harvest yield, Northern Territory, 2000.
Figure 4.
Correlation of fruit number with maximum and minimum temperature for trellis type (a) and cultivar (b).
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Executive Summary Bitter melon (Momordica charantia L.) is frequently found growing in tropical and sub-tropical climates, and is consumed in most Asian countries. It is also produced in relatively smaller volumes in Australia, with winter production in the Northern Territory (NT), Queensland and northern Western Australia and summer production steadily southwards to include New South-Wales (NSW) and Victoria (Vic). Varieties used in Australia are generally open-pollinated (OP) and selected by growers, even though hybrid varieties are available from overseas. In order to strengthen the industry in Australia, from 1999 to 2001 a series of trials were established to identify national production capability, and supply and productivity issues for supply chain development of domestic and future export markets. This report presents the outcomes of those trials, and a brief review of relevant literature and market situations. Bitter melon is harvested at a physiologically immature stage, before the true onset of ripening. It is important, if fruit is to be transported overland (taking from 1-5 days from origin to market place), that fruit be selected that have not started the physiological process of ripening, for they will produce ethylene that hastens ripening of adjacent stored fruit. Yields of around 30 t/ha in the NT, and 25-80 t/ha in northern NSW are in line with reported yields overseas. Hybrid varieties did not out-yield OP varieties, but tended to have more fruit set and lower individual fruit weight. This inverse relationship was evident in Queensland too. The height at which fruit set in NT may have been responsible for the recorded individual fruit weights of hybrids not reaching their claimed size, but effects of planting density may also have been involved in this anomaly. A period of about three weeks from fruit set to first harvest was evident in Queensland (and reported for the Philippines), and earliest harvest in NT was 56 days after sowing pre-germinated seed, in line with the 60 days after sowing in Rockhampton (Qld). Premature maturity (ie before fruit reaches a marketable size generally considered to be 18-22 cm long) occurred more frequently in OP than hybrid varieties in NT. The main harvest peak in NT was 11-12 weeks after planting, which coincided with the flush of flowering and fruit set on primary lateral branches. Trellising to spread the canopy and to contain growth to primary and secondary branches is important for bitter melon production, and a small trial at Rockhampton showed that overhead trellising was superior to vertical (fence) trellising. The former made for easier harvest (fruit were more visible), less fruit blemish and better fruit set and aeration for diminished disease outbreak. Based on the trials reported here, the recommended cultivars for NT are Moonlight, Baizin, Long Type and the white-fruit cultivar Moon Beauty (although market acceptance of this cultivar is uncertain), and for northern NSW Baizin and Moon Beauty.
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1. Introduction Bitter melon is a member of the cucurbit family commonly grown in tropical and sub tropical countries. There are a number of other commonly called melons such as winter melon, hairy melon, long melon. In this publication we are concerned only with bitter melon, Momordica charantia. In Australia bitter melon is grown in the Northern Territory, Queensland and New South Wales and a small amount in Western Australia. Small amounts are also grown in polyhouses in Victoria and South Australia to meet local market demand. Most is grown by Vietnamese growers and hence the most common varieties are those favoured by Vietnamese consumers which are pearly green and have a very rough or bumpy skin. The bumps are usually small to medium size and are irregular in size and shape. It is particularly difficult to determine when to harvest bitter melon. Consumers eat bitter melon when the fruit is physiologically immature or unripe and therefore when discussing bitter melon, maturity refers to maturity for eating quality. Maturity is very hard to judge from the outward appearance of the fruit but external fruit colour of the whole fruit can be used. This needs to be complemented with some assessment of seed coat colour which is a better indicator, but obviously has disadvantages as a tool in decision making. The seed coat must be creamy or pale green-brown with over maturity indicated by any shade of pink seed coat. Fruit continues to mature after harvest. Therefore fruit for local markets should be harvested when mature (still physiologically immature) for eating and fruit for long distance transport (interstate or export) when immature. Sections 4.4 and 4.5 in the Bitter Melon Quality Description Language Manual, BMQDL, (Vujovic et al. 2000) have colour photos which show these colour maturity indicators. Most bitter melon grown in Australia is open pollinated with seed usually selected by individual growers to suit their customers’ requirements and their production methods. There are hybrid varieties available in Australia and from overseas which have the potential to increase yield and hence profitability. It is unknown whether hybrids have better yields and meet market requirements or whether they have the same maturity issues. This report draws together research undertaken at regional, state and national level between 1999 and 2001. The aim of the research was to identify national production capability and supply and productivity issues for supply chain development of domestic and future export markets. Recommendations for the highest yielding cultivars which meet market, particularly Flemington Market and Melbourne Markets, requirements are made.
1.2 Current Knowledge Bitter melon, Momordica charantia L. is a member of the Cucurbitaceae family. It has also been called: Citrillus lanatus (Thunb.) Matsum. & Nakai Momordica chinensis Sprengel Momordica elegans Salisb. Momordica indica L. Momordica muricata Bitter melon is known by many common names both between and within countries: African cucumber alligator pear amargoso ampalaya assorossie balsam pear balsamapfel balsamina balsamini longa balsamini lunghi bitter cucumber bitter gourd bitter melon bitterer Balsamkürbis bittergourd calabaza africana caranza carilla gourd Chinese melon cundeamor daun peria (leaves) daun peria katak (leaves) estropajo foo gwa yip (leaves) foo gwa fu kua fu kwa haix jin li zhi karela karella kaveli khô qua kor-kuey ku gua kugua la khô qua (leaves) la kwa lao pu tao maha maiden apple
English English Filipino Filipino French English German Spanish Portugese Italian English English English German English Spanish Italian English English Spanish Malaysian Malaysian Spanish Chinese Chinese Chinese Chinese Laotian Chinese Danish, Indian English Indian Vietnamese Chinese Chinese Chinese Vietnamese Vietnamese Chinese Thai West Indian
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maiden's blush mara margase melão de São Caetano momordique a feuilles de vigne mreah muop dang niga-uri palia pare pahit pare paria paroka paya-aki peria katak (short variety) peria laut peria periok phakha pomme de merveille pomo balsamo reishi s'aix springkomkommer tsuru reishi vite indiana wunder-Balsampfel
West Indian Thai French Portugese French Khmer Vietnamese Japanese Filipino Indonesian Indonesian Filipino, Indonesian French Thai Malaysian Malaysian Indonesian, Malaysian Malaysian Thai French Italian Japanese Laotian Dutch Japanese Italian German
Bitter melon is thought to have been domesticated in east India and southern China (Yang and Walters 1992) and is a commonly grown in South East Asia, India, South America, East Africa and the Caribbean. It is used as a food and a medicine. The immature fruit is valued for its bitter flavour and is considered to have an enormous range of health benefits. Cooking styles vary between regions, and produce can be sold fresh, pickled, canned in brine or dehydrated. Young shoots, leaves and flowers are also eaten, for their flavour and for medicinal purposes. The fruit is rich in vitamins A, B and C and minerals such as calcium, phosphorous, potassium and iron (according to the Philippines Food and Nutrition Research Institute (1980), in Rasco and Castillo (1990)). People of different nationalities have their own distinctly favoured shape and size of bitter melon, requiring different varieties (Table 1). Table 1: Bitter melon market preferences (Peter McLaughlin 1998, pers. comm.). Country
Size (length. x diam., cm)
Description
Japan Vietnam China
35-45 x 5-7 16 x 4-5 20-26 x 5-7
Long, skinny and very bitter. Pearl coloured round, rough skin Dark green, smooth skin
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Cultivars Most of the bitter melon produced in Australia is open pollinated (usually the Vietnamese type) with many growers selecting their own seed of these open pollinated varieties to produce their customers’ requirements. More recently, as a result of this project, growers are adopting hybrid cultivars which have greater yields and can meet customer expectations. Considerable improvement in quality, consistency and yield can be achieved with hybrid seed. Both hybrid and open pollinated seed is available through Australian seed companies, though the range is limited and hybrid seed is usually obtained from overseas. A white cultivar is also available. Hybrid cultivar (seed catalogue) descriptions For seed supply contacts see Appendix 1. Kiew Yoke 59 Productive cultivar with long, smooth light green fruit. Fruit weight 500-600 g. Kiew Yoke 68 Vigorous, disease tolerant cultivar with large, broad shouldered, glossy fruit. Fruit weight 500-600 g. good shelf life and recommended for raining season production. Known You Green A Taiwanese cultivar with a smooth, shiny, beautiful green skin. Plants are early, vigorous and prolific. Fruit has ribbed stripes and weighs 400-700 g. The flesh is green and mildly bitter. Fruit is good for salad and frying. Verdure An early, vigorous, productive, high yielding cultivar. Fruits are short, beautifully shaped with a maximum weight of 500 g. Its green skin and light green flesh are suitable for stewing. Moonrise Plants are early, vigorous and prolific. Fruit are long shaped, with light green skin and flesh and weigh up to 700 g. It has an excellent crispy and tender taste and is ideal as a fresh vegetable or for stir frying. Moonlight An early, prolific cultivar which produces medium-long fruit that seldom crack. Fruit weigh up to 650 g. and have light green skin and flesh. This cultivar is suitable for use as a fresh vegetable and for stir frying. Moon Beauty Plants are early, vigorous and high yielding. Fruit are oblong shaped and have shiny white skin with a wart like surface. Moon Beauty fruit are 30 cm long and 9 cm width and weigh 700 g. It has thick and crispy flesh with great taste. New South Wales Local OP selection The variety called Local OP, used as a “control” in trials in NSW and NT is the F8 selection of a cross between a locally grown Vietnamese type (of unknown origin) and Okinawa (Kurname Vegetable Seed Co., Japan). It is not commercially available.
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Production Weed Wild varieties exist in Australia, which have much smaller fruit than the commercial varieties. Weedy forms of bitter melon have escaped ornamental cultivation and become a problem in citrus groves of Florida (Robinson and Decker-Walters 1996). Climate / season Bitter melon is grown commercially along the Australian east coast from Melbourne to Cairns, and in the Northern Territory (Lee 1995, Table 2). It is tolerant to a range of environments (Lim 1998) and can be grown in tropical and subtropical climates (Reyes et al. 1994). Two crops are produced annually in Florida (Lamberts 1992). Table 2: Seasonal margins for bitter melon planting in Australia (E: early, L: late, +: all).
Location
J
F
Victoria Gosford Murwillumbah Darwin Kununurra
+ . . .
. . . .
Planting date M A . . . E
. . . + +
M
J
J
A
S
O
N
D
. . . + +
. . . + +
. . . + +
. . . L.
. . E .
+ + + .
+ + + .
+ + + .
In Murwillumbah bitter melon is harvested from early January through to May, in Darwin from May to October and in Kunannura, June to September. Temperature A minimum temperature of 18 C during early growth is preferred (Larkcom 1991), with 24-27 C being optimum (Desai and Musmade 1998). This range has been confirmed at Murwillumbah, with prolific growth occurring at day / night temperatures of 28-35 / 20-25 C and severe reduction in growth with night temperatures of 16 C or less (Peter McLaughlin 1998, pers. comm.). It requires more heat than the other gourds to produce maximum yield (Larkcom 1991), but is also more resistant to lower temperatures (Desai and Musmade 1998). pH Optimum is 6.0-6.7 (Desai and Musmade 1998). Soil type Bitter melon grows best in a well drained sandy loam, rich in organic matter, but will tolerate many soils (Cantwell et al. 1996, Reyes et al. 1994). Soil preparation It is preferable to grow the crop on raised beds or ridges (Lim 1998). Chicken manure may be dug in and watered 2-4 weeks before transplanting or sowing but can be associated with food safety issues. Base fertiliser should be applied to the top of the bed (Traynor et al 2001. In press). Germination Seeds rapidly lose viability, so pre-germinating is recommended for all but very fresh seed to ensure that only viable seed is planted. Soak for 24 hours and wrap in damp paper towelling, then keep in a plastic bag at 26-29 C for germination within a couple of days (Larkcom 1991). Germination ceases outside the range of 10-50 C (Singh 1991). Germination percentage can be increased by soaking in 1% KNO3 (Devi and Selvaraj 1994). Sow germinated seeds into pots, or directly in the field if the temperature is warm (Larkcom 1991). Seedlings emerge 5-7 days after sowing (Reyes et al. 1994). They require protection from wind, chill and excessive sun, and water should be prevented from collecting nearby (Desai and Musmade 1998). 5
Seed weight Weight varies considerably, with reports from 6,000 seeds/kg (Desai and Musmade 1998) to 17,000 seeds/kg (Reyes et al. 1994). Plant density Plant spacing of 50 cm to 1 m between plants and 2-3 m between rows are used in Australia (Traynor et al. 2001 In press). Optimum plant density varies with cultivar, from 6 500 to 11 000 plants/ha (Reyes et al. 1994) or 20 000 plants/ha (Huyskens et al. 1992). Transplanting It may be necessary to grow the first plants of the season in a hot bed to ensure enough warmth for immediate germination, and then transplant them at the 4-6 leaf stage (Peter McLaughlin 1999, pers. comm.). Trellising Bitter melon is grown on 2 m high fences or overhead trellising in Darwin. Higher yields are obtained with 2 m than 1 m high trellises (Abusaleha and Dutta 1994) and the crop is more accessible. Overhead or T-trellising may increase the proportion of marketable fruit (Huyskens et al. 1992). See section on trellises. Remove lateral branches below the first production wire of the trellis, and remove the tip of the main runner when it reaches the top wire, to induce early cropping. Removal of lateral branches in the first ten nodes has a positive effect on total yield. Without pruning, most of the female flowers occur between the 10th and 40th nodes, or at 0.5 - 2 m height (Rasco and Castillo 1990). Grafting Luffa provides an excellent root stock for bitter melon, and grafting can increase yields substantially in Taiwan, due to Fusarium wilt control (Lin et al. 1998). Luffa rootstock is also more resistant to flooding (Liao and Lin 1996). Nutrition If soil is highly fertile and prepared with enough organic matter, further feeding may not be necessary (Larkcom 1991). Add 2 L/ha Nitrofoska monthly after planting until the plant reaches trellis height, then potassium nitrate (at 50 kg/ha ) up to flowering. Reduce nitrogen application during fruit set as nitrate is known to suppress flowering in many species. The addition of calcium nitrate at 50 kg/ha until flowering improves shelf life (Peter McLaughlin 1998, pers. comm.). N:P:K basal applications of around 100:50:50 kg/ha respectively, are recommended by Robinson and Decker-Walters (1996). Water Irrigate at least weekly, beginning from the day of sowing (Desai and Musmade 1998). Tensiometers are used and watering is applied to maintain 10-20 centibar tension in the root zone (Traynor 2000 pers. comm.). The plant is intolerant to flooding (Reyes et al. 1994), with 4 days of flooding producing significant changes in morphology (Liao and Lin 1994).
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Flowering Bitter melon is monoecious with male and female flowers borne separately on the same plant. Yield is determined by the number of successfully pollinated female flowers. Bitter melon will produce its first flower at 45-55 (Reyes et al. 1994) or 35 days (Rasco and Castillo 1990) after sowing if conditions are optimal, and continue throughout a season of usually 6 months (Reyes et al. 1994). Pollination can be achieved with bees or, in prolonged overcast weather, by blowing with an empty mister. Pollen looses viability as the day advances and may be fully unviable by midday (Desai and Musmade 1998). The stigma is usually receptive for one day either side of flower opening, after which it turns brown and dries (Rasco and Castillo 1990). Flowering behaviour varies with cultivar and climatic conditions (Deshpande et al. 1979). Male/female flower ratio Average ratio of male to female flowers throughout the flowering period of two cultivars was 50 males for every female flower (Rasco and Castillo 1990). Long days cause the male flowers to bloom up to 2 weeks before the female flowers, while short days have the reverse effect (Huyskens et al. 1992 and references within). Nearly ninety percent of female flowers develop on the first forty nodes with the majority at nodes 21 to 30 (Rasco and Castillo 1990). Pruning the lower laterals increases the total number of flowers per plant by increasing the number of flowers on higher laterals (Rasco and Castillo 1990). Allowing the vine to grow on overhead trellis produced more fruiting nodes (Traynor 2001 pers comm.). Maturity It is difficult to determine when to harvest bitter melon. Indications include a slight change in fruit colour and the fullness of ridges and bumps. Both can be difficult to observe. Consumers eat bitter melon when the fruit is physiologically immature or unripe and therefore when discussing bitter melon maturity for harvest, this refers to eating quality (and is really immaturity). A physiologically mature fruit is unsuitable for marketing. Commercial maturity is very hard to judge from the outward appearance of the fruit but external fruit colour of the whole fruit can be used. This needs to be complimented with seed coat colour which is a better indicator but obviously has disadvantages as a tool in decision making. The fruit colour must be green which it is whilst commercially immature and mature and seed coat colour is needed as a further indication of maturity. The seed coat must be creamy or pale green-brown with over maturity indicated by any shade of pink. Since fruit continues to mature after harvest, fruit for immediate sale in local markets should be harvested mature (still physiologically immature) and fruit for long distance transport (interstate or export) when immature. Sections 4.4 and 4.5 in the Bitter melon Quality Description Language Manual, BMQDL, (Vujovic et al. 2000) have colour photos which show these colour maturity indicators. Harvest It typically takes about 15-20 days after fruit set (90 days from planting) to reach marketable age (Reyes et al. 1994), but bitter melon can be harvested at any stage before, depending on the market. Fruit should be light green, thick and juicy (Lim 1998) and the seeds should be soft and white (Huyskens et al. 1992) creamy to pale green-brown (Vujovic et al. 2000). Harvest every 2-3 days as the fruit ripens quickly (Desai and Musmade 1998). Fruits increase in bitterness with time due to a build up of the alkaloid momordicine, and then lose the bitterness during ripening (Cantwell et al. 1996). Harvest should occur before ripening (Traynor, 2000 pers. comm.) and the petiole (stem on which the fruit is found) should be cut cleanly with a sharp knife (Reyes et al. 1994). Yield Yields of 20-30 t/ha are common (Reyes et al. 1994), and over 50 t/ ha have been reported (Huyskens et al. 1992, Kuang et al. 1997). Yields of 61-108 t/ha were achieved in Taiwan with plastic housing and grafting (Liao and Lin 1996).
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Postharvest Bitter melon is a climacteric fruit that continues to ripen towards physiological maturity after harvest (David Hicks 2002, pers. comm.). Hence reducing fruit temperature is important to slow maturity. As it ripens bitter melon produces ethylene which can cause other bitter melon in close proximity eg. in a carton, to over ripen. Pick early morning and remove field heat immediately before storing at the correct temperature. Bitter melon should not be stored or transported with ethylene producing fruit such as banana, tomato, mango, papaya and guava. Storage temperature Optimal storage temperature for fruit is 7-10ºC (Gosbee and Lim, 2000). Fruit can be stored at temperatures down to 4ºC for short periods but prolonged exposure to low temperatures can cause chilling injury. Fruit stored above 10ºC continue ripening. The optimum temperature for setting refrigeration may be lower, and is different for each set of storage conditions. Transport refrigeration and cool room settings need to be calibrated. Temperature settings for transport of 5-7ºC. have been quoted by suppliers. If air circulation is low, heat will build up in the cartons causing fruit temperature to be higher than air temperature (Melinda Gosbee 2001, pers. comm.). Lower temperatures cause chilling injury, evident as pitting, decay and discolouration and as higher ethylene production (faster ripening) when temperature is subsequently later raised to 15 C (Zong et al. 1995). Higher temperatures cause ripening. More mature fruit (slightly soft but still green) will rapidly begin to ripen if the temperature is too high, risking the contents of the entire carton/container, but maturity has less effect on postharvest life when fruit is stored at the correct temperature (Zong et al. 1995). The effect of temperature on respiration and ethylene production is given in Table 3. Table 3: Respiration and ethylene production of selected Asian vegetables (Zong et al. 1992, Zong et al. 1995). 0°C
5°C
10°C
15°C
Respiration (µl CO2 /g/h) Bitter melon Hairy melon Luffa Yard long bean 20.0
7.8 8.7 13.7 23.0
15.0 11.4 19.0 46.0
26.6 21.1 34.4
Ethylene production (µl/g/h) Bitter melon Hairy melon Luffa
