Index
|
Search
|
Home
New Crop FactSHEET
Kiwano
Contributor: Aliza Benzioni
Copyright © 1997. All Rights Reserved. Quotation
from this document should cite and acknowledge the contributor.
- Common Names
- Scientific Names
- Uses
- Origin
- Crop Status
- Toxicities
- Traditional Uses
- Botany
- Taxonomy
- Morphology and Floral Biology
- Ecology
- Crop Culture
- Propagation
- Field Practices
- Pest and Diseases
- Post Harvest Treatment
- Marketing
- Germplasm
- Key References
- Selected Experts
English: kiwano, melano, African horned cucumber, jelly melon, hedged
gourd, horned melon, English tomato
French: metulon
Species: Cucumis metuliferus E. Mey. ex Naud or ex Schrad
Family: Cucurbitaceae
Cucumis metuliferus is currently being promoted as a specialty fruit for
export to the European and USA market.
Semiarid regions of southern and central Africa (Kalahari desert): mainly
Botswana, South Africa, Namibia, Zimbabwe, Malawi and Nigeria. Was introduced
to Australia 70 years ago and became a weed there.
C. metuliferus is grown as an ornamental fruit in New Zealand, Kenya,
Israel and the USA and its market is expanding. Since the fruits have a long
shelf life and retain their decorative appeal for many months at room
temperature it can be developed into a major ornamental fruit.
The present commercial cultigene has a rather bland taste which severely limits
its potential as an eating fruit. If its eating quality can be improved,
mainly by increasing sugar content, acidity, and aroma, it would be marketed as
a new fruit.
Cucurbitacines are present in some accessions of Cucumis metuliferus, making
it extremely bitter. These compounds are very toxic to mammals, however as they
are the most bitter substances known they are also feeding deterrents and very
rarely eaten by mammals. The non-bitter comercial cultivars do not contain cucurbitacines
and are not toxic.
Kiwano fruits are eaten as a supplement by the local population.
Cucumis metuliferus is a single species in the Metuliferus group
of the Cucumis, having a distinct morphology and being
cross-incompatible with other Cucumis species. It has 2n = 24
chromosomes.
The plant is a monoecious, climbing, annual herb, with staminate flowers
typically appearing several days before pistillate flowers. The ellipsoid
fruit is bright yellow-reddish orange in color when mature and shaped like a
short stout cucumber with many blunt thorns on its surface. These seeds are
embedded in the mesocarp which is emerald green and consists of juicy,
bland-tasting tissue. Parthenocarpic fruits are produced when temperatures are
low.
Cucumis metuliferus is endemic to the semi-arid regions of southern and
central Africa, where it is found at low to medium altitudes along road sides,
fallow and abandoned lands and on the fringes of gullies.
Seeding optimum germination temperatures are between 20° and 35°C (68° to 95°F).
Germination is delayed at 12°C (54°F), and inhibited at temperatures lower than
12°C or above 35°C. Thus it is recommended to sow in trays and transplant into
the field at the two true leaf stage. The best time for transplanting into an
open field is in the spring when soil and air temperatures rise to around 15°C
(59°F).
General field practices are similar to those for musk melons. Organic manure
(around 2 tonnes/ha) may be incorporated before planting. It was found in
Israel that without trailing a density of 10,000 plants per hectares gave good
yield (over 46 tonnes/ha of fruits, of which more than 60% were export
quality). Time from sowing to harvest was three and a half months.
Fertigation was done with 2-liters/hr drippers spaced 0.5 m apart. Water was
applied twice a week with amounts calculated to replenish 40% of
evapotranspiration measured by a type A pan till first flower stage, and 80%
thereafter. It is possible to grow kiwano under nets or in a greenhouse.
Under those conditions trailing is necessary, and for greenhouse production
bees must be introduced. The use of greenhouses and nets enable the growth of
kiwano in two seasons (early spring and autumn) and supply the market with
fruits year round.
It was found that kiwano is resistant to several root-knot nematodes, two
accessions were found to be highly resistant to water melon mosaic virus
(WMV-1), but very sensitive to the squash mosaic virus(SqMV). Some accessions
were found to succumb to Fusarium wilt. Resistance to greenhouse white fly was
reported. Kiwano was reported to be resistant to powdery mildew, however in
Israel powdery mildew as well as the squash mosaic virus(SqMV) attacked kiwano
fields and measures had to be taken.
Kiwano fruits have a very long shelf life and may keep for several months.
Storage temperature affected fruit shelf life, which is considerably longer at
20° or 24°C (68° or 75°F) than at 4°, 8° or 12°C (39°, 46°, or 54°F) (more then three
months in 20° to 24°C compared to few weeks in lower temperatures).
The approximate color turning point is 30-40 days from fruit set and at this
stage they reach their maximal weight. During the following month the
concentrations of reducing sugars and total soluble solids increases and the
peel color changes from green through whitish green to yellow and finally to
orange. Fruits picked mature green (at about turning point) fail to develop
the desirable uniform orange color even after three months in storage.
Exposure of mature green fruits to 160 ppm ethylene for 24 hours induces color
formation and they turned yellow-orange within afew days. Fruits left to ripen
in the field exhibit higher TSS and reducing sugar values than fruits allowed
to ripen in storage.
The market volume is restricted; supply must be continuous throughout the year:
and prices are optimal only for large and homogeneously orange colored fruits.
A market for edible kiwano does not yet exist, because the fruit lacks taste.
Increasing the sweetness and improving the aroma may give rise to a new product
for a large-volume market.
The seedlings derived from the commercial cultigene do not exhibit much
variability, however accessions from the wild have a wide phenological
variability which can be used for selection and breeding for improved taste,
resistances, etc. The North Carolina Regional Station, Ames, Iowa has a
collection of cultigenes which were tested for plant vigor, resistance to
Fusarium wilt and yield. Accessions are available at gene banks and the FAO.
Seven accessions were tested in Israel: the commercial cultigene, three lines
obtained from the FAO, 67868, 67869 and 67870, two collected in the Kalahari
desert (77313 and 77151) and one from Botswana.
Significant differences were found in important fruit quality characters
between the commercial cultigene and the accession lines. The Botswana and
commercial cultigenes had significantly larger fruit (up to twice as large) and
fewer thorns than the other accession lines. The commercial line had
significantly lower reducing sugar and higher pH than the other accession
lines, but some of the accession lines were bitter.
The line from Botswana had large and attractive fruits, with a slightly
different shape. Fruits of this line had high acidity and very good aroma.
Crosses between the commercial line and the five accessions were performed, and
seeds were produced.
- Bates, D.M., Robinson, R.W., and Jeffry, C. (eds). 1990. Biology and
utilization of the Cucurbitaceae. Cornell University Press, Ithaca, NY.
- Benzioni, A., Mendlinger, S., Ventura, M., and Huskens, S. 1991. The effect
of sowing dates and temperatures on germination, flowering and yield of
Cucumis metuliferus. HortScience 26:1051-3.
- Bruecher, H. 1977. Cucurbitaceae, In: Tropische Nutzpflanzen. Springer
Verlag, Berlin. 1977:258-297.
- Keith, M.E. and Renew, A. 1975. Notes on some edible wild plants found in the
Kalahari. Gemsbok Park. Koedoe 18, 1-12.
- Mendlinger, S., Benzioni, A., Huskens, S., and Ventura, M. 1992. Fruit
development and postharvest physiology of Cucumis metuliferus Mey., a
new crop plant. J. Hort. Sci. 67:489-493.
Aliza Benzioni, Institutes for Applied Research, Ben-Gurion University of the
Negev, P.O. Box 653 Beer-Sheva 84105 Israel; Tel. 07-6461970; Fax: 07-6472984; email: benzioni@bgumail.bgu.ac.il
Dyremple B. Marsh, Lincoln University, 900 Moreau Drive Jefferson City Missouri 65101; Tel: (314)681-5530; Fax: (314)681-5596
Noel D. Vietmeyer, National Research Council, BOSTID, 2101 Constitution Avenue NW, Washington DC 20418; Tel: (202) 334-2692; Fax: (202)334-2660
M. Ventura, The Institutes for Applied Research, Ben-Gurion University of the Negev P.O.Box 653, Beer-Sheva 84105 Israel; Tel: 07-6461916; Fax: 07-6472984
Cohen Yair, Moshav Zofar, Arava Zfonit; Tel: 07-581461
[Contributor: Aliza Benzioni, Institutes for Applied Research, Ben-Gurion University of the Negev]
Copyright © 1997. All Rights Reserved. Quotation
from this document should cite and acknowledge the contributor.