From Plant Resources of South-East Asia No 2: Edible fruits and nuts, PROSEA Foundation
by A. M. Gurnah,
Taxon
Passiflora edulis Sims
Protologue
Bot. Mag. 45: 1989 (1818).
Family
PASSIFLORACEAE
Chromosome Numbers
2n = 18
Vernacular Names
Passionfruit,
granadilla (En). Grenadille (Fr). Indonesia: buah negeri (Java), pasi
(Sunda), konyal. Malaysia: buah susu, markisa. Philippines: pasionaria
(Tagalog), maraflora (Ilokano). Laos: linmangkon, not. Thailand:
linmangkon (Bangkok), benchawan (Chiang Mai). Vietnam: chùm bap.
Origin and Geographic Distribution
Passionfruit is a native of southern Brazil where it grows on the edges of rain forests. There are two distinct forms: forma edulis, the purple passionfruit, occurs in cool environments at higher altitudes, whereas forma flavicarpa,
the yellow passionfruit, is at home in the tropical lowlands. The two
types were distributed throughout the tropics and subtropics via Europe
and Australia during the 19th Century. In South-East Asia passionfruit
is mainly a home garden crop.
Uses
The fruit may be eaten fresh,
but mostly the pulp is extracted and preserved by heating or cooling.
The juice has a unique and intense flavour and high acidity which makes
it a natural concentrate. When sweetened and diluted it is very
palatable and blends well with other fruit juices. Typical processed
products are ice cream, sherbet, nectar, juices, concentrate, squash,
jams and jellies.
Production and International Trade
Passionfruit
is a small crop; the estimated commercial area in a dozen major
producing countries is only about 4500 ha. Roughly 3000 ha is in South
America, mainly in Brazil, Peru and Ecuador. Sri Lanka is by far the
most important producer in Asia with 800 ha. Australasia has about 550
ha, including Papua New Guinea (80 ha) and Fiji (70 ha). A cooperative
in the Philippines grows 200 ha of passionfruit and plans to expand.
The
commercial crop is largely converted into juice, about half of which —
equivalent to some 25 000 t fresh fruit — enters world trade. Export of
fresh fruit is in the order of 1000 t and includes small quantities
from Thailand and the Philippines. In the later 1980s processors in
Queensland paid US$ 20—30 per 100 kg fruit. The price in the fresh
fruit market showed extreme fluctuations; in Queensland growers were
getting US$ 1—4 per kg, depending on the season.
Properties
The
fruit shell is about 45% of the fresh weight; 100 g of the edible pulp
contains: water 69—80 g, protein 2.3 g, fat 2.0 g (almost all in the
seed), carbohydrates 16 g, fibre 3.5 g, Ca 10 mg, Fe 1.0 mg, vitamin A
20 IU, trace thiamine, riboflavin 0.1 mg, nicotinamide 1.5 mg and
vitamin C 20 mg. The energy value amounts to 385 kJ/100 g.
Description
A vigorous
perennial but short-lived semi-woody vine, up to 15 m long. Stems
glabrous, grooved, green. Tendrils axillary, spirally coiled, terete,
longer than the leaves. Leaves with stipules and petioles; stipules
lanceolate, 1 cm long; petiole 2—5 cm long, glabrous, grooved above, 2
circular glands at top; blades unlobed when young, later palmately
3-lobed, cordate at base; lobes ovate-oblong, 10—15 cm x 12—25 cm,
acuminate, margin with curved teeth that are glandular tipped. Flowers
solitary, axillary, fragrant, showy, 7.5—10 cm in diameter; peduncle
triangular, 2—5 cm long, near the apex with 3 leafy, ovate to
lanceolate bracts; calyx tubular at base, lobes 5, spreading, reflexed,
yellow-green below, white above, margins with up to 4 glands, apex with
a thornlike appendage; petals 5, free, white and thin, alternating with
calyx lobes; corona with 2 outer rows of wavy, radiating threads, 2—3
cm long, white with purple base, and 3 inner rows of short
purple-tipped papillae; stamens 5, filaments united into a tube round
the gynophore for about 1 cm and then widely parted for 1 cm, anthers
large, versatile, 2-celled, transverse, pale yellow, hanging downward;
ovary on gynophore, ovoid, 1-locular with 3 parietal placentas, styles
3, horizontal, clavate, with longitudinal furrow, 1 cm long, stigmas
reniform or cordiform, 0.5 cm in diameter. Fruit a globose or ovoid
berry, 4—12 cm x 4—7 cm, deep purple or canary yellow; exocarp hard and
thin, mesocarp greenish, endocarp white. Seeds many, attached to
peg-like funiculi on the ovary wall, surrounded by yellowish aromatic
pulpy/juicy edible arils; testa hard, black, 3-toothed at base.
Growth and Development
Seeds
lose their viability within a few weeks. Germination takes 2—4 weeks;
the seedlings grow slowly and require 3—4 months to reach the
transplanting height of 20—25 cm. Within 5—7 weeks after transplanting,
each plant will have up to four healthy laterals. From then on the vine
grows very rapidly; the first flowers are produced 5—7 months after
transplanting when the vine can be 10—15 m long.
Flower buds emerge
sequentially on the new shoots. They take 40—46 days to anthesis; the
purple fruit matures 60—90 days later, the yellow fruit after 60—70
days. Initial fruit set is usually excellent and when the shoot bears
some 9 fruits, extension growth slows down and both fruit set and
flower bud formation tend to fail, although vigorous young shoots may
bear more than 20 fruits. Sequential flowering during a flush results
in fruit maturing over a period of 2—3 months. Thus flowering and
fruiting are closely linked to shoot growth. As in many vines, light is
the essential factor for flowering and in passionfruit this is
particularly true for floral development and fruit set. That is why
training and pruning are important to ensure adequate exposure of the
shoots. In a monsoon climate most flowers are produced on the flush
occurring at the end of the rainy season. Depending on the climate
there may be 1—3 harvest peaks (purple passionfruit) or a single, often
very long harvest season (more common with the yellow passionfruit).
Flowers
open shortly after sunrise and remain open until mid-morning the next
day, but the stigma is receptive only on the first day. The purple
passionfruit is self-compatible, setting well if selfed, but the yellow
passionfruit often requires cross-pollination. Bees are the main
pollinators; when and where they are not sufficiently active, hand
pollination can be practised. The fruit follows a smooth sigmoid growth
curve and attains its maximum diameter in about 3 weeks. The juice
content is negligible until shortly before harvest.
Other Botanical Information
In Passiflora edulis two forms are distinguished:
— f. edulis:
the purple passionfruit with deep purple fruits 4—5 cm in diameter,
with green tendrils and leaves. This is the most common form, said to
have the best flavour.
— f. flavicarpa
Degener: the yellow passionfruit with canary-yellow fruits 6—12 cm x
4—7 cm and reddish-purple tinged tendrils and leaves; larger, more
showy flowers with deeper purple corona and more vigorous growth.
In
most countries cultivars of the yellow passionfruit are commonly grown,
such as 'Waimanalo Selection', 'Yee Selection' and 'Noel's Special'
(Hawaii) and 'Mirim' or 'Hawaiiana' (South America). Purple
passionfruit dominates in southern and eastern Africa and in New
Zealand ('Bali Hai'); in Australia cultivars are planted which are
hybrids of the two forms: 'E 23', 'Purple Gold', 'Lacey' and 'Black
Beauty'.
Of the 400 known species of Passiflora
L. about 50—60 bear edible fruits. In South-East Asia 5 non-edible
species are endemic; about 13 edible species have been introduced. In
addition to Passiflora edulis, Passiflora quadrangularis
L. is important. Some minor introduced species are described in the
chapter on minor edible fruits and nuts. Frequently, Passiflora plants
are cultivated as ornamentals for their showy flowers.
Ecology
The
yellow passionfruit grows best at altitudes of 0—800 m; the purple
passionfruit forms virtually no flowers below 1000 m and should be
grown at altitudes of 1200—2000 m. The mature purple passionfruit
tolerates light frosts and can be grown in the subtropics, as in
Australia and New Zealand. Both crops grow on a wide range of soils;
heavy clay soils have to be drained and very sandy ones need heavy
manuring. A pH of 6—8 is preferred. In South-East Asia the crops are
grown in areas with 2000—3000 mm annual rainfall, but especially the
purple passionfruit grows well on as little as 900 mm in Africa and
Australia, provided the rainfall is well distributed.
The vines
require sheltered locations without extreme temperatures: below 20°C
pollen does not germinate and at 18—15°C both growth and flowering are
set back, whereas temperatures above 30—32°C stimulate growth at the
expense of flowering and fruit set. These critical temperatures were
established for hybrid cultivars in Australia.
Propagation and planting
Passionfruit
is generally propagated from seed, although cuttings and grafting can
be used. Seed viability declines rapidly after 2 months. Storage at a
relative humidity of around 10% in sealed packages in air-conditioned
rooms maintains a high germination rate (> 70%) for up to 12 months.
Seed should be rubbed clean of pulp and dried in the shade. Nowadays
seedlings are often raised in polythene bags, 15 cm wide and 25 cm
deep. Three seeds per bag are sown at a depth of 1 cm and thinned to
leave one after two months.
Cuttings are set in steam-sterilized
coarse sand and later transplanted into bags or a nursery bed. In
trials with purple passionfruit, terminal cuttings with 3—4 nodes and
one or two leaves gave better rooting than other types of cuttings.
Application of 3000 mg/l indole butyric acid (the optimum rate)
improved and speeded up rooting. Grafting is often employed to control
diseases. Yellow passionfruit is used as resistant rootstock although
other Passiflora species, in particular Passiflora caerulea L., show much greater resistance to Phytophthora root rot and Fusarium collar rot. Moreover, Passiflora caerulea
is tolerant of rootknot nematode and to exposure to —1.5°C; it can be
propagated from leaf and stem cuttings and is compatible with Passiflora edulis.
Wedge and whip grafts on seedling rootstocks — sometimes on rooted
cuttings — are used. Micro-propagation using axillary buds gives good
results.
In most parts of South-East Asia passionfruit is a backyard
crop and seeds are often sown at stake. Support is essential even under
such conditions. Commercial plantations adopt a row spacing of 1.2—1.8
m and a within-row spacing of 3 m. This gives 1851—2777 plants/ha.
Planting holes of 45 cm x 45 cm x 45 cm should be filled with topsoil
mixed with up to 10 kg compost or manure and about 120 g double
superphosphate where P is required. Transplanting is done at the start
of the rainy season.
Husbandry
Early
growth of passionfruit is slow and regular weeding is essential.
Mulching along the rows or around the base of the plants greatly
facilitates weed control and protects the roots. Being a short-term
perennial, passionfruit is an ideal intercrop during the establishment
period of crops such as oil palm and rubber.
Elaborate trellises
have been used in Australia and South Africa but in East Africa,
especially at closer spacing, a single wire trellis has been found to
be as good. A 14-gauge galvanized wire is tightly stretched along the
tops of hardwood posts 15 cm in diameter and 3 m long, dug in to a
depth of 0.6 m; these posts are spaced 8 m apart. The trellis should be
erected when the field is planted so that the main shoot and one
vigorous lateral can be tied to the wire with a string. If laterals do
not emerge in time, they can be forced to leaf out by pinching off the
shoot tip. When the vines reach the wire they are trained in opposite
directions along it. All laterals below the wire are pruned off.
Laterals emerging along the wire are allowed to hang down freely; they
are the secondary shoots branching into tertiary shoots. Secondary and
higher order shoots are the fruiting wood which has to be thinned and
rejuvenated by pruning.
Side dressing is practised with 50 kg N per ha 4 weeks after transplanting and every 12 months after that.
Diseases and Pests
The most important disease in the region and worldwide is brown spot (Alternaria passiflorae and Alternaria plagiata) on leaves, vines and fruits. Phytophthora blight (Phytophthora nicotianae var. parasitica)
causes the wilting of shoot tips and crown rot, particularly where
water stagnates occasionally. Septoria spot, caused by the fungus Septoria passiflorae,
causes extensive spotting of leaf and fruit, and occasionally of the
stem. These three fungal diseases can be controlled by fortnightly
sprays of copper fungicides or Ridomil. Pruning to open up the canopy
for fungicide penetration is also essential. Yellow passionfruit and
its hybrids are more tolerant of the diseases. Fusarium wilt is caused
by the soilborne fungus Fusarium oxysporum f. sp. passiflorae;
the shoots wilt, followed by a complete collapse of the plant. Grafting
to wilt-resistant yellow passionfruit rootstocks is the most practical
way of control. Damping- off caused by Rhizoctonia solani and Pythium spp. can be a problem in nurseries and soils should be sterilized.
A number of virus diseases has been reported; the most widespread and serious one is woodiness. It is spread by aphids (Aphis gossypii, Myzus persicae) and
pruning knives. Other virus diseases are ringspot from Ivory Coast,
which is similar to woodiness and spread by aphids and passionfruit
mosaic (PFMV-K and PFMV-MU) reported in Sarawak and other areas, which
is spread by aphids and pruning knives. The most practical control is
to use clean planting material, clean pruning tools and resistant
hybrids, or rootstocks of yellow passionfruit.
Nematodes, especially the rootknot nematodes (Meloidogyne incognita, Meloidogyne javanica and Meloidogyne arenaria), are the most serious pest. Practical control measures are crop rotation and the use of tolerant rootstocks. The cocoa mirid Helopeltis clavifer, the passion vine bug Leptoglossus australis and the green vegetable bug Nezara viridula suck and pierce leaves and young fruits; these, together with the leaf-eating caterpillars of Tiracola plagiata, are minor pests.
Fruit flies include the oriental fruit fly (Dacus dorsalis), the melon fly (Dacus cucurbitae), the Mediterranean fruit fly (Ceratitis capitata) and the Queensland fruit fly (Dacus tryoni).
Pierced young fruit shrivels and falls; later injuries cause damage
which lowers the grade. Spraying insecticides may be essential if
destruction of infested fruit and the use of baits do not adequately
check the pest to safeguard fresh fruit export markets.
Mealy bugs (Planococcus citri) are usually controlled by their natural enemies (Cryptolaemus montrouzieri). The same applies to scales and mites which incidentally do much damage: the red scale (Aonidiella aurantii) and soft brown scale (Coccus hesperidum) as well as the red spider mite (Brevipalpus papayensis) and the passion vine mite (Brevipalpus phoenicis).
Harvesting
Fruit
drops to the ground when fully mature. It is collected once or twice
per week; at this stage it looks shrivelled and unattractive. For fresh
fruit markets, especially the export market, fruit is picked after full
colour development when the whole fruit is purple or canary yellow, but
before shrivelling and drying set in.
Yield
A
plantation is usually cropped for 3 years; of the total crop, roughly
50% is produced in the first year, 35% in the second, and 15% in the
third year. The sharp decline in yield level, which is even more marked
in areas with disease problems, is the main reason to replant fields
after the second or third crop. Average yields amount to 10—15 t/ha per
year for the purple and 20—25 t/ha per year for the yellow
passionfruit. Much higher yields are possible; yields as high as 50
t/ha per year for purple passionfruit have been reported from Kenya.
Handling After Harvest
Fruit
for processing is delivered to the factory where the pulp is extracted
and the juice is expelled by centrifugation. Passionfruit juice can be
produced and bottled by small factories at village level. The aroma and
flavour of the juice are sensitive to heat; preservation by freezing is
therefore preferred. Where pasteurization by heat is necessary, it
should be done by agitation in the can (spin pasteurization).
Fresh
fruit can be stored at 5—7°C, 85—90% relative humidity, for 3 weeks;
there is a weight loss of 32% when fruit is removed from such storage.
In Kenya standards have been laid down for fresh fruit for export,
including a diameter size larger than 25 mm, and a smooth, clean,
unblemished and freshly coloured skin. The fruit is packed in a single
layer in rigid containers with ventilation slots. The containers are
lined with tissue paper and on top of the fruit comes a layer of
padding material to ensure a firm pack.
Genetic Resources
Large
germplasm collections are kept in Queensland (Australia), Hawaii
(United States) and Brazil. A few lines of yellow passionfruit are at
the University of Technology, Lae (Papua New Guinea).
Breeding
The
major breeding objective is to incorporate resistance to nematodes and
diseases such as Fusarium wilt and woodiness virus. Most of these
traits come from the yellow passionfruit; in Queensland the purple
passionfruit has been completely replaced by yellow/purple hybrids. Passiflora caerulea, which is more tolerant of many pests, diseases and low temperature, has not yet featured in any breeding programme.
Prospects
Passionfruit
has a history of ups and downs in many parts of the world. Easy
propagation and good early yields facilitate expansion of production at
such a pace that markets are upset. The other threat is that diseases
catch up with the expanding crop and become ruinous before the growers
have come to grips with them.
In spite of this volatile history, the
prospects for passionfruit in South-East Asia appear to be favourable:
the large home market provides a solid basis for expansion, and more
resistant cultivars and improved crop protection should go a long way
towards maintaining crop health. The possibilities for exporting fresh
fruit pulp or juice to countries such as Japan and South Korea, as well
as to Europe and America, should also be explored.
Literature
Gachanja,
S.P. & Gurnah, A.M., 1978. Flowering and fruit growth of purple
passion fruit. East African Agriculture and Forestry Journal 44: 47—51.
Gachanja,
S.P. & Gurnah, A.M., 1980. Pruning and trellising of purple passion
fruit I. Yields and seasonal trend. Journal of Horticultural Science
55(4): 345—349.
Gurnah, A.M. & Gachanja, S.P., 1980. Pruning and
trellising of purple passion fruit II. Disease incidence, fruit size
and quality. Journal of Horticultural Science 55(4): 351—354.
Gurnah,
A.M. & Gachanja, S.P., 1984. Spacing and pruning of purple passion
fruit. Tropical Agriculture, Trinidad 61(2): 143—147.
Inch, A.J., 1978. Passionfruit diseases. Queensland Agricultural Journal 104: 479—484.
Menzel,
C.M., Winks, C.W. & Simpson, D.R., 1988. Passionfruit in
Queensland. 1 Prospects for commercial expansion. 2 Botany and
cultivars. Queensland Agricultural Journal 114(1): 13—18 and 114(4):
217—224.
Pruthi, J.S., Ranganna, S. & Girdhari Lal, 1959.
Chemistry and technology of fruit and fruit products. Food Science
8(6): 191—197.
Robles, M.J.M., 1978. Multiplication végétative, in vitro, des bourgeons axillaires de Passiflora edulis var. flavicarpa Degener et de P. mollissima Bailey. Fruits 33: 693—699.
Teulon, J., 1971. Propagation of passion fruit (Passiflora edulis) on a Fusarium resistant rootstock. Plant Propagator 17: 4—5.
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