Table of Contents
Zee, F.T. 1993. Rambutan and pili nuts: Potential crops
for Hawaii. p. 461-465. In: J. Janick and J.E. Simon (eds.), New crops.
Wiley, New York.
Rambutan and Pili Nuts: Potential Crops for Hawaii
Francis T. Zee
- Postharvest Diseases
- Wild Nephelium species
- Future Prospects
- PILI NUTS
- Future Prospects
Rambutan and pili nuts are important crops of commerce in Southeast Asia but
are relatively unknown in the United States. The lack of a postharvest
quarantine treatment for fruit fly infestation in rambutan, and the
inconsistent production and lack of quality control in pili nuts are some of
the causes hindering the expansion of these crops. With the decline of the
sugar industry and the diversification of its agricultural industries, Hawaii
could become a potential production and launching site for these crops into the
mainland United States.
Rambutan fruits are consumed fresh, canned, or preserved. The colorful fruits
of rambutan are frequently used in displays with flower and fruit arrangements.
Nephelium lappaceum Linn., Sapindaceae, is native to Malaysia and
Indonesia. Rambutan, a tropical relative of the lychee (Litchi
chinensis Sonn.), is grown in Southeast Asia, Australia, South America, and
Africa, but only exported from Malaysia and Thailand (Laksmi et al. 1987).
The word rambutan is derived from the Malay word "hair," which describes
the numerous, characterizing, long, soft, red or red and green colored
spine-like protuberances (spinterns) on the surface of the fruit. The pericarp
of this attractive oval-shaped fruit can be red, orange, pink, or yellow in
color and is removable by a twist of the hands. The edible, pearlish white,
juicy, crispy, sweet and subacid flavored flesh (sarcotesta) conceals a single
seed with a thin, fibrous seed coat (testa).
Rambutan is an evergreen tree about 10 to 12 m tall, has pinnately compound
leaves without the presence of an end-leaflet. On the lower surface of each
leaflet are the domatia, small crater-like hills located in the axils between
the mid and secondary veins. The function of the domatia is unknown (Van
Welzen et al. 1988).
Rambutan has perfect flowers, however, they are functionally pistillate or
staminate. Most commercial cultivars behave hermaphroditically and are self
fertile, with 0.05 to 0.9% of the functional females possessing functional
stamens. Insect pollination is needed. Flowers are produced on matured
terminal or sub-branches in panicles; they are small, greenish white in color
and in large numbers (1,200 to 1,700 flowers per panicle). Depending on the
cultivar, flowering may spread over a period of 23 to 38 days, with an average
of 3.4% setting fruit. Fruits may be produced in large bunches, with 40 to 60
fruits per panicle, but most often only 12 to 13 per panicle are retained to
maturity. Final fruit set is usually between 0.7 to 1.45%. Time required from
fruit set to harvest is about 107 to 111 days (Van Welzen et al. 1988).
Fruit size ranges from 27 to 80 g. Edible flesh weight, depending on season
and cultivar, may range from 28 to 54% of the fruit weight. Total soluble
solids can reach 24% (Lye et al. 1987). Economic life of a tree is about 15
to 20 years and may be up to 30 years. Depending on the location, rambutan can
produce up to two crops a year (Laksmi et al. 1987).
Rambutan trees prefer deep, loamy, well drained soil with a high organic
content. Optimum temperature range is above 22°C. An absolute temperature
of 5° to 6°C will cause defoliation and poor cropping. Trees need to
have well distributed rainfall and wind protection.
At the National Clonal Germplasm Repository, USDA/ARS, in Hilo, Hawaii,
rambutan seedlings grew best in full sun, protected from wind, in a 1:1:1
medium of soil, macadamia compost, and volcanic cinder, and fertilized with a
high potassium (10-2-33 NPK) fertilizer. Young seedlings given a lower potash
formulation (16-7-13 NPK) produced severe marginal necrosis of leaves, stunted
growth, and die-back of apical growth.
Well grown rootstocks are bud grafted at 8 to 12 months. Dormant buds with
well-healed petiole scars from one to two year old branches averaged 80%
success between May and October. Rootstocks should be cut back 25 cm above the
bud union and all foliage removed at two weeks after budding. This cutback and
defoliation promoted bud break of the new graft 14 to 17 days later (Zee and
Rambutan trees exhibit strong apical dominance and have a tendency to produce
long, upright growth if not properly managed. Early pruning and training in
the field is needed to develop proper branch scaffolds.
Over 187 clones of rambutan are registered in Malaysia and over 25 additional
cultivars are known in Indonesia, the Philippines, Thailand, and Singapore (Lye
et al. 1987). Some of the most popular and recommended rambutan cultivars are
'Lebakbulus', 'Benjai' and 'Rapiah' (Indonesia); 'Seematjan', 'Seejonja', and
'Maharlika' (Philippines); 'Deli Cheng' and 'Jitlee' (Singapore); 'Gula Batu'
(R3), 'Muar Gading' (R156), 'Khaw Tow Bak' (R160), 'Lee Long' (R161), 'Dann
Hijau' (R162), R134, and R167 (Malaysia); 'Rongrien', 'Seechompoo', 'Seetong',
and 'Namtangruad' (Thailand).
Most postharvest problems are related to latent infection, injuries incurred
during harvesting, and high humidity and temperature during packaging and
transport. The major postharvest diseases are caused by Botryodiplodia
theobromae, Gliocephalotrichum bulbilium, and
Colletotrichum spp. A survey conducted in Bangkok markets identified about
30% of the postharvest diseases caused by Colletotrichum spp., 10% by
Gliocephalotrichum bulbilium, and 5% by Botryodiplodia
theobromae. Postharvest storage of fruit in the dark, with low
temperatures, may discourage fruit rot (Visarathanonth and Ilag 1987).
Rambutan is host to 118 different species of insects, but only 17 were
identified as attacking rambutan fruits. The following pests are listed in the
order of importance: Acrocercops cramerella Snell., Phenacaspis
sp., Planacoccus citri Risso., Dichocrocis punctiferalis Guen.,
Dacus dorsalis Hend., Carpophilus dimidatus L., Carpophilus
marginelius Mot. (Osman and Chettanachitara 1987). Rambutan infested with
Acrocercops cramerella, cacao pod moth, showed no external symptoms,
with up to 40% infestation observed in some cultivars and damage generally
between 10 to 15%.
Some native Nephelium species in Malaysia and Indonesia are N.
aculeatum, N. maingayi, N. reticulatum, N. compressum Radlk., N.
uncinatum Leenh., N. muduseum Leenh., N. laurinum Blume.,
N. daedaleum Radlk., N. juglandifolium Blume, N.
hypoleucum Kurz. (also in Thailand), N. cuspidatum var.
eriopetalum, N. cuspidatum var. robustum, N.
lappaceum var. lappaceum, N. lappaceum var. pallen,
N. lappaceum var. xanthioides, and N. ramboutan ake
(Van Welzen et al. 198?). Species in other Southeast Asian countries include
N. obovatum L. (Thailand); N. bassacense Pierre (Malaysia and
Vietnam); N. chryseum Blume, N. philippinense, and N.
xerospermoides R.D.K. (Philippines) (Martin et al. 1987).
Thailand is the leading producer of rambutan in the Asian region with about
60,000 ha and 430,000 t (1983/84). Production is concentrated in the provinces
of Chanthaburi, Rayong, Trad, and Prajineburi in the east and Surattani,
Choomporn, Naratiwart, and Nakornsritummarart in the south. Peak harvest
season is between May and August (Laksmi et al. 1987). In recent years, many
rambutan plantings in the Chanthaburi area have been replaced by durian,
Durio zibethinus L., due to overproduction, high postharvest costs
(Hiranpradit pers. commun. 1991) and low return--U.S. $0.10/kg for rambutan vs.
U.S. $2.00/kg for durian.
In the northern territory of Australia, rambutan plantings have increased to
about 20,000 trees. Production is geared for November and December, when the
value of the fruit is the highest at between $7 to $16/kg (Lim 1991).
In Hawaii, small plantings of rambutan are coming into production on the
islands of Kauai and Hawaii. Average price is between $9 to $13/kg. The
current nursery price for a grafted plant is about $45.
Rambutan can become a potential industry in Hawaii. The population of 1.1
million residents and approximately the same number of visitors each year are
potential customers of this exotic fruit. Moreover, the west coast of the
United States is only six hours away by air for a potentially feasible export
A market analysis conducted by the University of Hawaii for exotic tropical
fruit in 1990 identified the lack of a postharvest fruit fly disinfestation
treatment and the lack of a cultivar testing program as the major obstacles to
rambutan production (unpublished); additionally, the high cost of production
and the presence of large competitors in Southeast Asia contributes to the
risk. To avoid direct competition with large producers in Southeast Asia and
poor market price, the production of rambutan in Hawaii should be geared
towards the winter months of November to January, which can be achieved through
the use of selected cultivars and better understanding of the environmental,
cultural, and cultivar interactions.
Canarium ovatum Engl., one of 600 species in the Burseraceae (Neal
1965), is native to the Philippines and is abundant and wild in the southern
Luzon part of Visayas and Mindanao. The Philippines is the only country that
produces and processes pili nuts commercially. Production centers are located
in the Bicol region, provinces of Sorsogon, Albay, and Camarines Sur, southern
Tagalog, and eastern Visaya. There is no commercial planting of this crop,
fruits are collected from natural stands in the mountains near these provinces.
In 1977, the Philippines exported approximately 3.8 t of pili preparation to
Guam and Australia (Coronel et al. 1983).
Trees of Canarium ovatum are attractive symmetrically shaped evergreens,
averaging 20 m tall with resinous wood and resistance to strong wind. C.
ovatum is dioecious, with flowers borne on cymose inflorescence at the leaf
axils of young shoots. As in papaya and rambutan, functional hermaphrodites
exist in pili. Pollination is by insects. Flowering of pili is frequent and
fruits ripen through a prolonged period of time. The ovary contains three
locules, each with two ovules, most of the time only one ovule develops
Pili fruit is a drupe, 4 to 7 cm long, 2.3 to 3.8 cm in diameter, and weighs
15.7 to 45.7 g. The skin (exocarp) is smooth, thin, shiny, and turns purplish
black when the fruit ripens; the pulp (mesocarp) is fibrous, fleshy, and
greenish yellow in color, and the hard shell (endocarp) within protects a
normally dicotyledonous embryo. The basal end of the shell (endocarp) is
pointed and the apical end is more or less blunt; between the seed and the hard
shell (endocarp) is a thin, brownish, fibrous seed coat developed from the
inner layer of the endocarp. This thin coat usually adheres tightly to the
shell and/or the seed. Much of the kernel weight is made up of the cotyledons,
which are about 4.1 to 16.6% of the whole fruit; it is composed of
approximately 8% carbohydrate, 11.5 to 13.9% protein, and 70% fat (Coronel and
Zuno 1980a,b). Kernels from some trees may be bitter, fibrous or have a
Pili is a tropical tree preferring deep, fertile, well drained soil, warm
temperatures, and well distributed rainfall. It can not tolerate the slightest
frost or low temperature (Chandler 1958). Refrigeration of seeds at 4° to
13°C resulted in loss of viability after 5 days. Seed germination is highly
recalcitrant, reduced from 98 to 19% after 12 weeks of storage at room
temperature; seeds stored for more than 137 days did not germinate (Coronel et
Asexual propagations using marcotting, budding, and grafting were too
inconsistent to be used in commercial production. Young shoots of pili were
believed to have functional internal phloems, which rendered bark ringing
ineffective as a way of building up carbohydrate levels in the wood. Success
in marcottage may be cultivar dependent. Production standards for a mature
pili tree is between 100 to 150 kg of in-shell nut with the harvest season from
May to October and peaking between June and August. There are high variations
in kernel qualities and production between seedling trees.
Most pili kernels tend to stick to the shell when fresh, but come off easily
after being dried to 3 to 5% moisture (30°C for 27 to 28 h). Shell nuts,
with a moisture content of 2.5 to 4.6%, can be stored in the shade for one year
without deterioration of quality (Coronel et al. 1983).
The most important product from pili is the kernel. When raw, it resembles the
flavor of roasted pumpkin seed, and when roasted, its mild, nutty flavor and
tender-crispy texture is superior to that of the almond. Pili kernel is also
used in chocolate, ice cream, and baked goods (Rosengarten 1984). The largest
buyers of pili nuts are in Hong Kong and Taiwan, the kernel is one of the major
ingredients in one type of the famous Chinese festive desserts known as the
Nutritionally, the kernel is high in calcium, phosphorous, and potassium, and
rich in fats and protein. It yields a light yellowish oil, mainly of
glycerides of oleic (44.4 to 59.6%) and palmitic acids (32.6 to 38.2%) (Mohr
and Wichmann 1987; Coronel et al. 1983).
The young shoots and the fruit pulp are edible. The shoots are used in salads,
and the pulp is eaten after it is boiled and seasoned. Boiled pili pulp
resembles the sweet potato in texture, it is oily (about 12%) and is considered
to have food value similar to the avocado. Pulp oil can be extracted and used
for cooking or as a substitute for cotton seed oil in the manufacture of soap
and edible products. The stony shells are excellent as fuel or as porous,
inert growth medium for orchids and antherium.
According to Richard A. Hamilton, University of Hawaii at Manoa (macadamia
breeder), the current status of the pili is equivalent to that of the macadamia
some 30 years ago. It has great potential to develop into a major industry.
The immediate concern in pili production is the difficulty of propagation. The
lack of an effective clonal propagation method not only hampers the collection
of superior germplasm but also makes it almost impossible to conduct
feasibility trials of this crop. Few elite pili trees, such as 'Red', 'Albay',
and 'Katutubo' were selected in the Philippines (Coronel et al. 1983). The
National Clonal Germplasm Repository at Hilo, USDA/ARS, has initiated studies
in in vitro and vegetative propagation for the multiplication and long-term
preservation of pili.
A recently released pili cultivar in Hawaii may further stimulate the interest
in this crop. This new selection, known as 'Poamoho', was released by R.A.
Hamilton. Besides the desirable production and quality attributes, its kernels
separate easily from the hard shell without the need of prior drying (30deg.C
for 27 to 28 h). This is an important cost saving feature for processing.
- Laksmi, L.D.S., P.F. Lam, D.B. Mondoza Jr., S. Kosiyachinda, and P.C. Leong.
1987. Status of the rambutan industry in ASEAN, p. 1-8. In: P.F. Lam and S.
Kosiyachinda (eds.). Rambutan: fruit development, postharvest physiology and
marketing in ASEAN. ASEAN Food Handling Bureau, Kuala Lumpur, Malaysia.
- Lim, T.K. 1991. Rambutan industry in the Northern Territory current status,
research and development emphasis, p. 119. In: International symposium on
tropical fruit, working abstracts. May 20-24, 1991. Pattaya, Thailand.
- Lye, T.T., L.D.S. Laksmi, P. Maspol, and S.K. Yong. 1987. Commercial rambutan
cultivars in ASEAN, p. 9-15. In: P.F. Lam and S. Kosiyachinda (eds.).
Rambutan: fruit development, postharvest physiology and marketing in ASEAN.
ASEAN Food Handling Bureau, Kuala Lumpur, Malaysia.
- Martin, F.L., C.W. Campbell, and R.M. Ruberte. 1987. Perennial edible fruits
of the tropics: An inventory. USDA/ARS. Agr. Handb. 642.
- Morton, J.F. 1987. Fruits of warm climates. Julia F. Morton, 20534 SW 92 Ct.
Miami FL. p. 262-265.
- Osman Mohd, S.B. and C. Chettanachitara. 1987. Postharvest insects and other
pests of rambutan, p. 57-60. In: P.F. Lam and S. Kosiyachinda (eds.).
Rambutan: fruit development, postharvest physiology and marketing in ASEAN.
ASEAN Food Handling Bureau, Kuala Lumpur, Malaysia.
- Van Welzen, P.C., A. Lamb, and W.W.W. Wong. 1988. Edible Sapindaceae in
Sabah. Nature Malaysiana. 13:10-25.
- Visarathanonth N. and L.L. Ilag. 1987. Postharvest diseases of rambutan, p.
51-57. In: P.F. Lam and S. Kosiyachinda (eds.). Rambutan: fruit development,
postharvest physiology and marketing in ASEAN. ASEAN Food Handling Bureau,
Kuala Lumpur, Malaysia.
- Chandler, W.H. 1958. Evergreen orchards. Lea & Febiger, Philadelphia.
- Coronel, R.E. and J.C. Zuno. 1980a. Note: The correlation between some fruit
characters of pili. Philippine Agriculturist 63:163-165.
- Coronel, R.E. and J.C. Zuno. 1980b. Note: Evaluation of fruit characters of
some pili seedling trees in Calauan and Los Banos, Laguna. Philippine
- Coronel, R.E., J.C. Zuno, and R.C. Sotto. 1983. Promising fruits of the
Philippines, p. 325-350. Univ. Philippines at Los Banos, College of Agr.,
- Mohr, E. and G. Wichmann. 1987. Cultivation of pili nut Canarium
ovatum and the composition of fatty acids and triglycerides of the oil.
Fett Wissenschaft Technologie 89(3):128-129.
- Neal, M.C. 1965. In gardens of Hawaii. Bernice P. Bishop Museum. Special
Pub. Bishop Museum Press.
- Rosengarten, F. Jr. 1984. The book of edible nuts. Walker and Company, New
Last update April 24, 1997