1483

2: Edible fruits and nuts

Canarium ovatum Engl.

A. DC., Monogr. Phan. 4: 110 (1883).

BURSERACEAE

2n = 46

Canarium pachyphyllum Perkins (1904), Canarium melioides Elmer (1911).

Pilinut (En). Philippines: pili.

Pili is indigenous to the Philippines (Bicol region; also in other parts of the country, mainly as avenue tree). In other countries, pili is found only in botanical collections.

The kernel is used commercially in the manufacture of various confectionary and bakery products and as a flavouring for ice cream. The commercial feasibility of extracting the edible oil from the kernel, which is comparable in quality to that of olive oil, has not yet been explored.
The hard and thick shell that encloses the kernel makes an excellent fuel for cooking. Polished and varnished, it becomes an attractive ornament. In industry, its use for making charcoal and activated carbon has yet to be explored.
The pulp of the ripe fruit becomes edible after boiling and is usually eaten seasoned with salt or fish sauce. It also contains an oil that is occasionally extracted and used for cooking and lighting. The young shoots are edible and may be used in salads. The resin-rich wood makes good firewood.
The evergreen pili tree makes an excellent windbreak as it resists strong winds and even typhoons. With its symmetrical branches it is an attractive avenue and shade tree.

The Philippines is the only country that produces and processes pili in some commercial quantity. In 1983—1987, the annual volume was 2925 t of dried nuts from an estimated area of 2700 ha. The most important pili-producing region was Bicol.
Export of processed pili products is rather erratic, depending largely on the adequacy of local supply.

The kernel, which is about 11% of the whole fresh fruit by weight, has 41.8% moisture and contains, on dry weight basis, 13.9% protein, 73.1% fat. Energy value is 2700 kJ per 100 g. Its oil contains 59.6% oleic glycerides and 38.2% palmitic glycerides.
The pulp, which is about 65% of the fruit by weight, has about 73% moisture and contains, on dry weight basis, 8% protein, 33.6% fat, 45.8% carbohydrates, 9.2% ash. Energy value is 2230 kJ per 100 g. Its oil contains 56.7% oleic glycerides, 13.5% linoleic glycerides and 29.3% saturated fatty acids. Fruit weight ranges from 15—46 g, seed weight from 0.74—5.13 g.

Evergreen dioecious tree, up to 20 m tall and 50 cm in diameter. Stipules persistent, deltoid to lingulate, 5—20 mm x 3—10 mm. Leaves 2—4-jugate, imparipinnate, spirally arranged, about 40 cm long; leaflets ovate to elliptic, 4—24 cm x 2—12 cm, stiff-coriaceous, entire, base oblique, rounded to subcordate, apex abruptly acuminate, 8—12 pairs of nerves. Inflorescences axillary, close together at the ends of the branches, narrowly thyrsoid, 3—12 cm long, few-flowered; flowers 3-merous, unisexual, subsessile, pubescent, up to 12 mm long; calyx cupular, 7 mm long in male, 8—9 mm in female flowers; petals 2 cm x 1 cm; stamens 6, slightly adnate to the disk in male, inserted on the rim of the disk and sterile in female flowers; pistil absent in male flowers, in female ones 7 mm long, ovary 3-locular, style 1.5 mm, stigma 3-lobed. Fruit drupaceous, ovoid to ellipsoid, 3.5—6.25 cm long, 2—2.75 cm in diameter, acute, triangular in cross-section, exocarp thin, glabrous, shiny, turning from light-green to purplish-black; mesocarp fibrous, fleshy and thick; endocarp (shell) elongated, stony, trigonous, pointed at base, blunt or obtuse at apex, tawny to dirty brown, sterile cells strongly reduced. Seed 1 with brown papery seed-coat.

Germination begins with the uptake of water through a heart-shaped, grooved opening at the basal end of the broadest side of the shell. The shell may crack as early as 30 days after sowing. First the radicle appears, followed by the surfacing hypocotyl, with the shell still enclosing the cotyledons. About 70 days after sowing, there is a mature pair of true leaves, the cotyledons have withered after unfolding briefly, and numerous root hairs and secondary roots are present. The transplanted seedling initially grows slowly, but soon the growth rate picks up, stem height and girth increasing rapidly and new leaves unfolding continuously. After 3—4 entire leaves, leaves with 3 leaflets follow, until in the mature tree the leaves have 5—9 leaflets.
The juvenile tree produces lateral shoots late. It may grow to a height of 2 m or more in about 3—4 years before branching occurs. At this stage the tree may produce its first flowers.
Lateral shoot growth ultimately gives the tree a more or less round canopy. The inflorescences emerge from the leaf axils of current season's growth, so that flowering coincides with the annual flush, in the Philippines between March and June. In both male and female trees, the order of blooming of the flowers in the inflorescence is basipetal. Anthesis of male as well as female flowers takes place between 4—6 p.m. Anthers dehisce and stigma becomes receptive at or immediately after anthesis. The flowers are insect-pollinated. Fruit set is about 85%.
If pollination is successful the ovary begins to enlarge after one week and the petals start to drop off. Fruit growth lasts 10 months and follows a sigmoid curve, during which the short dark green fruitlet changes into an oblong, purplish-black fruit at ripening. On the average, seedling trees start producing fruit 5—6 years after planting. Clonal trees bear fruit 3—4 years after planting.

Canarium ovatum is related to Canarium luzonicum (Blume) A. Gray, also from the Philippines. Canarium ovatum is especially characterized by its stiff, lingulate, persistent stipules. Of the approximately 100 Canarium species, known from the tropics of the Old World, about 50 occur in Malesia. Possibly the oily seed of more species is edible but usually these seeds are too small to be of economic importance. In the Philippines three cultivars of Canarium ovatum have been selected and named: 'Katutubo', 'Mayon' and 'Oas'. They are now propagated for distribution to farmers.

Pili grows well on both light and heavy soils. It also thrives over a wide range of climatic conditions, growing successfully from sea level to an elevation of 400 m. It has also been reported to grow and fruit well in the highlands, although in Florida it did not tolerate cool periods and slight frost. Mature trees can resist strong winds.

Pili is still largely propagated by seed, although it does not breed true to type. The seedlings take about 40—50 days to emerge; they are potted up into polybags, cared for in the nursery and planted in the field when about 1—2 years old, or are used as rootstocks. Patch budding is now the recommended method of asexual propagation giving as much as 85—90% success. Cleft grafting is also successful.
Some pili cultivars respond well to marcotting, but recovery is very poor after the rooted layers are severed from the tree.

Pili trees are found mostly in the forest, in home gardens, and on the roadside. The husbandry of improved clonal material needs to be investigated under orchard or plantation conditions.

Pili is not known to be attacked by any serious disease or pest. Anthracnose of young seedling shoots has been observed but this is easily controlled by fungicides. Maturing fruits are often found coated with algal growth, but apart from marring the appearance of the skin, this does not affect the pulp or the kernel.

Ripening season is from May to October with a peak in June to August.
Although all fruits that show various shades of purple are harvested, each tree needs to be picked several times. Usually one man climbs the tree to pick the fruit and another collects the fallen fruit. A bamboo pole with a wire hooked at the tip is used to pick the fruit. Fallen fruit is collected in baskets or sacks and brought to the house for processing.
The use of growth regulators to induce uniform ripening and abscission of the fruit needs to be investigated.

Productivity of seedling trees varies considerably, but there is a lack of yield records and this also applies to clonally propagated trees. An actual count during the harvest of a 45-year-old tree came close to 10 000 fruit.

The pulp is removed by hand after soaking the fruit in water for 2—3 days, or for a much shorter period in water heated to 40—50°C. In both methods, the nuts are thoroughly washed in water to remove the slimy material adhering to the shell. All nuts that float in water are discarded. The nuts are dried in the sun for 2—3 days after which they are bagged and stored. The optimum moisture content for long-term storage is 2.5—4.6%, that is the equilibrium moisture level of the nuts and the ambient air at room temperature.
Manual labour is also needed for kernel extraction, an operation for which a machine should be developed. A worker cuts across through the middle of the shell, shelling 3 sacks of nuts a day. After cutting the shell, the whole kernel can easily be removed. The kernels are soaked in warm water after which the testa slips off readily when the kernel is squeezed between the fingers. The clean kernels are then ready for processing.

Being a dioecious species, cross-pollination is the rule in pili, resulting in a great genetic variation among seedlings. Studies at Los Baños show that sex expression, productivity, fruiting season, growth habit and other morphological features, and physical and chemical properties of the fruit are all very variable. There is, therefore, much room for selection. A single tree bearing bisexual flowers — and very small fruit — has been found. Hermaphroditism would be advantageous, as this would eliminate the need to plant male trees.

Pili has the potential to become a major export crop. To achieve this, however, the cultural requirements of pili as a commercial nut crop need to be studied. Processing of the nuts should also be mechanized to some extent. Finally, feasibility studies should be conducted on the commercial processing of oil from the pulp and kernel as well as on the commercial utilization of the shell for making charcoal and activated carbon. As the ecological requirements of pili are not very exacting, there should also be scope for the crop elsewhere in South-East Asia.

Coronel, R.E., 1966. Let us save our pili industry. Philippine Farms and Gardens 3(12): 16—17, 28.
Coronel, R.E. & Zuno, J.C., 1980. Note: The correlation between some fruit characters in pili. The Philippine Agriculturists 63: 163—165.
Coronel, R.E. & Zuno, J.C., 1980. Note: Evaluation of fruit characters of some pili seedling trees in Calauan and Los Baños, Laguna. The Philippine Agriculturists 63: 166—173.
Linsangan, E.S., Coronel, R.E. & Rivera, F.N., 1979. Floral morphology and fruit set of pili. The Philippine Agriculturists 62: 219—225.
Maránon, L. T., Cruz, A.D. & Tuazon, A.M., 1954. Composition of pili pulp and pili pulp oil from the fruit of Canarium ovatum. Philippine Journal of Science 83: 359—363.

R.E. Coronel

Coronel, R.E., 1991. Canarium ovatum Engl.. In: Verheij, E.W.M. and Coronel, R.E. (Editors): Plant Resources of South-East Asia No 2: Edible fruits and nuts. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea