Pili Nuts Growth and development

Agronomy:

Pili Nut Tree

The germination of the pili seed begins with the uptake of water through a heartshaped, grooved opening at the basal end of the broadest side of the nut (Fig. 9). The shell of the nut may crack open as early as 30 days after sowing. First, the radicle appears, followed by the surfacing hypocotyl, with the shell still enclosing the two cotyledons. Then the hypocotyl becomes erect, with the cotyledonary leaves still closed (Fig. 10a). About 70 days after sowing, the seedling has a mature pair of true leaves (Fig. 10b), the cotyledonary leaves have withered after unfolding briefly, and numerous root hairs and secondary roots are present.

Initially, the pili seedling grows slowly after transplanting, but the growth rate soon accelerates, stem height and girth increase rapidly and new leaves unfold continuously. After 3-4 entire leaves have developed, leaves with 3 leaflets follow, until in the mature trees, the leaves have 5, 7 or 9 leaflets. The juvenile pili tree produces lateral shoots rather late. They may grow to a height of 2 m or more over a period of about 3-4 years, before the first 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.

In the Philippines, the pili tree flushes in March to May, with such flushes abscissing a year later, from March to September (Fig. 11). The following year, when leaves from the previous season’s flush are starting to fall, new leaf and flower buds begin to open. As leaf abscission progresses, flowering and leaf development continue, and when the last leaf falls, the current season‘s flush has grown to its fully mature size. This sequence of events makes pili a deciduous tree. However, the overlapping of the previous and the current season’s leaf development makes the pili appear to be an evergreen tree.

Flowering in the Philippines occurs from March to June (simultaneously with flushing) and the flowers open in April-July (Fig. 11). In the female trees, fruits set from May to July and they ripen in May to August of the following year, about the time that the fruits of the previous season’s flush are ripening, and new fruits are setting and starting to develop. This gives rise to shoots bearing young, green mature and ripe fruits. In turn, this gives the (wrong) impression that the pili is an everbearing tree, when in fact flowering and fruiting are highly seasonal events.

Growth of the pili fruit exhibits a sigmoid curve (Fig. 12). When pollination is successful, the ovary begins to enlarge after 1 week, and the petals start to drop off. By 2 weeks after pollination, the young fruit is dark green, and there is no significant difference between fruit length and diameter. Fruit growth then becomes rapid, up to the 10th to 12th week, with a more rapid increase in length, compared with diameter. Growth gradually slows down, and levels off as the fruit approaches maturity (at about 10 months after pollination). Fruit ripening, however, takes a further 2 months, at which stage the fruit skin colour turns to dark purple or almost black.

It is interesting to note that the kernel (anatomically, the cotyledons with the tiny embryo within) remains relatively undeveloped, even when the fruit has reached its maximum size. It does not begin substantial development until the fruit has reached maturity, and the kernel growth occurs during fruit ripening. On the average, pili seedling trees start flowering and fruiting 5-6 years after seed germination. Most flushes in mature trees are reproductive, and the trees may live to be more than 100 years old. Female trees are usually smaller than male trees of the same age, owing to the exhausting and dwarfing effect of fruiting.

Nut selection and germination:

Pili nuts intended for commercial planting, or for use as rootstocks in asexual propagation, should be obtained from fully ripe fruits from outstanding trees, preferably of known cultivars. Removing the pulp before sowing the nuts is advisable, because clean nuts germinate earlier, with a higher germination percentage than whole fruits (Dalisay 1961). The pulp is easily removed by soaking the newly harvested fruits for 24-48 hours in water, until the pulp becomes soft and is readily separated from the nut by hand.

The nuts are thoroughly rinsed to remove all the slimy material that adheres to the shell. All nuts that float are discarded, as they are either empty or have undeveloped seeds that germinate poorly (Dalisay 1961). The nuts are simply air-dried. Sun-drying of nuts reduces seed viability (Lanuza 1969-70). Pili seeds are recalcitrant, and the nuts should be sown immediately because the seeds lose viability quite rapidly when kept, even at room temperature. Nuts kept at low temperature (4-13o C) lose viability after 5 days.

These may be shipped without moist packing, but should be sown immediately upon arrival at their destination (Wester 1924). Percentage germination decreases rapidly as the duration of storage at room temperature increases (Dalisay 1961). Nuts planted immediately after harvest give 98% germination, while those sown 12 weeks later have only 19% germination. Cabrera (1932) found that pili seeds lost all viability in about 137 days.

Pili seeds have a long dormancy, which brings about a marked delay in their germination (Coronel 1966; Adriano 1977). This is mainly owing to the thick, hard shell, which impedes gas exchange and water absorption (Juliano 1937; Adriano 1977). Efforts to break seed dormancy by cracking or removing the shell have not produced encouraging results, because although these practices hasten germination, percentage germination is greatly reduced (Cabrera 1932; Adriano 1977).

Pili nuts are sown in a seedbed, using very light porous soil (Wester 1916), such as sand, or an equal mixture of sand and garden soil as media (Coronel 1966). Coir dust and sawdust may also be used as the germinating medium. The nuts are laid flat, with the broadest side facing down, at a depth of not more than 2 cm, and at a distance of about 1-2 cm between rows, and between nuts in a row. They may also be sown directly in individuals containers, thus reducing the cost of transplanting.

Pili Nuts

On the average, the seeds will germinate 57 days after sowing (Operio 1979; Operio and Coronel 1980). Seedlings are transplanted in black polyethylene bags (polybags), preferably using an equal mixture of sand, garden soil and compost (Coronel 1966). Transplanting may be done when the seedlings are at the cotyledonary-leaf stage, or when the first pair of leaves has matured (Fig. 10). The seedlings need shade for about 1 week, but later should be fully exposed to the sun. They are watered as the need arises, given a small dose of nitrogen fertilizer, preferably every 2 months, and treated against pests and diseases.

Seedlings that are established during the harvest season in the Philippines in May-June may be planted in the field, during the onset of the rainy season in May-June of the following year. It is advisable to plant in the second year, when the seedlings are larger, however.

Propagation:

Propagation of the pili can be accomplished using seeds/seedlings, or by asexual methods, such as marcotting, grafting and budding (Galang and Elayda 1924; Cabrera 1932; Gonzalez 1934; Galang 1955; Coronel 1966; Dacanay 1968; Lanuza 1969-70; Coronel et al. 1972, n.d.). Today, almost all of the pili trees in the Philippines have been grown from seeds. However, seed propagation is being discouraged for the following reasons:

  • being a dioecious species, 50% of the resulting trees would turn out to be male
  • the long juvenile period of seedling trees
  • The high degree of variability in many horticultural characters among seedling trees (Coronel 1994).

Marcotting, or air-layering, has been found successful (Dacanay 1968) and is the simplest propagation method for the pili (Coronel 1994). However, it is a very slow process, both in terms of the time it takes to root the branches and the number of propagules that can be produced from one tree. Individual seedling trees respond differently to marcotting, and the success rate in rooting the branches can range from 0 to 100% (Dacanay 1968; Coronel et al. n.d., 1972; Tuazon 1978). The cultivar ‘Katutubo’, for example, responds well to marcotting, with almost 100% rooting success, at about 55 days after girdling.

The biggest problem encountered in marcotting the pili is the low survival rate of the successfully rooted branches after they have been severed from the mother tree. Misting the fresh marcots in the nursery has been found to improve their survival rate. Cleft- or wedge-grafting is one of the two methods recommended to propagate the pili commercially (Coronel 1994).

The seedling rootstocks need to be established in large black polybags (at least 25 cm x 35 cm) or directly in the field, so that they attain sufficient stem girth faster, to match the diameter of the terminal shoots to be used as scions. It is better to use previously defoliated shoots as scions. Cleft-grafting done in the cool and dry months of November to February can give a success rate as high as 85%.

Patch-budding or bud-grafting is the most efficient way to propagate the pili, and is recommended for its large-scale propagation (Coronel 1994). As in cleftgrafting, the seedling rootstocks are best established in large black polybags, or directly in the field, to induce them to attain sufficient stem girth more quickly. Frequent watering and monthly applications of a small dose of nitrogen fertilizer help condition the seedlings to grow actively.

Previously defoliated budwoods are the best source of buds, and young, growing pili trees are better sources of budwood materials than old, dormant trees. This is because in young pili trees, the nodes on the shoots are far apart and the buds are more active. When performed during the cool and dry months between November and February, and with a lot of practice, patch-budding success rates can be as high as 75-80%.

Cultural practices:

At present, there are not enough asexually propagated planting materials to establish pili orchards. Therefore, seedlings are still the major form of planting materials to be used in the years to come. The seeds should be obtained from trees of named varieties, or from other outstanding trees. In the field, the seedlings should be planted at least 12 m apart. Since it is expected that about 50% of the trees will turn out to be male, it is recommended that two seedlings be planted at each tree posi- tion, 30-50 cm apart.

When the trees start to flower, at which time their sex can be determined, all male trees should be cut down, leaving only a few to serve as a pollen source. A ratio of 1 male to 20-25 female trees would be adequate. In the hills, when both plants turn out to be male, one can be cut down, and the other cut back and grafted with a known variety. Until such time that dwarfing rootstocks become available, asexually propagated planting materials (marcots, grafts and budlings) should be planted at least 8 m apart.

It is also necessary to interplant male pili trees, especially when the planting is quite isolated. Either the triangular or square system may be followed in setting the pili trees in the field. In areas with well-distributed rainfall, planting may be done in any month of the year. In other locations, the best time to plant is at the onset of the rainy season. Marcots lack a primary root system, and may not be able to withstand strong winds. It is therefore recommended that 2-3 seedlings be planted around the marcot and grafted onto its main stem to form a multiple rootstock, designed to strengthen its root system.

Little is known about the cultural requirements of the pili tree. Basic knowledge about its the growth and development, however, suggests the adoption of certain practices. Marcots usually form lateral branches early and do not require training. Seedling, grafted and budded trees initially tend to grow upright, and need to be trained at an early age to induce the formation of lateral branches.

This is done by pinching off the terminal bud when the tree is about 0.5-1 m tall. This should be done repeatedly on all the subsequent shoots, until the youngest set of shoots becomes reproductive, a process that may take 2-4 years. Once the pili tree starts fruiting, very little pruning is necessary. In the Bicol region, and in other places with a well-distributed rainfall pattern, irrigating the pili tree is not necessary.

Limited experience in other areas of the country suggests that the first dry season after planting is critical to the successful establishment of the pili tree, and it is therefore necessary to provide the trees with adequate water during this period. In areas with a distinct and long dry season, irrigation is also beneficial to those trees of bearing age. Although leaf abscission takes place from March to May in the Philippines, flushing and flowering also occur during this period, and these latter processes require an adequate supply of water to the trees.

The fertilizer requirements of the pili trees may be determined using the results of studies of nutrient content and uptake (Angeles 1981). These have shown that nitrogen content is high in the kernel (2.49%), leaf blade (1.16%) and pulp (1.03%). Phosphorus content is high in the kernel (0.47%), petiole (0.37%), stem (0.31%) and shell (0.24%). Potassium content is high in the pulp (2.62%), peduncle (1.74%) and stem (1.40%). Expressed as nutrient uptake (kg per tree), nitrogen uptake is high in the leaf blade (0.53 kg), fruit pulp (0.20 kg) and kernel (0.31 kg). Phosphorus uptake is high in the shell (0.24 kg). Potassium uptake is high in the leaves (0.18 kg) and fruit pulp (0.50 kg).

The nutrients that are absorbed by the leaves are returned to the soil when the leaves fall and decompose. After harvest, the fruits are removed from the site of production and the nutrients they contain are considered lost from the soil. Thus, the total nitrogen removed annually by the fruits of a pili tree is 0.60 kg; the total amount of phosphorus lost is 0.10 kg and potassium loss is 0.74 kg. In terms of fertilizer equivalents, these would correspond to an application of 3 kg ammonium sulphate (20% N), 0.52 kg superphosphate (20% P2 O5 ) and 1.23 kg muriate of potash (60 K2 O).

When conducting tissue analysis to determine the nutrient requirements of pili trees, it is recommended that the 6th and 7th leaves from the tip of the shoot be collected in September-December. The pili tree is not known to have been attacked by any serious pests and diseases, and for this reason no control measures are necessary. On average, seedling pili trees start fruiting 4-5 years after planting.

Marcots are productive 2-3 years after planting, while grafted and budded trees are productive after 3-4 years. Assuming an average yield per tree of 2000 nuts per season, for 10-to-15-year-old trees this would be equivalent to 20 kg dried nuts per tree (a dried nut weighs 10 g, on average). At the present price of P20 per kg, gross income is P400 per tree.

Harvest:

The harvest season in the Philippines extends over a long period, from May to October, and has its peak in June-August. The fruits on a tree do not ripen at the same time, and it is best to harvest only well-ripened fruits (whose skin colour is nearly black). The present system of harvesting is a laborious process. The harvester climbs the tree and, with a wooden stick, repeatedly thrashes the fruiting branches, in the process detaching even the immature fruit and severely defoliating the tree.

As mentioned earlier, there is a locally held belief (which has a scientific basis) that this ‘punishment’ is in fact beneficial to the tree, as it induces the tree to produce more flowers and fruits the next fruiting season. Should commercial pili orchards be established, however, ripe fruits may simply be allowed to fall to the ground for collection manually or by a machine.

Processing:

The harvested pili fruits are usually placed in sacks or bags and taken to people’s homes for processing. Since the fresh pulp is not edible, processing becomes an integral part of the pili industry. The first step in processing is the removal of the pulp. A de-pulping machine has not yet been developed, and two methods of separating the fleshy pulp from the nut presently exist, both of which involve softening the pulp.

The first involves soaking the fruits in tap water until the pulp becomes soft. On average, it takes 24-48 hours for the pulp of all the fruit in a batch to become soft. This method is recommended when the nuts are intended for germination to produce seedlings. The other method currently used to remove the pulp is to soak the fruits in water that has been heated to 40-50o C (Austria 1932). This method softens the pulp of all fruits within a few hours, but nuts cleaned this way have poor germination.

After removal of the softened pulp, the nuts are rinsed thoroughly, to remove the slimy material adhering to the shell. All nuts that float in water are discarded at this point. When they are to be used for germination, the clean nuts are simply air-dried. When they are to be stored as merchandise, the nuts have to be sun-dried for 2- 3 days. Figure 13 shows sun-dried pili nuts being sold in a public market in Guinobatan, Albay.

Studies have shown that oven-drying the pili nuts at a temperature of 30o C for 27-28 hours reduces the (harvest) moisture content from 40-50% to 3-5% (Villamor 1979). Kernels dried this way are milky white in colour, are not saturated with oil and have a pleasant flavour. Properly dried nuts will keep until the next harvest season.

The next step is kernel extraction from the shell, which is a purely manual operation at present. With the use of a ‘bolo’, a knife specially designed for this purpose, the worker cuts the shell crosswise, at the midsection. Great skill is required to ensure that the blade of the bolo does not cut through the kernel. An experienced worker can easily process 40 kg (2 sacks) of nuts per day.

The whole kernel, with the testa still intact, is simply pulled out of the halved shell. The kernel may be eaten raw or roasted, with or without the testa. When the kernel is used for making cakes and ice cream, etc., the testa is removed with the fingers, after being soaked in warm water.

Limitations:

  • Although the pili was identified and described in 1883, and has been cultivated in the Philippines since ancient times, it is still a relatively new commercial crop.
  • Importantly, little is known about its entire genetic diversity, information which is vital to the varietal improvement of the species.
  • The true climatic adaptability of the pili has not been formally investigated, and there is a need to conduct multilocational trials of known pili varieties to determine the most suitable ones to grow under a specific set of climatic conditions.
  • Although numerous basic studies of the botany, growth and development, varietal selection and asexual propagation of the pili have been conducted, little is known about its cultural requirements as a commercial crop. Probably for this reason, very few growers have gone into pili production.
  • Processing of the pili nuts is presently carried out manually. While this system employs many people, production of the crop on a commercial scale would require at least partial mechanization of processing.
  • It is known that the pili pulp and kernel contain substantial quantities of oil. However, the economic feasibility of pili nut oil processing has not been investigated, nor have the commercial uses of the shell and the seedcoat been explored.
  • Although the oil of the pili nut kernel is high in unsaturated fatty acids, it also contains a substantial amount of saturated fatty acids. Given the high level of health consciousness in many countries today, it needs to be determined whether these acids are of the medium-chain type, which are not harmful to human health, if the pili nut is to be successfully promoted in foreign markets.

Prospects:

  • Dried Pili Nuts

    The pili has a bright future as a commercial crop, for a number of reasons:

  • Superior varieties are available for cultivation, which are early bearing, prolific, responsive to asexual propagation, free from damage by pests and diseases, and responsive to low production inputs.
  • Pili nuts keep well, and the trees can therefore be cultivated in remote rural areas without any fear that the fruits will spoil if they are not marketed immediately. If properly dried and stored, the pili nuts can be kept until the next harvest season, thus ensuring a regular supply of raw materials for processing during the non-harvest months. This is advantageous to pili nut growers, whose produce would fetch higher prices during this period.
  • The pili nut pulp and kernel are extremely nutritious, forming good-to-excellent sources of minerals, vegetable fats and proteins.
  • The pili nut kernel can be used in the preparation of many food products, and is also the source of an edible oil of excellent quality.
  • There is an unmet local demand for the pili nut, which is popular with Filipinos; there is also a ready export market, should enough of the crop become available.Furthermore, the commercial utilization of all the by-products of the pili fruit would further increase the income derived from pili nut production.The following initiatives are being proposed to encourage pili production:
  • Government-established demonstration orchards in strategic locations in the Bicol region and other locations with similar climatic conditions, to show farmers the available production technologies.
  • Regular seminars on pili production for interested farmers, organized by the government.
  • Availability to farmers of reasonably priced, high-quality propagating materials.
  • Regular visits to the farmers’ orchards by extension personnel, to provide technical assistance.
  • Government assistance to pili farmers in marketing their produce.

Institutions involved in pili research and development:

Much of the present knowledge about the pili has been generated from research conducted by the various units of the University of the Philippines at Los Baños, particularly the Department of Horticulture and the Institute of Plant Breeding. Information provided by the Department of Horticulture was generated through the completion of undergraduate and graduate theses, some of which were undertaken under the supervision of the author (Tuazon 1978; Linsangan et al. 1979; Operio 1979; Villamor 1979; Angeles 1981; Javier 1983). The Institute of Plant Breeding, on the other hand, has been collecting pili germplasm since 1976 (Coronel 1980b), has registered three pili varieties with the National Seed Industry Council (PSB 1993), and has developed rapid asexual propagation methods for the pili (Coronel et al. n.d.).

The Crops Research Division of the Philippine Council for Agriculture, Forestry and Resources Research and Development (PCARRD) is coordinating two collaborative projects involving the pili. The first is concerned with the identification of outstanding pili trees, and the second with the mass production of pili planting materials.

The PCARRD has made the pili a research and development priority in the Bicol region, and the Department of Science and Technology, the Department of Environment and National Resources, the Department of Agriculture, the College of Agriculture and Forestry of the Bicol University at Guinobatan, Albay, and the Camarines Sur State Agricultural College in Pili, Camarines Sur are working together to upgrade the pili industry.

The Demontaño Foundation, Inc., a non-governmental organization, has recently been established to disseminate information on the pili and planting materials (Arribas 1994). The names and addresses of persons involved in research and development of the pili in the Philippines are given in Appendix II.

Research and development needs:

  • Collecting, characterization/evaluation, propagation and conservation of pili germplasm, and selection of superior trees, should be pursued with greater vigour, and emphasis should be placed not only on the identification of superior scion varieties, but also on the selection of desirable rootstock varieties. Research should be extended to include wild relatives of the pili, to determine their suitability as parents in varietal improvement and as rootstocks in asexual propagation of the pili.
  • Research and development should also concentrate on training farmers and field technicians on rapid asexual propagation methods for the pili. At present, one of the obstacles to promoting the commercial planting of the pili is the lack asexually propagated planting materials. At the University of the Philippines, in Los Baños, it has been shown that the pili could be propagated by cleft-grafting and patch-budding. However, very few plant propagators have mastered these techniques5 , and more training on this subject is required.
  • Basic research on the micropropagation of the pili, using the in vitro technique, should be initiated as an alternative to macropropagation, or to supplement Studies on appropriate culture media should be started.
  • Multilocational trials of the registered pili varieties should be conducted urgently, to discover the soil and climatic ranges of the pili and to determine the best varieties for a particular set of soil and climatic conditions.l
  • Experimental orchards need to be set up so that specific studies of the cultural requirements of the pili (e.g. training, pruning, irrigation and fertilization) can be conducted. The comparative economic advantages of (i) harvesting the pili nuts, using the traditional method, versus simply collecting the fallen fruits, and (ii) manually versus mechanically extracting the kernels, can be investigated. Furthermore, as stated in the previous section, the experimental orchards could also serve to demonstrate the available commercial production technologies to farmers.
  • There is a need to develop new and better processed pili products. Since the Philippines also cultivates cacao (Theobroma cacao L.) commercially, the development of chocolate-coated pili nuts could be considered.
  • More emphasis should be given to improved packaging that meets international standards.

Summary:

  • The pili nut (Canarium ovatum Engl.) is endemic in the Philippines, with the Bicol region as its centre of genetic diversity. The species has been confined to this region for quite a long time, and has not been introduced to many other countries.
  • There are about 75 known Canarium species, nine of which are found in the Philippines. At least four species are of economic importance: C. ovatum, C. indicum, C. album and C. luzonicum.
  • The production areas of the pili are likewise concentrated in the Bicol region. Production is mainly from unselected seedling trees.
  • The pili grows well over a wide range of soil conditions, including very acid soils, from sea level up to medium elevations. The species is adapted to areas with well-distributed rainfall, as well as those with distinct wet and dry seasons. It is a typhoon-resistant species.
  • The pili is a dioecious, deciduous, medium-sized to large tree. The leaves are imparipinnate, spirally arranged and about 40 cm long. The cymose inflorescences are axillary on young shoots. The fruit is a drupe, ovoid to ellipsoid, 4- 7 cm long and 2-4 cm in diameter. It has a thin, black exocarp (skin), a fibrous, fleshy mesocarp (pulp) and a hard, thick endocarp (shell). The seed has a brown papery seed coat and an embryo with two large white cotyledons.
  • Anthesis of male and female flowers, anther dehiscence and stigma receptivity take place in the late afternoon. The emission of a fragrant odour suggests that the flowers are insect-pollinated. Fruit set is high (about 88%). From pollination, the fruits take about 12 months to ripen. The pili nuts are dispersed by hornbills, monkeys, wild pigs and deer. Humans gather the pili nuts for food, and therefore effectively reduce the natural stands of pili trees.
  • The pili is a very variable species. Seedling trees differ in many important botanical and horticultural characters, and the species therefore possesses considerable genetic diversity.
  • The National Plant Genetic Resources Laboratory of the Institute of Plant Breeding at the University of the Philippines, Los Baños has collected and evaluated fruits of about 260 pili accessions, 180 of which were from the Bicol region. Some accessions were planted in Los Baños, but many are being maintained in the areas of collection. The Department of Agriculture and the Bicol University College of Agriculture and Forestry are also involved in the collecting and evaluation of pili germplasm.
  • Although natural calamities (e.g. typhoons and volcanic eruptions) could have contributed to the erosion of the pili genepool, the greatest threat to the species today is humankind. Humans gather pili nuts for food (including those naturally dispersed by animals), seldom replanting the seeds, and fell the trees for building purposes and for fuelwood.
  • Varietal improvement of the pili is mainly done by selection of superior trees tablished for the pili, and three varieties have so far been registered with the National Seed Industry Council.
  • The pili seed takes an average of 57 days to germinate. About 70 days after sowing, the seedling has a pair of mature leaves. It initially grows slowly, after transplanting from the seedbed, but its growth rate soon accelerates rapidly. After 3-4 entire leaves have emerged, leaves with 3 leaflets follow. In the mature tree, the leaves have 5, 7 or 9 leaflets. On average, seedling trees start fruiting 5-6 years after seed germination. Pili trees may live to more than 100 years.
  • The pili can be propagated using seeds, or by asexual methods such as marcotting, grafting and budding. Almost all the pili trees that exist today have been grown from seeds. Seed propagation is not recommended, because half of the resulting trees would be male, and the female trees are highly variable in many horticultural characters and take much longer to fruit.
  • Marcotting may be used for small-scale propagation of the pili. Cleft-grafting and patch-budding are recommended for large-scale propagation.
  • Sexually propagated planting materials should be planted in the field, at least 12 m apart. A total of two seedlings should be set in a hole, and all male trees should be cut down as soon as their sex can be determined, leaving only one male tree for every 20-25 female trees. Vegetatively propagated trees should be spaced at least 8 m apart.
  • Little is known about the cultural requirements of the pili. However, basic knowledge of the growth and development of the pili plant may suggest certain practices (i.e. training and pruning, irrigation and fertilization). Pest control measures are not necessary because the pili tree and its parts are not known to be attacked by any serious pests or diseases.
  • Seedling trees start fruiting 4-5 years after planting. Asexually propagated trees are productive 2-4 years after planting. A 10-to-15-year-old tree that produces 2000 fruits per season would yield about 20 kg dried nuts. The peak harvesting period is June-August. Harvesting is traditionally done by repeatedly thrashing the fruiting shoots, thereby detaching even the immature fruits and severely defoliating the tree.
  • Processing of the pili fruits begins with removal of the pulp by soaking the fruits in water. The clean nuts are sun-dried for 2-3 days, and the kernel is extracted by cutting the shell with a ‘bolo’ knife. The testa is removed by soaking the kernel in warm water.
  • The pili tree is excellent for landscaping, as a windbreak, and for agroforestation. The young shoot is edible and the resin-rich wood makes excellent firewood. The green pulp can be made into pickle, while the ripe pulp is edible after boiling. It also contains an oil that may be used for lighting, cooking and in the manufacture of soap and other industrial products. The shell makes an excellent cooking fuel and can be made into attractive ornaments. The kernel is edible raw, roasted, fried or sugar-coated, and is also used in making cakes, puddings from existing seedling populations. Varietal selection standards have been es-and ice cream. It is rich in oil, which is suitable for culinary use.
  • The pili pulp contains 8% protein, 37% fats, 46% carbohydrates, 3% crude fibre and 9% ash. The pulp oil contains 57% oleic glycerides, 14% linoleic glycerides and 29% saturated fats. The kernel contains 12-16% protein, 69-77% fats and 3- 4% carbohydrates. It is also rich in minerals, but poor in vitamins. The kernel oil has 60% oleic glycerides and 38% palmitic glycerides.
  • The pili has a bright future as a commercial crop. Superior varieties, rapid asexual propagation methods and workable production technologies are available to prospective growers. The nuts keep well, and can be stored for several months. The pulp and kernel are highly nutritious, and can be used in the preparation of many food products, including edible oil.
  • Limitations to the pili include scarce knowledge of the true range of its genetic variability, its range of climatic adpatability, its cultural requirements as an orchard crop, mechanized nut processing, and commercial oil production from the pulp and kernel. The pili nut kernel’s high oil content may prove to be a hindrance to its success in international markets.
  • The University of the Philippines at Los Baños, notably its Institute of Plant Breeding and Department of Horticulture, has been very active in pili research and development. Some government agencies in the Bicol region (e.g. the Department of Agriculture, Camarines Sur State Agriculture College, Bicol University) are also involved in pili research and development. One nongoverment organization (Demontaño Foundation, Inc.) is promoting the cultivation of the pili.
  • The research and development needs of the pili include: collecting and conservation of pili germplasm and selection of elite trees; training of technicians on rapid asexual propagation methods; micropropagation; multilocational trials of registered varieties; the establishment of experimental and demonstration orchards, and studies of different cultural requirements and processing techniques.

Author:

Roberto E. Coronel