Ananas comosus (PROSEA)
Ananas comosus (L.) Merr.
- Protologue: Interpr. Herb. amboin.: 133 (1917).
- Family: Bromeliaceae
- Chromosome number: 2n= 50
- Bromelia comosa L. (1754),
- Ananas sativus (Lindley) Schultes f. (1830).
- Pineapple, ananas (En)
- Ananas, pain de sucre (Fr)
- Indonesia: nanas (Javanese), danas (Sundanese), nanèh (Sumatra)
- Malaysia: nanas, nanas pager
- Philippines: apangdan (Bontok), piña (Spanish)
- Cambodia: maneas, moneah
- Laos: ananas, nat
- Thailand: yaannat (peninsular), sapparot (central), bonat (Chiang Mai)
- Vietnam: dúa, thom.
Origin and geographic distribution
The pineapple has its origin in South America where it was domesticated before the time of Columbus. In the 16th Century the Spaniards took the pineapple to the Philippines and Peninsular Malaysia and possibly also Indonesia. The crop is now widely grown throughout the tropics and into the subtropics. The international canning industry is based on plantations in Thailand, the Philippines, Malaysia and north Sumatra as well as in Hawaii, Brazil, Taiwan, South Africa, Kenya, Ivory Coast, Mexico and Puerto Rico.
The pineapple is best eaten fresh, although it can be cooked in a number of dishes. The fruits were canned as early as the end of the 19th Century in Hawaii and Singapore and to date the bulk of the crop is grown for canning and exported all over the world. The fruits are canned as slices, spirals, chunks, spears, titbits and cubes. The flesh adhering to the shell after peeling is scraped and made into pineapple crush or juice. The latter is also made by crushing the shell, core and bits and pieces of flesh which could not be used as specified cuts. Pieces may be canned mixed with other fruits, e.g. rambutan in Thailand. The fruits are also made into jam or used for crystallized and glacé fruit. The by-products of canning can be used as cattle feed or to produce pineapple wine or vinegar. Organic acids such as citric, malic and ascorbic can be obtained from the fruit as well as from the plants. Pineapple proteases, used to tenderize meat, are obtained from the stems and fruits. In the Philippines and Taiwan the fibres from the leaves are woven into a fine pina cloth.
Production and international trade
The mean annual world production of fresh pineapple for 1984-1987 was 9.7 million t, of which the Philippines' share was 1.78 million and Thailand's 1.73 million. Vietnam's figure stood at 0.41; Indonesia 0.35; Malaysia 0.18; Laos 0.04 and Cambodia 0.01 million t. Of the 0.63 million t mean annual world export of canned pineapple between 1984-1986, Thailand's and the Philippines' shares were 32% (0.20 million t) and 28% (0.18 million t) respectively. The mean figure for fresh export was 0.45 million t, of which the Philippines' share was 0.15 million t and Thailand's a mere 0.01 million t.
The area under the crop has been estimated as 180 000 ha for Indonesia, 63 000 ha for the Philippines, 61 000 ha for Thailand and 10 680 ha for Malaysia. In Thailand 90% of production comes from smallholders and in Indonesia the situation is similar. In Malaysia however, two-third of the fruit comes from estates and in the Philippines large-scale production dominates even more.
The portion of the fruit that is canned varies from a low of 18% in "Singapore Spanish" to a high of 60% in "Smooth Cayenne". Contents per 100 g edible portion: water 85 g, protein 0.4 g, sugar 14 g, fat 0.1 g, and fibre 0.5 g. The properties depend on the environment: fruit from the lowlands is larger, sweeter and more juicy than fruit grown in the highlands. The juice contains 0.5-0.9% acids and 10-17% sugar. In the canned product the sugar content is increased to about 22% and citric acid is added to 0.6%. Pineapple also contains bromelin, a protein-digesting enzyme.
- Perennial or biennial herb, 50-150 cm tall.
- Leaves sword-shaped, up to 1 m or more long, 5-8 cm wide, margin spiny or almost entire, top ending in a fine point, fleshy, fibrous, grooved on upper surface, arranged in a close spiral, clasping the main axis at their base.
- Inflorescence compact with numerous (up to 200) reddish-purple sessile flowers, each subtended by a pointed bract; sepals 3, short, fleshy; petals 3, forming a tube enclosing 6 stamens and a narrow style with 3-branched stigma.
- Fruit a coenocarpium formed by an extensive thickening of the axis of the inflorescence and by the fusion of the small berry-like individual fruits; the hard rind of the fruit is formed by the persistent sepals and floral bracts, which more or less fuse; on average the fruit is cylindrical, about 20 cm long and 14 cm in diameter, weighing 1-2.5 kg; the fruit is surmounted by a rosette of short, stiff spirally arranged leaves, called the "crown"; flesh pale to golden yellow, usually seedless. Besides the "crown", also "slips" (shoots growing on the stem below the fruit) and "suckers" (shoots growing in leaf axils lower down the stem) are formed, which can be used for vegetative propagation.
Growth and development
The plant forms a rosette with gradually larger leaves up to a size that reflects the prevailing growing conditions. Thereafter leaf size remains constant and when the apical meristem has produced a total of 70-80 leaves - at the rate of one per week during periods of fast growth - it turns floral and the plant bolts: the central axis elongates to flower and fruit.
Pineapple is a xerophytic plant. Its photosynthetic pathway is the Crassulacean Acid Metabolism (CAM). Carbon dioxide is absorbed during the night and converted into acids which are used in the daytime synthesis of carbohydrates. This pathway allows for the closure of stomata during the day to limit water use. The plant is indeed very drought-resistant, but the root system is shallow so that under dry conditions growth quickly stagnates.
Sensitivity to daylength has been shown for the Cayenne group; the cultivars are quantitative but not obligate short-day plants. There is no evidence that cultivars in the other groups behave in the same way. Singapore Spanish in Malaysia flowers throughout the year and there are indications that low night temperature, low day temperature and a decrease in sunshine hours all hasten flowering.
Work with flower-inducing chemicals has helped to clarify the progress of floral development. The vegetative apex of the plant is dome-shaped with typical tunica-corpus organization. Counting from the day of application of flower-inducing chemicals, the apex starts to increase in height and width within 2 days, reaching a maximum in 8-14 days. Around the 6th day the first bract primordia develop on the flanks of the meristem and flower buds subsequently develop in their axils. The initiation of the full complement of florets is completed after 30-45 days. The peduncle elongates rapidly around day 20 and after 45 days the inflorescence head is just apparent as a reddish disk in the centre of the plant. Further elongation of the peduncle carries the inflorescence head upwards to the level of the leaves. For up to 40 days peduncle elongation results from cell multiplication; after this period cell expansion predominates. The development of the young inflorescence into a fruit involves both cell division and enlargement for up to 80 days. Subsequently, size increases through cell enlargement.
The first flower opens approx. 50 days after induction and flowering continues for 20-40 days. About 1-10 flowers open daily, beginning shortly after midnight and closing the following evening. Anther dehiscence occurs in the evening before the petals begin to unfold. Pollen fertility varies from 20% to 80% and bees and sunbirds are the pollinating agents. The plant is self-incompatible; growing different cultivars together brings about seed formation. Therefore in commercial cultivation only one cultivar is grown in an area.
As the fruit matures, up to 12 slips develop near its base. At the same time the terminal shoot on top of the fruit elongates into the crown. When the fruit matures one or two suckers develop, which produce the ratoon crop after the parent plant is chopped off at harvest.
Other botanical information
Many pineapple cultivars exist, differing in plant and fruit size, in the colour and flavour of the flesh of the fruit and in the entire or spiny leaf margin. Nearly all cultivars for commercial production can be grouped as follows (each group indicated by the name of the cultivar from which it originated):
- Cayenne: most widely grown (the Philippines, Thailand, Hawaii, Kenya, Mexico, Taiwan). It is a heterozygous group; leaves 100 cm × 6.5 cm, reddish mottling above, silver grey beneath, margins entire, only with some spines at base and at top; fruit ca. cylindrical, weighing about 2.5 kg, flesh pale yellow to yellow.
- Queen: mainly grown in Australia and South Africa for the fresh fruit trade. All parts are smaller than in the Cayenne group; leaves spiny; fruits 0.9-1.3 kg, with deep golden yellow flesh.
- Red Spanish: mainly grown in Central and South America. It is intermediate in its characteristics between Cayenne and Queen. The leaves are long and spiny, containing fibres with high tensile strength, used traditionally for making cloth in the Philippines. Fruit weighing 0.9-1.8 kg, with pale yellow flesh.
- Singapore Spanish: only grown in Malaysia for the canning industry. Leaves about 1 m long, only some spines near apex; fruit 1.6-2.3 kg, with golden yellow flesh.
- Abacaxi: only grown in Brazil for local markets. Leaves with spiny margins. Fruits 1.5 kg with very pale yellow flesh.
- Cabezona: only grown in Puerto Rico for the fresh fruit trade. A triploid group.
Pineapple is cultivated between 25°N and S. The temperature range of growing areas is 23-32°C, although plants can be grown in areas where temperature drops as low as 10°C. However, the plant does not tolerate frost and the fruit is sensitive to sunburn. Crop duration increases substantially further away from the equator and at higher elevations. Moreover, sensitivity to daylength has the effect of making the crop more seasonal at higher latitudes. Within the limits of its distribution the mean annual sunshine varies from about 33-71% of the maximum duration, with a mean annual value of 2000 hours. In Kenya it is grown at elevations of 1800 m where fruits develop a sugar:acid ratio of 16:1 which is ideal for canning. At higher elevations fruits become too acidic. The plants are tolerant to drought and a wide range of rainfall; 1000-1500 mm per annum is considered optimal. A well-drained sandy loam is preferred, with a high organic matter content and pH 4.5-6.5. However, plants can be grown over a wide range of soil types, such as the acid peats (pH 3-5) in Malaysia. Drainage should be perfect, because waterlogged plants quickly succumb to root rot.
Propagation and planting
Pineapple is propagated by crowns, slips or suckers. Slips are the preferred material. Suckers are mainly used when "Smooth Cayenne" is planted, because few slips develop. Crowns are seldom used for large-scale planting because their size is not uniform. However, in Thailand crowns of "Smooth Cayenne" are favoured, graded into three sizes. Generally a single type of planting material is used for a field to ensure uniform growth and fruiting. In smallholdings where pineapple is grown for the fresh fruit market and where all planting material is valuable, a mixture of shoot types may be used. Suckers are allowed to develop for the ratoon crop.
The leaf-bud method of vegetative propagation, where every single matured node from the crown, slip or sucker may produce a plantlet, is a useful technique for obtaining up to 40 plantlets per shoot, especially from crowns. A protocol for tissue culturing has been developed, allowing for mass multiplication; this is particularly useful with newly introduced clones or hybrids.
Planting is usually in double rows with a sufficiently wide path between the double rows to allow for field operations. Thus the recommended spacing of (90 + 60) cm × 30 cm for "Singapore Spanish" means that the path is 90 cm wide, the two rows in a pair 60 cm apart and the plants in each row 30 cm apart, giving a density of 4.4 plants per m2. For the larger "Masmerah", the spacing recommended is (120 + 60) cm × 30 cm (3.7 plants per m2).
In Thailand "Smooth Cayenne" is spaced (100 + 50) cm × 30 cm (4.4 plants per m2) in smallholdings and (85 + 50) cm × 25 cm (6 plants per m2) in estates. Yield increases at closer spacing but fruit size declines; spacing experiments in Malaysia showed a maximum yield of 60 t/ha at 72 000 plants per ha for "Singapore Spanish".
Planting is done by hand along planting lines marked with the plant positions. A planting stick is used to make a hole in which the shoot is placed; the soil around it is firmed with the feet. Where labour is expensive, mechanical planting is practised.
In a suitable tropical climate the growth rate of the crop mainly depends on a steady moisture supply to the shallow root zone. Growth stagnates when moisture is lacking and excessive wetness invites foot rot. A range of growing techniques is employed to maintain moderate moisture levels: excellent drainage, if necessary helped by planting on raised beds, careful weed control, a polythene mulch over each row. Weeding a pineapple plot is not easy, but experiments in Malaysia have shown that weeds can reduce yield by as much as 42% in a new planting and 21% in a ratoon crop. This also depends on the weed species. Lalang (Imperata cylindrica (L.) Beauv.) physically damages the pineapple plants with its underground rhizomes, and once it has gained a foothold, it can only be eradicated by killing the pineapple plants as well. The other noxious weed is nut grass (Cyperus rotundus L.). Systemic herbicides are recommended for the control of these weeds. Bromacil can be used as a pre-emergence herbicide against nut grass. Depending on the weed flora, other pre- and post-emergence herbicides are used too.
Some growers lay black polythene strips and plant through them. This suppresses weed growth, the polythene cuts down erosion, warms the soil and reduces leaching, in addition to conserving moisture. After 4-5 months growth, the crop cover is sufficient to limit weed growth. Hand weeding between each pair of rows is necessary, even with mulching. If the field is ratooned to produce two or more crops in succession, it must be weeded once a month, because the ratoon crop does not provide enough cover to completely suppress weed growth.
Where rainfall is not well distributed, irrigation maintains growth and so advances fruiting. A drip line between each pair of rows is ideal; it can also be used for fertilization.
The natural harvest peaks in May-June-July and November-December are flattened by forcing flowering, so that a continuous supply of fruit is obtained for the cannery throughout the year. Acetylene from calcium carbide in water, 2-chloroethylphosphonic acid (ethephon) or alpha-naphthalene acetic acid (NAA) are commonly used to force flowering. NAA can also be applied on the developing fruit to increase fruit size. This, however, delays the harvest. With "Singapore Spanish" plants, such chemicals are poured into the heart of the plant when they are 10 months old. Flowering response can be as high as 95%. Flowering occurs 45 days later and fruit is harvested after a further six months. "Smooth Cayenne" has been shown to be erratic in its response to flower-inducing chemicals. Applications at night or two applications one week apart have given better results. The effect of applications of ethephon is improved by adding urea. Whereas in an untreated field flowering is protracted and hence the harvest period extended, treatment leads to simultaneous flowering and a short harvest period. This is a great advantage since the harvest can be organized more efficiently.
Growers in Malaysia remove the crown on the fruit of "Singapore Spanish" when it is about 5 cm long. At the same time, slips below the fruit are broken off, leaving two as planting material. For "Smooth Cayenne" this is not necessary as the crown does not grow very large and there are few slips to compete with fruit growth. When growing pineapple for the fresh fruit market, it may be desirable to reduce the size of the crown rather than remove it. This is done by gouging the meristematic tissues of the crown with a sharp implement when it is about 8 cm long in order to retard its growth.
The importance of fertilizers, especially nitrogen and potassium, in pineapple culture is well known. Nitrogen is required for vigorous plant growth but not when flower induction is contemplated because vigorous growth reduces flowering response. Phosphorus is needed during the first few months of growth while potassium is needed for fruit development. In the nutrient-deficient peat soils of Malaysia the recommended rates are 14 g N, 0.7 g P2O5 and 23 g K2O per plant, given as a broadcast three months after planting and two foliar sprays at 6 and 9 months. For ratoon crops, two-thirds of the above levels are applied per year. In Thailand where the crop is grown on sandy loam, the rates are 9 g N, 2.4 g P2O5 and 7 g K2O per plant for a plant crop. This is applied as one basal dressing, two leaf axil dressings, five foliar sprays and two urea applications, the latter combined with the flower induction treatments. The rates for the first ratoon crop are 6.5 g N and 6.3 g K2O per plant.
Malaysia used to practise continuous cropping as it was not economical to replant, since mechanical clearing of the field after each crop is not possible on peat. The use of herbicides like paraquat and glyphosate to scorch the leaves of the ratoon crop, so they can be burnt 3-9 weeks later, has made replanting more economical. Burning may not be necessary in some cases and new plantings can be started once the leaves of the old plants dry up; the plant residue is left to decompose in the field. Currently many growers replant after the first crop. Pineapple fields in Thailand produce 2 crops, the plant crop plus a single ratoon crop.
Diseases and pests
One of the most serious diseases of "Singapore Spanish" and "Masmerah", seen only in Malaysia, is fruit collapse. The causal bacterium, Erwinia chrysanthemi, attacks the fruit a few weeks before maturity when it suddenly exudes copious fluid and bubbles of gas. There is no effective direct control, but spraying heptachlor on the ground at the time of flowering and 2 weeks later controls the ants which spread the bacteria. Diseased fruits need to be removed and destroyed elsewhere to reduce the population of the bacteria in the field. The pathogen also causes bacterial heart rot when it infects the tender bases of young leaves of 3-6 month old plants. The rot can cause serious losses and is characterized by its putrefying odour. The Cayenne and Queen pineapple appear to be resistant to this bacterium. In the Philippines and Thailand, heart rot is caused by the fungi Phytophthora cinnamomi and P. parasitica respectively. Marbling disease of the fruit, caused by Erwinia ananas, appears to be the most serious problem in Thailand. It is hard to identify the disease and there is no effective control apart from lowering the amount of inoculum by sanitation. Other diseases of the pineapple fruit include leathery pocket, fruitlet core rot, interfruitlet corking, soft rot and yeasty rot.
The mealybug (Dysmicoccus brevipes) is the most serious pest. The insect is common in the tropics and causes wilt of "Smooth Cayenne" and "Masmerah"; "Singapore Spanish" shows some resistance. Infected plants become yellowish-red to bright red at the leaf tips, this colouration spreading down the leaf with time. Soon other leaves turn colour and also show signs of wilting. Severely infested plants become stunted and produce small fruits. The mealybugs are found at the base of leaves, moving on to healthy plants once their host starts to wilt. Control of the mealybugs involves control of the ants which are responsible for their spread. Spraying or dipping the planting material using diazinon or malathion helps to control the wilt.
In Malaysia, fruits left to rot in the field as well as the large amount of fruit peel at canneries attract large populations of the beetle Carpophilus foveicollis, which find the over-ripe fruit an ideal breeding ground. These beetles are a nuisance, as they may accidentally be canned with the fruit.
For canning, the fruits are harvested at one-third ripe in the case of "Singapore Spanish" and one-sixth ripe with "Smooth Cayenne" and "Masmerah", the fraction referring to the part of the fruit that has changed colour. Fruits harvested for the fresh fruit market may be picked half-ripe. Workers move along the path between the double rows and harvest the fruits by hand, chopping off the crown and peduncle at the same time. If the fruit is destined for the fresh fruit market, the crown and a portion of the peduncle is left intact. The fruit is then thrown backwards into the rattan basket carried by the worker. When the basket is full, the fruits are piled up at the edge of the field to be loaded onto trucks which transport them to the canneries. The bulk of the fruit is picked in the first round; a second and third harvest round at weekly intervals may be needed to bring in the remaining fruit.
In Malaysia yield has always been low due to the small fruit of "Singapore Spanish". The plant crop gives about 30 t/ha after a period of 18 months. Ratoon yield is about 16 t/ha per year. The introduction of "Masmerah" helped increase yield, up to 60 t/ha for a plant crop. The mean annual yield is about 25 t/ha in Malaysia and also in Thailand and the Philippines, although in both countries "Smooth Cayenne" can yield 50-60 t/ha from a plant crop and about 35 t/ha from a ratoon crop. The annual yield for Indonesia has been estimated to be only 5 t/ha. Low yields are generally due to wide spacing and plant losses, low growth rates and inadequate flower induction.
Handling after harvest
"Singapore Spanish" fruit has a reasonably thick skin and is able to withstand the rough treatment meted out during bulk transport. Nevertheless instances of serious bruising occur, reducing cannery recovery. Other cultivars, such as "Smooth Cayenne", suffer even more and should not be handled in bulk but carried in wooden crates. At the cannery the fruits are graded into different sizes to facilitate skinning, which is usually done mechanically.
Fruit for the fresh market is treated better because appearance is important. The fruit can be stored for 4-6 weeks at 7-8°C and 80-90% relative humidity with adequate air circulation. Storage life may be prolonged if fruits are dipped in a wax emulsion containing a suitable fungicide; the cut end of the peduncle should be treated similarly. Shelf life can be extended for about one week by irradiation.
The Malaysian Agricultural Research and Development Institute's Agricultural Stations at Klang and Pontian have a collection of local cultivars and hybrids. In Thailand cultivars are maintained by the Department of Horticulture, Kasetsart University and the Siam-Agro Industry Co. in Rayong.
Breeding of pineapple aims at getting bigger fruits which are cylindrical in shape, with a thin skin, high and well-balanced sugar and acid contents, yellow flesh, spineless leaves and resistance to the more common diseases and pests. The breeding programme in Malaysia resulted in the recent release of a cross between "Singapore Spanish" and "Smooth Cayenne". Selection has been quite successful, resulting in the bigger fruited "Masmerah" to replace the smaller and thick-skinned "Singapore Spanish". Selection and breeding research in Malaysia has been scaled down as the pineapple acreage has been declining.
Thailand is the leading producer of canned pineapple in the world, having overtaken the Philippines in 1986. Thailand has the potential to maintain its position in view of available cheap labour, extensive agricultural land, expertise in horticultural science and innovation in export products. The world consumption of canned and fresh pineapple has been increasing steadily and there is a definite future for the crop. However, the leading role can only be sustained by a strong research effort and it is a matter of grave concern that research activities have been cut back, in the region (Malaysia) as well as elsewhere (Hawaii). The favourable prospects for pineapple in South-East Asia depend very much on a revitalization of research work.
- Lim, W.H., 1985. Diseases and disorders of pineapple in Peninsular Malaysia. MARDI Report No 97. Malaysian Agricultural Research and Development Institute, Kuala Lumpur. 53 pp.
- PCARRD, 1976. The Philippines recommends for pineapple. Philippine Council for Agriculture, Forestry and Natural Resources Research and Development (PCARRD). Los Baños, Laguna, the Philippines. 66 pp.
- Py, C., Lacoeuilhe, J.J. & Teisson, C., 1984. L'ananas; sa culture, ses produits. Maisonneuve & Larose, Paris. 562 pp.
- Thongtham, M.L. Charupant, 1985. The pineapple and pineapple industry in Thailand. Aksorn Pittaya Publishing House, Bangkok. 158 pp. (in Thai).
- Wee, Y.C., 1972. Some common pineapple cultivars of West Malaysia. Malaysian Pineapple 2: 7-14.
- Wee, Y.C., 1974. The Masmerah pineapple: a new cultivar for the Malaysian pineapple industry. World Crops 26: 64-67.
- Wee, Y.C., 1978. Natural flowering and fruiting of the Singapore Spanish pineapple in Johore, West Malaysia. Journal of the Singapore National Academy of Science 7: 9-14.
- Wee, Y.C. & Rao, A.N., 1979. Development of the inflorescence and "crown" of Ananas comosus after treatment with acetylene, NAA and ethephon. American Journal of Botany 66: 351-360.
Sources of illustrations
Koorders, S.H., 1922. Exkursionsflora von Java. Blütenpflanzen. Band 4. Atlas. 2. Abteilung. Jena, Gustar Fischer Verlag. p. 211, Fig. 419. Redrawn and adapted by P. Verheij Hayes.
- Y.C. Wee & M.L. Charuphant Thongtham