Ananas comosus, pineapple

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Taxonomy

Brief facts

• Taxonomic place

  Pineapple belongs to Bromeliaceae (pineapple family), which includes both terrestrial and epiphytic plants. Bromeliads are with few exceptions indigenous to tropical and sub-tropical America. One notable exception, native to the West Africa, is epiphyte Spanish moss Tillandsia usneoides, common site in some U.S. southern states. Genus Pseudoananas is closest to Ananas within Bromeliaceae.

• Features characteristic to A.comosus

  • The fruits are usually but not always larger and they contain a relatively large amount of palatable flesh.
  • The fruits are seedless and only rarely produce a few seeds.
  • The floral bracts are inconspicuous in the mature fruit and do not cover the top of the ovary.
  • The penduncle is usually thicker than in the wild species.

• History

  First people from Old World to see the pineapple were Columbus sailors when they landed on the island of Guadeloupe on November 4, 1493 on Columbus second trip to the New World. The Portuguese appear to have played a major role in carrying the pineapple to other tropical countries. About 1550 they were responsible for its introduction into southern India. By the end of 16^th century, the pineapple had become established in China, Java and Philippines. Philippine native learnt to make fine cloth from the fibers of pineapple leaves. Overall, Ananas comosus can be regarded as cultigen because all its varieties are cultivated types, with no recognizable wild ancestral form. Highly palatable almost seedless pineapples were being cultivated by the Indian when America was discovered.

• Chromosome numbers

  The basic haploid chromosome number for all species of Ananas appears to be 25. Triploids having 75 chromosomes have been reported for some A. comosus from South America. Tetraploids with 100 chromosomes and triploids with 75 chromosomes have been produced as a result of plant breeding work in Hawaii. Varieties of A. comosus plants are self-incompatible and their sparse seeds are infertile when self-pollinated. However, crossing between varieties usually produces abundance of viable seed. Likewise, crosses between A. comosus and the wild species produce viable seed and vigorous F₁ plants.

• Ecology

  Pineapple can grow up to 1,800 meters above sea level. The higher elevation the more acid the fruit become. Optimum temperature is in the range between 20°C and 36°C. Frost is not tolerated but mild cool weather in winter improves quality and induces flowering. Drought is tolerated but yields are reduced. Evenly distributed annual rainfall of 839-1742mm, with high relative humidity is ideal. Pineapple grows well in partial shade. Acidic soil with pH between 4.5 and 5.5 is ideal for pineapple: soil born diseases are reduced and iron in the soil become readily available to the roots of plants. In areas where soil pH is close to neutral, topical application of FeS²O⁴ is necessary to support normal growth. Inability to obtain iron from an iron-rich soil under certain conditions is a peculiarity of the pineapple not shared by other plants.

• Uses of pineapple

  • Pineapple fruits appear on the market in a variety of forms and guises: canned (slices, chunks, diced, juice), fresh fruit, frozen, dried, jam, glacé, alcohol and sugar syrup.
  • Fruit residue (bran) is used as a cattle feed.
  • Leaf fiber produces piña cloth in Philippines.
  • Variegated forms are grown as ornamentals.
  • Stump is a source of organic substances and enzymes collectively called bromelain that exhibit several pharmacological properties such as interference with tumor growth, inhibition of platelet aggregation, fibrinolytic activity, anti-inflammatory action, and skin debridement properties.

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Vegetative shoots used for pineapple propagation

• Crown A vegetative shoot produced at the top of the fruit, which is continuation of its core and of the penduncle. Crowns may take up to 22-24 months to produce fruit.
• Slip Small shoot that is produced on the penduncle below the fruit. When intended for propagation, they are harvested two to five months after the fruit harvesting when they are about 40 cm long (about 10-13 months after slip growth starts). Slips may produce fruits within 14-16 months after planting. Slips are found to be the best planting material because although slower than suckers, they bear larger and more uniform fruits.
• Sucker Shoots produced above or below ground from auxiliary buds on the stump.
  • Hapa Or side sucker. Produced from the above ground portion of the stem, when used for propagation they will produce fruit in 18-20 months.
  • Ratoon Or ground sucker. Shoots grown at or below ground from the stem. When used, ratoons will produce fruit in 12-14 months depending on whether they were transplanted or left on the mother plant.
• Stump bits Stumps from superior fruits without slips are collected. Leaves are cut off leaving the bases attached to the stumps. Each stump is cut longitudinally into quarters or sixth, which then cut into wedge-shaped sections weighing 15-20 g, each having at least one auxiliary bud. As many as 50 sections may be obtained from one stump. A section will produce another stump in about 2 years.

Pineapple plant with ground sucker (ratoon) on the left.

Pineapple plant with slip at the base of the fruit.

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Growth stages (life cycle)

Life Cycle Stages

Pineapple plant is biennial. Seeds are used only for breeding. They are difficult and slow to germinate (emergence takes up to 2 months and 4-leaf seedling takes up to 3 months to grow). Pineapple is easily propagated by vegetative shoots. Usually a four year crop cycle: a plant crop and one ratoon crop, with 6–9 months for land preparation.

• Planting Vegetative shoots used for planting are crown, slip, hapa, or ratoon.
• Vegetative growth During the first year the plant stores up starch in the thick central axis for production of the inflorescence. Differentiation usually occurs in the early part of winter. A night drop in the temperature was found to be a primary environmental factor that triggers change from a leaf-producing apical stem meristem to a flower-forming meristem. The bud that terminates the growth of the plant is not visible for about 3 months after initiation.
• Flowering Pineapple plant usually flower in 11-12 months after planting after formation of at least 40 leaves. Synchronized flowering is induced by application of compressed acetylene gas, a spray of calcium carbide solution or naphtalenacetic acid (NA), which induces formation of ethylene. The individual flower consists of (from inside to outside):
  (1) three-carpel ovaries, each carpel containing from 10 to 15 ovules;
  (2) three-lobed stigma;
  (3) six stamens;
  (4) three purplish-blue petals;
  (5) three thickened fleshy sepals;
  (6) the fleshy bract partially covering the sepals.
  It is believed that hummingbirds are principal natural cross-pollinators. The flowers open in the late morning (8:00 to 9:00 AM) and close before sunset. The flowering progresses from the oldest florets at the base of the inflorescence to the later ones at the apex. The progressive flowering continues for about 20 days, with only a few flowers opening each day.
• Ripening The fruit is mature in six to seven months after differentiation. The pineapple fruit is collectively made up of a number of individual berry-like fruitlets, each attached to the central axis core, and fused throughout its length to adjacent fruitlets. The fruitlets are arranged spirally in an 8/21 phyllotaxy in the larger-fruited varieties of A. comosus. The number of fruitlets varies with size of the fruit from around 110 to 180 for the Cayenne variety. The shell of the collective fruit is made up of the three sepals partially covered by the thick bract. These flattened fleshy sepals are weakly fused at their outer margins with the sepals of adjacent fruitlets, forming a continuous rind over the entire fruit.
• Harvest The fruits are usually harvested at 70-80% ripening stage when the surface color is between color break and one to three quarters yellow depending on time fruits are expected to be en route.
• Ratooning After the fruit from the mother plant is harvested, a second or ratoon crop develops on suckers produced on the mother plant stem. Ratoon crop is produced in only 12 months. Usually only one ratoon crop is recommended because the succeeding ratoon crops' yield declines.

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Fruit phyllotaxy and Fibonacci numbers

Phyllotaxy (from Greek phyllon, leaf and taxis, arrangement) is the mode in which leaves are arranged with regards to the axis of the main stem. In nature leaves or florets are arranged in a spiral.

One of principal methods of expression of this arrangement gives the ratio between the number of spiral's turns about the plant axis and the number of leaves (or florets in case of inflorescence) in the spiral when it makes full circle around the stem. These ratios generally belong to the so-called Fibonacci summation series, 1/2, 1/3, 2/5, 3/8, 5/13, 8/21, etc., in which each value of the numerator and denominator is the sum of the two corresponding values that precede it.

Phyllotaxy 8/21 was reported for Cayenne pineapple. Below is presented Del Monte Gold pineapple, which phylotaxy was determined to be 8/13.

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References

• Collins JL. History and Culture of the Pineapple. Economic Botany, Vol. 3, No. 4 (Oct. - Dec., 1949), pp. 335-359
• Carson J. Fibonacci Numbers and Pineapple Phyllotaxy. The Two-year College Mathematics Journal, Vol. 9, No. 3 (jun., 1978), pp. 132-136
• Miles Thomas EN. and Holmes LE. The Development and Structure of the Seedling and Young Plant of the Pineapple (Ananas sativus). New Phytologist, Vol. 29, No. 3 (Sep. 17, 1930), pp. 199-226
• Ekern PC. Phyllotaxy of Pineapple Plant and Fruit. Botanical Gazette, Vol. 129, No. 1 (Mar., 1968), pp. 92-94
• Carson J. Fibonacci numbers and pineapple phyllotaxy. The two-year college mathematics journal, Vol. 9, No. 3 (Jun., 1978), pp. 132-136
• Holmes LE. Studies in the Morphology and Biochemistry of the Pineapple II. Reserves in the Seeds of Two Genera of the Bromeliaceae and of Various Pineapple Hybrids. New Phytologist, Vol. 32, No. 5 (Dec. 15, 1933), pp. 382-392
• Kerns KR, Collins JL, Kim H. Developmental Studies of the Pineapple Ananas comosus (L) Merr. I. Origin and Growth of Leaves and Inflorescence. New Phytologist, Vol. 35, No. 4 (Oct. 28, 1936), pp. 305-317
• Taussig SJ and Batkin S. Bromelain, the enzyme complex of pineapple (Ananas comosus) and its clinical application. An update. Journal of Ethnopharmacology, 22 (1988) 191 - 203

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