COCONUT
Cocos nucifera L., family PalmaceaeThe coconut is found along tropical seashores around the world, and in some areas it is cultivated far inland. It provides man with food, drink, fuel oil, and many other products.
There are about 8.5 million acres of coconuts, of which 2.45 million are in the Philippines, 1.59 in India, 1.5 in Indonesia, 1.07 in Ceylon, 0.6 in Malaya, 0.6 in other south sea islands, and 0.7 million acres elsewhere (Minon and Pandalai 1958, Woodruff 1970). Apacible (1968) indicated that there were 4.5 million acres in 1967 as against 2.4 million in 1958. Apacible (1968) also stated that coconut production has increased at the rate of 5 percent a year for the last 50 years. In the United States, coconuts are found in Florida, Hawaii, and Puerto Rico. The largest coconut plantation in the United States consists of about 30,000 trees in Key Biscayne, Fla. (Woodruff 1970).
Plant:
The usually leaning, branchless trunk may reach a height of 100 feet (fig. 79). However, selections of dwarf plants as low as 6 feet are now being cultivated (fig. 80). Wrigley (1969) stated, however, that dwarf coconuts are short lived and inferior in copra production. The top, head, or crown consists of 20 to 30 mature feather-shaped leaves 15 to 20 feet long and 1 to 3 feet wide, with additional developing leaves. A leaf requires 1 1/2 years to reach full size, then it will last for 2 more years. A new leaf and an inflorescence forms about once each month (Chandler 1958*). The inflorescence produces from 1 to 20, but usually about half a dozen nuts, each nut weighing up to several pounds. The nut is enclosed in a thick fibrous husk, that when removed reveals the well-known brownish fiber-coated coconut, comprising the hard shell which contains the edible meat and milk. One tree may yield 100 fruits per year, and about 90 trees per acre are used (Woodruff 1970). The plant will withstand a light frost, but is basically a tropical crop.
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FIGURE 79. - Grove of "standard- height" coconuts
FIGURE 80. - Fruit of the dwarf coconut can be harvested from the ground.Inflorescence:
The coconut is monoecious, having both staminate and pistillate florets on the same many-branched inflorescence, the 2- to 4-foot long spadix or fleshy panicle in the leaf axil. As many as 8,000 staminate flowers may make up most of the inflorescence, with 1 to 30 pistillate flowers near the base (Aldaba 1921, Ochse et al. 1961*).
Flowering of larger plants begins at 5 to 8 years of age (Chandler 1958*), but on dwarf plants it begins in the third or fourth year (Woodruff 1970). Flowering occurs on the plant throughout the year.
The individual staminate flower described by Juliano and Quisumbing (1931), which is open only 1 day primarily between 6 a.m. and noon, and is only a few millimeters in size, has three cream-colored petals and six stamens. The stamens shed large amounts of pollen, some of it before the flower is open and altogether as much as 6.1 g per inflorescence (Whitehead 1963). There is also an abortive pistil whose stigmatic area is divided into three parts each bearing an active nectar gland. The much larger 1/2- to 1-inch oval pistillate flower has three stigmas on a short style and three ovules, two of which always abort. Sholdt and Mitchell (1967) mentioned that honey bees collect nectar from "the nectary orifices and stigmatic region." Menon and Pandalai ( 1958) stated that nectar secretion is most profuse between the stigma and the base of the ovary. Whitehead (1965) stated that considerable quantities of nectar were produced from three nectaries in the pistillate flower.
Patel (1938) stated that when the stigma is receptive a clear sweet fluid is profusely secreted in four places, at the base of the stigma and at three pores on the pericarp toward the top of the ovary.
Not all of the pistillate flowers mature fruit. Lever (1961) stated that there is a normal shed, comparable to the "June drop" of fruit trees, and also a shedding caused by harmful insects.
Usually only one spadix at a time opens on a plant. Furthermore, the staminate flowers frequently complete their flowering 3 to 6 days before the pistillate flowers open; therefore, crossing between flowers on a spadix or even a plant is unlikely, although the flowering periods tend to overlap in the newer dwarf selections (Woodruff 1970, Ochse et al. 1961*).
The period of staminate flowering on a spadix may extend from 18 to 38 days; the pistillate phase, from 2 to 12 days; and the interval between spadices, from 10 to 57 days, averaging 18 days (Kidavu and Nambiyar 1925). Overlapping of phases on a plant ranges from "seldom" to 20 percent of the time (Sholdt and Mitchell 1967, Ochse et al. 1961*). A pistillate flower may, therefore, receive pollen from staminate flowers of the same spadix or from a later spadix on the same plant. However, if there is no overlapping of spadices, the pollen must come from another plant (Chapman 1964*). Free (1970*) stated that staminate flowers of tall plants begin opening about a month earlier than the pistillate flowers, but pistillate flowers of dwarfs begin opening about a week after the staminate flowers.
The flowers are visited by honey bees and many other insects attracted by the nectar and pollen (Sholdt 1966). Nectar production, in terms of honey stored by a colony of honey bees, is not great (Pellett 1947*, Sholdt and Mitchell 1967), and the amount stored by a colony varies with the time of the year (Wolfenbarger 1970). Whitehead (1965) stated that nectar is produced in considerable quantity from the three nectaries in the female flower. During one 30-minute period, he recorded 103 visits by bees collecting nectar from one flower, and after each visit the nectar was rapidly replaced. Ochse et al. (1961 *) also referred to the large quantity of nectar that exudes from the flower.
Pollination Requirements:
Pollen must move from staminate to the pistillate flowers if coconuts are produced. Sholdt and Mitchell (1967) showed that the source of the pollen was not important from the standpoint of fruit set for they obtained good set whether the pollen came from the same plant or from another plant.
The pollen can come from the same inflorescence, another inflorescence on the same plant, or another plant. The pollen is most effective the first day the stigma is exposed, and, theoretically, only one pollen grain per pistillate flower is sufficient to fertilize the one ovule. Aldaba (1921) calculated that one inflorescence produced 272 million pollen grains.
Whitehead (1965) studied the flowering of coconuts in Jamaica and reported all variations in the pollination requirements. He believed that to conclude that the plants are either selfed or crossed was unsafe, but the extent of crossing depended upon the relative importance of wind, insects, proximity of other trees, efficiency of selfing, presence of nectaries on male and female flowers, and the frequency of insect visitation, particularly bee visits. Copeland (1931) stated that the succession of clusters is normally so timed that pollen must come from another plant, which insures cross-pollination. However, Tammes and Whitehead (1969) stated that this applies only to tall palms. In the dwarf palms, with the exception of 'Niu Leka', the female flowers are receptive before the male flowers cease; therefore, pollen may come from the same inflorescence. Wrigley (1969) stated that self-fertilization between flower heads on a dwarf coconut plant is normal.
Pollinators:
There has been considerable question about what agents are involved in transferring the pollen from the staminate to the pistillate flowers, a transfer that is required regardless of the flowering habits of the plant. Self-pollination is frequently mentioned, but this only refers to the source of the pollen, whether from the same inflorescence on which the stigma is located or another inflorescence. The flower cannot fertilize itself. Wind, birds, mites, and insects, including ants, bees, earwigs, flies, and wasps have been mentioned as cross-pollinating agents of the coconut (Davis 1954, Kidavu and Nambiyar 1925). The effectiveness of each doubtless is associated with local situations.
Furtado (1924) considered birds of doubtful value. Sampson (1923), Tammes (1937), and Whitehead (1965) stated that pollination was by insects. Huggins (1928) considered honey bees and various other hymenoptera important but ants unimportant. Hunger (1920), Patel (1938), and Ochse et al. (1961*) considered both insects and wind important. Sholdt (1966) collected 51 species of insects on the coconut inflorescences in Hawaii, but those found most often were ants, bees, earwigs, flies, and wasps. Sholdt and Mitchell (1967) considered both wind and insects important, with the honey bees the most important insects of all.
The recognition of the value of honey bees on coconuts is not recent. An anonymous (1916) author indicated that bees played an important part in the pollination of coconuts in Fiji. The inflorescences freely visited by bees when in flower gave a high yield of nuts, and the placement of colonies into coconut plantations was suggested. Sampson (1923) stated that on estates where bees were kept in large numbers for other reasons the yield of nuts was remarkably high. Huggins (1928) felt that the lack of adequate cross-pollination frequently depressed the yield of nuts. Haldane (1958) suggested that honey bees might be used to increase yields, but Tammes and Whitehead (1969) differed with this opinion. They stated: "There is, however, sufficient natural pollination by wild bees, as appears from trials, so the keeping of honey bees has no influence on the fertility of palms." They did not indicate what population of wild bees was adequate.
Pollination Recommendations and Practices:
Except for the above references, the use of bees has not been recommended in the pollination of coconuts. Sholdt and Mitchell (1967) suggested that, "it would appear advantageous to bring in colonies of bees in an effort to increase yields." They gave no indication of the number of colonies per acre or bees per inflorescence that might be adequate.
The evidence indicates that the presence of honey bees in adequate numbers could increase production. There is no indication as to what might constitute an adequate population on the flowers. One might ponder over the well-known relatively low production of coconuts per acre in the Philippines, where the bee population is quite low (Morse and Laigo 1969) as compared to the other areas of the world where coconuts are produced. The concentration of honey bees, even if it meant the development of a strong apicultural industry in the Philippines, might considerably improve the coconut industry.
LITERATURE CITED:
ANONYMOUS.
1916. BEES AND POLLINATION. Planters' Chron., Bangalore 9(46): 572.ALDABA, V. C.
1921. THE POLLINATION OF COCONUT. Philippine Agr. 10(5): 195 - 208.APACIBLE, A. R.
1968. THE PHILIPPINE COCONUT. Sugar News [Manila] 44(10): 599 - 606.COPELAND, E. B.
1931. THE COCONUT. Ed. 3, 225 pp. Macmillan, London.DAVIS. J. A.
1954. MYSTERIES OF CROSS-POLLINATION. Indian Cent. Coconut Com. Ernakulam, Bul. 7: 226-227.FURTADO, C.X.
1924. A STUDY OF THE COCONUT FLOWER AND ITS RELATION TO FRUIT PRODUCTION. Gard. Bul. [Singapore] 3(7-8): 261-273.HALDANE, J. B. S.
1958. SOME SUGGESTIONS FOR COCONUT RESEARCH. Indian Coconut Jour. 12: 1-9.HUGGINS. H. D.
1928. POLLINATION AND CROP PRODUCTION (CONCLUDED). Agr. Jour. Br. Guiana 1: 90-94, 164-169.HUNGER, F. W. T.
1920. COCOS NUCIFERA 518 pp. Scheltema and Holkema's Boekhandel, Amsterdam.JULIANO, J B., and QUISUMBING, E.
1931. MORPHOLOGY OF THE MALE FLOWER OF COCOS NUCIFERA LINN. Philippine Jour. Sci. 45: 449 - 458.KIDAVU, M. G., and NAMBIYAR, E. K.
1925. POLLINATION IN COCONUT. Madras Dept. Agr. Yearbook 1925: 43 - 49.LEVER, R. J. A. W.
1961. IMMATURE NUTFALL OF COCONUTS; THE WAR OF THE ANTS. World Crops 13(2): 60 - 62.MENON, K. P. V., and PANDALAI, K. M.
1958. THE COCONUT PALM - A MONOGRAPH. Indian Cent. Coconut Com., Ernakulam, 384 pp.MORSE, R. A., and LAIGO, E. M.
1969. THE POTENTIAL AND PROBLEMS OF BEEKEEPING IN THE PHILIPPINES. Bee World 50(1): 9 - 14.PATEL, J.S.
1938. THE COCONUT - A MONOGRAPH. Madras: Government Press. 262 pp.SAMPSON, H. C.
1923. THE COCONUT PALM. 262 pp. J. Bale, Sons, and Danielson, Ltd., London.SCHOLDT, L. L.
1966. INSECTS ASSOCIATED WITH THE FLOWERS OF THE COCONUT PALM, COCOS NUCIFERA L. IN HAWAII. Hawaii. Ent. Soc. Proc. 19(2): 293 - 296.______and MTTCHELL, W. A.
1967. THE POLLINATION OF COCOS NUCIFERA L. IN HAWAII. Trop. Agr. [Trinidad] 44(2): 133 - 142.TAMMES, P. M. L.
1937. ON THE INFLORESCENCE AND POLLINATION OF THE COCONUT. Landbouw, Buitenz. 13: 74-89.______and WHITEHEAD, R. A.
1969. COCONUT. In Ferwerda, E. P., and Wit, F., eds., Outlines of Perennial Crop Breeding in the Tropics, pp. 175-188. H. Veenman and Zonen, N. V. Wageningen, The Netherlands.WHITEHEAD, R. A.
1963. THE PROCESSING OF COCONUT POLLEN. Euphytica 12: 167-177.______ 1965. THE FLOWERING OF COCOS NUCIFERA L. IN JAMAICA. Trop. Agr. [Trinidad] 42(1): 19-29.
WOLFENBARGER, D. O.
1970. NOTES ON POLLEN DISPERSERS AND POLLINATION OF TROPICAL PLANTS AND ON ATTRACTANCY OF ALUMINUM MULCHED PLANTS FOR HONEY BEES. In The Indispensable Pollinators, Ark. Agr. Ext. Serv. Misc. Pub. 127, pp. 150 - 156.WOODRUFF, J. G.
1970. COCONUTS: PRODUCTION, PROCESSING, PRODUCTS. 241 pp. A.V.I. Publishing Co., Inc., Westport, Conn.WRIGLEY, G.
1969. TROPICAL AGRICULTURE. 376 pp. Frederick A. Praeger, N. Y. and Washington.
