sugarcane

/shoog"euhr kayn'/, n.

a tall grass, Saccharum officinarum, of tropical and warm regions, having a stout, jointed stalk, and constituting the chief source of sugar.

Also, sugarcane.

[1560-70; SUGAR + CANE]

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Giant, thick, perennial grass (Saccharum officinarum; family Poaceae, or Gramineae), cultivated in tropical and subtropical regions worldwide for its sweet sap, a major source of sugar and molasses.

The plant grows in clumps of solid stalks with regularly spaced nodes or joints, each with a bud that can be planted for commercial asexual propagation. Graceful, sword-shaped leaves, similar to those of the corn plant, fold in a sheath around the stem. Mature canes may be 10–20 ft (3–6 m) tall and 1–3 in. (2.5–7.5 cm) in diameter. Molasses, the syrup remaining after sugar is crystallized out of the juice, is used in cooking, in making rum, and as feed for farm animals. Residual cane fibre (bagasse) is burned as fuel or used as filler for paper and particleboard.

Sugarcane (Saccharum officinarum)

Ray Manley

Shostal Assoc.

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  (Saccharum officinarum), giant, thick, perennial grass of the Gramineae family cultivated in tropical and subtropical regions worldwide for its sweet sap, which is a major source of sugar and molasses. Sugarcane probably originated in what is now New Guinea, its cultivation spreading along the human migration routes to Southeast Asia, India, and Polynesia. Asia is now the largest producer, followed by South America and North America. In the United States, sugarcane is a major commercial crop of Hawaii, Florida, and Louisiana.

      The plant grows in clumps of solid stalks with regularly spaced nodes or joints, with a bud at each node. The graceful, sword-shaped leaves are similar to those of the corn plant. The sheath folds around the stem, protecting the bud. Mature canes may be 3–6 m (10–20 feet) tall and 2.5–7.5 cm (1–3 inches) in diameter. The colour of the stalk ranges from almost white to yellow to deep green, purple, red, or violet.

      The sugarcane plant is susceptible to more than 60 diseases, none of which occurs worldwide. Regional varieties are bred to resist specific types of disease, and extensive breeding programs continue to produce new varieties suitable to the major sugarcane-producing areas of the world.

      For commercial production, sugarcane propagation is conducted vegetatively (asexually); sections of stalk, each containing a node, are planted. The crop requires at least 1,500 mm (60 inches) of rainfall or irrigation per year and a minimum of nine months to mature. Cane is harvested in the cooler months in North America; in Cuba, Hawaii, Colombia, and other prime areas, it is harvested year-round. Most of the world's cane is cut by hand, using machetes, although mechanical harvesting has increased steadily since it was introduced in Louisiana in the 1940s.

      The sugar content of sugarcane ranges from 7 to 18 percent by weight. Cane yields range from 35 to 190 metric tons per hectare (15 to 85 tons per acre). About 75 million metric tons of raw sugar are produced from sugarcane each year in factories in the cane-growing areas. molasses, the syrup remaining after sugar is crystallized out of the juice, is used to make rum and is a feed for farm animals. The residual cane fibre, called bagasse, is often burned as a fuel for the cane factory; it is also sold as a filler for paper and particleboard.

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Introduction

      perennial grass of the genus Saccharum cultivated for its juice, from which sugar is processed. Most present-day commercial canes are the offsprings or hybrids of the species Saccharum officinarum, which was developed from a wild cane species, Saccharum robustom, and cultivated by natives of southern Pacific Islands. This article treats the cultivation of the sugarcane plant. For information on the processing of cane sugar and the history of its use, see the article sugar.

Culture

      The cane-growing areas of the world are located from 37° N (southern Spain) to 30° S (KwaZulu/Natal, South Africa), but most of the world's cane sugar is grown in subtropical and especially in tropical areas.

      The sugarcane plant produces a number of stalks that reach from 10 to 24 feet (three to seven metres) high and bear sword-shaped, long leaves. The stalks are composed of many segments and at each joint there is a bud. When the cane becomes mature, a growing point at the upper end of the stalk develops into a slender arrow, bearing a tassel of tiny flowers.

      Sugarcane is propagated primarily by the planting of cuttings. Sections of the stalk of immature cane used for planting are known as seed cane, or cane sets, and have two or more buds (eyes), usually three. Seed canes are planted in well-worked fields. Mechanical planters that open the furrow, fertilize, drop the seed cane, and cover it with soil are widely used.

      Seed canes are spaced from 4¹/₂ feet to 6 feet (1.4 to 1.8 metres) apart at densities from 4,000 to 10,000 per acre (10,000 to 25,000 per hectare). Under favourable conditions, each bud germinates and produces a primary shoot. Root bands adjacent to each bud give rise to a large number of roots, and each young shoot develops its own root system. Tillering, or sprouting at the base of the plant, takes place; and each original seed cane develops into a number of growing canes, forming a stool. The plant crop is obtained from these stools.

      Another method of cane propagation is by ratooning, in which, when the cane is harvested, a portion of stalk is left underground to give rise to a succeeding growth of cane, the ratoon or stubble crop. The ratooning process is usually repeated three times so that three economical crops are taken from one original planting. The yield of ratoon crops decreases after each cycle, and at the end of the last economical cycle all stumps are plowed out and the field is replanted.

      Sugarcane is grown in various kinds of soils, such as red volcanic soils and alluvial soils of rivers. The ideal soil is a mixture of sand, silt, and clay particles, with a measure of organic material. The land is plowed and left to weather for a time before subsoiling (stirring up the subsoil) is carried out.

      Sugarcane demands a well-drained soil, so that its roots have access to air and can absorb it. Drains—on the surface, underground, or both—are provided, according to the topographic conditions of cane fields.

      To attain good yields, sugarcane requires 80 to 90 inches of rain (2,000 to 2,300 millimetres) during the growing period. When precipitation is deficient, irrigation, either by spraying or by applying water in furrows, can make up for the deficiency.

      Fertilizers are applied to sugarcane from the beginning of planting through the whole growth cycle, but not during the ripening period. Optimum amounts of fertilizers (nitrogen, phosphorus, and potassium) vary greatly with soil types, climatic conditions, and the kind and length of the growing cycle.

      To secure a good cane crop, weeds in the cane fields must be attacked until the cane stools develop a good canopy, which checks weed growth. Weeding, still largely manual, is done with a hoe, though mechanical cane weeders with attached rakes have been developed. Chemical weed killers and herbicides are widely used.

      The growth period for cane crops varies considerably according to the region: 8–9 months in Louisiana; 15 months in Australia and Taiwan; 18–22 months in Hawaii, South Africa, and Peru.

      The lowest temperature for good cane-plant growth is about 68° F (20° C). Continuous cooler temperature promotes the maturation of cane, as does withholding water. Harvesting and milling begin in the dry, relatively cool season of the year and last for five to six months.

      The mature cane is harvested by both manual and mechanical means. In Hawaii and Australia, mechanical harvesters are effectively used. Some are able to sever and discard the tops of erect crops and cut cane stalks, which are delivered into a bin trailer for transport to the mill by tractor or light railway wagon.

Diseases

      The sugarcane plant is subject to many diseases. Sereh, a blackening and degeneration of the fanlike tops, is caused by an East Indian virus. Mosaic, mottling or spotting of foliage and sometimes curling, dwarfing, and narrowing of the leaves, may be caused by any of several viruses. Red rot (important in Java) is characterized by red patches within the canes, and is caused by the fungus Physalospora tucumanensis. Gumming disease (important in New South Wales, Australia) is characterized by gummosis, the pathological production of gummy exudates as a result of cell degeneration; it is caused by the bacterium Xanthomonas vasculorum. Fiji disease, a virus disease first reported from the Fiji islands, is characterized by elongated white to brown swellings on the underside of the leaves, followed by stunting and death. Leaf scald is a vascular disease caused by the bacterium Xanthomonas albilineans, characterized by creamy or grayish streaking and later withering of the leaves. Eyespot, characterized by yellowish oval lesions on leaves and stems, is a disease caused by the fungus Helminthosporium sacchari. Epidemics of these diseases have been checked by replacing the susceptible varieties of cane with varieties resistant to the disease.

Pests

      Sugarcane is attacked and damaged by various insect pests that bore into and feed on the different parts of the plant. Control measures include biological control by parasites or predators, chemical control by insecticides, and the introduction of resistant cane varieties.

      The moth borer, Diatraea saccharalis, which is widely distributed throughout cane-growing areas, is capable of causing extensive damage when out of control. The sugarcane leafhopper and the anomala grub yielded to biological control in Hawaii when other measures were unsuccessful. Various predator animals live on insects destructive to the sugarcane. In Queensland the bandicoot, an insectivorous marsupial, is a most diligent destroyer of white grubs.

      The insect pest responsible for the greatest crop losses in Queensland is the grayback beetle in its larval stage. The most effective grub control is obtained by applying the insecticide benzene hexachloride after the young cane plant has germinated and stooled. Cane is also protected effectively against wireworms by applying insecticides when cane sets are planted (plant breeding). Rats, which destroy part of the stalk, are controlled by poisoning and trapping.

Breeding

      The purpose of sugarcane breeding is to produce new hybrid varieties that will be immune, or resistant, to diseases and insect pests and will increase the production of sugar per unit area, yielding canes of higher sugar content and better fabrication qualities.

      The first task of breeding is to obtain new cane seeds by crossing selected parent varieties, and then to select seedlings from the new seeds. The crossing is effected by enclosing in a cloth lantern two tassels from two different cane varieties selected as a male and a female parent. The commercially superior varieties are not necessarily ideal parents. Many of the best varieties were bred from parents unsuitable for commercial use. The production of such cane seeds and seedlings by crossbreeding has been established in Java and Barbados since the 1880s.

      A selected seedling is planted and tested in the fields, and usually takes up to 10 years before being released as a new commercial variety.

      Most present-day hybrid commercial varieties are directly descended from the Cheribon cane, a Javan noble cane, species Saccharum officinarium. Noble canes, which represent the highest development of the species, are characterized by thick, barrel-shaped internodes, or segments; large, soft-rinded, juicy stalks; and high sugar content. Original noble canes were susceptible to some serious cane diseases; their hybridization with wild canes was successful because, although wild cane Saccharum spontaneum contains little sugar, it is immune to most diseases.

Takeo Yamane Ed.

Additional Reading

Studies include A.C. Barnes, The Sugar Cane, 2nd ed. (1974), a detailed description of worldwide cane-growing techniques; and Frank Blackburn, Sugar-Cane (1984).Takeo Yamane Ed.

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