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Week 7 (Unit 13)

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Sugarcane & Sugar Beets

Sugarcane
Origin, taxonomy, and reproduction
Growth requirements, physiological and adaptive traits
Production statistics, economics and marketing
Processing and utilization of sugarcane
Major diseases and insect pests
Cultural significance of the sugarcane industry
Sugar beets
Assignments
References

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Origin, Taxonomy, & Reproduction of Sugarcane

Sugarcane is a tropical grass, in the family Poaceae. Like maize and sorghum, it belongs to the subfamily Andropogoneae. Three species have been cultivated:

Saccharum officinarum - the most likely center of origin is Papua New Guinea and Indonesia, about 4,000 years ago.

Saccharum barberi - originated in India.

Saccharum sinense - originated in China.

All species in the genus Saccharum are polyploid. Clones of S. officinarum have 2n=80 chromosomes. Sugar cane varieties developed since the 1920's are artificial interspecific hybrids between S. officinarum and the wild species S. spontaneum. They are often aneuploids (do not have an exact multiple of a basic number of chromosomes) and highly polyploid (chromosome numbers range from 40 to over 140). S. spontaneum is considered to be the wild ancestor of S. officinarum.

Photo by Scott Bauer, USDA/ARS

In the mid-18th century, European explorers brought back clones of S. officinarum from the South Pacific which they referred to as "noble clones", due to their high sugar content. It was not until late in the 19th century that seed production was observed in Barbados, and efforts were initiated to develop varieties through seed propagation.

Early in the 20th century, sugarcane plantations in Java were ravaged by mosaic (a potyvirus) and sereh disease (which no longer exists). There were no resistant clones of S. officinarum available, so interspecific hybrids were developed with a resistant clone of S. barberi brought from India. Later, interspecific clones were developed from crosses with S. spontaneum, which were rapidly adopted in plantations around the world. These crosses were high in sugar content, and S. spontaneum provided resistance to several diseases, improved vigor, and better tolerance to drought and cold.

The inflorescence of sugarcane is a loose panicle. Each spikelet is bisexual and pollination occurs by wind. The seed is used only for breeding purposes. Short days are required for flowering to occur, and cultivated types are less likely to flower than wild types, because seed production has been bred out of cultivated sugar cane to some extent.

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Growth Requirements, Physiological & Adaptive Traits

Sugar cane is grown in tropical and subtropical environments throughout the world. It is a perennial crop that is propagated vegetatively using cuttings. Stalks are cut into short 20 inch (50 cm) segments, laid in furrow rows, and then covered with soil. Within a few weeks, plants grow from the buds in the stalk segments.

Sugarcane can grow in a wide range of soil types, from heavy clay types to organic soils. In West Africa, sugarcane is grown in fadamas, which are wet areas along rivers that are seasonally flooded. Ideal soils for sugarcane are well-drained, sandy loams to clay loams with adequate organic matter.

Temperature is one of the key factors determining adaptation of sugarcane. Temperatures must be above 21° Celsius (C) for satisfactory growth. Optimum temperatures for germination, stalk length and diameter are 30-32 °C. For this reason, many of the world's sugarcane growing regions lie between 20 °N and 20 °S, where high temperatures with relatively minor seasonal fluctuations occur.

Sugarcane is grown in areas receiving 500-2500 mm rain annually.

Unlike the cereal crops, it is the sugarcane stem that is harvested as a source of food rather than the inflorescence. After a harvest, the time required for the crop to regrow and be harvested again varies from 10 to 24 months, depending on conditions. In general, yields of cane decrease with successive ratooning, and the crop must eventually be replanted. The frequency of replanting varies a great deal, but is typically 2-4 years in the US.

The canes turn tough and pale yellow when they are ready for harvest.

Most crops accumulate starch, but sugarcane accumulates sucrose. Sucrose accumulates in the stem at the end of the growing period (e.g. at the end of the rainy season in the tropics). Accumulation of sugar is triggered by a drop in temperature, increased range between high and low daily temperatures, and reduced water uptake. Stem sugar content may be low if these conditions are not met.

 

Harvesting sugarcane in south Florida.
Photo by Scott Bauer, USDA/ARS

To see pictures of sugarcane harvest in Africa, go to http://www.africapictures.com/02culturepeople/sugarcane.shtml

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Production Statistics, Economics & Marketing

About 19.5 million ha are planted to sugarcane in the world each year. This is similar to the area planted to potatoes and sunflower. However, sugarcane is the leading crop in the world in terms of dry matter production. About 1273 million metric tons are produced annually, which is more than twice the weight of wheat grain produced.

FAO average production statistics for sugarcane, 2000-2002
Country Area Harv (Ha x 1,000) Production (Mt x 1,000)
Worldwide
19,514 1,272,864
Brazil 4,960 344,734
India 4,206 292,480
Cuba 1,080 35,467
China 1,075 76,514
Pakistan 990 45,993
Thailand 874 59,657
Mexico 640 45,808
Australia 419 33,884
USA 416 32,067
Colombia 401 34,783
Philippines 391 25,096
Indonesia 361 23,600
Viet Nam
334 16,314
South Africa 322 22,461
Argentina 267 15,333
Guatemala 182 16,807
Bangladesh 167 6,718
Cameroon
135 1,350
Venezuela 133 8,848
Myanmar 133 5,892
Egypt 132 15,661
Dominican Republic 125 4,600
Uganda 120 1,517

Sugarcane production in the USA

  • Florida - 52% of total crop
  • Louisiana - 34%
  • Hawaii - 11%
  • Texas - 3%

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Processing and Utilization of Sugarcane

Before sugar became an important food crop in the world, honey was the universal sweetener. Today, sugar is our cheapest energy source. The sugar in sugarcane is sucrose. A sucrose molecule consists of one molecule of glucose and one of fructose. Sucrose is not an essential food in our diet, yet we consume enormous amounts of it.

Sugarcane stalks are 85% juice. An average stalk will yield about 1/3 of a pound of sugar. The composition of the cane is 10.5 - 14% sugar.

Uses of sugarcane:

  • Cane sugar
  • cane syrup
  • molasses
  • wax
  • rum
  • preservative for fruits and meats
  • liqueur

Methods for processing sugarcane into sugar were developed in India around 400 BC. The stalks are cut at maturity and pressed to remove the juice. However, this juice does not store well. The juice must be boiled and allowed to thicken until the sugar crystallizes. Crystalline sugar stores well and can be readily transported.

Blackstrap molasses is the noncrystalline liquid that is left behind after as much of the sucrose as possible has been removed as crystals from the cane juice. Molasses consist mostly of glucose and is used primarily as animal feed, but it can also be fermented into rum. Bagasse is the cane refuse left over after sugar cane processing. It is used in the manufacture of paper, cardboard, and fuel.

Steps in the processing of sugarcane

  1. Cane handling: sampling, weighing, and washing
  2. Cane knives are used to cut the canes
  3. Milling to extract sugarcane juice, addition of water
  4. Heating and clarification
  5. Filtering
  6. Evaporation and concentration to produce syrup
  7. Crystallization in vacuum pans
  8. Centrifugation
  9. Drying and cooling
  10. Packaging, storage

See http://www.incauca.com/index.php?xlang=en&xskin=incauca&PHPSESSID=8092da3cf243e7e9632cf84f9doc3385 for more information and good photos of the steps in sugarcane processing.

Sugarcane as an energy source

Brazil is the leading producer of sugarcane in the world. In the late seventies, the Brazilian government introduced policies to promote production of alcohol from sugarcane for use as fuel. Sugarcane is processed in 128 ‘energy powerhouses'. These are mills and distilleries that process biomass from sugarcane: they produce sugar for use as a food, electric energy from bagasse burnt in their boilers, hydrated alcohol for use as a vehicle fuel and anhydrous alcohol to improve gasoline's energy and environmental performance. The program was quite successful, but has not received the same level of support from the government in recent years. To find out more about Brazil's alcohol program, read Sugarcane as an energy source in Brazil.

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Major Diseases & Insect Pests

See http://www.apsnet.org/online/slideset/sugrcane/ for images and descriptions of major diseases, pests, and nonnutrient disorders of sugarcane.

Diseases

Bacterial diseases

gumming disease - Xanthomonas vasculorum (Cobb) Dows. - yellowish stripes occur at the leaf tips and the vascular bundles exude a yellowish gum when cut

leaf scald - Xanthomonas albilineans (Ashby) Dows. - yellow stripes occur on the leaf blade, many side-shoots are produced, and the vascular bundles of the stalk are red

Fungal diseases

red rot - Colletotrichum falcatum Went - causes the setts to be seriously damaged at low temperatures.

root rot - Pythium graminicolum Subr. - responsible for the failure of "Otaheite" (a noble cane) in Mauritius in 1846

pineapple disease - Thielaviopsis parodoxa (de Seynes) C. Moreau - attacks the setts causing the center to turn black and smell like overripe pineapples

downy mildew - Sclerospora sacchari Miy

smut - Ustilago scitaminea Syd. - important in southeastern Asia and South Africa

Viral diseases

Mosaic - vectors include Aphis maidis Fitch; first recognized in Java in 1892; causes severe stunting in some cases

ratoon stunting

chlorotic streak

Fiji disease

Insect pests

stem-borers - the larvae burrow into the stem and cause loss of sucrose and weakened stems on emergence.

termites - India

white grubs - Queensland.

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Cultural Significance of the Sugarcane Industry

Sugarcane plantations

Sources:
http://www.hort.purdue.edu/newcrop/history/lecture34/lec34.html
http://www.ucalgary.ca/applied_history/tutor/eurvoya/Trade.html

The production of sugarcane and manufacturing of sugar requires large tracts of good land and access to specialized equipment. It is a fairly profitable business for those who are able to do it. Prior to the modern era, producing cane was a labor intensive undertaking. Mechanized harvesters became available in the 1950's.

When sugar was first introduced into Europe it was a luxury item, and the canes were used for chewing and medicinal purposes. It was only after 1700 that sugar was transformed from a luxury product into one that was used everyday by people from all walks of life. This took place as Brazil and the new West Indies colonies began producing sugar in such large quantities that the price was significantly reduced. Lower prices led to increased consumption, which, in turn, fueled demand.

The development of efficient roller mills for extracting juice from sugarcane in the 17th century was an important technical innovation for the sugar industry. The rollers could be turned by animal, water, or wind power. With this mill, it was no longer necessary to chop the stalks into pieces before processing.

Sugarcane was introduced to Madeira in 1432 and the Canary Islands in 1480 and was transported to the Hispaniola (the Island now consisting of the Dominican Republic and Haiti) by Columbus in 1493. Sugar plantations began to develop in the colonies in the early 1500s. The economies of Brazil, Cuba, Jamaica, Barbados and other places in the Caribbean became dominated by the production of sugar products. Sugarcane plantations marked the shift from agriculture as a way of obtaining food to a process for accumulating capital. Plantations possessed certain features that are hallmarks of modern commercial farms:

  • concentration on one crop
  • production to meet market demands
  • specialization
  • rationalization of production aimed at maximum capital yields

Negative aspects of plantation culture:

The development of sugarcane plantations led to reinvigoration of the slave trade as a source of labor, especially black slaves from Africa, resulting in the mass importation of Africans against their will into the New World.

Being a highly profitable enterprise, sugarcane plantations often displaced other farming systems once they were introduced. In Madeira, the Canary Islands, and São Tomé, it was possible to grow sugarcane year-round without irrigation. Yields were very high, and sugarcane rapidly displaced traditional crops on those islands.

Slavery has been abolished, but controversy surrounding the sugar industry continues. In the US the Friends of the Everglades advocates removal of sugar subsidies. In particular, they are concerned that the government's sugar price supports have led to rapid expansion of sugar plantations in the Florida Everglades, which has resulted in degradation of this important ecosystem. Representatives of the sugar industry in Florida believe that science can address many of these environmental concerns.

Large-scale production and processing of sugar can have undesirable effects on the environment in several ways:

  • provides an economic incentive that promotes deforestation
  • runoff of cane-washing water and the leaching of stillage may cause water contamination
  • sugarcane is burned in most countries were it is produced, which can pollute the air
    • preharvest burning promotes pest control and lowers harvesting costs
    • postharvest burning eliminates trashy residues and facilitates plowing and replanting.

Considerations for human health

Source: http://www.hort.purdue.edu/newcrop/history/lecture34/r_34-1.html

When we eat fruit containing about 10% fructose and 10% glucose, for example, the remaining dry matter must be digested before the sugars become available. When we consume pure white sucrose (table sugar), there is little digestion required, and energy is released in a sudden flood into our bloodstream, giving us a rapid, but short-lived burst of energy.

For people who consume large amounts of sugar, nearly the whole of the body's energy requirements are met by the sugar, and the rest of the food or drink consumed becomes merely a transport system for the sugar. Production of starch and fiber converting enzymes is inhibited once the body gets used to obtaining its sugar requirements directly from sucrose, so after a while the stomach finds it difficult to digest any accompanying starch or fiber. People will naturally avoid foods which they find hard to digest, so food manufacturers then reduce the fiber content in processed or packaged foods. A vicious cycle is created in which the victim becomes hooked on a constant flow of industrial sugar to the bloodstream while reducing intake of fiber. A diet high in fiber has many important health benefits.

The white sugar addict becomes prone to obesity, tooth decay, and malnutrition. Due to the speed with which white sugar becomes available for metabolism, the addict's blood sugar level rises and falls very rapidly and the pancreas works excessively hard to deal with high inputs of sucrose to the stomach. The body becomes used to a feast/famine syndrome in the blood sugar, and this produces an addiction which is chemical, not psychological. The bloodstream signals a deficiency, and the cycle is frequently repeated.

During the Renaissance, people consumed only about one teaspoon of sugar a day. Today, some people eat and/or drink over 4 pounds of sugar each week. Sugar is not necessary for any endeavor, but it is addictive. In effect, we have all become slaves to the sugar industry.

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Sugar Beets (Beta vulgaris)

Sugar beet is a member of the Chenopodiaceae (goosefoot) family. Other important crops in this family include table beets, swiss chard, and spinach.

Cane sugar and beet sugar are identical in chemistry and quality. Sugar beet provides about 38% of the world's sugar. It has C3 metabolism and is adapted to temperate climates, whereas sugarcane is grown primarily in the tropics and sub-tropics.

Sugar beet is a biennial plant that was developed in Europe in the 18th century from white fodder beets. In the first year it develops a large white succulent taproot filled with food reserves. In the second year it produces flowers and seeds. It requires both an exposure to cold temperatures (overwintering at 4-7 °C) and long days to initiate flowering. The roots are harvested for sugar at the end of the first growing season (after 5-6 months).

 

Photo by Scott Bauer
USDA/ARS

Sugar beet is cross pollinated by wind or insects and is strongly self-sterile through a self-incompatibility mechanism. The fruit is an aggregate that yields a seedball with two or more viable seeds. Fruits with one seed were discovered in 1948. This trait permits more precise planting and eliminates the need to thin stands after planting.

Use of beet sugar was initiated by the French when cane sugar was prevented from reaching Europe due to a British blockade during the Napoleonic wars of the 19th century. Beet sugar is produced in the United Sates and Europe but must be subsidized, as the plant is not as efficient as the tropical sugarcane.

For some nice images of sugar beet and a description of the sugar beet industry in Michigan, see http://www.michigan.gov/hal/0,1607,7-106-1751_18793-53367--,00.html.

The Ukraine, Russian Federation, and the USA grow the largest acreages of sugar beet. The leading producers of sugar beet are France, Germany, and the USA.

FAO average production statistics for sugar beet, 2000-2002
Country Area Harv (Ha x 1,000) Production (Mt x 1,000)
World
6,030 242,220
Ukraine 806 15,925
Russian Federation 746 14,153
USA 536 26,114
Germany 454 26,200
France 425 29,985
Turkey 393 16,051
China 378 10,175
Poland 319 12,099
Italy 238 11,392
Iran 175 4,744
UK 174 8,888
Spain 117 7,457
Netherlands 109 6,592
Belgium-Luxembourg 95 5,470

Disease, insect, and nematode pests can be very problematic for sugarbeet production. See http://www.beetseed.com/index.php for more information on these pests and available control strategies.

Uses of sugar beets

Human food

Sugar beets contain from 13 to 22% sucrose. The primary use of sugar beet is for sugar for human consumption.

High fiber dietary food additives are also manufactured from sugar beet pulp.

Animal feed

  • Sugar beet pulp and molasses (byproducts) are used as animal feed supplements
  • Beet tops (leaves and petioles) can be used as silage
    • good quality feed for cattle (slightly inferior to alfalfa hay)
    • dangerous for pigs, horses - too much oxalic acid

Industrial uses

Molasses by-products from sugar beet processing are used widely in the alcohol, pharmaceuticals, and bakers yeast industries.

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Assignments

Quiz

Take the quiz on this Unit on the Blackboard.

Additional Study (recommended)

Review the basic steps in the manufacturing of sugar from sugarcane as it is carried out at the INCAUCA sugar mill in Colombia:
http://www.incauca.com/index.php?xlang=en&xskin=incauca&PHPSESSID=8092da3cf243e7e9632cf84f9doc3385 tml

Read more about the history of the sugarcane industry and its cultural significance, particularly its connection to the slave trade:
http://www.hort.purdue.edu/newcrop/history/lecture34/lec34.html
http://www.hort.purdue.edu/newcrop/history/lecture34/r_34-1.html

References

American Phytopathological Society. 1999. Diseases, pests, and nonnutrient disorders of sugarcane.
http://www.apsnet.org/online/slideset/sugrcane/

Cattanach, A.W., A.G. Dexter, and E.S. Oplinger. 2000. Sugar beets. Alternative Field Crops Manual, University of Wisconsin Cooperative Extension Service.
http://www.hort.purdue.edu/newcrop/afcm/sugarbeet.html

Duke, J.A. 1983. Saccharum officinarum L. In Handbook of Energy Crops. unpublished.
http://www.hort.purdue.edu/newcrop/duke_energy/Saccharum_officinarum.html

Feldmann, P., A. D'Hont, E. Guiderdoni, L. Grivet, and J.-C. Glaszmann. 2001. Sugarcane. In A. Charrier, M. Jacquot, S. Hamon, and D. Nicolas (eds.) Tropical Plant Breeding. CIRAD, France.

Holly Hybrids. 2004. http://www.beetseed.com/index.php

Hunsigi, G. 1993. Production of sugarcane: theory and practice. Advanced Series in Agricultural Sciences. Springer-Verlag, Berlin, New York.

INCAUCA. 2003. Website for the INCAUCA sugar mills in Colombia.
http://www.incauca.com/index.php?xlang=en&xskin=incauca&PHPSESSID=8092da3cf243e7e9632cf84f9doc3385

Janick, J. 2002. History of Horticulture, Lecture 34: Horticulture, Politics, and World Affairs: Sugarcane and Plantation Agriculture. Purdue University.
http://www.hort.purdue.edu/newcrop/history/lecture34/lec34.html

Kiple, K.F., and K.C. Ornelas. 2000. Sugar. In The Cambridge World History of Food.
http://www.cup.org/Books/kiple/sugar.htm

Sharp, P. 1998. Sugar Cane: Past and Present. Ethnobotanical Leaflets.
http://www.siu.edu/~ebl/leaflets/sugar.htm

Solbrig, O.T. and D.J. Solbrig. 1994. So shall you reap: farming and crops in human affairs. Island Press, Washington, DC.

Sugar Knowledge International (SKIL). 2005. http://www.sucrose.com/home.html.

University of Florida Cooperative Extension Service. An overview of Florida sugarcane.
http://edis.ifas.ufl.edu/SC032

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