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Graminae
Common names
Sugar cane (general), shunkora (Ethiopia).
Description
Cane to 5 m, leaves broad. Panicle large, plumelike, tapering
from base to tip with silky spikelets. The sets, when planted, sends out
roots to nourish the growing shoot from the node and, beneath the surface
of the soil, the shoot forms a succession of very short joints; the buds
of these germinate in turn to give rise to secondary shoots to form a "stool"
below ground. These secondary shoots are fed by a further series of roots
to produce a root mass, spreading to a depth of 30 cm or more and laterally
for up to 1 m.
Distribution
First domesticated in India or Southeast Asia, now cultivated
extensively in tropics and subtropics throughout the world.
Altitude range
500-3 000 m.
Rainfall requirements
For economic sugar production an annual rainfall of 1 500 mm
is regarded as the minimum; in lower rainfall areas, the "noble" varieties
are irrigated.
Drought tolerance
It is fairly drought resistant, but production is low in drought
periods.
Soil requirements
It has a wide range of soil tolerance, but drainage is essential.
Heavy soils may be "bedded" to lift the soil level, and an open drainage
furrow provided every five to ten rows.
Land preparation for establishment
As the crop may occupy the ground for up to four years, thorough
land preparation is required. Deep ploughing and deep ripping should be
carried out and the final seed-bed prepared by disc cultivators.
Sowing methods
Sugar cane is propagated by burying whole stalks in furrows,
then chopping the stalks into at least two-node lengths in the furrow.
It can also be planted with a chopper-planter, cutting the stalk into two-node
lengths as it is fed into a planting chute. The setts are usually treated
with a fungicide as they are planted.
Sowing depth and cover
The setts are planted in furrows 25 cm deep, placed 1.3-1.4
m apart, and covered lightly with soil until "tillering" (stooling) has
progressed. Then the furrows are gradually filled by inter-row cultivation.
Sowing time and rate
Autumn and spring planting is common, at about 6 000-7 000
kg/ha.
Tolerance to herbicides
Herbicides are used widely to suppress weeds in sugar cane,
and are dealt with fully by Tilley (1977). See Phragmites australis, Themeda
quadrivalvis, Brachiaria subquadripara and Brachiaria mutica for application
information.
Vigour of growth and growth
rhythm
Sugar cane is a perennial. Growth is rapid in early summer,
and sugar production increases in autumn, though it may decline if frosted.
It matures in 12-14 months and is usually harvested then.
Response to defoliation
It is not usually grazed, the whole stalk being harvested at
maturity. It will then grow again from the roots and produce a succession
of ratoon crops, the number being dictated by the economics of retaining
the crop. When the old "stool" is reduced by subsoil ploughing, it will
give good regrowth after being shaved to ground level and fertilized.
Response to fire
Sugar cane is often burnt to ease harvesting. It is not killed,
and will sucker from nodes or regrow from the "stool" afterwards.
Dry-matter and green-matter
yields
At Grafton, New South Wales, cv. Pindar yielded 149 000 kg
green matter per hectare, and cv. 40 SN5819 produced 129 000 kg green matter
per hectare (Mead & Norman, 1950). In Brazil, Zuniga, Sykes and Gomide
(1967) recorded 69 900 kg and 66 200 kg DM/ha with two cultivars.
Suitability for hay and
silage
Silage has been made from sugar-cane tops in Queensland (Skerman,
1941), Argentina (Bragadin & Diaz, 1957), Puerto Rico (Vicente-Chandler
et al., 1953) and Taiwan. The silage is very low in crude protein (1.4
percent of the green matter) and is fed to cattle, with concentrates, as
low- quality, perennially-available roughage.
Value as a standover or
deferred feed
Sugar cane can stand in the field for several years and can
be used in emergency as low-quality roughage.
Cultivars
Numerous cultivars are bred for sugar production, disease resistance,
maturity, varying soils, dry conditions and flooding. They are available
in sugar- producing countries.
Optimum temperature for
growth
Tillering increases with temperature up to 30°C (van Dillewijn,
1952).
Minimum temperature for
growth
Stem elongation ceases at 18°C.
Frost tolerance
Sugar cane is susceptible to frost, the growing shoot and top
"eyes" (buds) being the first to die, but the buds from the lower nodes
may provide new growth, according to frost severity.
Latitudinal limits
30°N and S.
Response to light
Sugar cane will grow in shade, but sugar production is aimed
at the greatest use of incoming radiation to promote maximum photosynthesis.
Ability to compete with
weeds
Sugar-cane land has to have thorough pre- planting preparation,
inter-row tillage and herbicide treatment to suppress weeds until the cane
is "out of hand", when the dense shade from the canopy will control weeds.
Palatability
Sugar-cane stalks are quite palatable because of the sugar
content, but the high fibre makes chewing a slow process.
Response to photoperiod
It flowers in short and medium day lengths (Evans, Wardlaw
& Williams, 1964).
Chemical analysis and
digestibility
Where sugar cane is grown and harvested for sugar production,
the tops are usually fed green, chopped for stall feeding ("chop- chop")
or made into silage. Young sugar cane (two to three internodes) analysed
in the Philippines showed 79.8 percent moisture, 1.8 percent crude protein,
9.6 percent crude fibre, 1.9 percent sucrose (Azman, 1951). More recently
a product called "fith", consisting of de-rinded sugar-cane pith, has given
excellent results in livestock feeding. Sugar cane itself provides negligible
amounts of protein, and supplements are needed. Trials in the Caribbean
(Donefer, James & Laurie, 1973) have shown that freshly harvested and
processed sugar fith and cane tops (SF/CT) constituting 80 percent of the
cattle's dry-matter ration resulted in weight gains averaging 0.9 kg per
day during the traditional finishing period; additional energy supplementation
from molasses or maize significantly increased gains. Dairy trials have
indicated that SF/CT can constitute up to half of the total ration, replacing
energy-rich feeds as well as supplying a source of succulent forage. Digestibility
trials with sheep have indicated that a SF/protein supplement has a dry-matter
digestibility averaging 70 percent. The authors conclude:
"Based on an average sugar-cane yield of 88 t/ha for Barbados, a projected
annual live- weight gain per hectare would be 4 600 kg, with only protein/mineral
supplement supplied in addition to SF/CT. An assumed world average sugar-cane
yield of 50 t/ha could result in a 2 600 kg live-weight gain per hectare."
At Wollongbar, New South Wales, chopped ten-month-old sugar cane was
fed as a supplement to cows grazing nitrogen-fertilized Kikuyu grass pasture
(which is practically dormant during the winter). The sugar cane was very
low in protein, containing only 0.62 percent in the dry matter, and in
vitro digestibility was 52 percent. Milk production was 6.3 kg per cow
per day of 4 percent fat-corrected milk, compared with 9.7 kg with oats
and 9.6 kg with rye grass. Butterfat percentage was good at 4.9 percent
in the milk produced; protein content was 3.58 percent.
Natural habitat
Tropical rain forest. Cultivated.
Tolerance to flooding
Sugar cane will tolerate short floods, but, if approaching
maturity, it will become lodged and the sugar content will decline.
Fertilizer requirements
Soil tests are usually conducted in commercial sugar- growing
areas to determine these needs. There is usually a basic planting mixture
of complete NPK fertilizer, followed by side-dressings of nitrogen during
growth. In Hawaii "crop-logging", to decide fertilizer needs after planting,
is carried out by tissue-testing.
Genetics and reproduction
2n=60, 68, 80, 90 (Fedorov, 1974).
Seed production and harvesting
Seed production is controlled by ecological factors. "Arrowing"
(emergence of seed-heads) usually reduces the sugar yield, so the sugar
cane is generally harvested before this would occur. Cane breeders encourage
it artificially for cross-breeding purposes, and pollen can be deep frozen
for future use.
Economics
Sugar cane is one of the two main world sources of sugar for
domestic and industrial use. Its products, such as molasses and sugar-cane
tops, are available for livestock feeding and industrial use.
The nutritive value of sugar-cane molasses based on all
the sugar mills in Queensland, Australia, expressed as a percentage of
the dry matter, is shown in Table 15.62. Table 15.63 shows the analyses
in comparison with maize grain. Molasses is low in crude protein but supplies
a lot of energy. It is also low in fibre and so has a laxative effect on
cows if fed in large amounts. Protein, phosphorus, sodium and fibre should
be added to molasses when feeding.
Molasses will give on average 0.7 kg of milk per kg of grain fed,
and maize grain will give 1 kg. The maximum intake of molasses per cow
should be 3.6 kg per day. Milk production falls sharply when more than
25 percent of the dry- matter intake is molasses, that is, more than 4
kg per day.
Molasses may be used successfully for survival feeding of cattle
when roughage supplies are limited.
It is advisable to add 30 g of urea for each kilogram of molasses.
As a liquid, a suitable mixture is 80 percent molasses, 17 percent water
and 3 percent urea. The urea can be dissolved first in the water, which
makes the molasses easier to handle. Once the molasses has been mixed in,
care must be taken to avoid fermentation. Cattle should be introduced slowly
to this type of mixture; 1-2 kg per head for the first week, reaching full
strength by the third week. In 3.5 kg of the mix are 130 g of urea, the
required daily amount.
Further reading
Donefer, James & Laurie, 1973; King, Mungomery & Hughes,
1965.
Value for erosion control
Sugar cane can be used to hold soil and act as a wind- break,
but retention of small areas for this purpose would endanger disease- quarantine
efforts. For erosion or wind control, should be sown in rows on the contour.
Tolerance to salinity
Sugar cane gave maximum yields at ECe 1.8 mmhos/cm, 50 percent
of maximum at 10 mmhos/cm and nil at 18.7 mmhos/cm (Maas & Hoffman,
1976). In India, the varieties Co 75, Co 453, B 37172 and Co 1148 show
good tolerance to salinity (Yadav, 1975).
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