Sincere thanks are due to Dr. Harry F. Clements, Senior Plant Pathologist
at the University of Hawaii, for his written permission to include three
reprints of his investigations about "Crop Logging" in this text.
THE PRODUCTION OF SUGARCANE
F. le Grand, Associate professor for tropical crops
A contribution to the series of text books covering the field
of tropical agriculture. Prepared by the Department of Agronomy and
sponsored by the Center for Tropical Agriculture, University of
Florida, Gainesville, Florida.
International trade and consumption 7
The stem 13
The eye 26
The leaf 31
The root system 34
Elements of growth 40
Vegetative propagation 44
Breeding and selection 47
Chemical composition 63
Other elements 83
Foliar diagnosis 92
Factors affecting the growth of sugarcane 98
Recent developments in the crop-logging of sugar
cane phosphorus and calcium 138
Tissue analyses--the basis of crop logging and crop
Literature relating to crop logging of sugarcane 175
Insect and rodent pests 177
Diseases and disorders 186
Maturity testing of sugarcane growing on organic
soil of Florida 196
Payment regulations 207
Social aspects 217
Glossary of terms 224
This text will cover the growing of sugarcane for sugar, an important
commodity for numerous countries in the tropics. In general, growing sugar-
cane is rather easy as it is a deep rooting and sturdy plant. Growing
sugarcane for commercial sugar production, however, is difficult. With
the prevailing price structure and marketing arrangements for sugar, the
profit margin per unit produced is relatively small. It means that the
grower must obtain a high sugar yield per acre to remain competitive. To
optimize sugar production efficient application of modern agricultural
technology has become mandatory. This text will cover most of the aspects
of modern agricultural technology as applind to the production of sugarcane.
To aid in the understanding of the importance of sugarcane as a crop,
a historical review of its development will be presented.
Domesticated tropical sugarcanes were selected and grown for chewing
purposes by the people of the Malayan Archipelago. During the last part
of the 19th century and the first part of the 20th century, expeditions to
New Guinea in the Netherlands East Indies collected noble canes, varieties
of S. officinarum. Other domesticated canes were collected around Coimbatore
in Northern India. It is unknown whether these domesticated canes originated
from the same area. There is also a lack of unanimity among the geneticists
about the expression "noble canes". Originally, this expression simply
meant that forms of wild S. spontaneum were improved by hybridizing these
varieties with S. officinarum. In more recent literature, nobilization
generally implies the increase in chromosome numbers for hybrids. To avoid
confusion, the canes collected during those expeditions should be called
"native" instead of "noble". During the last expedition in 1928, S. robustum
was added to the collection of native canes.
The soft S. spontaneum was dispersed to Indonesia, the Philippines,
Indochina, and to the area around the Bay of Bengal. Noell Deerr reports
in his historical studies that sugar made from sugarcane was known to the
soldiers of Alexander the Great when they returned from an expedition to
Western India in 325 B.C. By 1768 Tahiti became an important supplier of
cane seed to the "sugar colonies" of the New World.
Sugar produced from cane is a non-perishable commodity, and was easily
transported by slow moving vessels between the colonies and the motherland.
The climatic and soil conditions of Indonesia and the Caribbean Islands are
ideally suited for sugarcane production. These areas became the sugar
suppliers for the major colonial powers of Europe, especially after the in-
troduction of slaves in the Caribbean provided a permanent labor force for
During the Napoleonic wars, Europe was blockaded by England, thus
severing the sugar supply from the colonies. Sugar produced from sugar-
beet (Beta Vulgaris L.) then replaced the sugar produced from cane.
After the end of the hostilities, sugar production from the beet continued
in the countries of central Europe. Due to less demand, the amount of
sugar produced from cane was consolidated in the colonies.
Sugar consumption per capital was still low because of the relatively
small annual income. Widespread industrialization at the turn of the 20th
century changed this income. Demand for sugar from the colonies increased.
In exchange for raw materials, food, and fiber commodities, the colonial
powers supplied machinery to their colonies. This exchange provided the
means to establish in these territories a large sugar industry working
efficiently and marketing sugar at a reasonable price. Java, the Philippine
Islands, Cuba, and the Caribbean Islands became the "sugar bowl" for
Europe and North America.
The Great Awakening
After World War II, most colonies obtained their independence. During
this process, the land -- formerly managed by efficiently working but
foreign-dominated sugar companies -- was either expropriated or severe re-
strictions were applied to the management of these holdings. A fast-
declining production followed. For instance, Java exported in excess of
one million tons of sugar annually prior to 1940. During the sixties this
country, now called Indonesia, was forced to import sugar.
A second result of independence was the creation of a national sugar
industry in areas which did not produce sugar prior to World War II. India
thus has become one of the largest sugar producers of the world in just a
few decades. Judging from the growing conditions, which are sometimes mar-
ginally suitable for sugarcane, it appears that a sugar industry is often
established in a developing country as a result of national pride.
The change of ownership for land was not the only cause for declining
sugar production in the Caribbean. Sugarcane production in this area often
is associated with former slavery and colonialism by the younger generation.
The annual harvesting of sugarcane is a back-breaking and dirty task.
thesee conditions, together with the social stigma attached to sugar pro-
duiction, have caused the decline of employment in the sugar industry by
the present generation. Having enjoyed a more advanced education than
their parents, these people are now able to find alternative employment in
tourism and other small-sized industries in the West Indies. To counter-
act this trend, the sugar industry in the developing countries is faced
with an increasing need for field mechanization.
Sugarcane will remain a very important agricultural commodity in the
future. On the average, this crop provides one of the highest yields per
acre in carbohydrates and this food is essential in the daily diet of man
and animal. The rapidly expanding world population calls for an ever-
increasing annual production of carbohydrates for its survival in the near
The developing countries in the Caribbean and Asia may play an im-
portant role in feeding this future world population by virtue of the pre-
vailing soil and climate conditions which are well suited for sugar pro-
Governments of these areas should realize that total field mech-
anization must be encouraged in the future, in spite of the social hardship
that this may temporarily cause, to remain competitive in sugar production.
A modern sugar factory, being in the category of a heavy industry, can
be considered as a training ground for establishing other and light in-
dustries in developing countries. Emphasis in developing countries should
be placed on a vocational-technical training to meet the future challenge
for total field mechanization in cane sugar production.
A shift from areas now important in sugar production to other areas
which are presently less important also may occur. Countries such as
Australia with excellent climatic and soil conditions for a high sugar
production per acre is sparsely populated, have already taken advantage
of total field mechanization. During the past decade Australia has become
an important producer, supplying sugar at a moderate cost to Japan in
exchange for needed industrial production. Such a trend may continue;
countries having idle land resources available and having favorable
climatic and soil conditions may become important suppliers of agricultural
commodities through the application of modern field mechanization and
agricultural technology. These food commodities will be exchanged for in-
dustrial production by countries which have a scarcity in land resources.
The importance of the sugar industry for the Caribbean or other areas
may diminish unless modern agricultural technology is maintained. The
basis on which this technology is founded will be covered in the various
chapters of the text.
1. Artschwager, E and E.W. Brandes, Sugarcane (Saccharum Officinarum L.),
Origin, Classification, Characteristics and Descriptions of Repre-
sentative Clones. USDA Agriculture Handbook No. 122, 1958.
2. Barnes, A.C. The Sugar Cane. Interscience Publishers, Inc., 1964.
International Trade and Consumption
The world population consumes more than 70 million tons of sugar
annually. Of this quantity about 70% is consumed domestically in the
producing countries. Twenty percent of this world production enters the
international trade and is sold to markets which grant some form of pre-
ference. The remaining 10% constitutes the so called "world market" or
England has arranged a quota system for its former Caribbean colonies
under which a substantial part of the annual sugar production can be sold
at a preferential price. Sugar produced by the French overseas provinces
is regarded as being grown in the motherland and receives the same price
advantage. Cuba, which practically had a monopoly to export sugar at a
preferential price into the United States during the past, now sells a
large portion of its annual production through barter rarngments to
the Iron Curtain countries.
The United States imports sugar at a preferential price from every
nation which has been granted a permanent import ouota by the Sugar Act.
Thirty-one nations are involved, among which are 20 areas on the South
American continent (Table 1). About 70% of the U.S. sugar consumption is
derived from sugarcane, whether grown domestically on the mainland, Hawaii
and Puerto Rico, or in foreign nations. A modern cane sugar refining in-
dustry has been established as a result. The remaining consumption is
derived from sugar-beets which produces a sugar quality directly suitable
The same price, based on the amount of raw sugar (970 polarization)
recoverable, is paid by the processor to the grower for his cane or beet
supply. In addition, the domestic grower receives a subsidy; this subsidy
is paid on a declining scale with increased sugar production per farm.
The federal government collects a tax on the refining of sugar, whether
from cane or beet, and partly distributes this revenue as a subsidy to
domestic growers. The subsidy is granted in exchange to the grower's
compliance with the regulations of the Sugar Act.
The Sugar Act requires the Secretary of Agriculture to estimate
during the last quarter of each year the sugar supply needed by the nation
for the following year. The Act further requires that the price for
sugar over the long period should relate to the Parity Index as the
average sugar price in 1957/59 did relate to the average parity index
of this period 1/.
The annual sugar consumption per capital in the United States remained
fairly constant during the past decades. Increase in the nation's annual
sugar consumption, therefore, is mainly caused by a larger population.
Hence, the once per year estimation of demand for sugar can be accurately
determined since short range population increase can be closely predicted.
1/ An index reflecting prices which farmers have to pay for production,
interest and taxes.
Holding the sugar price closely to the target price, which is relative
to the Parity Index is achieved with the help of the demand for sugar as
a known factor. When the sugar price remains below the target price for
a long period, the Department of Agriculture may revise and lower its
estimation for annual sugar consumption. As a result, less sugar will
be allowed for marketing and the price will eventually increase. The
reverse holds equally true. Persistent and large differentation between
the actual and target price for sugar will ultimately result in a change
in acreage quota for the domestic industry and a change in import quotas
for foreign suppliers. Small and temporary fluctuations in the sugar
price are corrected often by withholding or enlarging the quantity of
sugar allowed to be marketed during a specific period of the current year.
During the past, the Department of Agriculture has been remarkably
successful in maintaining the target price for sugar closely to the one
required by the Sugar Act. The system has provided an adequate sugar
supply at reasonable prices to the consumer, an orderly marketing for the
commodity, and reasonable returns to growers, domestic and foreign pro-
cessors, and refiners (Figures 1 and 2). The system was aided by the fact
that sugar was supplied by domestic industries and 31 foreign nations;
production deficits in the domestic areas are reallocated to foreign
countries while deficit in a particular foreign quota are assigned to
other foreign countries.
Only a few decades ago, two-thirds of all sugar sold in the United
States was used in the home kitchen while the rest was utilized by food
processors. Today only one-third enters the household kitchen and the
remainder is employed for curing hams, for the production of ketchup,
bread, and an infinite number of readily available food products. The
advent of convenience food products resulted in a major shift from con-
sumption in crystal form to the utilization of liquid sugar which product
is exclusively used by food processors.
As sugar is an important ingredient in many foods, the predictable
price has given stability to the production and price level of food
commodities. Hence, the price and supply stability as a result of the
Sugar Act has benefitted the consumer as well as the food processor in
general. It does not mean that sugar is provided at the lowest possible
price to the consumer.
Sugarcane and sugarbeet are subsidized crops in the United States.
The price of sugar is kept in accordance with a price level established
through the Parity Index, thus providing a fair return to the grower for
his funds and efforts expended. In addition, the federal government partly
returns to the grower the tax funds levied on refining of sugar as a sub-
sidy. Sugar is taxed by many nations when imported or refined. Unlike
the United States these nations utilize their revenue funds to provide
services to the population at large. Some persons claim that the price of
sugar in the United States could be lowered if all requirements would be
met by importation only. The nation now consumes close to 11 million
tons of sugar annually and total importation could disrupt the now constant
supply in times of international tensions.
The world produces about 70 million tons of sugar every year. The
United States, although only representing a fraction of the world's
population, annually consumes close to 11 million tons of sugar or about
17% of the world's total production. Such a phenomena can only be ex-
plained by the sugar consumption per capital.
Sugar consumption per capital appears to be closely related to the
per capital disposable income. It follows that sugar consumption per
capital in developing countries is lower than in the developed countries.
As an example, the approximate annual sugar consumption per capital in
Haiti and India is 25 and 30 pounds, respectively, while for the United
States and Sweden is about 110 pounds.
Sugar may be regarded as a basic food commodity; it is cheap and is
the purest form of carbohydrates available on the market. People with
low incomes will first satisfy their total food requirements with car-
bohydrates because of price. When income increases, the purchase of car-
bohydrates will only increase to a certain level after which a change in
purchase is made in favor of foods having a protein base. Hence, the
normal sugar consumption is around 100 pounds of sugar per capital per year
in developed countries, and this amount remains fairly stable.
The population, especially in the developing countries is increasing
at a compounded rate. At the same time, the disposable income in these
countries is increasing, although more slowly than in developed countries.
Both factors will cause an accelerated need for greater sugar production
to fulfill future demand.
Whether new and suitable land resources in the developing countries
are still available for sugar production is an unknown factor. The
greatest potential seems to be in the development of far superior sugar
yields from acreage already devoted to sugarcane production. A significant
yield increase, thus, is the challenge for developing countries during I
the next few decades.
1. A Background Discussion: The United States Sugar Act. Published
under the Sponsorship of 12 organizations, engaged in the production I
of beetsugar, cane sugar or refined sugar, not dated.
2. Special Study on Sugar; A Report of the Special Study Group on Sugar
of the U.S. Department of Agriculture. Committee print of 87th
Congress, Ist Session. U.S. Printing Office, Washington D.C., 1961.
The stem is economically the most important part of the sugarcane
plant. The root and leaf systems are responsible for the uptake of
nutrients and photosynthesis, respectively. The stem is the end result
of these processes; it is the plant part to be harvested for sugar.
Hence, tonnage harvested, together with the stored concentration of
sugar formed by photosynthesis, determines the sugar yield obtained per
cultivated unit. A second major function of the stem is to provide the
planting material for asexual propagation.
The stem usually is tapering toward the bottom and top; maximum
stem elongation occurs when optimum climatic and other conditions prevail.
The bottom nodes are below the soil surface and gradually extend into
the root system. This part is high in sucrose content. The sucrose con-
tent in each successive joint declines towards the top of the stalk.
The average length and diameter of internodes is a varietal characteristic
but also depends on the prevailing growth environment. Conditions adverse
to optimum growth such as deficiency in nutrients, moisture, and low
temperatures, will cause short internodes and will reduce cane tonnage
at harvest. The position of the dwarfed internodes on a stalk is an in-
dication of the time when adverse growing conditions prevailed. Even under
optimum conditions, the elongation rate for internodes increases with
age till a maximum has been reached, after which further elongation de-
Depending on the photoperiod, the top part of the stem will change
from a vegetative to a reproductive stage. The growing point will cease
its vegetative development in favor of an inflorescence. Later, when
vegetative growth resumes, a certain number of nodes will be void of eyes.
The varietal characteristic of excessive flowering, therefore, is un-
desirable; specifically because the top part of the stem is used in many
countries as planting material since this part is of little value for
commercial processing due to its low sugar content.
The external color of the stem may vary as a varietal characteristic.
The observed color is caused by two basic pigments: Anthocyanin, a red
pigment predominant in the epidermal cells, and chlorophyll located in
the interior tissues. The intensity of color depends on the amount
of exposed sunshine and the altitude at which the cane is grown. It
follows that the coloration of the stems even within the same stool may
be different. Both pigments are extracted with the juice and are diffi-
cult to remove during juice clarification.
The entire stem, with the exception of the growth rings, is covered
by a wax layer. The thickness of this layer varies with the variety and
the color ranges from white to black. The latter color is caused by a
fungus. Numerous attempts have been made to recover this wax for commercial
sale. The present process in uneconomical; the type of wax recovered
after refining resembles carnauga wax which is often used in the production
of shoe polish and varnish. The interest in the economical recovery of
cane wax was greatly reduced with the discovery of synthetic waxes.
Longitudinal cracks sometimes appear in the outer tissues of the
internode. They are caused by a fast rate of growth, and appear when
growing conditions are very favorable. Moreover, some varieties are
more susceptible to the formation of cracks than others. The formation
of cracks is an undesirable characteristic since each opening forms
an entrance into the stalk for undesirable organisms.
The stem, in cross section, may vary in color, especially at the
internodes. This color may range from brown to green; the intensity
depends on the variety, and is caused by rapid action of oxidases. Hence,
an observed discoloration may be natural and not necessarily exhibit
a disease symptom.
A root band is located at the base of each internode. This band
is bordered by a growth ring on the top and scar tissue on the bottom.
The growth ring identifies the region of cell division and enlargement
which contributes to internode elongation. Auxins often cause the under-
side of a stalk to elongate more rapidly when in a horizontal position,
thereby causing a more erect position of the terminal internodes. This
characteristic is especially important for lodged cane, and enables the
stalk to "straighten" after wind damage. The root band also contains
several rows of root primordia, its number depending on the variety
employed. The largest root primordia are located on the upper part of
the band; the small ones located near the lower part are the most vigorous
ones and develop rapidly when the internode is planted.
In examining a cross section of the stem, three main layers of
tissue can be observed:
2. Rind (or cortex)
3. Vascular bundles which are embedded in soft tissue.
The epidermis consists of two major cell types; the so-called long
cells and short cells. The short cells are differentiated into cork
cells and silica cells. Relatively few stomata are located in the
The rind consists of several layers of cells, being mainly sclerenchymatous
(lign ified fiber cells), which give support to the stem. Some of the cell
layers contain red anthocyaninn) and green (chlorphyll) pigments.
The vascular bundles consist of a sclerenchymatous sheath which
encloses the xylem and phloem. A ground tissue is composed of thin-
walled parenchematic cells in which the bundles are embedded. The soft,
less lignified cells of the ground tissue are known in the trade as the
"pith" fraction of bagasse.
From the foregoing description some interesting conclusions may be
1. The wax layer greatly reduces the loss of moisture after the
stalk has been harvested and therefore preserves the quality
of cane for processing. On the other hand, the wax layer enters
the processing and is difficult to remove during juice clarification.
The remaining wax adheres to the raw sugar crystal and forms
a significant obstacle for refining. For this reason, the
wax layer should be removed from the cane prior to milling in
order to prevent this material from entering the clarification
2. The epidermis fraction is detrimental to sugar recovery. The
crushed cells absorb sucrose containing liquid during milling
and will actually reduce sugar recovery from cane. Moreover,
the inherent colors are difficult to remove during clarification
and form a nuisance for refining. The epidermis should there-
fore be discarded before cane is allowed to enter processing.
The rind fraction consists largely of lignified cells which give
the stalk its upright support. Sugar concentration in these cells is
low. Moreover, the purity of the juice extracted from these cells is
inferior, making undesirable the mixing of this juice with the one ob-
tained from the ground tissue having a much higher purity. The lignified
rind cells are valuable for further processing of fibrous by-products.
The quality of juice recovered from the ground tissue is excellent.
In contrast to the rind cells, the cells of the ground tissue are thin-
walled. These "pith" cells adversely interfere with the further pro-
cessing of bagasse.
Presently, cane is regarded as a major source for carbohydrates only.
On the average, this plant contains equal quantities of sucrose and fiber.
The latter is occasionally used for the production of paper or construction
board. The production of these commodities in the tropics is only
economically warranted when measures are taken to prevent the marketing
of similar materials produced at a lower cost elsewhere.
Bagasse as a raw material for paper making is expensive mainly
because the "pith" cells have to be separated from the vascular bundles
and the rind tissue. This separation process is cumbersome and only
partly effective, causing the chemical consumption for paper making
to be high and subsequently the cost of paper production from bagasse.
Annual requirements for paper and suitable building materials will
sharply increase in the developing countries during the next few decades.
The world's potential of 70 million tons of fiber per year is presently
wasted. Such a valuable resource may only be utilized effectively in the
future when the method of cane processing can he changed.
Sugar extraction from cane by milling has basically changed little
through past centuries. In the future, a new method for extraction should
be found to remove the wax and epidermis layers and to separate the rind
from the ground tissue fraction of cane prior to juice extraction. Total
sugar recovery from cane should be greater when these fractions are ex-
tracted separately. At the same time, the major portion of the "pith"
cells are kept separate from the lignified cells, thus making the portion
of bagasse derived from the rind more suitable for further processing.
Two challenges, therefore, are apparent for the future. First, an
increase in sugar yield per acre is needed in order to satisfy the demand
for carbohydrates by the ever increasing world population. Secondly, the
present method of juice extraction should be modified in such a manner
that the fiber resource from cane can readily be utilized for the economic
production of paper and building products. Succeeding with both challenges
will mean the maximum utilization of the sugarcane resource for the
benefit of mankind.
1. Barnes, A.C. The Sugar Cane. Interscience Publishers, Inc., 1964.
2. Dillewijn, C. van. Botany of Sugarcane. The Chronica Botanica Co:
Book Department, 1952.
The number of stalks or tillers formed by a particular cane stool
is primarily a varietal characteristic. Varieties producing stalks
with a large diameter generally produce less tillers per stool while
wild canes with a small diameter will tiller profusely. Hence, the
parentage of a variety will affect its tillering pattern.
In addition to being a varietal characteristic, tillering also
will be influenced by prevailing environmental conditions such as
altitude, light intensity, day length, temperature, nutrients, and
moisture. Varieties are mostly bred and selected for commercial pro-
duction in a certain area. When grown in other areas, the growth
characteristics often may be different. Varieties which tiller pro-
fusely in the original area may tiller sparsely in other areas.
Tillering is important because the number of stalks per stool
contributes to the final sugar yield per acre. Sugar yield is a
function of sucrose content in cane and tonnage per acre. In turn,
the latter is the result of several independent factors such as number
of tillers per stool, average diameter and length of internodes, and
the number of internodes suitable for processing. The sugar content
in cane depends on varietal characteristic, prevailing climatic and
soil conditions, and the average maturity of the stalk population.
Growers often believe that dense planting within the rows and narrow
inter-row spacings will produce a maximum of tillers, and consequently
tonnage per acre at harvesting. Early research in Java has proven that
such an assumption is not necessarily true.
Light intensity is a major factor governing tillering. Tillers
will be formed until light intensity accordingly becomes a limiting
factor; the cane crop is called "closed in" at that time. No new tillers
are normally formed after this period. Hence, an acre can support a
fixed number of cane stalks, the magnitude depending on the variety em-
After the crop has "closed in", the existing stalks should be
allowed to elongate until maturity. Lodging of the cane will admit
additional light, and as a result will promote the formation of new
tillers. Tillers formed when the original stalks are already six months
or older are often called "water shoots" or "suckers". These late tillered
stalks are low in sucrose content when the original tillers are ready
for harvest, therefore, they can considerably lower the average sucrose
content for the crop.
As the number of stalks per acre is determined for each variety,
the grower should space the distance between rows so that the crop will
"close in" in about three months of a 12-month growing cycle. Likewise,
the tonnage of planting material employed should be such that no empty
spaces of more than two feet between stools within the row will occur.
Allowance for reduction in cane stand by insects, diseases and adverse
weather conditions should be made, therefore, when determining the
quantity of planting material needed, whether it be cane tops or stalks.
Normally 2 to 2L tons of planting material will achieve a uniform cane
stand within the rows and "closing in" of the crop at three months.
Rows 4- feet to 6 feet apart are commonly employed to obtain the
required stalk population. Experimentation in most parts of the world
has revealed that harvested cane tonnage is the same whether cane was
planted in rows 4- or 6 feet apart. This discovery is not surprising,
taking into account the foregoing explanation. With narrow rows, the
actual number of tillers present at the time of "closing in" will
exceed the optimum number which can be harvested. The excess of tillers,
therefore, will perish between the periods of "closing in" and harvesting
of the crop.
Temperature, together with available light and nutrients, are the
most important factors that govern tillering. For sub-tropical areas
such as Florida, temperature will significantly influence the formation
of tillers. With increase in temperature, the formation of tillers
also will gradually increase until a maximum is reached at about 300C.
Light-covering of the cane cuttings with soil after planting will pro-
mote tillering in these areas during winter.
Nitrogen, followed by phosphorus are the most important nutrients in
promoting tillering of sugarcane. The effect of phosphorus is apparent
only on soils which are deficient in phosphorus, while nitrogen applied
to mineral soils commonly stimulate profuse tillering, regardless of the
original nitrogen content of the soil.
Earthing up of the seed pieces is possibly the most effective tool
to control tillering./ The tillering of the plant crop is promoted by a
light soil cover over the seed piece. Under these conditions, new
tillers are quickly exposed to light.
Subsequent tillering can be governed by the timing and the degree
of additional soil applications. Small and infrequent soil applications
will continue to promote tillering, while heavy or frequent soil
applications will delay tillering. Excessive tillering should not be
allowed. As a rule, tillers to equal twice the number of stalks which
are present at harvest are desirable as an optimum cane stand.
Spacing between the rows and soil applications to cane in the rows,
therefore, are the most important variables affecting tillering, pro-
viding that no "gaps" are present within the row. Presently, the
variability in spacing between rows is limited by the need for mechanical
or chemical weed operations. To accommodate the machinery, a minimum of
5 feet, and preferably 6 feet between rows is recommended. This arrange-
ment leaves soil applications to cane as the only variable to control
tillering. Initial removal of soil from the space between rows should
be made as near as possible to the small cane plant as to avoid dis-
turbance of the root system. Also, the timing of split fertilizer applications
should coincide with earthing up in order to achieve optimum placement
2/ Earthing up, a commonly used term among sugarcane growers, means
the removal of soil from the inter-row spacing and the placing of
this soil on the cane stools in the row.
of fertilizers for growth of tillers. In this manner cultivation
practices can be combined into one operation to reduce cost. The
formation of a shallow furrow between rows should facilitate drainage
and later mechanical operations such as weeding and possibly harvesting.
The fact was mentioned that the ultimate number of permanent
stalks per unit of surface is fixed within fairly narrow limits for
each variety. Also, that under the same climate conditions, the final
cane tonnage at harvest is about the same, regardless of the amount
of cane planted per unit of row length or the distance between rows.
If so, why are soil applications necessary?
After planting, the sprouted eye will develop ultimately into the
so-called primary shoot which in turn, also carries eyes. When these
eyes sprout, secondary shoots will be formed. This process continues,
but each subsequent phase will originate closer to the soil surface.
Hence, for ridged anchoring of the stools and to reduce later "lodging"
of stalks, an effort should be made to allow the survival of primary,
secondary, and tertiary tillers only. The method of adding timed soil
applications to the row will achieve such a control.
The distance between rows and the quantity of planting material
used within the row are variables in planting of the crop. In contrast,
these variables are fixed for ratoon crops. The stools in ratoon
crops may expand in diameter, and thus compensate for a wide-spacing
between or within rows, by developing the desired number of stalks
per unit of surface area.
As in the plant crop, soil applications to ratoon crops are used
to limit the tillering to the formation of primary, secondary and
tertiary shoots only. Otherwise, the cane stool in a subsequent ratoon
will originate substantially nearer to the soil surface than the stool
grown during the previous crop. After a few years, the stools in the
ratoon appear to grow out of the soil. Failure to properly time and
supply soil applications to the cane, therefore, may limit the number
of ratoon crops which can be obtained economically.
Dillewijn, C. van. Botany of Sugarcane. The Chronica Botanica, 1952.
The eye is a bud containing a small stem with leaves. The outer
leaves of this miniature stalk consist of scales. These scales contain
hair groups which shape is used as a reliable indicator in variety
identification. Also, the shape of the eye and the manner of implant
on the stalk serve as additional means for differentiation among varieties.
The eye is located in the rootband of the stalk, each node normally
contains one eye. Sometimes double or even triple eyes occur either
together enclosed or singly adjacent to each other. The characteristic
of multiple eyes usually is not permanent; multiple eyes may change into
singular ones during the next crop generation.
Germination is the development of the organs already present in an
embryonic stage. The rate and speed of germination not only depend on
climatic factors such as prevailing temperature or available moisture, but
also on the presence of growth regulators (auxins) and the metabolism
of different food compounds.
Went performed basic research on germination of cane at the turn
of the century. He found protein and starch present in meristematic
areas of the plant. In parts undergoing cell elongation (growth), glu-
cose was prevalent with starch and protein absent. These findings serve
as the basis for the modern diagnostic techniques.
Producers rarely grow cane specifically for seedcane production.
Seedcane is more likely chosen at random from commercial fields or from
abandoned fields. Experiments with seedcane have shown that germination
of seedcane markedly improves by heavy applications of nitrogen to
standing cane or even by placement of nitrogen within the seedpiece.
Also, soaking of seedpieces overnight in lime water or even plain water
has also been found to improve the speed and rate of germination. This
treatment may possibly have an effect on the metabolism and compounds
present within the seedpiece.
The eyes located near the base of the stalk are the oldest. The
factors which mainly influence the germination of these eyes are moisture,
nutrients, and growth regulating auxins. Nitrogen, moisture, and glu-
cose content in the stalks decrease with increasing distances from the
top while the reverse is true for the sucrose content. Starch formation
is the next step after invert sugars, and the highest concentration of
starch together with protein can be expected in the top part of the stalk.
This is one of the reasons why the eyes located in this stalk section
will easily germinate.
The eyes on a standing stalk normally remain dormant as long as the
growing point is intact. This phenomenon is called apical dominance.
The eyes nearest to the top of the stalk germinate when the growing point
is either removed or inactivated by insect or frost injury. These side
shoots, forming a kind of fan-like growth pattern, take over the function
of the growing point. In turn these shoots exert apical dominance over
the eyes lower on the stalk.
Apical dominance has an important effect on the stalk when used
as planting material. Only the topmost eyes germinate readily. The
germination of the eyes placed lower on the stalk will be delayed to
such an extent that they are an easy target for insect damage or bac-
terial rot. To secure an even cane stand, the cane stalk in the row
should be cut into lengths of two nodes each to eliminate the effect
of apical dominance on germination rate.
Cane elongation, root development and eye inhibition (apical)
dominance) are functions originating from growth-regulating sub-
stances. Two of these functions can be demonstrated as follows:
A section of cane stalk, consisting of a root band and one eye with
a length of internode left intact on both sides, is placed in a
vertical position. The growth ring will elongate and the roots will
develop when a mixture of heteroauxin (betaindoleacetic acid) and
lanolin is applied to the lower cut. Likewise, the roots will develop
on one side and the growth ring will only elongate on that side when
this mixture is applied to only half of the cut surface.
Elongation of the growth ring on one side will also take place when
the cane cutting is placed horizontally in the plant furrow, exposed
to climatic conditions without covering with soil. Only the roots in
contact with the soil surface develop while elongation at the growth
ring will take place at the lower side, causing the cane cutting to
This curvature is very pronounced when whole stalks are used for
planting, causing both ends of the stalk to protrude above the soil
surface, even if this stalk is covered with soil at planting. There-
fore, cane should be planted in two-node lengths, not only to reduce
eye inhibition from apical dominance but also to avoid poor germination
from curvature. Planting of two eye cuttings will assure an even cane
stand while allowing for the possibility of loss of one eye. Cane tops,
discarded as having little value for sugar production at harvesting
time, can thus be made an excellent source for planting material.
At planting the seed material is subjected to rough handling. Eyes
are easily damaged resulting in an erratic cane stand during successive
years. For this reason the leaf sheaths, serving as a protective shield
for the eye, are left on the stalk. A leaf sheath which fits tightly
around the stalk can be regarded as a favorable characteristic for the
planting operation. In contrast, a leaf sheath is difficult to remove
from the stalk, even when burned prior to harvesting. These sheaths
increase the trash content in harvested cane, an undesirable characteristic
for commercial sugar production.
Most cane fields are burned prior to harvesting. The eyes of the
top part of the stalk, being well protected by the green leaf sheaths,
are not damaged by this quickly passing fire. When used as planting
material, the eyes of the top part will germinate faster after cane
burning than the eyes which were not subjected to this burning process.
The reason for this is still unknown.
Cane grown in the sub-tropics is sometimes subjected to freezing
temperatures which damage and even kill the eyes. Eyes are often
discolored when exposed to low temperatures. When cut diagonally, the
presence of the black and round discoloration inside the eye does not
signal the killing of the eye; these eyes produce a normal cane stand
after planting. Only eyes which are soft when touched must be re-
garded as having been killed by low temperatures.
Dillewijn, C. van. Botany of Sugarcane. The Chronica Botanica, 1952.
Artschwager E. and E.W. Brandes. Sugarcane (Saccharum Officinarum L.)
USDA Agricultural Handbook 122, 1958.
The leaf is truly the sugar factory. The building, widely referred
to as the sugar mill, is only an extraction plant processing the sugar-
bearing juice which yields raw sugar as final product. The sugars first
formulated by photosynthesis in the cane leaf are translocated to the
stalk and are either used for additional growth or temporarily stored.
These stored sugars will be utilized by the plant, if not harvested,
when favorable climatic conditions for further growth prevail.
The young leaves are located at the top and near the growing
point and are utilized for diagnostic purposes. Any deficiencies pre-
sent in these leaf blades and sheaths will be reflected in a reduced
rate of growth.
The leaves are alternately attached to the stalk. Each leaf
consists of a blade, the dewlap and liguie with the auricle, and the
sheath with its base. The leaves are small when the plant is young
and grow to a maximum length of 3 feet or more as the plant grows older.
Each stalk carries about 10 leaves after the crop has closed in. New
and small leaves formed in the plant top will replace the older leaves
below renovating the leaf surface while the stalk continues to elongate.
The width and length of the leaf, as well as the total active leaf
surface per plant, vary according to variety and prevailing climatic
conditions. No relationship has been found between the total active
leaf surface per plant and sugar content of the cane stalk. The total
green leaf surface of the cane crop equals about seven times the area
of soil surface utilized.
The blade is divided lengthwise with one distinctive midrib. The
sheath is broadest at the base and gradually tapers towards the tip.
The sheath envelopes the internode and often is covered with hair.
The blade and sheath join at a collar called the dewlap. The shape
of this dewlap helps to identify specific varieties. Also, the
position of the auricles and shape of the hair groups serve this pur-
Only the sheath, leaf, and dewlap can be distinguished in fully
developed leaves. Hence, only the leaf blade and often only partly
can be noticed on the young leaves while the sheath and dewlap are
still concealed within the "spindle", the embryonic part of the plant
The blade and sheath will desiccate after the leaf matures. Finally
the leaf will fall, revealing a scar on the stalk where the sheath was
formerly attached. Often the dried sheath still envelopes the internode
after the blade from the sheath severs at the dewlap. Burning of cane
prior to harvesting only partly removes the dried sheaths, and the re-
maining part clings to the stalk as it enters the processing plant.
These sheath particles have a detrimental effect on sugar recovery from
cane. Therefore, self-shedding varieties, which drop their dried leaves
to the soil surface are preferable for high sugar recovery.
Finally the leaf blades can be used for visible diagnostic purposes.
Especially the fully developed leaves of the spindle tend to reveal
symptoms of any existing nutritional imbalance or of certain diseases
which may be present.
Dillewijn, C. van. Botany of Sugarcane. The Chronica Botanica, 1952.
The Root System
The root system performs two principal functions. First, it is
responsible for the uptake of moisture and nutrients. This uptake in
turn results either in growth or maturity processes, depending on the
prevailing moisture supply or temperature at a specific time period.
Secondly, the root system anchors the plant so that the leaf sur-
face can be exposed to maximum light intensity for optimum photo-
synthesis. This photosynthesis produces energy to be used in either
growth or sucrose accumulation. Hence, in the root system one may
distinguish two main types of roots: ones which have as primary
function the feeding of the plant and those roots which are principally
used to anchor the plant.
The root system has been extensively examined by growing cane in
boxes which contained wire netting stretched at different heights.
These boxes were buried in the soil and planted with cane. Later the
boxes were recovered and the soil adhering to the root system was care-
fully washed away leaving the root layers intact and supported by the
wire netting. The deep, penetrating roots, especially those important
for anchoring, were studied by careful excavations.
These studies revealed that 80 percent of the root system is lo-
cated in the first foot below the soil surface. This portion of the
root system serves mainly as feeder roots to the plant. The rest,
acting as anchor roots, may extend more than 10 feet below the soil
surface with the majority of these anchor roots located in the first
five feet below the soil surface.
Horizontally, the feeder root system extends nearly 10 feet, with
the greatest concentration within the first three feet from the plant.
With the cane rows 5-6 feet apart, the entire interrow space is solidly
penetrated with feeder roots. For this reason, fertilizers applied
to the subsoil in young cane fields should be placed in the center of
the interrow to avoid extensive injury to the root system.
The study also has indicated the desired depth of the free water
table. As feeder roots need adequate oxygen for proper functioning
and as the feeder roots are concentrated in the first foot below the
surface, it follows that the free water table should be kept below
Optimum depth of the free water table for cane has been a con-
troversial topic in areas like the Florida Everglades where this water
table can be controlled. Studies and practical experience suggest
that a constant, non-fluctuating free water table between one and two
feet below the soil surface is more important than the exact depth of
this water table.
A fluctuating water table will actually create conditions of pruning
off or new formation of the feeder root system. In areas with heavy
clay, as in Guyana, the topsoil layer becomes waterlogged by the rains
after a dry season. The sugarcane reacts by the leaves turning pale
green, a condition often associated with nitrogen starvation. The pale
color will disappear after water recedes without the need for artificial
correction, but the period of stress is permanently characterized by
shorter internodes formed during this time.
Most likely, the root system is pruned off during the time of water-
logging of the topsoil causing reduced uptake of elements. The formation
of new feeder roots corrected this imbalance during the period after which
no severe waterlogging took place. The free water table, therefore,
should be kept constant at a depth between 1l and 2 feet below the soil
surface by irrigation and drainage as needed.
When the free water table is maintained at a constant depth ranging
between 1' and 2 feet from the soil surface, the feeder root system,
concentrated in the first foot, must obtain its moisture requirement
through soil capillary action. This moisture supply is easily obtained
in soils containing a heavy loam or clay fraction and in organic soils.
To reduce surface evaporation and to increase the availability of this
moisture resource, shallow mechanical interrow cultivation should be com-
bined with chemical weed control.
The cane plant originated in the tropics on the banks of rivers
where it was frequently subjected to flooding. The rate of transpiration
by cane is low after planting, but increases rapidly until a maximum is
reached after six months. The relative transpiration (the ratio of
transpiration to evaporation) was measured by a Piche evaporimeter and
amounted to 0.36 for humid exposure and 0.19 for dry exposure, both expressed
in grams of water per square centimeter and per day for variety Co. 421.
Other investigations revealed that a 7-month old cane plant transpired
550 grams of water per day and addition of water immediately increased
this amount to nearly 1300 grams per day. It follows that the water
requirement for the feeder root system of cane may be in excess of 20
tons of water per day and per acre. This confirms the practical obser-
vation by the grower that an abundance of water is beneficial in obtain-
ing maximum cane tonnage.
Another expression by the grower is that "the cane crop can stand
wet feet". Indeed, cane will survive when subjected to prolonged flood-
ing, as is sometimes true when flood-fallow is practiced prior to re-
It is not surprising, therefore, that the anchor root system can
extend to a depth of 10 feet or more, and well below the free water
table. It appears that the cane plant has the ability to translocate
oxygen within its system. This may be the reason why the anchor roots
can survive under hostile conditions.
The deeply penetrating anchor roots are needed to support the portion
of the cane plant above the ground which often exceeds 12 feet in height
at the time of harvesting. A poorly developed root system will cause the
cane plant to topple. This is especially true for areas which are sub-
jected to damage by hurricanes and which grow cane in soil types of a
loose consistency like the organic soils of the Everglades region in Florida.
Finally some general remarks about the root system in ratoon crops.
When a new crop cycle is started, the root system develops from the root
primordia present in the growth ring of the planted cane cutting. When
this crop is harvested, the stubble (the part of the stool located in
the soil), if left in place, acts as the planting material for the
successive crop. The existing root system will perish and is completely
immobilized about three months after the previous crop. An entirely
new root system will take its place, originating from the root primordia
which are present in the stubble. Hence, every successive ratoon crop
will produce its own root system.
The yearly renovation of the root system provides important quantities
of organic matter to the soil. In the tropics the same fields are utilized
for cane production year after year without an appreciable change in
organic matter of the soil during the past century. The root and stubble
system represent nearly 17 percent of the total vegetative composition
of cane. Only 49 percent of the total vegetative crop is removed from
the field in the form of cane stalks to be processed. With a yield of
40 tons per acre a year of millable cane, about 20 tons per acre of
vegetative material is returned to the soil each year in the form of
roots, trash and tops. The root system and stubble play an important
role in recycling organic matter to the soil, which is especially impor-
tant in tropical areas.
Evans H. The Root System of Sugarcane 1. Methods of Study. Emp. Jour.
Exp. Agric. 3, 1935.
Negi, O.P. et all. Root Studies of Outstanding Sugarcane Varieties
of Bihar, India. Proc. of the I.S.S.C.T., Louisiana (in press), 1971.
Exner, B. Anatomy of the Branch Roots of Sugarcane, Proc. of the
I.S.S.C.T., Louisiana (in press), 1971.
Elements of Growth
The main function performed by the root system is to supply the
cane plant with nutrients and moisture, necessary for growth (the
formation of cane tonnage). In contrast, ripening of the cane calls
for partly inactivation of nutrient and moisture uptake through the
root system. During this period the energy from photosynthesis is stored
instead being utilized for further growth.
The root does not respond chemotropically to fertilizers (the
change in direction of root growth to locations where heavy con-
centrations of nutrients are present). The root system, however, is
able to vigorously branch out in locations with heavy concentrations
of nitrogen and potassium, thus, facilitating the uptake of these elements.
The ability of feeder roots to branch has important implications
for soil applications of nitrogen and potassium. A small application
should be given at planting time and placed in the furrow prior to
planting, followed by other split applications drilled into the topsoil
anywhere in the space between rows. Chances that a root will penetrate
the fertilized area are nearly guaranteed, while a rapid uptake of these
elements takes place by the subsequent branching of feeder roots. There-
fore, placement of nitrogen and potassium to accommodate the root system
is of minor importance.
Unfortunately, the same rule does not apply to the uptake of phos-
phorus. A heavy concentration of phosphorus does not stimulate branching
of feeder roots. The cane plant is able to secure an adequate supply
of this element only when as many as possible roots penetrate the phos-
phorus-containing area. It follows then that phosphorus should be applied
in a relatively wide band at a location having the greatest potential for
Experiments in Hawaii with radioactive P32 have revealed that only
a fraction of the required phosphorus is taken up by the cane plant
when applied as a top dressing. A somewhat greater quantity is utilized
when this element is applied as a side dressing. The major part of applied
phosphorus, however, was taken up when phosphorus was applied underneath
The discovery is in accordance with the fact that greatest root
penetration at random takes place just below the plant. Phosphorus is
relatively immobile and does not readily move to deeper placed soil
layers; the cane receives its greatest benefit from a phosphorus application
when this element is applied in a wide band at the bottom of the furrow
prior to planting. As cane can be regarded as a perennial crop, place-
ment for optimum uptake by the root system can only be achieved once
per cycle, and the entire dosage of phosphorus for the plant crop as well
as all subsequent ratoon crops should be applied in bottom of the furrow
prior to planting.
Growth includes the process of cell elongation which is also associated
with the intake of moisture. Therefore, a close relationship should
exist between the cane tonnage to be harvested (growth rate over time)
and the quantity and distribution pattern of water available.
Seasonal changes from wet to dry take place in most tropical sugar-
producing countries. Cane ripening occurs most readily during the
dry season while the rainy seasons are optimum for vegetative growth.
Under ideal rainfall distribution, cane should be planted at
the end of the major dry season. Transpiration rate is relatively
low for the young plants and, therefore, only a limited amount of
irrigation is needed during a period when this commodity is often
scarce. During the following wet season enough rainfall should be
available to meet the heavy moisture requirements of fully grown cane
plants at a maximum rate of transpiration. By the end of this rainy
season, rainfall becomes often a limiting factor for maximum rate
of growth. At this time a large quantity of irrigation water should
be made available to sustain the maximum growth rate. Irrigation water
should be withheld about 4 weeks prior to the date of harvesting.
The date of planting, therefore, will have a significant influence
on the cane tonnage to be harvested, especially in areas having limited
or no irrigation facilities. Cane planted too early may die due to
lack of moisture. Cane planted too late may be severely reduced in cane
tonnage at harvesting due to lack of much needed moisture at a time when
the plant is at the point of maximum transpiration. In the tropics,
date of planting becomes less important in areas with adequate irrigation
facilities to supply the need for moisture during both critical periods.
Withholding moisture from the plant will reduce the rate of growth.
The root system becomes partly inactivated during the dry season, re-
sulting in the reduced uptake of nutrients. Photosynthesis continues,
however, and the photosynthate is stored as sucrose in the cane plant.
In essence this process represents cane ripening.
A drop in temperature also partly inactivates the root system and
therefore, will enhance cane ripening. The low temperatures often
experienced in the sub-tropics have the same effect on the maturing
process as drought in the tropics. A close relationship, therefore,
exists between prevailing day-degrees and rate of growth per time unit.
Finally, optimum moisture, temperature, and fertilizer placement
may not automatically guarantee the required functioning of the root
system and the rate of growth. Soil pH may significantly influence the
rate of uptake by the cane plant for needed nutrients, regardless of
whether adequate quantities of these nutrients and moisture were applied.
Humbert, R.P. Basic Problems of Sugarcane Nutrition II. Applying
Basic Facts in Sugarcane Fertilization. Intern. Soc. Sugarcane Techn.
Proc. 8, 1953.
Halliday, D.J. The Manuring of Sugarcane. Centre d'Etude de L'Azote,
Cane is propagated vegetatively by planting stalk cuttings in
commercial sugar production. This method normally should preserve
specific and favorable characteristics with the very infrequent
exception of spontaneous bud mutations. Theoretically then, cane
tonnage and sugar production will continue indefinitely at the same
rate once a superior yielding variety has been adapted for commercial
In practice this statement is incorrect. Sugar production per
unit of surface will decline gradually and progressively. The cause
of this yield decline is not clear but is likely a combination of a
many related causes. Therefore, a commercial cane variety must be
replaced by a newly developed variety at least once every 10-15 years,
just to maintain the current level of sugar production per unit of
plant surface. Ideally, this new replacement would have yielding
abilities superior to the previous commercial variety.
Two-eye cuttings are preferably used for propagation on a commercial
scale. Such a cutting contains a large food reserve which, in turn,
promotes the speedy development of the root primordia and eye under
favorable conditions. Actually, only a small chip of the growth ring
containing at least one of the root primordia and the eye is needed
for the development of a cane plant. When being shipped over long
distances, these small chips sometimes are sent by air-freight to
save on transportation costs.
The cane cuttings are placed either horizontally in a furrow of
about 12 inches deep, or they are planted in a more slanted position.
The latter method often is used where weather patterns are unpredictable.
The theory behind this method is that the lower placed eye will germinate
well during dry spells but may perish during wet weather; the reverse
is true for the eye located near the soil surface. The method of
planting thus provides the best chance for uniform germination and sub-
sequent cane stand.
The method just described must be performed manually; because of
increasing scarcety and cost for labor, it is being replaced by plant-
ing cane cuttings horizontally in a furrow. Similarly, gaps in the
cane row formerly were planted by splitting and planting parts of
neighboring stools in the open row spaces. Planting short open gaps
in the cane row, whether in the plant or ratoon crops has been generally
abandoned because of high labor cost.
Presently, the only economical method of securing a full and even
cane stand is to plant an excess of cane cuttings horizontally in a
mechanically prepared furrow. The excess of shoots thus germinated
will be adjusted automatically when light intensity becomes a limiting
factor when the cane crop "closes in." The need for preparation of the
planting furrow by mechanical means will exclude the use of mountainous
terrain for growing sugarcane in the future.
Breeding and Selection
Vegetative propagation of cane for commercial sugar production
is practiced to retain the favorable characteristics associated with
a variety such as disease resistance, tolerance to damage by insects,
favorable cane tonnage and high sucrose content.
Breeding is practiced to develop improved varieties. Desirable
characteristics for which selection is practiced include resistance
to diseases, improved tolerance against insect damage, and increased
tonnage and sucrose content in cane. Selection criteria are not
always chosen to increase sugar production. For instance, varieties
selected for stalk erectness to facilitate mechanical harvesting
usually result in an increase of fiber content in cane and, sub-
sequently, a lowering of sugar recovery and production per unit of
surface. Rejection of otherwise high yielding varieties because of
disease susceptibility must be mandatory; otherwise, the entire sugar
industry in a region may be annihilated.
At the turn of the century researchers in Java found that cane
could be multiplied through true seed. Since that time numerous
breeding programs have been established in prominent sugar producing
areas to provide cane varieties adapted to those areas.
The change from vegetative growth to florescence is dependent
on the day length. The flowering of S. Robushum and S. officinarum is
responsive to photoperiod; cane is known as a "short day" plant.
Therefore, the breeding program for the U.S. mainland is carried out
in south Florida, where the day length is more favorable to the
development of florescence. Under favorable circumstances every
cane variety is capable of producing bisexual flowers. Some varieties,
however, are unable to produce viable pollen.
Temperature influences cane breeding, especially in subtropical
areas like south Florida. Low temperatures adversely affect the
formation of viable pollen; a florescence, when normally capable of
producing viable pollen, will often become sterile when the pollen
production takes place below 60 degrees F. For this reason the plants,
selected for pollen production are placed in heated greenhouses during
cool spells in the subtropics.
Pollen is produced before the "boot" stage of the flower. At this
moment the viable pollen may be used directly for cross pollination with
prior selected varieties, or the mature pollen may be harvested and
stored in paper bags. Pollen will retain its viability for a long term
when these bags are placed in a deepfreezer. This storage technique
makes the timing of pollen production independent from the timing of
the selection for "female" arrows in the cross-breeding program.
The technique of cane breeding is rather simple. After determining
whether a variety produces viable pollen, selected varieties for breeding
may be planted side by side in the field. After the emergence of flowers,
the female and male arrows with viable pollen are placed in a type
of lantern, covered with cheese cloth to prevent cross pollination
by unwanted varieties. Cane stalks with the male arrow are shaken
at least once a day to facilitate the release of the viable pollen.
Since it gives a better control against low temperatures another
method is used specifically in south Florida. The base of the cane
stalk of both female and male varieties is packed in moss which, in
turn, is wrapped with plastic and the package is kept wet. The moisture
will cause development of the root primordia in contact with the moss.
Just prior to the full development of the arrow, the cane stalk with
its developed root system is cut from the stool and transferred to
a greenhouse. Here, the plant base including the root system remains
wrapped in moss and is placed in water, continuously aerated. The
arrows of the selected female and male plants are wrapped in a lan-
tern hood, again to avoid undesirable pollination.
The "male" and "female" flowers for crossing of selected varieties
may not necessarily mature at the same time for crossing purposes.
The flowering of certain varieties may have to be delayed for success-
ful pollination. In this case, the stools are grown in large containers
and are subjected to artificial light or darkness to increase or de-
crease the day lengths. The same effect can be obtained in the field
by using a photographic flash light close to midnight.
A successful pollination will produce a large number of viable
seed per female arrow. Under controlled conditions, with only one
or more "male" arrows of the same variety and one or more "female"
arrows from possibly different varieties per lantern, the percentage
of the true seed can be identified. Sometimes "male" arrows from
different varieties are placed in the same lantern to increase the
success of pollination. This is called a polycross and, of course,
only the "female" variety can be identified as a parent. The seed
obtained can be kept in cold storage for several years without sig-
nificantly losing its viability. This method guarantees a constant
supply of seed for use in the breeding program, even during years
when seed production is low due to wind damage or frost.
The technique for cross breeding cane varieties has been well
established and simplified. The choice of varieties for cross
breeding to obtain superior yielding offspring is much more difficult.
Cane varieties greatly differ in chromosome numbers. The basic
number for both S. officinarum and S. robustum appears to be 10.
Most forms, however, are polyploids and aneuploids. For instance,
in S. robustum chromosome numbers in many multiples of 10 have been
discovered while the majority has 2n = 80, in the form of octoploids.
The number of seeds with different characteristics but from the same
parents approaches infinity, due to the large range in chromosome
numbers and the magnitude of possible combinations. Hence, results
from cross breeding of cane varieties cannot be predicted with even
remote certainty; the discovery of a superior variety can, therefore,
only be regarded as a matter of chance. Random selection from pre-
determined cross breeding is the principle behind a sugarcane
variety improvement program.
The planting of large numbers of seedlings annually and carrying
these through an elaborate selection program is one method to improve
the chances for the discovery of a superior variety. For instance,
the USDA Sugarcane Field station in Canal Point, Florida releases
one variety for commercial production per 200,000 seedlings planted
and tested. To secure such a release once every 4 years it will be
necessary to plant and select through different stages at least
40,000 seedlings annually.
The release of a new variety does not necessarily mean a yield
increase per unit of surface. Varieties which appear to have a
better resistance against diseases or are better adapted to cultural
practices needed to reduce man-hour requirements also may be released
for commercial production, whether or not such a variety will yield
better than the standard commercial ones.
Improving the techniques presently employed in the program is
another way to increase the selection frequency. This approach is
difficult at least. Research has revealed a low correlation for
stalk diameter and length, erectness in stalk growth, and the number
of stalks per stool between the plant crop and ratoons when single
stools were selected. A somewhat better correlation was obtained
for the percent Brix in cane juice; even then, however, the factor
obtained was relatively low, suggesting that selection for Brix in
single stools should not be practiced rigorously. It is, therefore,
recommended that a liberal number of varieties be selected in an
effort to retain as many as possible of the valuable ones.
Failure to improve significantly the techniques for selection
may result in an ever increasing selection ratio. Each variety
released for commercial sugar production will augment the plateau
to be reached or surpassed by future releases.
In general, the following stages are present in a variety selec-
Stage 1: Germination. Fuzz (a name specifically used for sugarcane
seed), either from cold storage or fresh from a recently completed
crossing program, is planted in flats. The flats contain sterilized
soil and are placed in a greenhouse. Prior to planting, a germination
test for each crossing was performed to estimate the number of seed-
lings to be processed annually. The flats in the greenhouse are partly
covered with a glass plate to retain the moisture during germination.
Cane seedlings need an abundance of light for successful development.
Seedlings are clipped several times in the flats to enhance a sturdy
development of the small stem.
The seedlings are transferred to the field when about 6 inches
high. They are planted in hills. Each hill is one foot apart in
rows with 5 feet between rows. Each hill may contain one to several
seedlings. The latter is called "bunch planting."
Bunch planting has the advantage that up to 5 seedlings can be
accomodated per hill, thus considerably reducing the area and manual
maintenance needed for the seedling program. In theory bunch plant-
ing may be regarded as a natural selection method; only the vigorous
growing seedlings will survive. On the other hand, this method greatly
favors the selection for optimum vegetation characteristics. Proof
is lacking whether these characteristics are also related with sugar-
producing qualities (sucrose content in cane). Furthermore, the re-
searcher is able to select only one stalk with certainty from seed-
lings planted in bunches. Every additional stalk may be either an
additional stalk from the same selection or a different seedling.
Selections made from singly-planted seedlings are not subjected to
Seedlings are mostly selected as plant crop. Selections are
made by visual observation on the basis of vigorously growing stools.
This disadvantage is somewhat reduced by selecting about 10 percent
of the seedlings for vegetative multiplication and observation during
the next stage.
Stage 2: First line tests. Selections from the seedling stage are
planted in rows 5 feet long. Visual evaluations are made when cane
is about 12 months old, when a Brix test by hand refractometer is
made. Again as much as 10 percent of the first line tests are selected
to avoid placing a too great emphasis on the Brix test. Selections
often are made during the plant crop as well as in the first ratoon.
All selections are carried into the next stage.
Stage 3: Second line tests. Selections from the first line tests
are planted in a random pattern in 20 foot lengths, replicated several
times. Selections are made in the plant crop and first ratoon for
growth habits, ratooning ability, and susceptibility to prevailing
climatic conditions, as well as juice yields generally obtained by
a milling test. For the latter, 10 stalks are harvested at random
and juice yields generally determined after extraction in a small mill.
Also, the milling test will reveal whether a variety is early,
medium or late maturing. Selections from this stage, about 5% of the
total planted in the second line tests, are multiplied vegetatively to
obtain sufficient planting material for testing in replicated variety
Stage 4: Replicated variety trials. Material from selected varieties,
together with a standard commercial variety, are planted in a formal
experiment for comparison of cane tonnage, juice quality, and yield
in the plant crop, and in the first and second ratoons. Plot size
is at least 1/20 acre. At harvesting the cane from each plot is
weighed, and a sample of 20 stalks from each plot is milled for the
determination of juice quality and yield.
Each variety is tested similarly at about 10 locations over a
wide area to eliminate the effects of different soil types and micro-
Stage 5: Testing for disease susceptibility and commercial use.
During the years of replicated testing, investigations also are
initiated to screen promising varieties for disease resistance.
Varieties not susceptible to major diseases and which have shown
superior qualities are released for limited trials on a commercial
Testing for a minimum of 10 years is required before a seedling
can be released as a commercial variety. Hundreds of acres are needed
for this purpose. The program is very costly since many man-hours
are required in the tasks of planting, transplanting and maintenance
of seedlings, replanting cane cuttings, drawing cane samples, and
milling these samples.
Visual observations are the only criteria for selection during
the early stages when the numbers of cane varieties is enormous.
An accurate and simple technique to test for juice quality during
these stages is needed that would allow the elimination of a large
portion of material now selected and carried throughout the program.
Failure to develop such a technique together with the ever-rising
yield plateau for commercial varieties, ultimately will cause cane
variety improvement programs to become too expensive.
Finally, varieties selected for commercial production carry
numbers instead of names. Examples are C.P. 50-28, B. 41-223 and
H. 37-1933. By international agreement, the letters in front designate
the place of origine for the clone; C.P., B. and H. designate Canal
Point (Florida), Barbados and Hawaii, respectively. The first set of
numbers denotes the year in which the crossing was made, while the
second set of figures designates the selection number of clones
during that year.
Stevenson, G.C. Genetics and Breeding of Sugar Cane. Longmans, England,
The methods employed for cane cultivation reflect the soil type,
climatic conditions, and local customs that prevail in a sugar-
producing area. Since World War II land reform has caused a shift
in ownership from large estates to small holdings. Ownership of
only a small acreage is not conducive to effective field mechanization.
The formation of cooperatives as common owner for field equipment
is contributing to the solution of this problem.
Most cane in the tropics is produced on flat, low-laying
land in need of drainage. Closely spaced drainage ditches are essential
and should be connected by culverts to main canals. The slope of the
ditches must be at least 1% to obtain an adequate flow. The short
distances between adjacent ditches result in small-sized fields
(often 10 acres or less). The necessity for an adequate drainage
system and the resulting short cane rows is not conducive to effective
The Louisiana bedding system was invented to avoid these difficulties.
Beds are shaped by removing soil from the sides and depositing this soil
on the crown of the bed. The result is a shallow excavated area on
the sides, gently sloping and easily crossed by mechanical equipment.
The cambered bed also is sloping toward the sides and hap a width to
accommodate four or five cane rows, each at 6 feet apart. Soil is re-
moved from the inter-row space into the cane row several times per
year to further facilitate drainage. The entire system provides effective
drainage, even in heavy clay soil, with a minimum of idle acreage
and restrictions to full mechanization and cane transportation. The
shallow furrow between rows also promotes the effective use of har-
Areas where drainage may prove to be a problem are gradually
adopting a type of Louisiana bed field lay-out. This lay-out also
allows surface application of irrigation water. Methods of irrigation
other than surface application by gravity are seldom used as the profit
margin per ton of cane normally will not justify the relative high
cost of irrigation by these methods.
Cane growth in areas with a sparse rainfall, like Peru, depends
entirely on surface irrigation. The cambered bed system is of little
use in this area. Surface irrigation is applied via each shallow
furrow between the bedded cane rows. Also, cambered beds would be of
little use in areas like Florida where cane is grown on organic soils.
Drainage is still obtained through a system of ditches, spaced far
apart. Irrigation is supplied by virtual absorption of water through the
porous soil from a water table maintained at constant depth. Lateral
movement of drainage and irrigation water is improved by mechanical
made mole drains spaced 12-15 feet apart and 11-2 feet deep.
If water supply permits, some countries inundate the fields for
several months successive crop cycles. This flood fallow will kill
most of the dormant weed seeds and will reduce the population of nematode
and insects built up during the previous crop cycle. When the flood
water is drained, a heavy oxidation of certain elements follows
which is beneficial for optimum cane growth during the next cycle.
This practice usually is limited to low laying and flat areas
where removal of the flood water often requires pumping.
After planting, or harvesting of the previous crop in ratoons,
the soil must be kept clear of weeds. Experiments during the early
thirties have shown that poor weed control is a false economy re-
sulting in severe reduction in cane tonnage. Weed control can be
practiced mechanically or chemically; a combination of both methods
Mechanical weed control is accomplished by means of a rototiller,
scratcher or interrow disking. Rototilling is especially recommended
for the first opercaion in ratoons as the equipment will cause the
pulverizing of plant material left on the surface from the previous
crop. Scratchers, using a set of tines, is especially effective in
light soils such as the organic soils of the Everglades. The operation
of off-set disking is used to add soil to the cane row to check tillering.
All operations are meant to reduce moisture loss through the soil
surface and to effectively control the weed population. Shallow inter-
row cultivation is practiced to prevent injury to cane roots. For
this reason, adding soil to the cane row must be carried out in several
operations. In heavy soils, an inter-row cultivation with heavy tines
up to two feet in length often is used in the middle of the inter-row
when the cane is young; this process creates a soil mulch which allows
adequate soil aeration that encourages better root development.
Two principles are employed for chemical weed control. In pre-
emergence application, the soil is sprayed with a herbicide which
ideally prevents the emergence of all weeds. Concentrations applied
are such that the chemicals do little harm to the emerging of cane
cuttings. Obviously this treatment is applied to the bare soil
surface just after planting.
Cane fields are past emergence after the cane has germinated.
Normally, the weeds have germinated prior to the emergence of the
cane. Grass weeds are the most difficult to control as they belong
to the same family as sugarcane. The herbicides presently used for
weed control almost invariably will destroy germinated broadleaf weeds,
and either severely damage or kill the emerged grass weeds. At the
same time these chemicals may reduce the growth rate of the emerged
cane when absorbed by the plant.
Several principles, apart from the type of herbicide used, are
important for success in chemical weed control.
1. When preemergence treatments are used, the chemical film on
the soil should remain undisturbed. Breaking this film by mechanical
inter-row cultivation will instantly destroy the effectiveness of the
application. Chemical weed control should always follow and never
preceded mechanical interrow cultivation.
2. A continuous and uniform film can be obtained only with equip-
ment suitable to perform such a task. Ground speed for application,
pressure under which the application is carried out, nozzle pattern
and concentration of mix are often as important as the type of her-
bicide used. Uniform coverage of the soil by the herbicide is achieved
by spraying as large a volume as possible. Reducing the volume of
water in the mix to save on cost of application is often false economy.
3. Spray nozzles should be shielded when applying herbicides which
are known to reduce the growth rate of cane. The shielding mechanism
should effectively prevent wetting of the cane leaf surface to pre-
vent the chemical from being absorbed by the plant.
4. Apply the chemicals at a dosage and frequency for which they
Mechanical as well as chemical weed control has severe limitations.
The need for effective weed control is greatest during the period prior
to closing in of the crop while the rainy season exists. During this
period it is difficult for machinery to proceed through the field.
Even then, mechanical weed control has the advantage of visible and
instant results. Results from chemical weed control depend on the pre-
vailing climate conditions in the future, and are revealed only on a
delayed schedule. Because of this factor, the results from chemical
weed control are at least uncertain of nature.
Barnes, A.C. Agriculture of the Sugarcane. Leonard Hill, Ltd., London,
Humbert, R.P. The Growing of Sugar Cane. Elsevier Rublishing Company,
Only one percent of the fresh weight of cane consists of elements
other than hydrogen, oxygen and carbon. The application of these
other elements, so essential for cane production, represents the cost
Research efforts have been directed toward the need, concentration
and distribution of these elements throughout the plant.
The mineral content after ashing of the plant decreases as the
internode grows older. The lowest ash content is found in the bottom
part of the cane while the highest mineral content can bg found in
the top, the most active tissue of the plant. The latter finding is
of importance to the sampling method adapted for the modern diagnostic
Research findings also suggest that translocation of elements takes
place from the older to the younger tissues. Indeed, most nitrogen
and potassium are withdrawn from the old leaves before they die.
Necrosis starts at the tip and edges of the leaf blade aid resembles
acute potassium deficiency symptoms. The potassium content of the top
part of the stalk is about twice as high as the content :in the bottom
Apart from the differentiation in mineral content between top
and bottom parts of the cane plant, it is also evident that this con-
tent decreases for every plant part with age. This finding was of
great importance for development of diagnostic techniques to determine
optimum mineral levels for growth at different ages of the plant.
Silica is the most concentrated component in the mineral con-
tent of fresh cane, accounting for more than 50% of the total. And
yet, the element is rarely found in short supply and the plant
rarely responds to applications of silica. Some of this element is
expressed with the juice and enters the sugar processing where it
forms a deposit on the evaporator tubes. The major part, however,
remains in the bagasse and forms a persistent, glass-like deposit
in the furnace of the boilers.
Mineral content in expressed juice is associated with the elements
available for uptake by the plant. The major mineral constituent of
expressed juice is potassium. This element is highly water-soluble
and difficult to remove by the clarification process. Hence, it
passes through the processing and forms an integral part of final molasses.
The latter often contains 20% potassium on a dry basis and is used
in some countries as a potassium fertilizer. A high concentration of
potassium in the juice is undesirable since it enhances molasses
formation with a consequent reduction in the recovery of sugar.
Uptake of potassium interacts with the uptake of calcium and mag-
nesium by the cane plant. Potassium content in juice is low when cal-
cium and magnesium content are high. The reverse also is true. A
high calcium and magnesium content in juice is undesirable as these
elements become insoluble in concentrated sugar solutions and are
deposited together with silica as heavy encrustations on the inside
of the evaporator tubes.
Juice should not contain less than 300 ppm of P205, below which
point adequate clarification of juice becomes difficult. Often
phosphoric acid is added to the extracted juice, deficient in this
element. A better method would be to supply phosphorus to the growing
cane plants, providing that the applied phosphorus remains available
for uptake by the plant and results in an increase in tonnage.
Concentration of elements in juice and fresh cane varies only
slightly between varieties grown in the same area and under the same
climatic and soil conditions. The concentration of these elements
in the same variety grown in different areas, however, may differ
markedly. Therefore, the values reported for different areas may
not be compared. Also, the effect of season on juice composition
may greatly differ from year to year and between plant and ratoon
crops. It appears that climatic and soil conditions are more impor-
tant to juice composition than the varieties employed.
A large proportion of the macro-nutrients ultimately is returned
to the soil in the form of decomposed roots, leaves, and tops. The
millable stalk is removed for the production of sucrose, bagasse,
and finally molasses. On the average about 80 pounds of N, 20 pounds
of P205, and 120 pounds of K20 per acre are removed yearly with the
Finally, the chemical composition and the concentration of each
element within the plant is dependent on the extent of root development
and numerous external factors. Uptake of nutrients to the plant may be
investigated by the following technique.
One stalk of a stool is cut about two inches above the ground while
the other stalks of the same stool are left standing. A tight fitting
rubber hose is placed over the stump of the cut stalk. The osmotic
pressure exerted by the still active root system forces the liquid
through the vascular bundles of the stump and into the rubber hose.
An aliquot can be collected and analyzed for type and concentration
of elements. This method may determine the effectiveness of the
root system for uptake of elements and the influence of soil pH on
the availability of certain elements to the plant without actually
disturbing the root system.
Malavolta, E, Andall. On the Mineral Nutrition of Some Tropical
Crops. International Potash Institute, Berne, 1962.
The cost for nitrogen is a major factor in the fertilizer budget.
Familiarization with the interaction between nitrogen and other ex-
ternal factors, therefore is in order.
Nitrogen assimilation occurs under influence of light. During the
process the nitrogen is transported from the root system to the leaves
and stalk where it becomes a major constituent of protein compounds
mainly present in the cell protoplasm. Nitrogen assimilation may
occur in the absence of light, providing that carbohydrates are avail-
able at the same time. Hence, light which is essential for carbohydrate
assimilation, is a secondary and indirect requirement for nitrogen
Research with the isotope 15N showed that nitrogen was assimilated
within five days after application. Within the plant, most nitrogen was
located in the spindle and green leaves near the top. Also, nitrogen
was found in the older internodes in the area of the root bands, al-
though in lesser quantities.
As suggested by high concentration of accumulated nitrogen in
meristematic tissues, a close relationship seems to exist between
nitrogen available for uptake and that for growth. The nitrogen content
of the leaf blade in these tissues was about twice as large as that of
the sheath. This discovery implies that the leaf blade is a more useful
tissue than the sheath for diagnostic purposes.
The highest concentration of assimilated nitrogen is present in
the fully developed blades of leaves 1, 2, 3, and 4 when counting the
non-emerged spindle leaf as number zero. Nitrogen also can be
accumulated in the node directly under the root primordia and bud,
but this nitrogen content diminishes rapidly with aging. The older
node, therefore is a temporary storage space for nitrogen which can
be quickly translocated to other plant parts when needed. The top
parts have priority with regards to available nitrogen and moisture,
and will draw these materials from the lower tissues when shortages
exist. By the same mechanism the nitrogen in the older leaves will be
translocated to the younger ones. Therefore, symptoms of mild deficiency
for nitrogen will initially reveal itself in the older leaves.
Under favorable conditions the nitrogen absorbed during the initial
growth period of 90 days is stored and will afford an additional
growth period of 70 days without needed uptake of the element. Storage
capability and readily available nitrogen, especially when applied
even in split applications, will afford an adequate supply of this element
during the entire growth period of cane. Split doses of nitrogen can
be applied with a minimum risk for losses by leaching until the crop
"closes in", and then carry the crop until maturity.
The effects of nitrogen on plant behavior:
The cane plant needs macro-elements in decreasing order of nitrogen,
potassium, and phosphorus. Increasing quantities of nitrogen applied
result in higher nitrogen uptake by the plant. The concentration of
nitrogen in the plant, however, varies only slightly; therefore, the
increased uptake of nitrogen results in additional growth and dry
weight of the plant. Hence, a close relationship normally exists
between the uptake of nitrogen and the recovered dry weight of the
Increased nitrogen available to the plant also will cause greater
succulence. The sugar recoverable is more diluted from plants at
maturity which received nitrogen applications. Nitrogen application
beyond the optimum rate, therefore, exerts an adverse effect on juice
quality. Likewise, the percentage of reducing sugar and sucrose is
affected by applications of nitrogen. As more nitrogen is applied,
quantity of reducing sugars in Juice increases and sucrose concentration
decreases. A close prritive correlation is apparent, then, among
reducing sugars, moisture content of the plant, and amount of nitrogen
applied; a negative correlation exists between these components and
sucrose content in cane. Also, increased nitrogen results in decreased
fiber content in cane.
Nitrogen applications have a limited effect on stooling out of
cane. In the plant crop, the number of millable stalks sometimes in-
creases with nitrogen apo ications. This advantage, however, ceases
in the subsequent ratoon crops when mortality of shoots is much greater.
Hence, the number of primary, millable stalks per unit of surface area
is influenced very little by nitrogen applications.
Nitrogen applications markedly increase total green weight, es-
pecially the leaves. Increasing amounts of nitrogen result in a wider
leaf and faster leaf formation. Also, experiments with water cultures
have shown that leaves of plants lacking nitrogen contained only half
the amount of chlorophyll as compared to normally developed plants
and their photosynthetic use of radio-active carbon was reduced to one
fifth of controls.
Nitrogen increases internode length and stalk size. Likewise, a
negative relationship exists between rate of nitrogen application and
fiber content in cane. Both conditions promote cane lodging.
Adequate moisture for the plant is essential to the efficient
utilization of nitrogen, since this element promotes succulence. Up-
take of nitrogen and hence, optimum growth is restricted when the average
day and night temperatures fall below 670F. Light intensity and number
of light hours per day have little effect on the utilization of nitrogen.
Types of nitrogen and symptoms:
The cane plant shows little difference in response to the type
of nitrogen supplied, whether in nitrate or ammonia form. The latter
can be directly absorbed by the root system, more rapidly than the
nitrate form. Conversion of ammonia to nitrate in the soil is not
essential for use by the cane plant.
The choice for type of nitrogen fertilizers, therefore, largely
depends on price per unit of N and soil pH. Sugarcane is adapted best
to a slightly acid soil, but relatively high tonnages are also obtained
from clay soils with pH 4.0-4.5. Accordingly, a continuous supply of
accidifying components like sulphate of ammonia is not objectionable.
Urea and liquid ammonia are used most commonly because of economy in
price. Both materials are drilled between rows to prevent losses of
nitrogen by evaporation.
Urea also is used for foliar application when needed after the
crop has "closed in". Dry application of 20 pounds per acre does not
burn the leaves; most of the urea granules rest in the top part of
the leaf sheath from where it will be readily absorbed when humidified
To replace the nitrogen which is removed by the crop pr lost
through leaching, a normal application of 45 pounds and 90 pounds of
N to the plant and ratoon crops, respectively, is needed. The exact
amount varies among areas and can be determined only by foliar diagnosis,
a topic to be covered later. Normally, a plant crop requires about
one-half as much nitrogen as a ratoon crop especially where flood
fallow is practiced prior to replanting. The exact cause for the re-
duced need of nitrogen in the plant crop is unknown.
Sugarcane grown on organic soils does not respond to applications
of nitrogen. These soils are continuously subjected to oxidation,
which releases large amounts of nitrogen that is readily available to
the plants. In fact, the amount of available nitrogen is so great
that cane rarely reaches full maturity. Sucrose content ip cane grown
on organic soils is normally low while the large amounts of nitrogen
stimulates the promotion of a higher than normal cane tonnpge.
Finally, sugarcane grown on mineral soils with inadequate nitrogen
shows short internodes with pale green colored leaves. This color may
change to nuances of yellow, depending on the severity of nitrogen
deficiency. Much of this same discoloration on the lower plant leaves
often may be associated with aging.
With adequate nitrogen, the sugarcane leaf becomes dark green.
The intensity of this green color increases with increased nitrogen
application. Very heavy dosages of nitrogen may result in a blueish-
green color of leaves.
Malavolta, E. and All. On the Mineral Nutrition of Some Tropical Crops.
International Potash Institute, Berne, 1962.
As with most other nutrients, the highest concentration of phos-
phorus may be found in the meristem parts of the cane plant. In con-
trast to nitrogen, the phosphorus content of the internodes increases
with the age of the cane.
The phosphorus concentration in the leaf, especially the sheath
portion is high. This is important for diagnostic purposes and will
be dealt with later. The notable presence of phosphorus is not sur-
prising as this element forms an integral part of every living cell,
especially the ones active in carbon assimilation. Most of the phos-
phorus harvested in the form of millable stalks is recovered in the ex-
tracted juice. Phosphorus translocates from the older leaves before
they become physiologically inactive.
The necessity for placement of phosphorus fertilizer below the
cane plant was mentioned already. Surprisingly, the sugarcane plant
is able to absorb its phosphorus requirements from very low concentrations
of this element in the soil. Experiments have indicated that concentrations
of 0.05, 0.2, 0.5, and 1.0 mg of phosphoric acid per liter of nutrient
solution resulted in the uptake of 20, 50, 78, and 96% of the maximum
At the same time speed and ability to absorb phosphorus is sig-
nificantly influenced by soil pH. At 4.5 pH, the rate of absorption
for phosphorus per unit of time is high and is little influenced by
concentrations of the element in the soil. At 6.0 pH, this absorption
rate follows a close relationship with the phosphorus concentration
in the soil. At pH 7.0 and 7.5 the -'bsorption rate per time unit is
markedly less than in acid surroundings, regardless of the prevailing
These findings have important consequences. Phosphorus will he
assimilated by the plant at extremely low concentrations present in
the soil. Therefore, severe phosphorus deficiency rarely occurs in
acid soil. Further applications of a slowly releasing phosphorus
material, such as the cheao ground rock-phosphate, may Furnish adequate
amounts to the plant throughout the growing season, providing that the
soil pH is low enough to facilitate the uptake of this element.
The cane plant must be aided for adequate uptake of phosphorus
when the soil pH is approaching neutrality or is alkaline. Either
higher rates of application are essential, or the use of a more readily
available form of phosphorus such as the granulated form of triple
super-phosphate, will be required. The cane plant growing in an alkaline
medium may be able to absorb an adequate quantity of phosphorus from
very low concentrations in the soil if the particles surrounding the
root could be temporarily acidified by an application of granulated
sulfur. Also, the granulated triple super-phosphate serves two purposes
when applied: it will locally acidify the soil particles in contact
with the granule, and at the same time release a high concentration
of phosphorus readily avail-ble to the cane plant.
To raise the concentration of phosphate in the soil, very lara
applications of phosphate fertilizers should be avoided. High ap-
plication rates of granulated triple super-phosphate have significantly
reduced the cane tonnage on organic soils in the Florida EverqlpdHes,
Similar application of rock phosphate or basic slag did not have the
same effect. Whether the reduction in cane tonnage is simply a result
of high concentrations of available phosphorus in nearly neutral and
alkaline soils, or is due to an interaction in uptake of high phbs-
phorus and other nutrients, especially nitrogen or potassium, is still
The uptake of phosphorus is markedly influenced by the availability
of moisture to the cane plant. Although the phosphorus content in
leaves does not materially change during the entire growth period,
temporary fluctuations do exist. A significant and positive correlation
has been established between the amount of moisture available to the
plant and the phosphorus content on a dry basis. It follows that a
relatively low phosphorus content in the plant prevails during the
dry seasons. The accumulation of phosphorus in the stem during the
first three months is small and increases to a higher and more con-
stant level thereafter.
Cane growing in soil deficient in phosphorus shows a marked re-
duction in the rate of tillering. Phosphorus application to soils,
not necessarily deficient in this element, will promote even tillering.
The number of tillers thus formed may easily exceed the optimum, and
from the discussion in a previous chapter does not result in an ultimate
increase in harvested tonnage. Also phosphorus deficiency may result
in short internodes and small stem diameter. Applications to soil
deficient in phosphorus increase the millable cane available to be
The maturity of grain crops is enhanced by applications of phos-
phorus to deficient soils. Some beneficial effects in expediting
maturity also have been noticed occasionally for sugarcane, but these
benefits do not occur consistently. In general, it can be stated
that phosphorus applications have little or no effect on the ripening
Visual symptoms, of phosphorus deficiency, such as poor tillering
with short internodes and small stalk diameter, were already mentioned.
In addition, the cane leaf tends to become a blueish-dark green in
color when severe phosphorus deficiency occurs. The same discoloration,
however, is also associated with high applications of nitrogen fertilizers.
In practice, whether or not the cane plant is deficient in phos-
phorus can be determined only by analysis. Even then, deficiency
is difficult to correct due to the important role of soil pH and the
nature of phosphorus uptake by the plant. The latter conditions are
the main reason why phosphorus often must be added to the extracted
juice for satisfactory juice clarification during processing.
Approximately one pound of P205 is removed annually with every ton
of cane processed.
Malavolta, E. and All. On the Mineral Nutrition of Some Tropical Crops.
International Potash Institute, Berne, 1962.
Potassium is used in sugarcane in association with photosynthesis
and protein synthesis, starch formation, and translocation of sugars,
as well as in transpiration. Since protein and starch play an important
part in germination of the eye and photosynthates the final crop pro-
duct, potassium is constantly needed throughout the crop life and cycle.
Potassium is completely soluble in water, making this element highly
mobile within the plant.
The highest concentration of potassium is found in the elongating
and meristematic plant parts. Next highest concentration is present
in the young leaf system while the lowest potassium concentration is
present in the active, older leaves. The fully formed internodes con-
tain the least amount of this element. The translocation of potassium
takes place in the same order: From the mature internodes to the active
leaves and from these parts to the stalk top. In the final stage,
most potassium removed with the juice from the crushed stalk is a com-
ponent of the final molasses.
As with other macro-nutrients, the greatest accumulation of po-
tassium takes place during the six months after planting or ratoon re-
growth. This suggests that all potassium applications should be made
to the cane prior to "closing in". Like many other plants, sugarcane
will enjoy luxury consumption of potassium when this nutrient is applied
at excessively high rates. Cane shows little preference for either
the chloride or sulphate form of potassium; because of the cost dif-
ference, muriate of potash is most commonly used.
Growth of sugarcane becomes depressed about 2-5 months after po-
tassium deficiency occurs. Deficiency symptoms include decreased
tillering and stalks with a small diameter which quickly taper towards
the spindle. These symptoms are less pronounced but somewhat similar
to those already discussed for deficiency from nitrogen or phosphorus.
The most pronounced characteristic for potassium deficiency can
be found on the leaf of sugarcane. With a moderate potassium deficiency,
a yellow discoloration occurs in a narrow strip along both sides of
the leaf blade. This discoloration commences at the tip of the blade
and extends in the form of an inverted letter "V" towards the middle.
In a more severe case, the discolored tissue at the top and edges of
the leaf blade will die, resulting in a brown top and inverted V along
the edges of the blade followed by an area of yellow discolored tissue.
At this stage a red discoloration also will appear at the surface of
the entire midrib of the leaf blade. The latter discoloration, however,
should not be confused with similar symptoms caused by borers or red
In a more advanced stage, necrotic areas will continually increase
in size on the leaf blade. This spotting, however, is similar to the
injury caused by Helminthosporium sacchari. Likewise, necrotic tips,
edges, and spots on the leaf blade should not be confused with the
normal aging process of the leaf surface. Hence, a leaf analysis
always should be carried out to confirm a deficiency of potassium. An
application of either muriate or sulphate of potash will quickly correct
A deficient supply of potassium to the cane plant not only re-
duces cane tonnage, but also enhances an excessive uptake of other
elements. Nitrogen, phosphorus, and in particular, iron content in
cane is significantly increased due to potassium deficiency (also
called Kalimati disease). Iron in this case is accumulated in the
nodes and its presence in excessively great concentration may be de-
termined by the "Hoffer" test. The stalk is cut length-wise and a
few drops of a strongly acidified solution of 20 percent potassium
rhodamide are placed on the nodes. A deep reddening caused by the
formation of F(CNS)3 takes place, an indication of potassium shortage
to cane. Conversely, heavy applications of potassium may result in a
luxury uptake of this element by the cane plant which may prevent an
adequate absorption of other elements. Magnesium or calcium deficiency
may follow heavy applications of potassium to clay soils having pH of
An application of potassium to cane deficient in this element has
several effects. It will reduce the concentrations of other elements,
particularly nitrogen, to a more normal level. As a high concentration of
nitrogen in the plant will inhibit maturity, it follows that an adequate
supply of potassium also plays an important role in the formation and
translocation of hexose and sucrose. A positive correlation has been
found, therefore, between the potassium content and sugar content of
the cane plant. As with nitrogen, an application of potassium promotes
uptake of moisture and will increase the succulence of cane.
Potassium has a distinct effect on the anatomy of sugarcane.
An adequate supply of the element reduces lignification and promotes
thickening of the cuticle. Injury from eye spot disease is reduced
by applications of potassium mainly because of the thickening of the
cuticle. This also may be the reason why applications of potassium
are claimed to reduce injury by freeze in the sub-tropics.
Sugarcane deficient in potassium shows a poor development of the
hairroot system. An adequate supply of this element promotes development
of a normal root system through which the uptake of nutrients and
moisture can contribute to higher cane tonnage per unit of surface
and to the succulence of the stalk. The better developed root system
also may explain the positive interaction in uptake of other elements
and potassium, which was mentioned already in the chapter concerning
In general, about 2.5 pounds of potassium in the form of K20 is
removed with .every ton of cane harvested. About 100 pounds of K20 is removed
annually when assuming a crop of 40 tons of millable stalks. This
quantity of potassium and a certain amount which is lost due to
the physical properties of the soil during the year, must be added.
Malavolta, E. and All. On the Mineral Nutrition of Some Tropical Crops.
International Potash Institute, Berne, 1962.
In most countries, cane is fertilized annually with nitrogen,
phosphorus and potassium, singly or in combination, to replace the
nutrients depleted by the removal of the crop. Exceptions are some
developing countries as Bolivia, Haiti, and India where either the
educational standard and standard of living, or excessive transportation
cost prohibit the use of inorganic fertilizers. Fields produce a
very reduced tonnage; the sugar yield is corrected somewhat, however,
by a higher than normal sugar content in cane due to the absence of
In contrast to the macro-nutrients, the micro-nutrients are not
normally supplied to cane with the exception of a few areas where ah
application of certain micro-nutrients has proven beneficial or eveh
essential to cane growth, such as in south Florida. The following
elements may be classified as essential for cane production:
Calcium: The highest concentration is found in the meristematic
tissue. In severe calcium deficiency, the young cane leaf becomes
somewhat chlorotic, while the older leaves become rusty in appearance.
In extreme deficiency even the leaf spindle may die. In practice, leaf
symptoms associated with calcium deficiency are rarely noticed. It
appears that the extensive root system of the cane plant is able to
absorb an adequate amount of calcium to satisfy its growth requirement
even on very acid tropical clays.
Calcium may be applied to cane for a dual purpose. First, to
supply the necessary amount as plant food and secondly, to change the
chemical and sometimes physical soil properties, especially in very
acid tropical clays, by increasing the pH level. The former purpose
takes only a moderate application rate of calcium, mostly banded.
Many tons of calcium per acre, applied as a broadcast and disked into
the top soil layer, however, are needed to raise the pH of the soil
Raising a low soil pH only slightly may release enough elements
such as phosphorus or iron which formerly were unavailable, for ab-
sorption by the cane plant. Experimentation in the tropics has often
shown the beneficial effects from heavy calcium applications. Funds
spent for these applications should be regarded as long term capital
investment for improving the soil resource. Unfortunately, capital
funds are scarce in most tropical areas and hence, cane must often be
produced in soils with 4.0 pH or even lower. Permanent improvement of
soil pH may have a significant influence on future sugar yield in such
About 20 pounds of calcium in the form of CaO is removed per 40
tons of cane crop harvested annually.
Magnesium: This element is one of the essential components in the
chlorophyll chain. Magnesium behaves similarly to calcium in its
effect on the cane plant. Even the deficiency symptoms, the rustlike
appearance on the leaves is identical. Results from plant analyses
will only indicate whether calcium or magnesium need to be supplied
for correction of the symptoms. About 30 pounds of magnesium in the
form of MgO is removed per 40 tons of cane crop harvested annually,
Iron: The element is also essential in the chlorophyll chain
and it is present throughout the cane plant with the greatest con-
centration located in the spindle portion. Iron is rather immobile
within the cane plant. In contrast to most other elements, iron in
the older plant parts is not readily translocated to the meristematic
part when shortage occurs. Symptoms due to iron deficiency will show
first on the leaves of the spindle and will later extend to the older
When iron is deficient, the normal green color disappears between
the vascular bundles of the leaves. The deficiency is characterized
by a pale striping extending over the entire length of the leaf blade.
In severe and prolonged iron deficiency, these stripes may convert
into a uniform chlorotic leaf blade and ultimately into pure white
leaves. Sometimes a sudden unavailability of iron to the plant may occur
when the plant crop or ratoon is germinating. One or more shoots in the
same stool may appear as pure albinos while other shoots of the same
stool develop a normal, although a somewhat, pale green color.
Iron deficiency frequently occurs in heavy tropical clay soils and
lateritic soils having a low pH. Under this condition phosphorus com-
bines with iron into compounds which make the iron unavailable for ab-
sorption by the cane plant. Additional fertilizer applications with
iron will not correct this condition.
Iron deficiency is efficiently corrected by foliar applications.
About 10 pounds of iron sulphate or iron oxide per acre applied in
a large volume of water to secure an optimumcoverage will quickly
correct the deficiency within 48 hours; a small green island will
develop at the spot where the spray droplet struck the leaf blade.
This island will enlarge rapidly until the entire leaf blade has
returned to a healthy green color. This method of recovery once
more suggests the slow mobility of iron in the cane plant. The spray
application should be repeated every 4-6 weeks to insure an adequate
supply of iron to the cane plant as long as soil conditions remain
unfavorable for uptake of iron through the root system.
Manganese: Deficiency symptoms caused by a shortage of this
element are similar to the ones already described for iron deficiency.
One main difference, however, is apparent. Manganese is perfectly
mobile within the cane plant. Hence, deficiency symptoms will be-
come evident first on the older leaves as the manganese from that
section is translocated to the younger plant parts. To distinguish
between deficiency symptoms caused either by manganese or iron, one
has to observe the location at which the leaf discoloration occurs.
Confirmation, however, should be obtained from the results of foliar
Manganese deficiency in sugarcane is always associated with a
soil pH of about 7.0 or higher. Manganese is relatively unavailable
to most plants.
A foliar spray with 10 pounds of manganese sulphate or oxide
may be applied to alleviate the influence of high soil pH. Sugarcane
responds equally well to both the sulphate and oxide forms; manganese
oxide is used most frequently for foliar sprays because of its low
As an additional precaution, manganese fertilizer applied to the
soil frequently is premixed with 400 pounds of granulated sulphur to
counteract the adverse effect by high soil pH on the absorption of
manganese by cane. The sulphur granules will dissolve slowly and
acidify the surrounding soil particles, and thereby manganese remains
available to the plant.
Manganese deficiency frequently occurs in cane grown on organic
soils in the Florida Everglades region. Roads serving the cane fields
are topped with crushed lime rock. Run-off from these roads causes
a high soil pH and subsequently, cane bordering these roads frequently
show acute signs of manganese deficiency, despite an adequate soil
application of this element in conjunction with granulated sulphur.
The symptoms associated with manganese deficiency in cane are
sometimes confused with similar symptoms caused by a disease and known
in Hawaii as Pahala blight.
Copper: This micro-nutrient has gained special importance for
cane grown in the Florida Everglades region. An application of 25
pounds of brown copper oxide to the virgin, just drained, organic
soil is essential to avoid a total crop failure and normal develop-
ment of cane during the initial few months after planting.
Cane planted without an application of copper to the virgin
soil will germinate normally, but will soon stagnate in growth;
very short internodes and shoots with a small diameter will result.
The plant usually dies when about 3 months old and one foot in
height. The cane cutting itself likely contains enough copper
to sustain plant life during the initial weeks after planting.
The cane plant may still show a decreased rate of growth at about
5 months old, in spite of the copper application to the soil.
Inclusion of zinc together with copper in the fertilizer dosage,
however, has produced a normal cane crop at maturity.
A banded application of copper in the furrow of virgin organic
soil was not effective. An initial and one-time broadcast application
of 25 pounds of brown copper oxide or sulphate, properly mixed
with the first.foot of top soil by frequent diskings, provided
for the maximum absorption of copper by cane. After the initial
heavy broadcasted application, the copper fertility level in these
organic soils is maintained by the inclusion of 4 pounds of CuO in
the form of brown copper oxide in the fertilizer applied to each
plant or ratoon crop. It appears that feeder roots do not speci-
fically branch at areas in the soil having a heavy concentration of
copper. The uptake of copper by the cane plant can, therefore,
be compared with the reaction of cane to an application of phos-
phorus to the soil.
The copper application to the soil fails to increase the
concentration of this element within the plant tissues. Hence,
tissues of plants suffering from copper malnutrition show the same
concentration as tissues from normally developed cane plants.
The amount of copper removed by the crop, which is many times
greater for normally developed plants than for plants stunted
by lack of copper, is the only reliable criteria for judging
whether or not a soil is deficient in this nutrient.
Copper deficiency symptoms on the leaf blade consist of a
pale yellow leaf with small islands of perfectly healthy, dark
green colored tissue. mI an advanced stage these islands will
disappear, leaving the leaf blade chlorotic and similar in appear-
ance to the one caused by nitrogen deficiency.
The reverse process takes place when 5 pounds of copper sul-
phate per acre is applied to the foliage. First, small green islands
will appear on the chlorotic leaf blade where the droplet of the
copper solution adhered. Next, these islands will enlarge until
finally the whole leaf blade shows a healthy green color. All
leaves of the plant show copper deficiency at the same time, sug-
gesting that copper is relatively mobile within the cane plant.
Zing: Symptoms produced with the help of water cultures show
light yellow streaks between the veins of the leaf blade. In prac-
tice these symptoms do not appear when cane is produced commercially.
The most pronounced symptom caused by zinc deficiency' is a severe
reduction in cane tonnage at harvest. This reduction in stalk
elongation starts when the cane is about 5 months old in the plant
crop, Deficiency is easily prevented by the inclusion of about
4 pounds of zinc oxide or zinc sulphate per acre into the fer-
tilizer applied to the plant and ratoon crops.
Molybdenum; Sporadically molybdenum deficiency is mentioned
and then mainly associated with acid soils having a pH of well below
4. In these soils molybdenum deficiency often occurs in conjunction
with calcium or magnesium starvation. Heavy applications f ground
limestone to raise the soil pH will usually make enough molybdenum
available for normal cane growth.
Finally, aluminum, sodium, strontium, boron, and lead are.
known to be essential for cane production. Minute quantities of
these elements are present in the plant. The soil in cane pro-
ducing areas appears to contain an adequate reserve of these elements,
as little and only localized response in cane growth to soil applications
of these elements have been reported to date. The role of the large
concentrations of silica in the cane plant is still largely un-
known. Some response to fertilization in Hawaii was recently re-
ported. Conclusive evidence, however, is still lacking in general.
Malavolta, E. and All. On the Mineral Nutrition of Some Tropical
Crops. International Potash Institute, Berne, 1962.
Sugarcane, being a very competitive crop with only a small pro-
fit margin per unit produced, should produce optimum yields for
economic survival. Yield will have declined below profitability
long before deficiency symptoms become apparent. For this reason
certain fertilizer mixtures, mostly based on prior cropping ex-
perience, are applied to plant and ratoon crops. Foliar diagnosis
often is used to establish these levels of fertilization.
Sugarcane is a crop for which modern diagnostic techniques
are used to their fullest extent. An intensive processing plant
is needed, and fertilizers are comparatively expensive in the
tropics because of the long hauling cost..
The spindle of the cane, having the highest level of physio-
logical activity in the plant, is used for the collection of tissue.
Counting the spindle as number zero, the youngest leaf with a visible
dewlap is designated as number one. Blades and sheaths of leaf
numbers one through four are collected from 10 stalks each taken
at random throughout the cane field. Mostly one set of 10 stalks
is taken for every 10 acres of cane. To facilitate collecting the
tissue, the entire top of each cane stalk is harvested. By removing
the joints, one at a time from below, each successive sheath with
the attached blade can be carefully separated from the enveloped
internode. Each of the four sheaths and blades so collected from
each stalk is now separated at the dewlap.
The midrib of each blade is discarded.! Only a section of the
green tissue measuring between 10-12 inches in length serves as
the sample for future chemical analyses. The leaf sections are
dried at 800C to a constant weight prior to pulverization in a
Wiley mill. The leaf sheaths are used for other determinations
to be discussed in the next chapter.
Results from chemical analyses of sugarcane tissues differ
with different countries and soil types. Also, they may differ
slightly among varieties, and between plant and ratoon crops
within the same region. The following table reports average
acceptable analytical values in elemental form for sugarcane leaves :
Table 2. Percentage of different elements in sugarcane leaves to
obtain optimum yield at harvesting.
Element Index or percentage Remarks
of element in leaf
blade, dry basis
Nitrogen 2.5-2.6% of N when cane is 2 The critical period for
months old; maintaining the nitrogen
2.0% of N when cane is 3 index is between the
months old; second and sixth month of
1.75% of N when cane is 4 cane growth. Failure to
months old; maintain the levels of
1.65% of N when cane is 51 N will result in a severe
months old. reduction of cane tonnage
at harvest. The nitrogen
index is reduced with
inadequate or excessive
Index or percentage
of element in leaf
blade, dry basis
o.2-0.22% of P.
1.20% of K.
0.17% of Ca.
Timing of application
is not as critical as
for nitrogen. The avail-
ability of phosphorus for
the remainder of the growing
period can be assumed
as adequate when the
reported index is reached
for 2 and 4 month old cane.
The critical periods
occur when cane is 3 and
6 months old. Leaf sam-
ples, therefore, should
be taken and analyzed
at least twice to correct
a possible deficiency
for this element.
An adequate fertiliza-
tion program with nitro-
gen will facilitate the
uptake of calcium and
reach the suggested index.
0.10% of Mg.
210 and 250 ppm.
10 and 100 ppm.
5 and 15 ppm.
2 and 100 ppm.
10 and 110 ppm.
0.02 and 0.80 ppm.
The analytical results from leaf samples are used for numerous reasons,
ranging from applied research to improving commercial yields. For in-
---Fertilizer dosage and type of mixture to be routinely applied to
cane can be determined, based on correlations between soil analyses,
leaf analyses, and final sugar yields.
---Nutrient deficiencies, either by visual or suspected symptoms, may
be confirmed by foliar Inalyses.
---Interaction between the uptake of two or more elements by cane
can be studied or confirmed, and can be correlated with sugar yield.
--The influence of chemical and physical soil properties on nutrient
uptake and sugar yield may be studied and appropriate steps may be
taken to correct adverse influences.
---The role of soil pH, moisture, and frequency of application and
placement of fertilizers on the uptake of nutrient by the cane
plant and sugar yield may be studied.
As a next step, the results from leaf analyses may be used for cor-
relating the efficiency for uptake of nutrients with growth indices
and, in turn, correlate these growth indices with the final sugar
yield. Such a step-wise correlation will achieve the guidance towards
optimum growth and sugar yield by human effort through manipulations of
nutrient and moisture applications. This, then, is the principle
behind the "crop logging" system to be discussed in the next chapter.