Table of Contents
Downey, R.K. 1990. Canola: A quality brassica oilseed. p. 211-217. In: J.
Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland,
Canola: A Quality Brassica Oilseed
- A NEW CANADIAN CROP
- OPPORTUNITIES AND PROBLEMS
- OIL QUALITY MODIFICATION
- MEAL QUALITY IMPROVEMENT
- AGRONOMIC ADVANCES
- CANOLA IN THE UNITED STATES
- Table 1
- Table 2
- Table 3
- Table 4
- Table 5
- Fig. 1
- Fig. 2
- Fig. 3
In many parts of the United States a crop called canola is being promoted. To
many, both the word and the crop will be largely unknown. This is not
surprising since canola is a coined name recently given to nutritionally
superior seed, oil and meal produced by genetically modified rapeseed plants.
Oilseed rape (Brassica napus L.) and turnip rape (B. campestris
L.), although relatively recent crop introductions to the north American
continent, are very new to most U.S. states. However, they have long been
cultivated as oil crops in Asia and northern Europe. The seed harvested from
these crops is small, round and black, brown or yellow in color. Upon
crushing, the seeds yield 40 to 44% oil and a nutritionally well balanced high
protein (36-37%) meal. The seed looks very much like turnip or mustard seed or
seed of cabbage and broccoli, to which these crops are closely related.
The rapeseed/canola crop is the world's third most important edible oil source
with an annual growth rate exceeding that of palm (Table 1). The main
rapeseed-producing regions of the world are China, Canada, the Indian
subcontinent, and Northern Europe, where, depending upon the duration and
severity of the winter, either the annual or the biennial form of these crops
is grown. In general, the biennial form of rapeseed/canola is considered to be
less winter-hardy than winter barley. Throughout much of the Indian
subcontinent, a third Brassica oilseed species, Brassica juncea (L.)
Czern., commonly known as tame mustard, is grown on about 60% of the oilseed
The oilseed Brassicas are cool season crops and in Canada production is
centered in the more northerly areas of the Great Plains. The Canadian
development of the rapeseed/canola crop is frequently referred to as a
Cinderella story. The crop has undergone a great metamorphosis in quality and
production since it was first grown as an emergency war measure on a few acres
in 1942. At that time, rapeseed oil was considered an essential lubricant
because it could cling to water- and steam-washed metal surfaces better than
any other oil. Since the naval ships and trains of the time were
steam-powered, and with the European and Asian rape oil supplies cut off,
Canada was asked to undertake production. The annual form of the B.
napus species was introduced first, followed shortly by B.
It quickly became evident that both these crop plants were well adapted to the
Canadian climate and required only minor modifications to the existing grain
growing and handling system. The small round seeds necessitated seed drill
adjustments to uniformly sow only a few pounds per acre. Likewise, the throat
of the grain swathers had to be enlarged and a swath roller developed to reduce
the risk of swaths moving in the wind. It was also found necessary to reduce
the combine cylinder speed by about one-half and open the concaves wide to
reduce seed cracking and expedite the handling of a large volume of material.
Fortunately these adjustments were of a minor nature and did not hinder the
early acceptance of these new crop species.
Under a guaranteed price support system, crop area expanded (Table 2).
However, with the loss of the price support following the war and the
replacement of steam power by diesel, the crop faltered until private
entrepreneurs established a market in Japan where the oil was, and still is,
considered a premium oil for deep fat frying.
From the outset, it was realized that oilseed rape could be a major source of
edible oil for Canada, which until that time was importing almost 90% of its
edible oil needs. The domestic market penetration of rapeseed oil and meal was
hampered by the presence in the seed of sulfur compounds called glucosinolates.
These compounds, of which about 90 are known, give the desired flavor and odor
to the cole vegetables, mustard and many other cruciferous crops, but are
undesirable in concentrated feeds, both for palatability and nutritional
reasons. When cells of the seed are broken and moisture is present, the
myrosinase enzyme hydrolyzes the glucosinolates to release sulfur, glucose and
isothiocyanates (Fig. 1). The isothiocyanates are active goitergens and
interfere with the iodine uptake by the thyroid gland in non-ruminant animals,
such as swine and poultry. Further, some of the sulfur-containing breakdown
products were often carried over into the oil, resulting in the inhibition of
the catalyst required for hydrogenation in the manufacture of margarines and
shortenings. To overcome these problems, the method of oilseed extraction was
modified to exclude moisture from the process and to heat-inactivate the
myrosinase enzyme as one of the first steps in the oil extraction process.
This innovation proved to be a partial solution to the glucosinolate problem
since these compounds remained intact in the meal and as such were relatively
innocuous feed constituents. Based on this process, a domestic market for oil
and meal began to expand. This development, together with a strong demand for
seed exports, provided growers with a cash market in times of relatively high
Average yields increased over the years as growers realized that by sowing
rapeseed on their best land and applying extra management and inputs, both
returns and marketability were better than for cereal grains. The availability
of the herbicide, Treflan, that became available about 1970-71 and which gave
good control of many of the most serious weeds of rapeseed/canola, also
assisted in raising average yields. Thus, by 1970, the canola crop had
expanded to a total of 1.6 million hectares with an average yield of 1,259
kg/ha (1,123 lb./acre) (Table 2) and rapeseed oil had captured some 35% of the
domestic edible oil market.
Canadian and European nutritionists were interested in rapeseed oil because it
differed from other edible vegetable oils in its fatty acid composition.
Rapeseed oil contains significant amounts of the monoenoic fatty adds with 20
(eicosenoic) and 22 (erucic) carbon chains as opposed to the common carbon
chain lengths of 16 and 18 carbon atoms found in most vegetable oils (Table 3).
Feeding studies with laboratory rats in the late 1940s and early 1950s
suggested that these long chain fatty adds may not be the most desirable from a
nutritional point of view and studies were undertaken to see if they could be
reduced through plant breeding. In those days, gas chromatography was in its
infancy but it did provide a relatively fast and accurate method for seed oil
fatty acid analysis. The application of this technique led to the
identification of low erucic acid plants in both species, with the first low
erucic B. napus variety being released in 1968 and the first B.
campestris variety in 1971. This change in oil composition was achieved by
genetically blocking the biosynthetic pathway for fatty add carbon chain
elongation as the oil is laid down in the developing seed (Fig. 2). By 1970,
the nutritionists had found that the low erucic rapeseed oil was nutritionally
superior to the original high erucic acid oil. As a result, Canada completely
converted its 4 million acres to low erucic varieties within two years. This
entirely new edible oil was found to have superior properties as a salad and
cooking oil as well as being suitable for margarine and shortening blends. The
shift in Canadian usage between 1971, the last year that the high erucic acid
oil was used, and 1987, has been dramatic both in the proportion and amount of
canola oil utilized (Fig. 3).
Further modifications in the fatty acid composition of rapeseed oil are being
investigated. Of considerable interest is the development of a Brassica
napus variety with a low linolenic content of less than 3%. Such an oil
has been shown to have superior keeping qualities. Similarly, it is possible
to raise the level of the polyunsaturated fatty acid linoleic to 30% or more
and at the same time reduce the linolenic values. The breeder's dilemma at the
moment is that nutritionists are saying that the present composition of the low
erucic acid rapeseed oil is almost ideal, with the lowest saturated fatty acid
content of any of the vegetable oils coupled with approximately 8 to 10%
alpha-linolenic acid. Indeed, low erucic acid rapeseed oil was awarded the
1987 American Food Product of the Year by the American Heart Foundation of New
Although the development of a superior edible oil had been achieved by 1971,
the continuing presence of glucosinolates in the high protein meal was a major
constraint to market expansion. Even though the intact glucosinolates were
only mildly anti-nutritional in non-ruminant animals, some adverse effects on
feed efficiency and weight gains were found in some classes of swine and
poultry when high levels of rapeseed meal was fed. Again, the development of
fast, accurate chemical methods to determine the presence and amounts of the
various glucosinolates led to the identification of plants of the B.
napus cultivar `Bronowski' from Poland which were essentially free of the
glucosinolates normally found in rapeseed. These low glucosinolate genes were
incorporated into adapted high-yielding varieties of B. napus and
transferred to the B. campestris species. The result has been the
virtual removal of all non-economic constraints to the feeding of low
glucosinolate rapeseed meal to all classes of livestock and poultry
As a result of the nutritional upgrading of the oil and the meal, a new name
was required to distinguish these products from the old-style rapeseed and thus
the word "canola" was coined and trademarked and defined as having less than 2%
erucic acid in the oil and less than 30 micromoles of the aliphatic
glucosinolates in the oil-free meal. Thus, all canola is rapeseed but not all
rapeseed is canola.
As important as these new quality traits are to the market, farmers will only
produce the crop if it's agronomically well-adapted and gives superior yields.
Canadian breeders have not ignored this requirement, and substantial advances
have been made in increasing the seed yield of B. napus while at the
same time reducing the length of the growing season required (Table 4). Oil
contents have also been raised significantly while protein content of the meal
has been maintained. Agronomic improvements in the early maturing B.
campestris cultivars that are self-incompatible cross-fertile have been
more difficult to achieve, but new strains shortly to be released will have at
least 7% higher seed yield and the oil content increased by about 1.5% (Table
It should also be noted that as the area of canola has expanded, the problems
with diseases and insects have increased substantially. Flea beetles,
(Phyllotreta sp.), which attack the emerging seedlings, are a continuous
threat that requires seed treatment for protection of all fields. Likewise,
the lepidopterous insects can be very damaging in some locations and years. It
is anticipated that the introduction of genes for specific Bacillus
thuringensis toxins to control both insect genera will be possible
within a few years. Diseases such as Sclerotinia, blackleg
(Leptosphaeria maculans), Rhizoctonia solani and white rust
(Albugo candida) are all important diseases which must be controlled
either through incorporating resistance into the plant or through the use of
In weed control, a number of herbicides are available for use in canola and
cultivars tolerant to the triazine family of herbicides have been developed.
Unfortunately, the triazine-tolerant material developed to date is about 20%
lower yielding than the triazine-susceptible cultivars, thus limiting their use
to fields that are heavily infested with cruciferous weeds such as stinkweed or
wild mustard. More recently, the gene for glyphosate (Roundup) resistance has
been transferred into B. napus canola plants and the progeny are now
under field evaluation. There is also indication that genes for resistance to
chlorsulfuron (Glean) and glufosinate ammonium (Basta) have also been
transferred into canola.
In the future, hybrids are expected to raise the yield of both species of
canola. Commercial hybrids of B. napus are now in their second year of
official Canadian trials and it is expected that they will make their way into
commercial production within the next few years.
The rapeseed/canola story has been an exciting one for Canada and it's far from
over. Canola could experience a rapid growth in the United States over the
next few years; however, comparative trials have yet to clearly define the area
and rotations where the crop can economically compete within the presently
established cropping system.
- Downey, R.K. 1966. Rapeseed botany, production and utilization. p. 7-23. In:
Rapeseed Meal for Livestock and Poultry-a Review. Canad. Agric. Publ. 1257.
- Downey, R.K. and G.F.W. Rakow. 1986. Rapeseed and mustard. In: W. Fehr (ed.).
Principles of cultivar development, Vol. 2, Crop species. p. 437-483. Macmillan
Pub. Co, Inc.
- Downey, R.K. and B.R. Stefansson. 1988. Canola. In: D. Evans and N. Brown
Foulds (eds.). The Canadian encyclopedia. 2nd Ed. Hurtig Publishers Ltd.
- Kramer, J.K.G., F.D. Sauer and W.J. Pigden. 1983. High and low erucic acid
rapeseed oils. Academic Press, New York.
- McLeod, A.D. 1974. The story of rapeseed in Western Canada. Saskatchewan Wheat
- Thomas, P. 1984. Canola growers' manual. Canola Council of Canada, Winnipeg,
- Tsunoda, S., K. Hinata and C. Gomez-Campo. 1980. Brassica crops and wild
allies. Jap. Sci. Soc. Press, Tokyo.
Table 1. World vegetable oil production as percent of the 10 major oil
crops and percent change 1982/83 through 1987/88.
Source: Oil World
|Vegetable oil ||1982/83 ||1984/85 ||1986/87 ||1987/88|| % change on |
|Millions of tonnes|
|Total 10 major oils ||46.1 ||49.8|| 55.2 ||58.0 ||26|
|Percentage of 10 major oil crops|
|Soybean ||30.4|| 27.5 ||27.8 ||26.5 ||9|
|Palm|| 12.1 ||13.1 ||14.1 ||14.2 ||48|
|Rapeseed ||10.8 ||11.6|| 13.1 ||13.2 ||53|
|Sunflower ||13.0 ||13.0 ||12.8 ||12.9 ||25|
Cotton ||6.7 ||7.8 ||5.7 ||5.9 ||10|
Groundnut ||6.1|| 6.2|| 6.0 ||5.1 ||5|
Table 2. Production trends in Western Canada (selected years).
|Year ||Area (1000 ha) ||Yield (kg/ha)|
1943 ||1 ||969|
1944 ||4 ||793|
1946 ||9 ||756|
1948|| 32 ||1,132|
1950 ||<1|| 352|
1952 ||7 ||1,057|
1955 ||55|| 799|
1960 ||305 ||1,032|
1965 ||574 ||1,107|
1970 ||1,620|| 1,259|
|1975|| 1,580 ||1,259|
|1979 ||3,280 ||1,277|
|1980 ||2,100 ||1,510|
|1982 ||1,720 ||1,592|
|1984|| 2,820 ||1,384|
|1985 ||2,711 ||1,239|
|1986 ||2,642 ||1,440|
|1987|| 2,655 ||1,438|
|1988 ||3,626 ||1,102|
Table 3. Percent fatty acid composition of Canadian vegetable oils.
|Fatty acid|| Symbol ||Brassica |
| Brassica |
Sunflower ||Soy bean|
|Palmitic ||C16:0 ||4.0 ||4.9 ||4.7 ||7.2 ||11.5|
|Stearic ||C18:0|| 1.5|| 1.6 ||1.8 ||4.1 ||3.9|
|Oleic ||C18:1 ||17.0 ||33.0 ||63.0 ||16.2 ||24.6|
|Linoleic ||C18:2 ||13.0 ||20.4 ||20.0 ||72.5 ||52.0|
|Linolenic ||C18:3 ||9.0 ||7.6 ||8.6 ||0.0 ||8.0|
|Eicosenoic ||C20:1 ||14.5 ||9.9 ||1.9 ||0.0 ||0.0|
|Erucic ||C22:1 ||41.0|| 23.0 ||0.0|| 0.0 ||0.0|
Table 4. The relative performance of some Canadian cultivars of
Brassica napus in Western Canada.
zE = erucic acid; G = glucosinolates
|Year released ||Cultivar name|| Yield (%) ||Days to |
|% oil |
|% protein |
|1943 ||'Argentine' ||100 ||101 ||40.5 ||47.1 ||HiEG|
|1954 ||'Golden' ||101 ||= ||41.1 ||43.9 ||HiEG|
|1963 ||'Tanka' ||106 ||= ||42.7 ||46.3 ||HiEG|
|1966 ||'Target' ||109 ||-2 ||43.9 ||45.4 ||HiEG|
|1970 ||'Turret' ||111 ||-3 ||44.5 ||45.4 ||HiEG|
|1968 ||'Oro' ||107 ||+5 ||41.7 ||43.4 ||LowE|
|1973|| 'Midas' ||118 ||-3 ||43.8 ||42.9 ||LowE|
|1974 ||'Tower' ||112 ||-4 ||42.6 ||47.2 ||LowEG|
|1977|| 'Regent' ||115 ||-3 ||43.1 ||47.0 ||LowEG|
|1981|| 'Andor' ||119 ||-6 ||43.6 ||45.9 ||LowEG|
|1982 ||'Westar' ||127 ||-6 ||44.3 ||46.0 ||LowEG|
Table 5. Advances in agronomic performance in Brassica
|% oil |
|% prot. |
|1943 ||'Polish' ||100 ||40.5 ||43.6 ||HiEG|
|1964 ||'Echo' ||112 ||40.8 ||43.7 ||HiEG|
|1969 ||'Polar' ||109 ||42.3 ||44.2 ||HiEG|
|1973 ||'Torch' ||111 ||40.1 ||43.2 ||LowE|
|1977 ||'Candle' ||103 ||42.0 ||43.2 ||LowEG|
|1981 ||'Tobin' ||110 ||42.5 ||43.2 ||LowEG|
|1989 ||'Parkland' ||117 ||44.0 ||43.7 ||LowEG|
Fig. 1. Products of myrosinase hydrolysis of the glucosinolates.
Fig. 2. Biosynthetic pathways of the major fatty acids in vegetable
Fig. 3. Canadian vegetable oil usage.
Last update August 27, 1997