Resistance and Quality Breeding in Winter Oil Rapeseed
Resistance and Quality
Breeding in Winter Oil Rapeseed
June 19, 2014
Bharati Singh - Resistance and Quality Breeding in Winter Oil Rapeseed 1
Winter rapeseed (Brassica napus) is one of the signiﬁcant agricultural crop which is grown commonly for
production of oil and biofuel. After the extraction of the oil, oil cake which contains high protein can
be used for animal feed. It is mainly grown in Europe, Asia, North America and Australia. It is generally
produced in a crop rotation including winter wheat and barley. This contributes in decreasing the occurrence
of root diseases and increasing organic matters in the soil. It is believed that the nutritional requirement of
crop is the most signiﬁcant factor. The nitrogen plays a very important role in intensifying the yield. In one
of the studies, Hocking, et. al.  published that the requirement of nitrogen by rapeseed in comparison to
wheat is 25% more. The yield response of the rapeseed with increasing nitrogen concentration in soil varies
with different environmental factors, like weather, soil type, residual fertility of the soil, water content and
cultivar. Many of the studies have pointed out that the both growth and yield of the rapeseed are increased
remarkably by high dose of applied nitrogen. Nitrogen enhances yield by regulating many growth factors,
such as number of branches and pods per plant seeds per pod. Selecting an adequate dose, source and
timing of nitrogen fertilizer application and the gap between the sowing of the seeds are notable aspects for
the promising production of rapeseed .
1.1 Fluorobiology of rapeseed
The ﬂower is radial having four petals, four sepals and six stamens. Out of the six stamens, two of the
stamens are short which face outside than the inner ones which surrounds the stigma. The yellow colour of
leaves attracts insects. The pollination could be either self pollination or cross pollination. The studies have
shown that the cross pollination increases seed yield which results in increase of oil content and heavier
seeds . The cross pollination reduces inbreeding depression. It also results in gene exchange.
1.2 Plant architecture
The rapeseed is an annual herbicide plant consisting of 1-2 cm high erect stem branches, and long thin tap
root. The ﬂowers are yellow in colour and are present in bunch on the shoots in the form of racemes .
The branching of the plants enables to compensate the gap in the ﬁeld. This makes rapeseed very ﬂexible
and adaptable. Further, the branching contributes to the stability of the plant. Generally 50 to 70 seeds are
sown per square meter. The immature seeds are elongated pods and green in colour which, ﬁnally, turns
into brown. Each pod contains up to 20 seeds. The brown colour of the seeds at the maturity is due to the
Bharati Singh - Resistance and Quality Breeding in Winter Oil Rapeseed 2
presence of phenolic compound, tannin.
Determining harvesting period is very hard. This is not only because of long ﬂowering period but matu-
ration is also irregular. The most ideal time of harvesting is when the ﬁrst pod cracks which are present
on the main stem. The lower moisture content in the seeds helps in saving cost for drying up seeds to the
adequate parameters. In Germany, harvesting is completely machine dependent. The yield of the rapeseed
in Germany is 4-5 million tonnes per hectare.
2 Aspects of Quality Breeding
1. Reduction of anti-nutritional factors
(a) Glucosinolate content: It is a secondary metabolite which occurs in most of the plants of the
order Brassicales. The glucosinolates provide bitter taste. Genotype, developmental state, en-
vironment and age of the plant have great impact on the content of glucosinolates. It is present
in many parts of plants like root, stems, leaves but their highest occurrence is seen in the seeds.
The hydrolysis of glucosinolate results in the production of many goitrogenic and toxic com-
pounds. The enzyme responsible for this is myrosinase . The hydrolysis results in the forma-
tion of isothiocynate, thiocynate and nitrile. The goitrin produced interferes with the secretion
of thyroxine hormone. Therefore, the rapeseed oil is harmful for the person suffering from
(b) Tannine content: In rapeseed, the tannine causes dark colour of seed coat and they deposits
in the endothelium cell layer between outer integument and aleuronic layer. It can have major
inﬂuence on animal nutrition because of their capability to form indigestible bitter tasting com-
plex with protein. One possibility to minimize this problem can be done by breeding rapeseed
with reduced tannins which occur in seed coat .
(c) Sinapine: It is a choline ester of sinapic acid. It has several unsatisfactory properties to animal
feed like bitter taste, which make it less acceptable to animals. The presence of sinapine at the
level of 1gm/kg, in the diet of certain brown egg laying hens, results in ﬁshy odour or taste in
Bharati Singh - Resistance and Quality Breeding in Winter Oil Rapeseed 3
(d) Phytic acid: It is one of the main components of all plant seeds and has great afﬁnity to bind
positively charged molecules like cations and proteins. The interaction between phytic acid and
minerals results in the formation of complex molecules which are insoluble at the pH which oc-
cur in intestines. Therefore, adsorption becomes hard. Further, the complex molecules between
protein and phytic acid may also have negative effect on the enzymatic digestion of protein.
2. High oil content and high yield
(a) 00 quality: Zero euric acid is essential when rapeseed oil is used as food oil. Low glucosinolate
content is necessary when used as animal feed. High erucic acid rapeseed (HEAR) + 0 quality
varieties are cultivated for industrial purpose. In Germany, it is cultivated on around 20,000
(b) HOLLI types: This is the special variety having higher content of oleic acid (up to 80%) and
reduced content of linolenic acid (less than 4%). It makes suitable for its use at high temperature
and cooking. Post ﬂowering temperature are believed to have great impact on the composition
of fatty acid in many oil seed crop species. The yield also depends on factors such as number
of pod per plant and seeds per pod.
(c) Omega 3 fatty acid: In the rapeseed oil reduces the risk for heart disease. It is also rich in
vitamin E which act as antioxidant and reduces the risk for cancer disease.
Other aspects of quality breeding include shortness of stems, stem stiffness, earliness of ﬂowering
3 Aspects of Resistance Breeding
1. Blackleg diseases: This is the main disease occurring in Brassica crops such as cabbage, turnip and
rapeseed. This disease is caused by L. maculans. For the ﬁrst time it was observed on the stem
of red cabbage. Winter and spring crops, both types, are damaged by blackleg disease mainly in
Australia, Europe and North America. This pathogen is capable to kill plants even at the seedling
stage, infecting cotyledons, leaves, stems, roots, pods. Therefore, control of occurrence of Blackleg
disease is one of the important breeding programs.
Symptoms of this disease are leaf lesions and stem canker. The onset of fungus is represented by
dirty whitish spot on the leaves with small dark fruiting bodies. Usually black lesions are also seen
Bharati Singh - Resistance and Quality Breeding in Winter Oil Rapeseed 4
on the leaves. It can also occur on pods and results in premature pod shatter. During the infection
stage, the pathogens move downward towards the tap roots of the plants .
2. Clubroot disease: This disease is a soil borne disease which is caused by plasmodiophora brassicae.
Research has shown that infection of 90% of the plants leads about 50% loss in seed yield and also
remarkable reduction in seed oil content and an enhancement in chlorophyll content are generally
correlated with the onset of this disease . When plant root is invaded by fungus, it causes imbalance
of hormone which results in increased cell division and growth, and forms characteristic crown galls.
3. Verticilium wilt: One of the most signiﬁcant pathogen of oilseed rape in Europe is Verticillium longis-
porum, which is a soil borne, vascular fungal pathogen that infects roots and leads to premature ripen-
ing of the seeds . This fungus is capable to survive for many years in the soil and block nutrient
ﬂow. Use of fungicides is not promising. Therefore new resistant cultivar line is required to prevent
losses to the seed yield caused by pathogen .
4. Sclerotinia stem rot: This is caused by the fungal pathogen sclerotinia sclerotiorum which is a serious
problem in Germany and other European countries. Plant is generally manifested by pathogen as
mycelia or airborne ascospores. Although partial resistance against the disease has been achieved but
fully or highly resistant line has not been achieved yet.
3.1 Breeding methods in oil seed rape
(a) Resynthesized rapeseed
(b) Line breeding
(c) Hybrid breeding
(d) Male sterility system
The Hybrid varieties are produced by crossing a female plant which does not produce pollen. It means
they are male sterile with a male plant that produce pollen. This restores100% male fertility.
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Bharati Singh - Resistance and Quality Breeding in Winter Oil Rapeseed 5
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