Types
of oilseed rape.
Winter
swede rape accounts for most of the rape crop grown in the UK.
Rapeseed oil is mainly used in cooking fats, spreads and margarines.
The protein rich meal is used for animal feed.
Double
low varieties.
All "double low" varieties recommended
for food use contain less than 2% erucic acid and 25 micromoles/g
of seed glucosinolate.
HEAR rapes. These high erucic acid varieties are
non-food types and are grown for industrial use. The oil has
anti-slip properties that are suitable for products such as
cling film and polythene.
Variety
types.
Traditional varieties. These varieties are maintained
by self-pollination
Hybrids.
These types depend on crossing differing male and female parents
at the seed production stage. F1 hybrids are more vigorous and
higher yielding than their parents. This vigour drops off quickly
in successive generations, as plants self-pollinate and segregate
into parental types.
Types of hybrids.
Restored hybrids. (Royal, Disco). Although the
female parent is male-sterile, the pollen from the male parent
over-rides this effect and therefore the F1 hybrid plants are
fully fertile.
Varietal
associations. (Synergy). These comprise a mixture of
male sterile hybrids and one or more male fertile varieties.
Usually in a 80:20 mix, which pollinate the hybrid plants. Varietal
associations carry some risk of poor pollination and hence reduced
yield in adverse conditions.
"Super"
varietal associations. (Gemini). In this system a restored
hybrid is used as the pollinator. Both components should be
equally competitive and pollination assured.
3-way
hybrids. (Cohort). This system uses two successive hybrid
crosses to overcome high glucosinolates contents. The commercial
crop is 100% fertile or segregates into 50:50 mixture of male
fertile/male sterile plants.
Varieties
With a myriad of varieties in the market place, choosing a variety
or varieties of oilseed rape for the coming season is no mean
task. There are in excess of 30 varieties on offer, all with
an over enthusiastic seed merchant looking for an order. It
is important to make the right choice.
What
do we need to consider when choosing a variety?
1) Potential yield?
2) Is it suitable for drilling early?
3) Can we keep home saved seed from it for planting next year?
4) Is it early, medium or late to mature?
5) Does it stand well or is it prone to lodging?
6) What levels of oil and glucosinolates are to be expected
from it?
7) Does it have good levels of disease resistance?
8) What is its stem stiffness like?
9) Are we interested in growing a hybrid or a conventional variety?
Hybrids.
Hybrids are created by crossing parental varieties, to produce
an F1 generation with greater vigour and yield. Hybrid seed
is produced by preventing self-fertilisation of the maternal
parent. A few years ago many of the top yielding varieties were
hybrids, however over the last year or so, conventional varieties
have been bred that can now give hybrids a run for their money.
At the present time hybrids offer no more than can be achieved
from conventional varieties and so there seems little need to
change.
Due to the inherent vigour and to some degree the cost of producing
a hybrid seed, seed rates used are below those of conventional
varieties. This helps promote branching, reduce the likelihood
of lodging of the vigorous hybrid plants, and in the case of
varietal associations, avoids the risk of pollinator plants
being lost through competition during early establishment and
growth. The downside of drilling at low seed rates is the risk
of poor establishment through poor seedbed conditions, slugs
or pigeons. Good pest and disease control is essential if the
full rewards are to be had from growing a hybrid.
Pollen beetle control is important for varietal association
as the beetles may concentrate on the pollinator plants and
threaten pollen supplies, which in turn will reduce seed and
pod set.
Good disease control is essential in varietal association to
ensure the health of both the hybrid and the pollinator. Without
this, poor seed set could result.
Hybrids grow rapidly in the spring and so it is very important
to get an early top dressing on. Sulphur is particularly important
to hybrids and so this must be amply supplied.
It is not wise to keep seed from a hybrid for sowing the next
year due to reversion and an imbalance of pollinator plants.
Hybrids are drilled later than conventional varieties for the
same reasons as for seed rates.
Disco 104. This variety has been around for a couple
of years now and offers a high potential yield with high oil
content. It has good all-round disease resistance but is not
suitable to early sowing. It has medium maturity.
Royal
104. One of the most popular hybrids grown at the moment.
It offers high yield, but its quality traits (oil % and glucosinolate
level) are now surpassed by other varieties. It is very susceptible
to stem canker (4). Matures reasonably early and has good lodging
resistance.
Toccata
105. This variety offers a yield similar to winner. It is
tall but reasonably stiff, offering slightly better disease
resistance than Royal. It has a stem canker rating of 5 and
is a medium-late maturing variety.
Summary.
Hybrids need attention to husbandry detail and good seedbeds
for correct establishment. In return they will offer you the
excellent yields and in some cases high oil contents. They must
not be drilled early and seed cannot be saved for growing the
following year. Royal, Toccata and Disco are restored hybrids.
It must be stressed that there are now conventional varieties
offering similar yields but if you wish to give them a try consider:
Disco, Royal and Toccata.
Conventional
varieties.
Many of the conventional varieties are very similar in what
they can offer and so we will only be summarising what we consider
are the ones that offer that little something extra and stand
out from the rest.
Winner
107 Top of the HGCA (2004) recommended list, a tall variety
that has shown high yields over the last 4 years. It has always
had a question mark against its ability to stand in a wet spring
and unfortunately its ability to stand has proved to be its
Achilles heel this year. Many winner crops were flat with a
high degree of secondary growth present It generally has good
all-round disease resistance. It is a variety offering medium-late
maturity. For the coming season we suggest reducing the amount
of winner grown and avoid putting this on very fertile soils.
Canberra
98/Fortis 101. These varieties have performed very similarly
over the last few seasons and can therefore be discussed together.
They have Apex characteristics, being both short and stiff with
Canberra being the shorter of the two. They define the low biomass
variety type and coupled with good resistance to light leaf
spot and stem canker are a model for ease of management.
Caracus/Labrador.
Both failed to gain recommendation last year (2004), but are
up for reselection this year. Caracus is a short variety, however
it shows a less erect canopy type as it matures. Labrador is
fairly short and offers high yields. It has been observed that
this variety has shown more lodging this year than in previous
years and is a variety that needs to be sown at fairly low seed
rates and managed with a PGR in the spring. Very late to mature.
Courage.
100 It offers good yield with high oil content and stiff,
short straw. The performance of this variety has been variable
over the last few seasons. This may be due to the fact the variety
has a low rating for Phoma resistance where the disease may
not have been adequately controlled. It is an early to mature
variety.
Tequila
100 A good yielding variety with stiff straw (one of the
best to stand) and good disease resistance, this is another
Apex type. It matures a couple of days later than Winner and
flowers a week later.
Expert
106 A high yielding variety suitable for growing in the
East. It is stiff with good lodging resistance, moderately late
maturing and has good resistance to stem canker.
Lioness.
109.A new variety with exceptional gross output due to its
potential high oil content. It is fairly short and stiff although
it has only moderate resistance to stem canker. It will be a
variety that will warrant a full fungicidal programme, particularly
in the autumn. Perhaps worth a small dabble with if you can
get the seed.
Castille.This
is a short variety with good stem canker resistance and represents
a yield advance on Canberra in the low biomass category. Early
flowering variety.
There
are four new varieties that are more or less equal to Winner
for gross output, with three of them offering a better resistance
to lodging.
SW
Gospel. 105 Yet another high yielding short variety. Lodging
9, later maturing and weak on canker. Done well in Morley trials.
Astrid.
104 Good yielding variety that stands extremely well and
matures at a similar time to Winner. Good resistance to canker.
Aragon.
108. Good yield with medium height but slightly weaker straw
than the 3 other varieties. It has good resistance to light
leaf spot. This variety has done well in the Morley trials.
Grizzly.
101 Offers good all round disease control with high oil
content. It is a short variety, lodging rating 9.
Choice
All of the above are worth consideration for different reasons.
Try to spread acreage over two varieties, or more if the acreage
is large. This will help sprayer and harvesting capacity.
For
the coming season.
If a very large acreage is to be drilled consider growing varieties
that mature at differing times.
For an early start consider Fortis, Courage, Disco
and Royal.
For middle of the road consider Winner, Astrid,
Aragon and Recital and for later maturing consider
Lioness, Gospel, Grizzly, Canberra, Toccata, Expert and Tequila.
The last two should in theory be the latest to mature.
Once you have selected the varieties for early, middle and late
maturity then select the ones of these that offer good resistance
to both lodging and canker.
For early drilling Disco followed by Fortis would
be the best choice.
Middle of the road drillings Astrid, Aragon, Winner
and Recital and for the later to mature varieties,
Expert, Tequila, Gospel and Lioness.
For that low biomass situation eg.where direct combining is
of high priority then consider Castille and Canberra.
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