Canola and Frost: What Happens to the Seed?

Canola and Frost: What Happens to the Seed?
Robert Park, Oilseed Specialist, Manitoba Agriculture, Food and Rural Initiatives, Soils & Crops Branch
Carman, MB R0G 0J0 Email: [email protected]
Canola and Frost – What
happens to the seed?
Robert Park
Oilseed Specialist
MAFRI
Growing Degree Days
•
2004 Examples of low temperature impact on Growing Degree
Day accumulation1:
Location
Edmonton
Saskatoon
Regina
Winnipeg
2004 GDD
936
1030
1009
1045
30 year av. GDD
1092
1328
1380
1454
% of 30 year av.
86%
78%
73%
72%
Occurrence
Lowest since 1977
Lowest on
record
(>30 years)
Lowest on
record
(>30 years)
Lowest on record
(>30 years)
•
1Growing Degree days (GDD’s) are heat units accumulated each day during the growing season.
GDD’s are
determined by adding the high and low temperatures of each day and dividing by two. The base temperature
for a specific crop is subtracted from this average. For canola a base of 5 C is used.
Canola and Frost: What Happens to the Seed?
Robert Park, Oilseed Specialist, Manitoba Agriculture, Food and Rural Initiatives, Soils & Crops Branch
Carman, MB R0G 0J0 Email: [email protected]
Minimum Temperatures (˚C)
June 24, 2004
Minimum Temperatures (°C)
August 20, 2004
(°C)
Manitoba Canola 2004
• Manitoba planted 2.6 million acres in 2004,
average yield est. of 30.7 bushels / acres, above
average
• Very cool & wet conditions in all parts of
Manitoba. Some more than others
• 30% early planted, 50% mid to late planting and
20% very late planted.
• Early frost SW / NW and SE Manitoba – Aug 20
• Killing frost all of Manitoba – Oct 1
Green Seed in Canola
• What are the causes
-Frost of immature seeds
-Disease - Alternaria Black spot
-Hot dry conditions during and after
swathing
-Variable stands = Variable development
-Variety characteristics?????
The impact of abiotic stress during
seed development
• Depends on 2 major factors – level of
stress and moisture content in the seed
(maturity)
- Seed shriveling
- Altered protein and / or oil synthesis
- Loss of germination
- Retention of chlorophyll and other
pigments
- Precocious germination
Frost on immature Canola
• Degrees and duration of the frost and the
moisture content of the seed influence the
level of damage.
- e.g. Frost > -5 at high seed moisture is
lethal
- Lethal due to the formation of ice crystals
that physically disrupt membranes and
enzymes.
Canola and Frost: What Happens to the Seed?
Robert Park, Oilseed Specialist, Manitoba Agriculture, Food and Rural Initiatives, Soils & Crops Branch
Carman, MB R0G 0J0 Email: [email protected]
Frost on immature Canola
• Visual Pod Damage
- Heavy damage will
result in the pods
turning black, total
seed collapse, pod
drop
- Light frost will turn
pods white or whitespeckled, some seed
collapse????
Green Seed Problems
• We generally say that frost causes a
disruption in chlorophyll degradation due
to enzyme damage. Resulting in high
Chlorophyll…..
• This season we predicted a very high level
of green seed following the Aug 20 frost
but it didn’t happen.
• Majority of early to mid-late planted canola
was all #1 – What happened????
Green Seed Problems
• Research has shown that chorophyllase
activity is activated and synthesized
following frost. NEWS TO ME…..
• Peroxidase activity is inhibited following
sub-lethal frost and could be responsible
for de-greening failure????
• Seed moisture is the over riding factor in
chlorophyll breakdown. The wet fall
allowed for more breakdown than
expected.
Green Seed Problems
• After a sub-lethal frost
there is rapid moisture
loss from pod walls,
followed by rapid
moisture loss from the
seed.
• Min of 20% seed
moisture is need for
enzyme activity.
• Frosted canola - go
from 50% to 12% in a
week.
Green Seed Problems
• Re-hydration of frostinduced green seeds to
20% moisture for 7
days led to a 25%
reduction in total
pigment content
(Johnson-Flanagan et
al, 1994)
• 40% required for germ.
• Did this happen in
2004? Maybe???
Canola and Frost: What Happens to the Seed?
Robert Park, Oilseed Specialist, Manitoba Agriculture, Food and Rural Initiatives, Soils & Crops Branch
Carman, MB R0G 0J0 Email: [email protected]
Last time we had green seed 2001
• Very hot, dry (low humidity) conditions at
and after swathing
• Rapid dry down of the swath - from 40 to
50% moisture to 4 to 7% in a week
• No time or moisture for chlorophyll
breakdown
• Result - canola in swath for 4 + weeks and
limited change in green seed count
Green seed reduction in the
bin????
• Green seed levels will
NOT decrease in bin.
• 15 to 20% seed
moisture is required
for enzyme activity
• Stored canola should
be less 10%
moisture.
Will sunlight reduce green
seed?
• Sunlight will bleach
the chlorophyll and
make it a lighter
green.
• May or may NOT help
• Very small changes
will occur over time.
Common Green Seed
Questions
• Will green seed be reduced in the bin?
• Will time in the swath simply reduce the
green seed count?
• Will sunlight reduce green seed?
• Does early swathing contribute to high
green seed count?
Time in the swath????
• Unless the seed
moisture is raised
back up to 20%
moisture it can stay in
swath till Christmas.
• Rain showers, high
humidity and morning
dues will help.
• Sprouting ?????????
Time of swathing????
• Early swathing will
increase your
chances of high
green seed levels.
• The environment is
the major factor.
• HOT, DRY, WINDY,
LOW HUMIDITY in
combination with
early swathing is BAD
Canola and Frost: What Happens to the Seed?
Robert Park, Oilseed Specialist, Manitoba Agriculture, Food and Rural Initiatives, Soils & Crops Branch
Carman, MB R0G 0J0 Email: [email protected]
Conclusion
• Seed moisture seems to be the over riding
factor in the breakdown of chlorophyll in
the seed.
• The fall of 2004 was not normal – the cool
moist fall allowed seed moistures to
remain higher than normal.
• The rate of dry down of the seed the most
important factor to consider when
assessing green seed issues.
Robert Park
Oilseed Specialist
MAFRI
1-204-745-5665
[email protected]
Table 4. Average Dates of Last Spring and First Fall Frosts and Average Frost-Free Days
The Manitoba Problem 2004
• Enzyme activity within
the seed breaks down
chlorophyll (green)
• High Chlorophyll
levels give the oil a
green tinge
• Consumers like clear
golden oil, not green
Planting Date & Crop
Stage
No Frost Damage
Top Damage Only
Deep Canopy Damage
Seeded Before May 18 – 5
to 10% seed color change
•Monitor for firmness in seed
•Wait for seed color change
•Treat as normal
•Monitor rate of dry down
•May want to wait for top
pods to shatter (frost
damaged seed) before
swathing
•Monitor rate of dry down (can be
rapid)
•May want to swath now to avoid
shelling losses
Seeded late May & early
June – off flower but no
seed color change
•Wait for seed firmness and
seed color change
•Treat as normal
•Wait for open fall
•Monitor rate of dry down
•May want to wait for top
pods to shatter (frost
damaged seed) before
swathing
•Be patient as swathing now
can not help yield and
quality
•Monitor rate of dry down (can be
rapid)
•Be patient, swathing now can not
help yield or quality however be
prepared to swath earlier than
normal to avoid shelling losses
Seeded in mid to late June –
just finishing flower
•Wait for seed firmness and
seed color change
•Treat as normal and wait for
open fall
•Monitor rate of dry down
•Allow the plant to mature
as much as possible
•No action needed
•Monitor rate of dry down
•May have lost open flowers and
immature pods
•May continue to flower
•Wait and see
• Wait for open fall
Average Date of Last
Spring Frost
Average Date of First Fall
Frost
Average Frost-Free Days
Morden, MB
May 14
September 27
129
Winnipeg, MB
May 16
September 25
123
Brandon, MB
May 19
September 19
108
Portage la Prairie, MB
May 11
September 29
131
Regina, SK
May 24
September 11
109
Watrous, SK
May 25
September 10
107
Saskatoon, SK
May 21
September 16
117
Indian Head, SK
May 27
September 15
110
Scott, SK
June 1
September 7
97
Melfort, SK
May 28
September 7
101
Lethbridge, AB
May 23
September 17
116
Lacombe, AB
May 31
September 8
99
Ellerslie, AB
May 24
September 11
109
Vermilion, AB
June 1
September 9
100
Fort Vermilion, AB
May 28
August 30
94
Area
The Manitoba Problem 2004
• A minimum of 15%
moisture is required
for enzyme activity
• Cool, cloudy & wet
weather is the best to
reduce Chlorophyll
content
• The opposite for what
you need for wheat.