Recommended

List trial yields

Farm yields

UK Oilseed rape yield trends

World Record 6.7 t/ha

UK 2015

Components of yield

Yield = number of seeds x seed weight

Seed number determination

Determined by photosynthesis during a 200-300oCd period after flowering (2-3 weeks)

Pod & seed numbers

0

5

10

15

20

25

30

0 5000 10000 15000

pods/m2

Se

ed

s p

er

po

d

Pod & seed numbers

0

5

10

15

20

25

30

0 5000 10000 15000

pods/m2

Se

ed

s p

er

po

d

0

20000

40000

60000

80000

100000

se

ed

s/m

2

Optimum canopy size

0

0.5

1

0 2 4 6

Green area index

Fraction of light intercepted

Fraction of

light

intercepted

Green area index

Optimum Canopy

Determination of seed size

Seed Filling

0

2

4

6

8

10

12

14

15-Mar 14-Apr 14-May 13-Jun 13-Jul

Bio

ma

ss

(t/h

a)

seed

pod wall

stem

Leaf

mid-flowering

Seed number

Seed size

Photosynthesis

0

0.2

0.4

0.6

0.8

1

Leaf Pod Stem

Photo

synth

etic

rate

Dense or lodged canopies

• Fewer leaves

• Poor light penetration

to leaves & lower pods

• Less seed filling

• Lodging reduces yield by up to 50%

‘Canopy Management’ methods • Nitrogen fertiliser • Plant Population • Plant Growth Regulators

Nitrogen for optimum canopy

y = 0.0219x

R2 = 0.8661

0

1

2

3

4

5

6

7

0 100 200 300

N uptake (kg/ha)

Gre

en

Are

a In

de

x (G

AI)

Canopy Management rules

• Target an optimum GAI of 3.5 units

• Takes 50kg N/ha to make 1 GAI

• Soil and crop N (SNS) ~ 100% efficient

• Fertiliser N ~ 60% efficient

Example Kg/ha N

Target N needed in crop (3.5 GAI x 50 kg N for each GAI)

175

GAI =1 at end Feb Soil mineral N

50 25

Shortfall (Target N – crop & soil N)

100

Fertiliser requirement

(Shortfall 0.6)

167

Calculating N inputs

Example Kg/ha N Kg/ha N

Target N needed in crop (3.5 GAI x 50 kg N for each GAI)

175 175

GAI =1 at end Feb Soil mineral N

50 25

100 25

Shortfall (Target N – crop & soil N)

100 50

Fertiliser requirement

(Shortfall 0.6)

167 83

Calculating N inputs

GAI=2

Assessing GAI is important

0.6 0.9

1.2 1.8

How to estimate crop N: OSR

• Digital photo for GAIs of up to 2.5 • Use BASF or Yara apps

• Crop fresh weight for GAIs above 2.5 • Record fresh weight in kg of 1m x 1m area

• Multiply by 0.8 to give GAI

• Fraction of soil covered by crop • Third: 25 kg N/ha

• Half: 50 kg N/ha

• Three quarters: 100 kg N/ha

• Crop height • 10cm: 35-45 kg N/ha

• 15cm: 55-65 kg N/ha

• 20cm: 75-85 kg N/ha

High yielding crops

• Crops with a yield potential of more than 3.5 t/ha require more N

• Apply an extra 30 kg/ha for each 0.5 t above 3.5 t/ha

• High yielding crops need extra N to prolong seed filling

Establishment

Optimum Plant population

4.0

4.2

4.4

4.6

4.8

20 40 80 120 160

Seed rate per m2

Yie

ld (

t/h

a)

Excalibur

Castille

PR45D03

25 plants/m2 35 plants 59 plants 76 plants 98 plants

Optimum seed rate

26 seeds/m2

20 seeds/m2 - 25 plants/m2 160 seeds/m2 - 98 plants/m2

Summary: Optimum plants/m2

0

20

40

60

80

100

Yor

ks09

Yor

ks10

Here

11

Norf1

1

Yor

ks11

Here

12

Norf1

2

Yor

ks12

Optim

um

pla

nts

/m2

Conventional

Hybrid

Plant Growth Regulators

Assessing GAI is vital

0.6 0.9

1.2 1.8

Yield effects (Metconazole applied March GS3.3 to 3.5)

-0.2

-0.1

0

0.1

0.2

0.3

GAI at application in March

Ch

an

ge

in

yie

ld (

t/h

a)

du

e to

me

tco

na

zo

leN=14

A

N=13

B

N=5

B

<0.8 >2.00.8 to 2.0

Future Challenges

• Canopy Management: continue to increase usage • Limited by pigeons!

• More reliable plant establishment • Cabbage stem flea beetle

• Increase rooting below 40cm soil depth

• Improve disease control: Light leaf spot

• Increase Sulphur use

• Other • Low yields from close rotation

• Turnip Yellow Virus

• Verticillium wilt

Thank you