Canopy management and PGR
use
Sarah Kendall, ADAS
Outline
• Optimum canopy size
• Methods for canopy management
- Nitrogen fertiliser: rates and timing
- PGR products
Canopy Management Principals
Fraction
light intercepted
• Target
anofoptimum
GAI of 3.5 units
1
Fraction of
light
intercepted
0.5
0
0
2
4
area index
Green Green
area index
6
N for optimum canopy
7
Green Area Index (GAI)
6
5
4
3
2
y = 0.0219x
R2 = 0.8661
1
0
0
100
200
N uptake (kg/ha)
300
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
Accounting for yield potential
Soil N + Crop N + Fert N (kg/ha)
300
250
200
y = 36x + 58
R2 = 0.46
150
100
Each additional tonne of yield
above 3.5 t/ha requires an
extra 60 kg of fertiliser N
50
0
3.0
3.5
4.0
4.5
Yield at optimum N (t/ha)
5.0
5.5
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
Calculating N inputs
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
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
175
GAI=2
Assessing GAI is important
www.totaloilseedcare.co.uk
0.6
0.9
1.2
1.8
How to estimate crop N: OSR
• Crop height
• 10cm: 35-45 kg N/ha
• 15cm: 55-65 kg N/ha
• 20cm: 75-85 kg N/ha
• Fraction of soil covered by crop
• Third:
• Half:
• Three quarters:
25 kg N/ha
50 kg N/ha
100 kg N/ha
• Digital photo for GAIs of up to 2.5
• Use BASF or Yara app, or upload digital photo on www.totaloilseedcare.co.uk
• 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
Timing of spring N
N timing
• Applying all N early will often over-shoot optimum
canopy size
• Particularly for crops with large GAI or high yield
• Need to apply some N later
• N uptake slows after flowering
Example 1 (small crop)
•GAI = 0.6 (30 kg N/ha)
•Soil N = 30 kg N/ha
•190 kg N/ha for optimum canopy
•Extra 60 kg N/ha for 4.5 t/ha
•100 kg in late Feb or early March
•90 kg at green bud
•Mid-late March / early April
•60 kg at yellow bud / early flowering
•Early to late April
Example 2 (medium crop)
•GAI = 2 (100 kg N/ha)
•Soil N = 20 kg N/ha
•90 kg N/ha for optimum canopy
•Extra 60 kg N/ha for 4.5 t/ha
•90 kg at green bud
•Mid-late March / early April
•60 kg at yellow bud / early flowering
•Early to late April
Lodging
• Lodging reduces yield by up to 50%
Aerial Survey 2012 & 2014
• Aerial photos taken of areas
representing main OSR
growing region.
• Estimated % area lodged
• 35% area lodged in 2012
• 27% area lodged in 2014
5% area lodged
85% area lodged
• 31% area lodged on average
Sponsored by BASF
Artificial Lodging experiments
• Artificial lodging induced
by two people using a
wooden plank
• Lodging carried out
gradually so stems
remained intact
• 4 growth stages & 3 lodging
angles (22.5°, 45°, 90°)
•
•
•
•
Early flowering
Mid flowering
Early seed fill
Mid seed fill
Sponsored by BASF
Yield losses due to lodging
70
60
Yield Loss (%)
50
40
30
2013
20
2014
10
2015
0
-10
Sponsored by BASF
Cost of Lodging
• Late leaning can have dramatic effects on yield – often
considered to have no detrimental affect
• Seeds/m2 most affected – early lodging affects determination of
seed number; late lodging causes pod abortion.
• Severe lodging could cost UK industry £120M, whilst moderate
lodging could cost £47M.
Sponsored by BASF
PGR products
•
•
•
•
•
•
Metconazole (Caramba, Sunorg Pro, Caryx)
Tebuconazole (Folicur, Prosaro)
Mepiquat chloride (Caryx)
Paclobutrazol (Toprex)
Triazole fungicides which inhibit gibberellin biosynthesis
Gibberellins affect;
• Cell elongation
• Flowering time
• Fruit set
Mechanisms of yield improvement
- in absence of disease
• Shorten crops and reduce lodging
• Reduce canopy size, increase seed set and yield
potential
• Increase rooting
Yield responses
• 174 comparisons (in absence of disease)
• Metconazol responses ranged from:
• -0.45 to +0.74 t/ha
• Tebuconazol responses ranged from:
• -0.41 to +1.09 t/ha
E.g. of large yield response to PGR
5.4
5.2
Untreated
Aut Caramba (0.6)
Aut(0.6)+Spr(1.2) Caramba
Yield (t/ha)
5
4.8
4.6
4.4
4.2
4
0
80
160
N rate (kg N/ha)
240
320
Yield responses
• Spring canopy size had greatest effect on the yield response
• Threshold canopy size at green bud (March) = 0.8
• Threshold canopy size at green/yellow bud (April) = 2.0
• Similar sized effects on open pollinated and hybrids
Yield effects (Caramba applied March GS3.3 to 3.5)
Change in yield (t/ha)
due to metconazole
0.3
N=14
A
N=13
B
N=5
B
0.8 to 2.0
>2.0
0.2
0.1
0
-0.1
-0.2
<0.8
GAI at application in March
Assessing GAI is important
www.totaloilseedcare.co.uk
0.6
0.9
1.2
1.8
Optimum timing
• Greatest yield responses from applications between
late green bud (GS3,6) and flowering (GS4,5)
• up to 0.74 t/ha
• Smaller yield response from early green bud timings
(GS3,3)
Height & Lodging
• Full dose reduced height by 7 to 11
cm
• Height reduced by Green bud to late
Yellow bud timings
• Greatest height reduction from mid
stem extension timing
• Splitting reduced height by an extra 2
to 4 cm
• Half dose had half the effect
Height & Lodging
• Each 5 cm reduction in height reduced
% area lodged by 10%
• Lodging was reduced by spring
applications before green bud to midflowering
• Indication that other characters
affected (e.g. stem strength?) which
reduce lodging risk
Mechanism of yield effects
Out of 43 comparisons with a yield response of 0.2 t/ha or more;
• 28 had a significant reduction in lodging
• 15 had no lodging
• either more seeds/m2 or/and more rooting
Avoiding over-large canopies
Light reflection & interception
% light reflected by flowers
% light transmitted below flowers
12
70
10
65
8
60
6
55
4
50
2
45
0
40
Untreated
Caramba (0.8 l/ha)
Untreated
Caramba (0.8 l/ha)
Caramba effects on rooting



Spring applications increased root length density from 0.48 to
0.60 cm/cm3 (40-100cm depth)
Additional water uptake of 6-9 mm
Additional yield in dry year of 0.22 – 0.34 t/ha
Data: HGCA & BASF
Branching (Metconazole)
• Branching effects from late green bud
or yellow bud applications
•Sunorg pro & Caryx increased
secondary branch number (9 trials)
• Secondary branches can contribute
over 1 t/ha
• Sunorg pro increased lower order
primary branches
Summary
• Canopy Management regularly shown to increase yield
• Correct N amount and N timing
• Account for N in canopy
• PGRs
• Reduces height and lodging
• Improves light penetration
• Increases branching
• Increases rooting
Thank you
[email protected]