Breeding for improved nitrogen use
efficiency in oilseed rape
Pete Berry
www.adas.co.uk
Breeding oilseed rape with a low
requirement for nitrogen fertiliser (LK0979)
Elsoms Seeds
N use efficiency in oilseed rape
Oilseed rape Wheat
Rate of N fertiliser (kg N/ha)
191
184
Yield (t/ha)
3.2
8.0
Dry matter in seed (kg/kg N) 15.2
37.0
Energy in seed (MJ/kg N)
387
666
Energy in straw (MJ/kg N)
535
666
Total energy (MJ/kg N)
922
1332
Variety trials with & without nitrogen
Variety trials
5.0
High N Yield
Low N yield
Yield (t/ha)
4.5
Mean of 6 site
seasons
4.0
Variety x N
SED = 0.13
t/ha
3.5
3.0
2.5
1
3
5
7
9
11 13 15 17 19 21 23 25 27 29
Variety
% of yield lost at low N
35
% of yield lost at low N
30
25
20
15
10
5
0
Variety
Effect of higher yielding varieties
5.0
30 kg N/ha
Yield (t/ha)
4.0
3.0
2.0
Variety A
Variety B
Variety C
Variety D
Variety E
1.0
0.0
0
100
200
kg N/ha
300
400
Traits for improving N use efficiency
Improve efficiency of N uptake
(kg N uptake / kg available N)
Increase rate of N uptake
Prolong duration of N uptake
Increase N utilisation efficiency
(kg seed yield / kg N uptake)
Achieve same yield with less N
Achieve greater yield with same N
N uptake efficiency
February soil mineral N
February crop N
Optimum fertiliser N rate
N uptake at maturity
Soil and fertiliser N uptake
efficiency
Mean of
6 trials in
2006&7
50
58
166
215
73%
Net mineralisation/immobilisation after February not accounted for
Data courtesy of Growhow Uk Ltd
Root length density
3
Root length density (cm/cm )
0
0
1
2
3
4
Soil depth (cm)
-20
-40
-60
-80
mean
Max
Min
-100
Blake et al., 2006
Root length density
3
Root length density (cm/cm )
0
0
1
2
3
4
Soil depth (cm)
-20
-40
-60
-80
mean
Max
Min
-100
Blake et al., 2006 & BASF
Root length density
Soil Mineral N
3
Root length density (cm/cm )
0
0
1
2
(mean of 6 trials 2006&7)
3
4
0-30cm: 21 kg N/ha
Soil depth (cm)
-20
-40
30-60cm: 15 kg N/ha
-60
-80
mean
Max
Min
60-90cm: 14 kg N/ha
-100
Blake et al., 2006 & BASF
N uptake efficiency
•Average root length density (RLD) below 40 cm =
0.74 cm/cm3
• Increasing RLD to 1.0 cm/cm3 is estimated to
increase N recovered from soil by 8 kg N/ha (26%)
• Increase soil and fertiliser N uptake efficiency
from 73% to 76%
Patterns of N uptake (2008)
Measured without N fertiliser
Top 5 yielding varieties
100
90
Bottom 5 yielding varieties
Seed
100
Seed
Pod wall
90
80
Stem
80
70
Leaf
70
N uptake (kg/ha)
N uptake (kg/ha)
Flower
60
50
40
30
30
10
Jun-08
Jul-08
Leaf
40
10
May-08
Stem
50
20
Apr-08
Flower
60
20
0
Mar-08
Pod wall
0
Mar-08
Apr-08
May-08
Jun-08
Jul-08
Patterns of N uptake (2007)
Measured without N fertiliser
Top 5 yielding varieties
140
Bottom 5 yielding varieties
140
seed
Flow er & pod w all
120
Flow er & pod w all
120
stem
Leaf
N content (kg/ha)
N content (kg/ha)
stem
Leaf
100
80
60
40
100
80
60
40
20
0
Mar-07
seed
20
0
Apr-07
May-07
Jun-07
Jul-07
Mar-07
Apr-07
May-07
Jun-07
Jul-07
Patterns of N uptake
Measured without N fertiliser
4 experiments
5 highest yielding varieties ;
yielded 0.55 t/ha more
took up 22 kg N/ha more (all after flowering)
18% greater N uptake efficiency
No difference in N utilisation efficiency between high and
low yielding varieties
N utilisation efficiency
(kg seed / kg N uptake)
Seed filling period is critical
Seed filling period is critical
Optimum Green
Area Index – 3.5
Pods: 1.5
Stems: 1.0
Leaves: 1.0
Optimum N for photosynthesis
Leaf N Content (g m -2)
3
2
1
0
0
200
400
600
800
PPFD (µ mol m -2 s-1)
Critchley, 2002
1000
Optimum N for photosynthesis
Split canopy into top half - (pods & upper stems)
and bottom half (leaves and lower stems)
Calculate the average light intensity in top and
bottom half
Estimate the specific tissue N based on light
concentration
Assume cylindrical surface area for stems &
pods
Optimum N for photosynthesis
at start of seed filling
200
Pod N
N content (kg/ha)
Stem N
Leaf N
150
100
50
0
Optimum for
photosynthesis
Typical crop
Patterns of N uptake & partitioning
250
Seed
Pod & Flower
Stem
Leaf
N content (kg N/ha)
200
150
100
50
0
14Mar
28Mar
11Apr
25Apr
9May
23May
6Jun
20Jun
4Jul
Mean of 3 experiments
Patterns of N uptake & partitioning
250
Seed
Excess pod
Pod & Flower
Excess stem
Stem
Leaf
N uptake (kg/ha)
200
150
100
50
0
14Mar
28Mar
11Apr
25Apr
9May
23May
6Jun
20Jun
4Jul
Improving N utilisation efficiency
Potential to either;
reduce the N in stems & pod walls by 30 kg N/ha, or
increase N remobilised from stems/pod walls to seed
Varietal differences for N concentration and N content in
stems and pods
Stem N concentration at flowering: 1.02 to 1.32% (P<0.01)
Stem N concentration at maturity: 0.55 to 0.68% (P<0.01)
Stem N content at flowering: 46 to 63 kg N/ha (P<0.01)
2-fold difference between varieties for stem N remobilisation
Potential for improving N use efficiency
Typical
crop
Yield (t/ha)
3.2
Total N uptake (kg/ha)
226
N already taken up by spring (kg/ha)
50
Soil & fertiliser N uptake efficiency
73%
N available in soil (kg/ha)
50
Fertiliser N (kg/ha)
191
Fertiliser N use efficiency
(kg seed dry matter/kg fertiliser N)
15.2
Potential for improving N use efficiency
Typical
crop
Increase N
utilisation
efficiency
Yield (t/ha)
3.2
3.2
Total N uptake (kg/ha)
226
196
N already taken up by spring (kg/ha)
50
50
Soil & fertiliser N uptake efficiency
73%
73%
N available in soil (kg/ha)
50
50
Fertiliser N (kg/ha)
191
150
Fertiliser N use efficiency
(kg seed dry matter/kg fertiliser N)
15.2
19.4
Potential for improving N use efficiency
Typical
crop
Increase N
utilisation
efficiency
Increase N
uptake
efficiency
Yield (t/ha)
3.2
3.2
3.7
Total N uptake (kg/ha)
226
196
216
N already taken up by spring (kg/ha)
50
50
50
Soil & fertiliser N uptake efficiency
73%
73%
84%
N available in soil (kg/ha)
50
50
50
Fertiliser N (kg/ha)
191
150
148
Fertiliser N use efficiency
(kg seed dry matter/kg fertiliser N)
15.2
19.4
22.8
N use efficiency in oilseed rape
Oilseed rape Wheat
Rate of N fertiliser (kg N/ha)
191 (148)
184
Yield (t/ha)
3.2 (3.7)
8.0
Dry matter in seed (kg/kg N) 15.2 (22.8)
37.0
Energy in seed (MJ/kg N)
387 (581)
666
Energy in straw (MJ/kg N)
535 (690)
666
Total energy (MJ/kg N)
922 (1271)
1332
Conclusions
Large potential for improving N use efficiency of
oilseed rape
Key traits
Increasing N uptake efficiency by prolonging N uptake
Increase N utilisation efficiency by reducing N stored
in stems, or increasing remobilisation from stems
Further work
Confirm importance of key traits
Identify genetic differences in key traits
Measure genetic differences in economic optimum N