Post on 26-Jan-2015
description
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Development of low-N tolerant maize varieties
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Savannas of WCA • Savannah is the most productive
environment for maize production
• Soils in the savannas are generally low in organic matter and available nitrogen
• Availability and use of fertilizer also limit maize productivity
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Concern
Although,
Combined use of organic manure and nitrogen fixing cover crop can make a difference to maize production
However, there is the concern on
- declining levels of soil fertility
- high proportion of crop residue being fed to livestock, burned or consumed by termites
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Therefore,
Maize genotypes with improved N-use efficiency (greater grain yield per unit available soil N) can increase productivity of maize based system
Especially,
In combination with technologies that improve soil fertility
- crop rotation
- organic manure
- judicious use of inorganic fertilizers.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Need
Generate
- N-efficient maize
that can be used in rotation with
- legumes
to reduce fertilizer requirement in a cereal-
legume system
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Model>N - use efficiency (>grain yield/unit of available N
Mechanism
> N uptake efficiency
> N utilization efficiency
> grain yield
Genotypic differences for the N-use mechanism traits usually significant but
G X N usually not significant
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Root
morphology
• Maximum rooting depth
– To capture N moving out of the
root zone especially at flowering
• Root size
– Exploratory tendency
Vertical root pulling strength directly
related to root characteristics of maize
(standability)
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Phenology traits
- Anthesis – Silking-Interval (ASI)
- Duration of grain filling
Significant G x N interaction in some locations
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Important
correlations
• Vertical root pulling resistant and N-uptake
• Grain yield and number of ears/plant
• Grain yield and N-utilization
• Grain yield and Plant ht
• Grain yield and ASI but with low R²
• Grain yield and Stay green (low-N)
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Selection
criteria• Grain yield (low-N)
• Grain yield (high-N)
• Stay green (1-10)
• ASI
• Ears/plant (Prolificacy)
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Selection
environment• Low - N
0 kg N/ha
30 kg N/ha
• High – N
90 kg N/ha
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Breeding methodology
• Generation of low-N tolerant populations
• Screening of germplasm from diverse sources
• Recurrent selection to improve on levels of N-tolerance in desirable populations
• Line development to generate inbreds tolerant to low soil-N
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Low N
Populations
generated• LNTP- Y
• LNTP – W
– LNTP X LNP
• TZPB Prolific
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
EntryGrain yield
LNStay
green 1
Stay green 2
Earsnumber ASI
Acr 97 TZL Comp 1 2469 2.3 3.3 25 2.9
TZL Comp 1-W C6 2343 2.3 3.6 25 3.6
DT-SR-W C1 F2 2260 2.3 4.1 25 3.5
LNTP-Y C5 2241 2.1 3.8 28 3.0
DT SYN-1 W 2239 2.1 4.1 22 3.5
TZPB Prol C3 2207 2.1 3.9 24 3.0
Mean 2053 2.4 3.9 24 3.0
SED 210.2 0.3 0.4 1.9 0.4
CV (%) 26.8 29.8 14.9 21.6 32.4
Performance of varieties with tolerance to other stresses identified under low-N (30 kg N/ha) in 2006
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Entry Stay green Ear aspect Ear/plant Grain Yld LN Grain Yld HN
65 4.5 3.0 0.46 725.35 1411.73
92 5.5 3.5 0.47 815.97 1866.07
50 5.5 3.5 0.45 633.55 1904.68
10 4.5 3.5 0.40 677.34 1391.36
138 5.0 4.0 0.45 819.11 1668.39
48 5.5 4.0 0.46 772.62 1346.75
144 4.5 4.0 0.52 728.53 1106.44
166 4.5 3.5 0.53 867.85 743.48
Mean of selected 15 5.2 3.8 0.48 750.77 1365.35
BR 9928 DMRSR 7 4.5 0.40 492.99 1611.12
SED 1.59 1.12 0.15 254.78 536.08
Sel Dif (%) -25.71 -15.56 19.01 52.29 -15.25
Performance of top 8 S1 lines from BR 9928 DMRSR evaluated for low-N tolerance in 2007
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
ENTRY Ear/plant Stay green Grain Yld LN Grain Yld HN
18 0.54 8.0 233.87 982.58
8 0.33 8.5 262.59 965.65
3 0.28 9.0 160.02 1145.76
19 0.44 9.0 233.87 975.74
51 0.42 9.0 160.02 1108.16
184 0.29 8.0 160.02 1487.50
26 0.25 8.5 160.02 999.95
44 0.34 9.0 336.44 947.83
89 0.33 9.0 160.02 1419.68
134 0.42 7.5 160.02 925.87
Mean of Selected 15 0.32 8.7 188.46 1130.18
TZL Comp 1C6 0.19 7 160.02 1178.20
SED 0.21 1.4 54.04 381.95
Sel Diff (%) 68.88 24.3 17.78 -4.08
Performance of top 10 S1 lines from TZL Comp 1 C6evaluated for low-N tolerance in 2007
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Genetic
studies • Rizzi et al (1993)
• Below et al. (1997
• Kling et al (1997)
σ²A > σ²D
• Katsantonis et al (1988)
• Bertran et al. (1997)
σ²D > σ²A
• Meseka et al (2006)
σ²D > σ²A
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Genetic studies 2
Maize populations
LNYP-Y
LNTP-W
TZPB Prolific W
Two progeny selection types
Full-sib family selection
S1 Testcross hybrid evaluation
Evaluation
2007 and 2008, Mokwa and Zaria, 2Reps, 3 N levels
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Genetic studies 3
Testcross (HS)
= σ²HS = 1/4σ²A
Full sib
= σ²FS = 1/2σ²A + 1/4σ²D
σ²A = 4σ²HS
σ²D = 4(2σ²HS - σ²FS)
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Relative values of add to non-
additive variances under low-N
Trait Populations σ²A σ²D
Stay green LNTP-Y 0.00 0.00
LNTP-W 0.00 0.00
TZPB Prolific 0.08 0.04
Ears/plant LNTP-Y 0.02 0.00
LNTP-W 0.00 0.00
TZPB Prolific 0.00 0.00
Grain yield LNTP-Y 0.03 0.00
LNTP-W 0.02 0.00
TZPB Prolific 0.10 0.04
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Comparison of full-sib and S1 selection evaluated
at two location in Nigeria in 2002 and 2003.
30kg N/ha 90 kg N/ha
Entry Yield Days to Plant ASI Yield Days to Plant
(kg/ha) silk ht (cm) (kg/ha) silk ht (cm)
LNTP-Y C4 FS 2075 65 172 1.9 4808 60 213
LNTP-Y C4 S1 1802 66 174 1.8 5157 61 211
LNTP-WC1 FS 1655 65 164 2.0 4974 60 208
LNTP-WC1 S1 1415 66 162 2.7 5070 60 214
Checks
Oba Sup 2 1712 66 158 2.8 4045 61 207
TZB-SR 1414 68 183 3.5 3618 63 222
Oba Sup 1 1544 67 167 2.6 4699 62 212
Mean 1559 67 169 2.7 4362 62 211
SED 163.9 0.6 4.8 0.5 276.6 0.5 3.9
CV(%) 41.5 4.2 9.3 86.1 19.9 2.7 7.1
VAR * ** ** ** ** ** **
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
y = 0.32x + 20.607
R2 = 0.2035
y = 15.77x + 1400.4
R2 = 0.0227
0
200
400
600
800
1000
1200
1400
1600
1800
0 1 2 3 4 5 6 7
Cycles of Selection
Gra
in Y
ield
(kg
ha-1
)
19
19.5
20
20.5
21
21.5
22
22.5
23
23.5
Ear
s ha
rves
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 0.1x + 21.1
R2 = 0.0568
y = 26.61x + 1154.3
R2 = 0.2228
1050
1100
1150
1200
1250
1300
1350
0 1 2 3 4 5 6
Cycles of Selection
Gra
in Y
ield
(k
g h
a-1
)
20.2
20.4
20.6
20.8
21
21.2
21.4
21.6
21.8
22
22.2
Ea
rs h
arv
es
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 1.55x + 14.833
R2 = 0.7742
y = -21.5x + 1363.6
R2 = 0.9892
1295
1300
1305
1310
1315
1320
1325
1330
1335
1340
1345
0 1 2 3 4
Cycles of Selection
Gra
in Y
ield
(k
g h
a-1
)
0
5
10
15
20
25
Ea
rs h
arv
es
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
A
C
B
y = 0.62x + 24.487
R2 = 0.1812
y = 138.83x + 2144.6
R2 = 0.5149
0
500
1000
1500
2000
2500
3000
3500
0 1 2 3 4 5 6 7
Cycles of Selection
Gra
in Y
ield
(kg
ha-1
)
0
5
10
15
20
25
30
35
Ear
s ha
rves
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 1.67x + 20.73
R2 = 0.6563
y = 228.91x + 1721.3
R2 = 0.9175
0
500
1000
1500
2000
2500
3000
3500
0 1 2 3 4 5 6
Cycles of Selection
Gra
in Y
ield
(k
g h
a-1
)
0
5
10
15
20
25
30
35
Ea
rs h
arv
es
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 3.65x + 17.633
R2 = 0.6687
y = 504.9x + 1482.5
R2 = 0.7337
0
500
1000
1500
2000
2500
3000
3500
0 1 2 3 4
Cycles of Selection
Gra
in Y
ield
(k
g h
a-1
)
0
5
10
15
20
25
30
35
Ear
s h
arve
sted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 1.0171x + 27.007
R2 = 0.3286
y = 274.46x + 2729.7
R2 = 0.6015
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 1 2 3 4 5 6 7
Cycles of Selection
Gra
in Y
ield
(k
g h
a-1
)
0
5
10
15
20
25
30
35
40
Ea
rs h
arv
es
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 2.33x + 19.71
R2 = 0.3871
y = 375.23x + 1956.6
R2 = 0.5645
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 1 2 3 4 5 6
Cycles of Selection
Gra
in Y
ield
(kg
ha-1
)
0
5
10
15
20
25
30
35
Ear
s ha
rves
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
y = 4.45x + 20.433
R2 = 0.8943
y = 329.15x + 2376.7
R2 = 0.3477
0
500
1000
1500
2000
2500
3000
3500
4000
0 1 2 3 4
Cycles of Selection
Gra
in Y
ield
(kg
ha-1
)
0
5
10
15
20
25
30
35
40
Ear
s ha
rves
ted
Grain yield
Ears harvested
Linear (Ears
harvested)Linear (Grain
yield)
30 N 90 N
Ear number and Grain Yield of different cycles of selections evaluated in Nigeria in 2006
A = LNTP-Y B = LNTP-W C = TZPB Prolific
ON
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
30 N 90 N
Population
Days to
silk
Plant ht.
(cm) ASI
Days to
silk
Plant ht.
(cm) ASI
LNTP C1 66.1ab* 172.8ab 3.0a 65.9a* 195.1a 2.3a
LNTP C2 67.4a 160.6b 2.9a 65.3ab 168.8c 2.0ab
LNTP-Y C3 63.3c 180.1a 2.6a 63.9bc 186.8ab 1.6b
LNTP-Y C4 63.5c 185.0a 2.6a 64.8abc 176.3bc 2.3a
LNTP-Y C5 64.1bc 184.4a 3.3a 61.8d 182.8abc 2.0ab
LNTP-Y C6 63.4c 173.4ab 2.9a 63.5c 180.6abc 2.0ab
b-value -0.66 2.27 0.02 -0.62 -1.17 -0.0
TZB-SR 66.8ab 185.9a 3.4a 66.8a 183.9a 1.0b
TZPB-SR 67.6a 190.4a 2.9a 66.0a 192.5a 0.8b
Oba Super 1 64.5bc 180.9a 3.3a 63.1b 201.1a 2.0ab
Oba Super 2 64.4bc 177.5a 2.9a 64.5ab 191.4a 2.6a
Changes in agronomic traits associated with
recurrent selection for low-N tolerance in maize
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Selected entries
Grain Yield low-
N (kg/ha)
Stay green
(1- 9) Ears/plant
Grain Yield High-N
(kg/ha)
5 2742 4 0.98 3712
180 3114 4 0.88 4131
174 3056 4 0.87 4118
8 2422 4 0.91 4690
170 2807 5 0.94 4304
160 3471 4 0.93 3307
127 2841 4 0.92 3327
Mean of population 2045 5 0.80 2901
Mean of selected 20 2749 4 1 3739
*Selection diff (%) 34.43 -20 25 28.89
SED 496.37 0.55 0.094 544.50
CV (%) 42.6 15.5 21.4 38
Means of top 7 full-sib progenies from LNTP-Y C6
evaluated at Mokwa and Zaria in Nigeria in 2008
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Inbred-Hybrid Correlation
• Dominance gene action in some studies
– Heterosis can be exploited
• Earlier studies from Maize Program (Akintoye 1994)
4 maize inbred
10 single cross hybrids
6 double cross hybrids from the 10
1 synthetic variety from the 4 inbred
Single cross > double cross > Synthetic
at all N levels
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Inbred-Hybrid Correlation 2
Inbred lines
Drought
tolerance
Base
Index
value
1824 T 21.93
9006 T 9.02
4058 T 7.52
Pop 10 T 4.63
9485 S -7.33
4008 S -7.75
Mok Pion Y-S4 S -7.93
(KU1403x1368)BC2 S -8.51
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Inbred-Hybrid Correlation 3
• Correlation between mid-parent yield values and corresponding hybrids significant (r = 0.22*)
• Average heterosis for grain yield (129%) and associated low-N traits highly significant
• T x T > T x S > S x T > S x S under low-N.
• No dosage effect under high-N
Selecting for drought or low-N tolerant lines under low-N for testing in hybrid combinations will lead to the development of good hybrids with tolerance to low soil N.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
On–farm trials of low-N tolerant populations
conducted in 2005 – 2008 in Nigeria
Location
Variety
Nasarawa
(49)
FCT
(10)
Niger
(10)
Bauchi
(42)
Gombe
(10) Average
LNTP- Y` 5.80 4.42 3.38 5.14 5.07 4.80
LNTP-W 3.30 3.30
Farmer's check 4.87 2.09 1.70 4.16 3.45 3.30
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Summary
• Newer generation of improved low-N tolerant
populations available
• Low-N tolerant synthetics are being generated
• Genotypes with tolerance to multiple stresses being
developed
• Inbred line development for hybrid production initiated
• On-farm trials conducted to demonstrate the
effectiveness of low-N tolerant populations in N deficient
situations.
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
2 OP varieties with tolerance to low
soil nitrogen for release in 2009
1. LNTP-Y
Yellow grained and low soil nitrogen tolerant variety
broadly adapted to the savannas.
2. LNTP-W
White grained intermediate-late maturing variety with
tolerance to low soil nitrogen
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Thank You
ContributorsSam AjalaAbebe MenkirAlpha KamaraJenny Kling