Development of low-N tolerant maize varieties

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


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

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.

Need
Generate

- N-efficient maize
that can be used in rotation with
- legumes
to reduce fertilizer requirement in a cereal-
legume system


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


Root • Maximum rooting depth
– To capture N moving out of the
morphology root zone especially at flowering

• Root size
– Exploratory tendency

Vertical root pulling strength directly
related to root characteristics of maize
(standability)


Phenology traits

- Anthesis – Silking-Interval (ASI)

- Duration of grain filling

Significant G x N interaction in some locations


Important • Vertical root pulling resistant and N-uptake
correlations
• 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)


Selection
criteria • Grain yield (low-N)
• Grain yield (high-N)
• Stay green (1-10)
• ASI
• Ears/plant (Prolificacy)


Selection
environment • Low - N
0 kg N/ha
30 kg N/ha

• High – N
90 kg N/ha


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


Low N
Populations • LNTP- Y
generated

• LNTP – W
– LNTP X LNP

• TZPB Prolific


Performance of varieties with tolerance to other stresses
identified under low-N (30 kg N/ha) in 2006

Grain yield Stay Stay Ears
Entry LN green 1 green 2 number 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 top 8 S1 lines from BR 9928 DMRSR evaluated for
low-N tolerance in 2007

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 10 S1 lines from TZL Comp 1 C6
evaluated for low-N tolerance in 2007

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


Genetic
• Rizzi et al (1993)
studies
• 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


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


Genetic studies 3

Testcross (HS)
= σ²HS = 1/4σ²A

Full sib
= σ²FS = 1/2σ²A + 1/4σ²D

 σ²A = 4σ²HS
σ²D = 4(2σ²HS - σ²FS)


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

Grain yield LNTP-Y 0.03 0.00
LNTP-W 0.02 0.00


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 * ** ** ** ** ** **

ON 90 N
1800 23.5 3500 30 N 35 5000 40

A 1600

1400
y = 15.77x + 1400.4
R 2 = 0.0227
23

22.5
3000
y = 0.62x + 24.487
R 2 = 0.1812
30
4500

4000
y = 1.0171x + 27.007
R 2 = 0.3286
35

30
Grain Yield (kg ha-1)


2500 25
1200 22
3500

Ears harvested

Ears harvested
y = 138.83x + 2144.6

Ears harvested
2
R = 0.5149 25
2000 20 3000 y = 274.46x + 2729.7
1000 21.5
y = 0.32x + 20.607
2 R 2 = 0.6015
R = 0.2035 2500 20
800 21
1500 15
2000
600 20.5 15
1000 10 1500
400 20
10
Grain yield 1000
200 19.5 500 Grain yield 5
Grain yield
Ears harves ted 5
Ears harves ted 500
0 19 Ears harvested
Linear (Ears 0 0
0 1 2 3 4 5 6 7 Linear (Ears 0 0
harves ted) 0 1 2 3 4 5 6 7 Linear (Ears
Linear (Grain harves ted)
Cycles of Selection Linear (Grain 0 harvested) 2
1 3 4 5 6 7
yield) Cycles of Selection Linear (Grain
yield) Cycles of Selection
yield)

B 1350 22.2

22
3500

3000 y = 1.67x + 20.73
35

30
4500

4000
35

1300 R2 = 0.6563
30
y = 26.61x + 1154.3 21.8
3500 y = 2.33x + 19.71

2
R = 0.2228 2500 25 R2 = 0.3871

21.6 25

Ears harvested

Ears harvested
1250 3000

Ears harvested
y = 0.1x + 21.1 21.4 y = 228.91x + 1721.3
2000 20 20
R 2 = 0.0568 R2 = 0.9175 2500 y = 375.23x + 1956.6
R2 = 0.5645
1200 21.2
1500 15 2000 15
21
1150 1500
20.8 1000 10 10
1000
20.6
1100 Grain yield 500 Grain yield 5 Grain yield 5
500
20.4 Ears harves ted
Ears harvested
Ears harvested 0 0
1050 20.2 0 0 Linear (Ears
Linear (Ears 0 1
harves ted)
2 3 4 5 6
0 1 2 3 4 Linear5(Ears 6 0 1 2 3 4 5 6
harvested) Linear (Grain Cycles of Selection
harvested) Linear (Grain yield)
Linear (Grain Cycles of Selection
Cycles of Selection yield)
yield)

C 1345

1340
y = 1.55x + 14.833
25 3500

3000
y = 504.9x + 1482.5
2
35

30
4000

3500
40

35
R = 0.7337 y = 329.15x + 2376.7
1335 R 2 = 0.7742 20 2
3000 R = 0.3477 30


2500 y = 3.65x + 17.633 25
1330 2
Ears harvested

Ears harvested
Ears harvested
R = 0.6687 y = 4.45x + 20.433
2500 2
25
1325 15 R = 0.8943
2000 20
1320 2000 20

1500 15
1315 10 1500 15
y = -21.5x + 1363.6
1310 R 2 = 0.9892 1000 10 1000 10
1305 5
Grain yield Grain yield Grain yield
500 5 500 5
1300 Ears harves ted
Ears harvested Ears harvested
0 0
1295 Linear (Ears 0 0 0 Linear (Ears
Linear (Ears 0 1 2 3 4
0 harvested)
1 2 3 4 harves ted)
0 1
harvested) 2 3 4 Linear (Grain Cycles of Selection
Linear (Grain Linear (Grain
Cycles of Selection Cycles of Selection yield)
yield) yield)

Ear number and Grain Yield of different cycles of selections evaluated in Nigeria in 2006
A = LNTP-Y B = LNTP-W C = TZPB Prolific

Changes in agronomic traits associated with
recurrent selection for low-N tolerance in maize

30 N 90 N
Days to Plant ht. Days to Plant ht.
Population silk (cm) ASI silk (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


Means of top 7 full-sib progenies from LNTP-Y C6
evaluated at Mokwa and Zaria in Nigeria in 2008

Grain Yield low- Stay green Grain Yield High-N
Selected entries N (kg/ha) (1- 9) Ears/plant (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


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


Inbred-Hybrid Correlation 2

Base
Drought Index
Inbred lines tolerance 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


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.


On–farm trials of low-N tolerant populations
conducted in 2005 – 2008 in Nigeria

Location

Nasarawa FCT Niger Bauchi Gombe
Variety (49) (10) (10) (42) (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


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.


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


Thank
You

Contributors
Sam Ajala
Abebe Menkir
Alpha Kamara
Jenny Kling


Development of low-N tolerant maize varieties

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