Development of low-N tolerant maize varieties

International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

Development of low-N tolerant maize varieties


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

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)


Phenology traits

- Anthesis – Silking-Interval (ASI)

- Duration of grain filling

Significant G x N interaction in some locations


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)


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

generated• LNTP- Y

• LNTP – W

– LNTP X LNP

• TZPB Prolific


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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

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


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

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


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

ContributorsSam AjalaAbebe MenkirAlpha KamaraJenny Kling

Technology

Development of low-N tolerant maize varieties