INTEGRATED AND LOCALLY ADAPTED STRIGA ASIATICA

CONTROL: Combining a Zero-tillage Rice–Maize

Cover-Crop Rotation System with Resistant Rice Varieties

Alain Paul Andrianaivo

(SRiD-FoFiFa, Antananarivo, Madagascar)

Roger Michellon

(SCRiD-Cirad, Antsirabe, Madagascar)

Jonne Rodenburg

(AfricaRice , Dar es Salaam, Tanzania)

Meva Tahiry Randrianjafizanaka

(Univ. Tulear ,Madagascar)

• Common weed in the mid-west of the Vakinankaratra region (800-1000 a.s.l.)

• Cropping systems: Rice//maize

• Serious yield losses

Striga asiatica (L.) Kuntze

Objective

Integrated• Striga control

• Soil conservation management

Hypotheses

• Combining zero-tillage with intercropping will- protecting the soil - improving the organic matter content- reduce Striga infestation rates

• Striga resistant rice varieties should enhance Striga suppression

• Stylosanthes has a suppressive effect on Striga

Material and methods

three seasons (2011-2014)

Split-Split plot design (6 rep.) 4 cropping systems(S1-S4)

3 rice varieties (V1-V3) 1 maize locally variety

• Treatments and experimental set-up

• Site Selection: Ivory

Material and methods

• S1: Rice//Maize + tillage + Crop residue removal • S2. Rice // Maize + Cowpea + Mucuna

• S 3. Rice // Maize + Vigna umbellata

• S4. Rice + Stylosanthes // Maize+ Stylo.

V1: B 22. , Striga susceptible

V2: Nerica 9. Striga moderately resistant

V3: Nerica 4. Striga resistant

System

Tillage and residue

management

 Phase

 Season 1 (2011-2012)

Season 3 (2013-2014) 

 Season 2 (2012-2013)

 

System 1

  

Tillage, No residues

 

P1 Rice Maize

P2 Maize Rice

System 2

      

Zero-tillage + Residues

 

P1 Rice Maize + cowpea + mucuna

P2 Maize + cowpea + mucuna Rice

System 3

P1 Rice Maize + Vigna umbellata

P2 Maize + V. umbellata Rice

System 4

P1 Rice + Stylosanthes(year 1)

Maize + Stylosanthes (year 2)

P2 Maize + Stylosanthes (year 1) + supplementary Stylosanthes residues

Rice in Stylosanthes residues of year 11

Table 1. Cropping systems plan for season 1 to season 3.

Material and methods

ResultsTable 2. Striga numbers (10 m-2) in rice at harvest

Season SystemRice variety  

 

 

MeanB22 NERICA-9 NERICA-4

 

2011/20121

S1: Rice//Maize 38.9   2.1   0.2    

 

 

 

 

 

 

 

 

 

 

4.3  

S2: Rice//Maize cowpea + mucuna 6.9   1.7   1.3   2.7  

S3: Rice//Maize V. umbellata 6.3   2.5   0.6   2.4  

S4: Rice + Stylosanthes//maize + Stylosanthes 9.1   1.6   0.9   2.7  

Mean 11.3 A2 2.0 B 0.7 B    

                 

2012/20133

S1: Rice//Maize 159.4 a4 37.4 ab 0.3 cd 65.7 x5

S2: Rice//Maize cowpea + mucuna 38.8 ab 22.4 ab 2.6 cd 21.3 x

S3: Rice//Maize V. umbellata 14.9 bc 17.5 ab 0.4 cd 11.0 x

S4: Rice + Stylosanthes//maize + Stylosanthes 3.9 bcd 1.9 cd 0.00 d 1.9 y

Mean 54.3 A 19.8 B 0.8 C 25.0  

1 In the 2011-2012 cropping season, phase 1, S1 till S3 are all rice-only.

2 Values in the same row followed by different letters (A-C) are significantly different (P<0.05).

3 Results on rice in season 2012-2013 are derived from plots that were preceded by maize or maize and cover crops in the 2011-2012 season (earlier referred to as phase 2).

4 Values followed by different letters (a-d) are significantly different (P<0.05).

5 Values in one column followed by different letters (x or y) are significantly different (P<0.05).

Table 3. Striga numbers (10 m-2) in maize in season 2 near harvest time, following different cropping systems and with different rice varieties in the preceding 2011/2012 season.

 

Season

 

System

Rice variety in preceding season  

 

 

 

 

 

 

 

Mean

 

 

B22

 

NERICA-9

 

NERICA-4

 

2012/2013

 

 

 

 

S1: Rice//Maize 306.8 a1 100.2 a 19.1 ab 142.0 x2

S2: Rice//Maize cowpea + mucuna 35.5 a 38.5 a 43.8 ab 39.3 y

57.8 y

S3: Rice//Maize V. umbellata 90.5 a 63.3 a 19.6 a

S4: Rice + Stylosanthes//maize + Stylosanthes 0.0 b 0.0 b 0.0 b 0.0 z

Mean 108.2 A3 50.5 AB 20.6 B    

1 Values followed by different letters (a-d) are significantly different (P<0.05).

2 Values in ‘Mean’ column followed by different letters (x or y) are significantly different (P<0.05).

3 Values in the ‘Mean’ row followed by different letters (A-C) are significantly different (P<0.05).

Results

Maize//NERICA9 Maize//B22 Maize//NERICA4

carry-over effect of resistance in Maize//Rice

Table 4. Rice yields (t ha-1) following different cropping systems and rice varieties

Season System Rice variety   Mean

B22 NERICA-9 NERICA-4

2011/20121

S1: Rice//Maize

1.8   1.9   2.1  1.9  S2: Rice//Maize cowpea + mucuna

S3: Rice//Maize V. umbellata

S4: Rice + Stylosanthes//maize + Stylosanthes 1.9   1.7   1.7   1.73  

Mean 1.8   1.8   1.9  

                   

2012/2013 S1: Rice//Maize 1.8 c2 2.3 bc 2.2 bc 2.1 y3

S2: Rice//Maize cowpea + mucuna 2.9 ab 3.2 a 3.3 a

3.2 x

S3: Rice//Maize V. umbellata 2.5 abc 1.9 c 2.2 bc 2.2 y

S4: Rice + Stylosanthes//Maize + Stylosanthes 0.74 d 0.5 d 0.5 d 0.6 z

Mean 2.0 A5 2.0 A 2.1 A  

 

1 In the 2011-2012 cropping season, phase 1, S1 till S3 are all rice-only; therefore these systems are combined in the analyses, for comparison with rice - Stylosanthes. No

significant yield differences were observed this season.

2 Values followed by different letters (a-d) are significantly different (P<0.05).

3 Values in the ‘Mean’ column, followed by different letters (x-z) are significantly different (P<0.05).

4 This system should be evaluated in the third year following all of the three stages: 1. Rice with Stylosanthes (year 1) followed by 2. Maize with Stylosanthes (year 2),

concluded by 3. Rice sown in the slashed residues of the Stylosanthes.

5 Values in the same row followed by different letters (A-C) are significantly different (P<0.05).

Results

Conclusions

• Striga densities are reduced by S2, S3 and S4. Particulary

with Vigna umbellata and Stylosanthes guianensis.

• With respect to rice yields, the best system, is S2 :(Rice//Maize

+cowpea+mucuna

• For subsistence farmers in central Madagascar, that have to

deal with soils that are both highly infested by Striga asiatica

and highly vulnerable to degradation, a system of rice rotation

with a maize – legume intercrop following zero-tillage, without

removing crop residues, is likely to represent an attractive

alternative to the current practice

Merci de votre aimable attention !

Acknowledgements

CGIAR /GRISPCirad