Th2_Integrated and Locally Adapted Striga asiatica Control

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3rd Africa Rice Congress
Theme 2: Intensification and diversification
Mini symposium: Rice pests: evidence of effects and management
Author: Andrianaivo

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Th2_Integrated and Locally Adapted Striga asiatica Control

  1. 1. 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)
  2. 2. Striga asiatica (L.) Kuntze • Common weed in the midwest of the Vakinankaratra region (800-1000 a.s.l.) • Cropping systems: Rice//maize • Serious yield losses
  3. 3. Objective • Soil conservation management • Integrated Striga control
  4. 4. Hypotheses • Combining zero-tillage with intercropping will - protecting the soil - improving the organic matter content - reduce Striga infestation rates • Stylosanthes has a suppressive effect on Striga • Striga resistant rice varieties should enhance Striga suppression
  5. 5. Material and methods • Site Selection: Ivory • Treatments and experimental set-up  three seasons (2011-2014)  Split-Split plot design (6 rep.)  4 cropping systems(S1-S4)  3 rice varieties (V1-V3)  1 maize locally variety
  6. 6. 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
  7. 7. Material and methods Phase Season 1 (2011-2012) Season 3 (2013-2014) Season 2 (2012-2013) Rice Maize P2 Maize Rice P1 Rice Maize + cowpea + mucuna P2 Maize + cowpea + mucuna Rice P1 Rice Maize + Vigna umbellata P2 Maize + V. umbellata Rice P1 Rice + Stylosanthes (year 1) Maize + Stylosanthes (year 2) P2 Maize + Stylosanthes (year 1) + supplementary Stylosanthes residues Rice in Stylosanthes residues of year 11 System 4 System 1 P1 System 2 Tillage and residue management System 3 System Table 1. Cropping systems plan for season 1 to season 3. Tillage, No residues Zero-tillage + Residues
  8. 8. Results Table 2. Striga numbers (10 m-2) in rice at harvest Rice variety Season System Mean B22 NERICA-9 NERICA-4 S1: Rice//Maize 38.9 2.1 0.2 4.3 S2: Rice//Maize cowpea + mucuna 6.9 1.7 1.3 2.7 2011/2012 S3: Rice//Maize V. umbellata 6.3 2.5 0.6 2.4 1 S4: Rice + Stylosanthes//maize + Stylosanthes 9.1 1.6 0.9 2.7 Mean 11.3 A2 2.0 B 0.7 B 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 2012/2013 S3: Rice//Maize V. umbellata 14.9 bc 17.5 ab 0.4 cd 11.0 x 3 S4: Rice + Stylosanthes//maize + Stylosanthes 3.9 bcd 1.9 cd 0.00 d 1.9 A 19.8 B 0.8 C 25.0 Mean 54.3 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). y
  9. 9. Results 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. Rice variety in preceding season Season System B22 NERICA-9 NERICA-4 Mean 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 S3: Rice//Maize V. umbellata 90.5 a 63.3 a 19.6 a 57.8 y S4: Rice + Stylosanthes//maize + Stylosanthes 0.0 b 0.0 b 0.0 b 0.0 z 108.2 A3 50.5 20.6 B 2012/2013 Mean 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). AB
  10. 10. carry-over effect of resistance in Maize//Rice Maize//NERICA9 Maize//B22 Maize//NERICA4
  11. 11. Results Table 4. Rice yields (t ha-1) following different cropping systems and rice varieties Season System Rice variety B22 NERICA-9 Mean NERICA-4 S1: Rice//Maize S2: Rice//Maize cowpea + mucuna 2011/20121 1.8 1.9 2.1 1.9 1.9 1.7 1.7 1.73 1.8 1.8 1.9 S3: Rice//Maize V. umbellata S4: Rice + Stylosanthes//maize + Stylosanthes Mean 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 2012/2013 0.74 d 0.5 d 0.5 d 0.6 z 2.0 A5 2.0 A 2.1 A Mean 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).
  12. 12. 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
  13. 13. Acknowledgements CGIAR /GRISP Cirad Merci de votre aimable attention !

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