Integrated and locally adapted Striga asiatica control: Combining a zerotillage rice-maize cover-crop rotation system with resistant rice varieties

Andrianaivo Alain-Paul, Michellon Roger, Rodenburg Jonne, Randrianjafizanaka Meva Tahiry. 2013. Integrated and locally adapted Striga asiatica control: Combining a zerotillage rice-maize cover-crop rotation system with resistant rice varieties. In : La science rizicole pour la sécurité alimentaire à travers le renforcement de l'agriculture familiale et l'agro-industrie en Afrique : 3ème Congrès du riz en Afrique 2013, 21-24 octobre 2013, Yaoundé, Cameroun. Programme et résumés. Centre du riz pour l'Afrique, IRAD, FAO. Cotonou : ADRAO [Centre du Riz pour l'Afrique], Résumé, p. 26. Africa Rice Congress. 3, Yaoundé, Cameroun, 21 October 2013/24 October 2013.

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Abstract : The parasitic plant Striga asiatica (L.) Kuntze is a common weed in central Madagascar and particularly problematic in the high altitude (800-1300 meters above sea level) rainfed upland rice-maize rotation systems, where it causes serious yield losses. Soils are characterized by low organic matter content and vulnerable to high degradation (soil erosion). To kill two birds with one stone, a 3-year integrated Striga management trial was initiated in the 2011/12 cropping season, to compare the conventional cropping system, mono-crop rice-maize rotation involving seasonal tillage and crop residue removal (System 1, S 1), with three rice-maize rotation systems combining zero-tillage and annual or perennial cover crops: a rotation with rice and maize intercropped with a Vigna unguiculata-Mucuna spp. relay-crop (S2), a rotation with rice and maize intercropped with Vigna umbellata (S3), and a rotation with rice and maize intercropped with the perennial cover crop Stylosanthes guianensis (S4). In S2-S4, crop residues are not removed. Three rice varieties were tested in parallel: the locally popular, but Striga-susceptible, B22; the locally adopted, Striga-resistant NERICA 4; and the locally newly released and moderately Striga-resistant NERICA 9. The hypothesis is that combining zero-tillage with intercropping will reduce the Striga infestation rates in both rice and maize, while protecting the soil and improving its organic matter content. The use of Striga-resistant rice varieties should enhance Striga suppression in these systems. In season 1, the mean Striga densities (at harvest) in rice variety B22 were 8 times higher than in NERICA 9, and 18 times higher than in NERICA 4 (P<0.05). In season 2, the mean Striga density (at 75 days after sowing; DAS) in B22 was 5.3 times higher than in NERICA 9, and 19.3 times higher than in NERICA 4. Moreover, a spectacular carry-over effect of Striga resistance from season 1 to season 2 was observed; where maize followed rice variety B22, the mean Striga density (at 70 DAS) was almost double that of maize grown after NERICA 9, and 21 times higher than in maize following NERICA 4. In season 1, mean Striga density (at harvest) in the rice mono-crop plots was nearly twice as high as in the rice-Stylosanthes plots (P<0.05). Striga densities in maize were too low to identify significant differences between cropping systems. In season 2, mean Striga densities (at 75 DAS) in maize S1 and maize S3 were significantly higher than the densities in maize S4 (no Striga) and maize S2. Striga densities in rice S1 and rice S2 were significantly higher (P<0.05) than in rice S3 and rice S4. The use of Striga-resistant rice varieties significantly reduced Striga densities in the rice as well as in the following crop. The results so far show that Striga densities are highest in a mono-crop rice-maize rotation system with conventional tillage and lowest in a rotation system where rice-Stylosanthes intercrop is alternated with maize-Stylosanthes intercrop using zero-tillage. The latter system, with continuous soil coverage, is the most promising one for resource-poor farmers in the highlands of central Madagascar, which are Striga-infested and highly susceptible to soil erosion. (Résumé d'auteur)

Classification Agris : H60 - Weeds
F08 - Cropping patterns and systems
F30 - Plant genetics and breeding

Auteurs et affiliations

  • Andrianaivo Alain-Paul, CENDRADERU (MDG)
  • Michellon Roger, CIRAD-PERSYST-UPR SIA (MDG)
  • Rodenburg Jonne, Centre du riz pour l'Afrique (TZA)
  • Randrianjafizanaka Meva Tahiry, Université de Tuléar (MDG)

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