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Legume cover crops can be successfully used as intercrop or relay crops in low‐input farming systems. To select appropriate species for intercropping, experiments were conducted in the savannah zone of Côte d’Ivoire during the wet seasons of 1997 and 1998 to determine the growth and nitrogen (N) accumulation of six cover legumes as well as the characteristics indicative of competitive ability. The species included the erect growing Crotalaria juncea and Cajanus cajan, the creeping species Mucuna pruriens var. cochinchinensis and Calopogonium mucunoides and the bushy herbaceous species Aeschynomene histrix and Stylosanthes hamata. Marked differences in phenology were observed as S. hamata and C. juncea flowered around 45–55 days after sowing (DAS) and the other species around 80–95 DAS. C. juncea and C. cajan produced close to 9 ton dry matter ha–1, whereas the other species produced less than half this amount. The average estimated amount of accumulated N, based on leaf material, was around 70 kg ha–1 for all species except S. hamata and A. histrix, which only produced around 25 kg ha–1. Based on morphological characteristics, C. juncea, C. cajan and the short‐lived M. pruriens were identified as potentially most competitive, indicating that productivity and competitive ability are strongly linked. The implications of these findings for intercropping systems in upland rice production are discussed.

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The parasite weed Alectra vogelii (Benth) causes significant yield reduction of cowpea in Africa. To find and map the resistance gene to A. vogelii in cowpea, a F 2 population from a cross involving a resistant parent IT81D-994 and a susceptible TVX3236 was screened. Amplified fragment length polymorphism (AFLP) in combination with Single Sequence Repeat (SSR) analysis was used to identify markers that may be linked to the gene Rav 3 conferring resistance to A. vogelii in the cowpea cultivar IT81D-994. The analysis of F 2 individuals scored for resistance showed that a single dominant gene conditioned A. vogelii resistance in IT81D-994 with a probability of 30 to 50%. Sixty-six AFLP/SSR markers were identified. Using MAPMAKER, four linkage groups were found. The first group showed 33 markers linked to the susceptible gene. The closest identified marker was 21.4 centimorgans away from the susceptible gene. The primer combination that showed the closest linkage was 809ACG8 (E-ACG 8 + UBC-809). The second group indicated 4 markers linked together while the third and the fourth groups showed 2 markers linked together respectively. No markers were found linked to the resistance gene Rav 3 conferring the resistance in the cultivated cowpea cultivar IT81D-994.

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