EVALUATION MULTI-SITE DE LEFFET DU PARASITISME AU STRIGA GESNERIOIDES (WILLD) VATKE SUR LES TRAITS FONCTIONNELS DES VARIETES DE NIEBE

Cowpea(Vigna unguiculata (L.) Walp) is a major legume crop in West African farming systems. Although cowpea is a drought tolerant crop, its production level is very low due to biotic constraints such as Strigagesnerioides parasitism. The present study aims to assess the effect of S. gesnerioides(Willd.) Vatkeon photosynthesis efficiency of cowpea varieties. Multilocal trialwas carried out rural areas during the 2017 rainy season to assess the number of Striga emergence likely to cause a change in photosynthetic efficiency on a panel of 26 cowpea varieties and to determine tolerant varieties. The observations were made on six experimental sites along a south-north climatic gradient representative ofMaradi region agro-ecological zones.The results showed a marked decrease of relative chlorophyll content when the number of visible Strigaemergence exceeded five per plant. Likewise, the LEF * PAR saturation curve is higher when the plants showed no visible attack of Striga. The Striga emergence have declined CRC in varieties CS001 and CS127 and led in rapid saturation in variety CS133.