Figure 3: Cowpea plants density (plants/ha) as affected by year × cropping system × cowpea variety interactions effects ( ) at harvest at Cinzana Agronomic Research Station, 2007 and 2008. Y1: year 1 (2007); Y2: year 2 (2008), S1: Alternate rows intercropping (1 row millet/1 row cowpea), S2: Inter hills inter cropping (2 hills millet/1 hill cowpea), S3: Cowpea sole crop, Cowpea varieties: IT89KD-374, CZ1-94-23-1 and CZ11-94-5C.