This study examined the adaptive response of the cowpea (Vigna unguiculata (L.) Walp.) to water stress at the beginning of pod formation. The regulation of carbohydrate levels, sucrose and starch in particular, was monitored in two varieties: local Gorom and KN1. In addition, the specific leaf mass and components of yield were studied. When the Gorom variety was stressed, its starch concentration diminished while the sucrose levels remained fairly elevated. In the KN1 variety, on the other hand, the water deficit considerably reduced the carbohydrate content. In these conditions of stress, leaf mass and agromorphological characteristics such as the number of pods per pot and the dry weight of 100 seeds were higher in the Gorom variety than in KN1. The Gorom variety showed its tolerance to water deficit by its variation in sucrose and starch, leaf mass, and agromorphological characteristics. The KN1 variety, on the other hand, is very sensitive to water stress, which strongly affected its morphophysiologic characteristics and lowered its productivity.