African conditions and the effect of a short period of water stress. In the wet season of 2007, pot experiment was carried out in the experimental station of Ndiaye in the delta of the Senegal river using a split-split-plot design. The three main effects studied were, soil, water regime and variety. An alternate wetting and drying (AWD) water regime results in a reduction of 21.8% yield compared to normal irrigation. Rice in an AWD regime resulted in a significant decrease in biomass production after five days of stress between the 44 and 50 days after sowing (DAS). The water stress lowers the leaf water potential (21%), the stomatal conductance (58%) and the transpiration rate (28%) of rice leaves. The assimilation rate is not affected by water stress but leaf temperature is significantly higher (8%) in stressed rice. Two weeks after the end of the drought period, the differences in biomass production and water status parameters between stressed and non-stressed rice disappeared. A drought period of five days in AWD regime during the basic vegetative phase does not influence the final yield of the crop. Stomatal conductance is correlated with transpiration rate (R2 = 79%), and transpiration rate is correlated with leaf temperature (R2 = 48 %). Moreover, leaf temperature is linearly related to assimilation rate (R2 = 63%). Transpiration in a high temperature environment may improve photosynthetic activity of rice by lowering leaf temperature. Lowland NERICA (WAS 161-B-9-2) creation was successful in combining O. sativa indica (IR64) yield with O. glaberrima (Tog 5681) drought resistance. The lowland NERICA succeeds in controlling water loss by low transpiration rate and leaf rolling, but can, at the same time, obtain a good yield because it does not stop its photosynthetic activity. Lowland NERICA can be a good option in water-saving-irrigation production systems in lowland. Upland variety NERICA 1 is not adapted to lowland condition, in normal or AWD irrigation. A low leaf temperature seems to be the main character to predict high yield in lowland conditions.