Drought stresses modify the phenology of plants, and thus affect the yield components. The impact of various periods of water stress on the organ appearance rate and on the durations of the main vegetative and reproductive periods was studied under greenhouse conditions on soybean cultivars differing by type of growth. The two cultivars, Weber and Spot, maturity group I, indeterminate and determinate respectively, were subjected to drought stress (30% PAW) during a main developmental stage: i.e., vegetative, flowering, pod lengthening or seed filling.Drought stress seemed to trigger a signal that caused an early switch of plant development from vegetative to reproductive. Appearance of nodes initiated during stress was delayed, resulting in a small number of nodes produced, whereas flower and pod appearance were hastened. Each reproductive phase was shorter under stress, mainly because of the appearance of new organs that prevented the emergence of organs belonging to the earlier ontogenetic phases. The seed-filling stage and the final stage in seed abortion began earlier in stressed plants and the duration of the maturation period was significantly reduced by stress during seed filling, leading to accelerated senescence.The cultivars differed mostly with respect to their strategies of partitioning between the main stem and branches. Under stress, the duration of the main reproductive phase was increased on the main stem but reduced on the branches in cultivar Weber, whereas the opposite response was noted in cultivar Spot.