Seventeen determinate soybean (Glycine max L.) cultivars from maturity groups V through VIII were screened for drought tolerance during germination and seedling stages. Germinating seeds and hydroponically‐grown seedlings were subjected to osmotic stresses of ‐0.3 and ‐0.5 MPa using polyethylene glycol M.W. 8000. Genotypic variability was found among the cultivars for all the parameters analyzed in both germination and seedling tests. Germination stress index was lower for seeds exposed to ‐0.5 MPa than for ‐0.3 MPa osmotic stress. Lower osmotic potential in the treatment medium was also correlated with lower leaf water potential in seedlings subjected to it. A significant relationship was found between fresh weight and height stress indices. The cultivars that grew taller under drought stress conditions had greater dry matter accumulation and higher germination stress indices indicating the reliability of height to predict cultivar performance under such conditions. The cultivars Lee‐74 and Wright had higher dry matter accumulation, greater height, and better germination under stress conditions than the other cultivars tested. Conversely, the cultivars Ra 401 and Bay performed poorly in the drought tests at both levels. In the seedling tests, there was no strong relationship between the leaf water potential and the overall performance of the plant suggesting no clear osmoregulatory mechanism. Based on results from germination and seedling tests, the cultivars Lee‐74, Wright, and Ra 401 were selected for further studies in greenhouse and field trials.

Three soybean {Glycine max L.) culivars, Lee-74, Wright, and Ra 401, were subjected to 100 % (control), 75 %, and 50 % of field capacity during vegetative (VI), flowering (R2), and pod-filling (R4) stages in greenhouse and field studies. Stress applied at R2 significantly reduced the yield in the greenhouse, while in the field, the maximum reduction was observed when the plants were subjected to stress at R4. Stress during VI reduced the yield components less than stress applied during R2 or R4 stages in both studies. The pod number and seed weight were the yield components most affected by drought stress, and the number of seeds per pod the least affected. Yield stress index was significantly correlated with the yield and its components. The reproductive stage was clearly more sensitive to drought than the vegetative stage. The cultivar Lee 74 had the hiehest vield and the second highest vield stress index whereas the cultivar Ra 401 had the lowest yield.