Abstract: Drought events have occurred more frequently under climate change, which greatly threaten agricultural development. With the cultivar “Liaodou 15”, we examined the drought resistance and the post-disaster recovery process of soybeans. There were three drought stress intensities (mild, moderate, and severe), with water being controlled at the beginning of the three-leaf stage and flowering stage of soybeans. After the stress was over, water was restored to the control level (with soil relative humidity maintained at 80% ± 5%). The changes in photosynthetic characteristics, quality and yield of soybeans under drought stress and re-watering conditions were investigated. The results showed that drought stress reduced net photosynthetic rate, fat content, pod number, pod weight, number of seeds, and the yield of soybeans, but increased water use efficiency, protein content, number of shriveled pods, and number of shriveled seeds. The more severe the drought stress, the greater the impacts were. After re-watering for 10 to 15 days, soybean plants under mild and moderate drought  nearly recovered to the control level, whereas those under severe drought  were irrecoverable and became non-stomatal. Compared to the seedling stage, soybeans showed a more significant response to drought stress during the flowering and podding stages. By investigating dynamic stress resistance indicators such as photosynthetic elasticity, resistance, and resilience, establishing a more comprehensive drought resistance evaluation system, this study provides important theoretical basis for drought-resistant soybean breeding and water management.

Key words: drought and rehydration, net photosynthetic rate, transpiration rate, water use efficiency, photosynthetic adaptability index, quality and yield