We investigated the role of pretreatment of seeds with hydrogen peroxide (H 2 O 2 ) in promoting the tolerance of seedlings of Glycine max to waterlogging. Soybean seeds were pretreated with a solution of H 2 O 2 70 mM or water for 24 h under aeration, and then were placed in plastic bags containing substrate. At 12 days after sowing, the seedlings were subjected to waterlogging for 32 days. There were three evaluations: 0, 16 days and 32 days of waterlogging. Biomass accumulation, root volume, stem diameter, gas exchanges, activity of antioxidant system and cell membrane damages were evaluated. The pretreatment of seeds with H 2 O 2 generated seedlings with elevated activity of antioxidant enzymes, low H 2 O 2 and O 2 −. content, and low cell membrane damages. Hydrogen peroxide pretreatment also resulted in increased content of photosynthetic pigments and net photosynthetic rate, high biomass accumulation, root volume and stem diameter. H 2 O 2 pretreatment of soybeans seeds generated seedlings more tolerant to waterlogging. There is probably a stress memory involved in the process of induction of tolerance in soybeans mediated by hydrogen peroxide. [ABSTRACT FROM AUTHOR]