Abstract: Studies were carried out in cement pools for 4 years to determine the effects of the 3-day flooding at 5 different growing stages on summer corn yield.Results indicated that the 3-leaf stage, elongation stage and developing stage of pistillate floret were more sensitive to waterlogging. The yield per plant was reduced by 13.2%, 16.2% and 7.9% respectively.But flooding at anthesis stage and premilk stage had no harmful effects on corn.Flooding during early stages first restrained the development and absorbing activity of roots, then retarded the aerial root growth and dry matter production. Waterlogging at different periods caused different results of yield decrease, such as lower developing rate and lower seed weight at the 3-leaf stage, less number of seeds per plant at the elongation stage and both decreases in seeds per plant and seed weight at the developing stage of pistillate floret.It was also found that flooding at the preta-sseling and silking stage could promote the growth of aerial roots and increase the number of aerial roots by 70%.

Key words: Maize, Waterlogging